Jams and Other Fruit Spreads

Transcription

1 Jams and Other Fruit Spreads

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3 C o n t e n t s G e n e r a l I n f o r m at I o n 4 r aw m at e r I a l s 5 G e l at I o n o f H & f P e c t I n s 11 Pectin 11 Gelling mechanisms 12 High methylester Pectins Gelling Behaviour 17 low methylester Pectins Gelling Behaviour 23 low methylester, amidated Pectins Gelling Behaviour 28 s y n e r e s I s B e H av I o u r 38 s ta n d a r d I s at I o n o f H & f P e c t I n s 42 c l a s s I c, c o m B I P l u s a n d a m I d P e c t I n s a n d t H e I r a P P l I c at I o n 46 P r o d u c t I o n m e t H o d s f o r J a m s a n d o t H e r f r u I t s P r e a d s 54 G e n e r a l c a l c u l at I o n s a n d d e s I G n o f f o r m u l at I o n s 60 I n d I v I d u a l I t y I s o u r s t r e n G t H 66 3 JAMS and Other Fruit Spreads

4 General Information cooking jams and other fruit spreads using fruit, sugar, pectin and edible acids is one of the oldest food preserving processes known to mankind and presents a way of making food stable by increasing the soluble solids content. the keeping properties of the products made this way with respect to microbial spoilage are improved by the following criteria: hygienically immaculate operating units, filling and production systems hygienically immaculate raw materials and packaging materials a high sugar content, which by way of hydration causes a lowering of the free water reduced a w -level (<0.8) a low ph-range (ph ) adequate pasteurisation or, where applicable, chemical preservation of low-calorie jams and other fruit spreads sufficient cooking time to achieve inversion and exchange of sugar between the medium and the fruit (otherwise zones with differing sugar concentrations could cause the risk of crystal formation or water exudation) high cooking and filling temperature head space sterilization of the jar after filling turning the sealed jar upside down capping under vacuum 4

5 raw Materials flavour, colour and consistency as well as the preservation and distribution of the fruit primarily determine the quality attributes of jams and other fruit spreads. these properties depend to a high degree on the raw materials Fruit Purée: The edible part of the whole fruit, peeled and cored as appropriate, that has been reduced to purée by being sieved or by being subjected to a similar process; used, whereby the selection of suitable fruit is of particular importance. the distinctive nature of the finished product is further determined by the addition of sugars, pectin and edible acids. Aqueous Extract of Fruit: Aqueous extracts of fruits which contain all water-soluble constituents of the fruits except for technically unavoidable losses. the German fruit Jams regulation defines the required quality of the raw materials as follows: Types of sugar: a) Sugar types as defined in the Regulation on Sugar Types, Fruit: a) Fresh, sound fruit, free from deterioration, containing all of its essential constituents and sufficiently ripe for use, after cleaning and removal of blemishes; b) Tomatoes, the edible parts of rhubarb stalks, carrots, sweet potatoes, cucumbers, pumpkins, melons and water melons also count as fruit; c) Ginger: the edible root of the ginger plant in a fresh or preserved state; ginger can be dried or preserved in syrup; Fruit Pulp/Pulp: The edible part of the whole fruit, peeled and cored as appropriate, also cut into pieces or crushed but not puréed; b) Fructose syrup, c) Sugars extracted from fruit, d) Brown sugar. Source: Konfitürenverordnung (German Jam Regulation), Annex 2 (to 2 section 1 and 4) Raw Materials stone fruit and pip fruit is generally processed without the stone, pip or core and in unpeeled condition; citrus fruits are generally peeled before processing, part of the peel is frequently added. for cost or seasonal reasons, fresh fruit is only used in small quantities to produce the finished products. the main quantities are produced using frozen, heat-stabilised (canned) fruit or fruit that has been preserved with sulphur dioxide. 5 JAMS and Other Fruit Spreads

6 the most important quality criteria for the fruit used are: optimum state of ripeness full, fruity flavour colour typical of the variety no blemishes (no spots, no bruises) adequate consistency (solidity of form) soluble solids content in compliance with quality standards perfect hygienic condition of raw materials and packaging Fruit Constituents: In fresh condition, fleshy, juicy fruit generally contains 80 85% water. the main constituents after water are the carbohydrates. fruit also contains organic acids, polymer carbohydrates such as pectins and starches, nitrogenous compounds, minerals, vegetable phenols, flavouring substances and vitamins. the composition of the fruit varies greatly, depending on the type of fruit, how ripe it is and on the weather and cultivation conditions. with fruit that is used to make jams and other fruit spreads, the following criteria have an influence on gelation: ph-value and titratable acid the ph-level and the titratable acid both indicate the quantity of organic acids and their salts contained in the fruit. Both factors affect gelation. In the production of jams and other fruit spreads with high methylester pectins, the ph-value is usually adjusted to about using citric acid, as this ph-range is very beneficial for gelation, flavour and shelf life. calcium content low methylester and amidated pectins gel with calcium ions. thus the calcium content of the fruit itself is also significant. Generally speaking, the insoluble parts of fruits are particularly rich in calcium. However, only part of the calcium, the so-called free calcium, is available to the pectin, not the entire calcium content. the remaining calcium, or bound calcium, is firmly bound to complexing agents. 6 the fruit s own Pectin content the pectin content of the fruit itself is generally of less significance. the cooking time does not usually suffice to solubilise the pectin in the fruit and thus enable it to gel.

7 Types of sugar all sugars listed in the German regulation on certain sugars destined for Human consumption (German Sugar Types Ordinance dated 23 October 2003 [Federal Gazette part I, page 2098, as amended) can also be used in solution and in any mixing ratio. sucrose is also used to make jam. during cooking, sucrose is partially inverted. this intended chemical reaction (by absorbing water sucrose is split into glucose and fructose) is influenced by: 7 sugars are one of the main constituents of jams and other fruit spreads and influence the shelf-life of these products by way of the soluble solids content. at the same time they are responsible for the taste, flavour, consistency and colour preservation. ph-value temperature time JAMS and Other Fruit Spreads

8 the formation of invert sugar prevents the sucrose from crystallising in the finished product. on the other hand, complete inversion of the sucrose may lead to crystallisation of the glucose in the product. finished product can be influenced by suitable combinations with other sugars. Starch-Saccharification Products: Glucose Syrup, Dextrose 8 Jams and marmalades produced on vacuum cookers are, as a rule, only slightly inverted. Liquid Sugar, Invert Liquid Sugar, Invert Sugar Syrup liquid sugar is an aqueous solution of sucrose with a minimum of 62% soluble solids and no more than 3% invert sugar, related to the soluble solids (tss). Invert liquid sugar is an aqueous solution of sucrose partially inverted in hydrolysis, in which the proportion of invert sugar does not predominate and the following criteria are given: at least 62% soluble solids and not less than 3%, but not more than 50% invert sugar, related to the soluble solids. Invert sugar syrup is an aqueous solution of sucrose partially inverted in hydrolysis, in which the proportion of invert sugar predominates and the following criteria are given: a minimum of 62% soluble solids and more than 50% invert sugar related to soluble solids. these sugar solutions are characterised by their relatively low viscosity, they are temperature tolerant and they do not crystallise even at low temperatures. they enhance the microbiological stability of the product owing to the higher osmotic pressure generated by the fructose. sweet taste, flavour and water activity in the Glucose syrup is a by-product of starch and contains glucose, maltose, dextrin and fructose. Glucose syrup is not as sweet as sucrose and inhibits the crystallisation of glucose and sucrose in the finished product. Its addition improves the texture (smoother consistency of the finished product). the composition of glucose syrups varies, depending on the various possible methods for its industrial production. Production, however, always starts with a partial starch hydrolysis. the use of the enzyme glucose isomerase has extended the range of available glucose syrups. this enzyme induces the conversion of part of the glucose into fructose. the glucose syrups produced in this way have a higher fructose content and thus greater sweetening power as the starting syrups. depending on the ratio of the fructose, these syrups are called glucose-fructose-syrup or fructose-glucose-syrup. High-fructose glucose syrups with approx. 42% fructose and 52% glucose related to the soluble solids content is one particular example. dextrose is made using starch hydrolysis. It does not play an important role in jam manufacture, since dextrose tends to crystallise and can give the products a dull, mat appearance.

9 Sugar Substitutes sugar substitutes form a group of substances that are used as sweetening agents instead of sucrose. similar to sugars, they provide foodstuffs with bulk and a physiological energy value. the sweetening power of most sugar substitutes lies in the range of that of sucrose or lower. the following sugar substitutes are of importance: fructose (fruit sugar) is a monosaccharide that is naturally present in practically all fruits. the physiological energy value of fructose is calculated as 17kJ/g (or 4 kcal), the same as for sucrose and glucose. fruit sugar is normally traded as fruit sugar syrup with 70% tss. sugar alcohols form the main group of sugar substitutes. the physiological benefits of these sugar substitutes lie in their suitability for diabetics (insulin-independent metabolism) as well as in their partially reduced anti-cariogenic effect and lower physiological energy value. the standardised physiological energy value for all sugar alcohols is 10kJ/g. when high dosages (more than 20g per person a day) are consumed, sugar alcohols may sometimes have a laxative effect. comparison of the sweetening power of sugar substitutes in relation to sucrose fructose * sorbitol * mannitol * isomalt * maltitol * lactitol * xylitol * Table 1: *The figures indicate the factor by which the sugar substitute in question tastes sweeter than sucrose. Sweeteners sweeteners are natural or synthetic compounds that have no or only a negligible energy value in relation to their sweetening power and a much higher sweetening power than sucrose. comparison of the sweetening power of sweeteners in relation to sucrose acesulfame-k * aspartame * cyclamate 30 40* saccharine * sucralose * stevia * Table 2: *the figures indicate the factor by which the sweetener in question tastes sweeter than sucrose. Modified as per K. Rosenplenter / U. Nöhle (editors), Manual of Sweeteners 9 JAMS and Other Fruit Spreads

10 the various sweeteners differ in their properties, such as flavour profile, or their stability in sour foods and during heating. when mixed together they sometimes demonstrate positive synergistic effects. Sweetening Agents deionised fruit juice concentrates and fruit extracts are increasingly used as natural sweetening agents. these products have no added sugar, they only contain the sugar from the fruits from which they are made. with the aid of state-of-the-art technologies, mineral nutrients, fruit acids and natural colours are derived from the concentrated fruit extract. the remaining concentrated sweetness of the apple can be universally used to replace sugar or starch-saccharification products for sweetening food. according to the German Jam regulation, these sweetening agents (different sugars obtained from fruits) are permitted. they are of particular interest for the so-called all fruit products, the ingredients of which originate exclusively from fruit. Herbasweet apple extract is a high-quality sweetening agent with a soluble solids content of Bx or 78 Bx, which is produced from the fruit extract of juice-extracted and carefully dried apples.

11 Gelation of H&F Pectins In jams and other fruit spreads it is pectin that provides the texture. the optimal formation of a gel is directly linked to the proportion in which the ingredients fruit, sugars, water, acid and pectin are present. added to this are the acid resistance of pectin, the fact that it has no specific smell or taste, which makes it an excellent flavour carrier, as well as the possibility of being able to control the consistency and the setting time. explains why the press residues from the production of apple and citrus juices are so valuable for large-scale extraction of highquality pectins. In the plant cell, pectin molecules are so tightly linked to the other molecules in the cellular wall that they cannot be extracted with water. this water-insoluble form is called protopectin. Pectin the gelling agent pectin, a constituent of the plant cell structure, binds the structure of the plant tissue, acting as a sort of cell binder. all raw materials from plants with a high pectin content are suitable for the production of pectins. different amounts of pectin are extracted from the various raw materials: Pomace 10 15% citrus peel 20 35% apples and citrus fruits have always been of significant importance for the production of pectin destined for the manufacture of jams and other fruit spreads. the high-grade pectin substances are present in the pulp and in especially high concentration in the cell walls. this Protopectin is made soluble using acid hydrolysis and then extracted with hot water. the pectin-rich extract is mechanically cleaned and gently concentrated. Pectin is then precipitated with alcohol from the liquid extract. alcohol-insoluble pectin substances in pure form are obtained by this alcohol precipitation. they are subsequently dried as pure pectin and ground to powder. the gel strength of pectin as a natural substance differs in accordance with the raw material used and is standardised by adding dextrose or other sugar types. the molecular structure of pectins is composed of d-galacturonic acid molecules, which are linked to each other in alpha-1-4-glycosidic formation to give polygalacturonic acid. the carboxyl groups are partially esterified with methanol. 11 JAMS and Other Fruit Spreads

12 neutral sugars such as arabinose, galactose and xylose, which are linked as side chains to the pectin macromolecule, as well as the interruption of the main chain by rhamnose make pectin a heteropolysaccharide. therefore, neutral polysaccharides like galactans, arabans and also starch are often concomitant substances of isolated pectin. However, the specific composition depends on the raw material. the gelling power of pectin is mainly based on its molecular weight, i.e. the number of chain links in a pectin molecule, and it is kept practically intact with the extremely gentle production process. If all carboxyl groups of the polygalacturonic acid are free, i.e. not esterified, this gives pectic acid; its salts are called pectates. In nature, however, pectic acid is esterified in different degrees with methanol and is then known as pectin. If the degree of esterification is higher than 50% it is called high methylester pectin, below 50% it is called low methylester pectin. Gelling Mechanisms the association of pectin chains leads to the formation of a three-dimensional network, i.e. gel formation. two or more chain segments bond together and start to interact. these are longer segments of regular sequence, which are ruptured by the incorporation of rhamnose or by the branching of the chain. there are various types of chain associations, which are defined by the degree of esterification. with high methylester pectins, two critical factors initiate gel formation: 1. the addition of sucrose or other sugars has a dehydrating effect on the pectin molecules, which facilitates the convergence of the polymer chains and enables a cross linkage of the hydrogen bridges. 2. a lowering of the ph-value in the medium suppresses the dissociation of free carboxyl groups and thus reduces the electrostatic repulsion between the chains. In specialist literature the mechanism described above is often referred to the "sugar-acid-gelling mechanism" (see fig. 2 on page 13). 12 Fig. 1: Section of a pectin molecule

13 Hydration shell Partially reduced hydration shell Partially reduced hydration shell Sucrose + Glucose Fructose + Acid ph Reduction of hydration shell Reduction in dissociation Negatively charged pectin chain A Negatively charged pectin chain B Pectin chain with low negative charge C Fig. 2: Preconditions for the gelation of pectin O COOCH 3 O OH OH O O OH OH O C O O O COOCH 3 O OH H + O OH OH O O OH C O OH Fig. 3: Dissociation of carboxyl groups according to the specialist literature, however, high methylester pectins need to be stabilised in the gel by a combination of hydrophobic interactions and hydrogen bridge bondings, which means that the term sugar-acid-gelling mechanism requires closer definition. methylester groups are the hydrophobic part of a pectin molecule. Hydrophobic forces force them into aggregate formations, while they are constantly striving to keep the contact surface with water as small as possible. moreover, hydrogen bridges are formed, e.g. between non-esterified carboxyl groups, if the ph-level in the gel is low enough and the dissociation of the carboxyl groups is largely suppressed. 13 JAMS and Other Fruit Spreads

14 14 Fig. 4: Structure of connecting zones of HM pectins (Walkinshaw and Arnott 1981) according to oakenfull and scott (1984), the free, non-methoxylated carboxyl groups decreases and if the ph-value is too high, the im- hydrogen bridge bondings are the responsible factor in the stabilisation of a pectin network, pact of interfering factors (-coo - ) decreases but for energetic reasons gelation would not as well (if the product ph-value is too high, take place without the hydrophobic interaction dissociated carboxyl groups interfere with the of the methylester groups. network formation). this affects the gelling-phrange. If the degree of esterification is extremely high, the suppression of dissociationis the higher the degree of esterification, the greater the impact of hydrophobic forces in the no longer so important. gelation. the impact of hydrogen bridges over

15 the higher the degree of esterification, the higher therefore the ph-value at which gelation sets in. completely methoxylated pectins (100% degree of esterification) do not require any acid for gelation (deuel et al., 1950). according to oakenfull, the high sugar concentration required for the gelation of high methylester pectins could be explained by the fact that certain sugars have an additional stabilising effect on the hydrophobic interactions. with low methylester, amidated pectins, the clustering of the pectin chains is effected in a more controlled manner than with low methylester, non-amidated pectins, as, given a comparable degree of esterification, the formation of the gel network is slower than the reaction of low methylester pectins with calcium ions because of the hydrogen bonds between the amid groups. low methylester pectins also gel according to the mechanism described above. However, they can, in addition, even form a gel relatively independently of the soluble solids content and ph-value if multivalent cations, e.g. calcium ions, are present. the following model has been used to describe this gelling mechanism: Pectin chains cluster during the gelation process. due to their bent shape cavities are formed between them, which are occupied by carboxyl and hydroxyl groups. Both the formation of cavities and the carboxyl and hydroxyl groups favour the association of pectin chains by chelation of the calcium ions. In the case of low methylester, amidated pectins, additional links are created by way of hydrogen bonds due to the presence of amid groups. the more amid groups are present, i.e. the higher the number of links are formed, the firmer the resulting gels will be. Fig. 5: The binding mechanisms for connecting pectin chains 15 JAMS and Other Fruit Spreads

16 Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ HO HO O O O HO O O HO O HO O COO HO O COO O O O O O OH OH Ca 2+ HO O OOC O OH O O O O Ca 2+ HO O OH OOC O OH OH O O O O O OH OH Fig. 6: Arranged sequences in the pectin-calcium gel (Rees and Welsch, 1977) ºBrix soluble solids gelled pre-gelled 60 liquid ph-value Fig. 7: Setting range of high methylester pectins, modified (Pilnik 1980)

17 High Methylester Pectins Gelling Behaviour Soluble Solids Content and ph-value fig. 7 on page 16 (setting range of high methylester pectins, mod., Pilnik, 1980) shows the basic setting ranges of sugar-acid gels with high methylester pectins. It identifies the soluble solids / ph areas in which pre-gelling or no gelling (liquid) occurs. Pre-gelling means that at the given filling temperature the products have already started setting. Pumping, stirring or pouring during filling destroys this incipient gel structure, the formation of a homogeneous gel is not possible any more. therefore the texture of a pre-gelled product is mushy with a reduced gel strength. the diagram makes it clear that sugar and acid can substitute each other within certain limits in contributing to the gel strength. for proper gelation, a lower sugar content requires lower ph-values; higher ph-values are possible with a higher sugar content. If the sugar content remains constant, gels with lower ph-values will be firmer and more brittle, the same applies if the ph remains the same and the amount of sugar increases. the ideal soluble solids content for high methylester pectins is 60 65%. replacing part of the sucrose with glucose syrup and using the optimal type of pectin can prevent the formation of brittle gels and the crystallization of sugar and dextrose. the lower limit for proper gelation of high methylester pectins is a soluble solids content of about 55%. Here and below, low meythlester and amidated pectins are used. substituting sucrose with other sugars or sugar alcohols has an influence on the gelling characteristics of pectins and the texture of the gels. the reasons for this phenomenon have not yet been sufficiently investigated. under discussion are the different water activities of the sweetening agents with the same soluble solids content and substance-specific differences in the stabilising effect (oakenfull et al., 1984). References: Oakenfull, D. and Scott, A. (1984): Hydrophobic Interaction in the Gelation of High Methoxyl Pectins, J. Food Sci., 49 (4): Deuel, H., Huber, G., Leuenberger, R. (1950): Über das Geliervermögen von Polygalakturonsäuremethylester, Helvetica Chimica Acta, Vol. 33, p. 1266ff. Rees, D.A., und Welsh, E.J. (1977): Sekundär- und Tertiärstruktur von Polysacchariden in Lösungen und Gelen, Angewandte Chemie, Band 89, S Pilnik, W. (1980): Pektine, in Gelier- und Verdickungsmittel in Lebensmitteln, Forster Verlag AG Zürich. 17 JAMS and Other Fruit Spreads

18 18 Setting Time and Setting Temperature High methylester pectins are available within a range of 50 to approx. 75% degree of esterification. this group of pectins this group of pectins differs in gelling behaviour. under virtually the same conditions, higher esterified pectins set faster and at higher temperatures than pectins with lower degrees of esterification. this explains the importance of the setting time and the setting temperature for the evaluation of high methylester pectins. the setting temperature is the temperature at which gelation of pectin gels starts during the cooling period subsequent to gel preparation. setting does not occur above this temperature, even though all criteria for gel formation are met. Gelation of extremely high methylester pectins, can, for example, start already at 90 c (194 f), that of less high methylester pectins at 60 c (140 f) using comparable test gels. Based on these differences in setting temperature and setting time, high methylester pectins are supplied as: rapid set with a high setting temperature medium rapid set with a medium setting temperature slow set with a low setting temperature the absolute setting temperature depends not only on the raw material, the production technology and the degree of esterification of the pectin, but also on the sugar content and the ph-value of the product as well as the amount of buffer salts added and the cooling rate. the faster the products are cooled, the lower the setting temperature. therefore, in order to be able to compare setting temperatures, pectin gels are usually produced under defined, reproducible conditions and it is monitored at which temperature setting begins. the setting time is defined as the period in which a fruit preparation starts to gel at a defined, constant temperature after termination of the cooking process. rapid-set pectins can be defined in such a way that under defined conditions gelation requires 10 minutes at 90 c (194 f) and slow-set pectins need 20 minutes at 65 c (149 f). rapid-set pectins differ in their optimal ph-value from slow-set ones. while slow-set pectins achieve their greatest gel strength at a ph-value of 3.0 and less, the optimal ph-value for rapid-set pectins tends towards higher ph-values.

19 for extra-rapid-set pectins, a ph-value of under 3.0 may even be disadvantageous, especially if the soluble solids content is considerably higher than 60%. Gelation can then set in during the production process, with a high risk of pre-gelling. If we look again at figure 7 on page 16 it becomes clear why with soluble solids contents of around 60% and ph-values of about 3.0 both rapid-set and slow-set pectins can be used. there are differences in the setting temperature, setting time and gel texture. with high soluble solids contents and low ph-values, slow-set pectins must be used, otherwise pre-gelling occurs; with high soluble solids and high ph-values, on the other hand, rapid-set pectins are indicated, otherwise gelation will no longer take place. when selecting the appropriate pectin type out of the high methylester pectins rapid, medium or slow set the following criteria are very important: Filling Temperature the appropriate pectin type is selected so as to ensure that the setting temperature of the product to be manufactured with the pectin is lower than the specified filling temperature. this prevents pre-gelling, which would weaken the gel and exert a negative influence on the texture. the filling temperature is determined by the machines and systems used in the process as well as the size of the packaging containers used. containers that cool down quickly permit filling at high temperatures of 85 c and 95 c (185 f and 203 f). In this temperature range, rapid set pectins provide for good gelation and for even distribution of the fruit in the gel. containers that undergo a long cooling phase, on the other hand, require low filling temperatures, e.g. 70 to 75 c (158 f to 167 f), otherwise the consistency in the core of the products will suffer due to heat damage. In this case, slowset pectins are used, as pre-gelling does not occur when they are used in this temperature range. furthermore, the setting rate can be regulated by the addition of suitable buffer salts (retarders). such gelling retardation is practiced primarily in the confectionery industry where very high soluble solids contents are used. 19 JAMS and Other Fruit Spreads

20 20 Texture texture is a very important parameter for sensory acceptance and depends largely on the composition of raw materials such as the type and quantity of fruit and the sugars used, but also on the type of pectin selected. 1. Pectins with a high degree of esterification set quickly and result in firm gels that are characterised by the rheological parameter "highly elastic with very low viscous shares" 2. Pectins with a medium degree of esterification set more slowly and result in firm gels which are characterised by the rheological parameter highly elastic with significant viscous shares. with the same degree of esterification, apple pectins form gels with distinctly higher viscous shares than citrus pectins. this means that when jam and other fruit spreads are spread on bread or rolls, gels with low viscous shares are more difficult to spread. In the extreme case, a large lump of gel will just break up into many smaller pieces during spreading. Gels with higher viscous shares, on the other hand, will spread easily and form a cohesive layer of jelly on the bread. the choice of the pectin type thus helps to fix the desired rheological parameters of these products.

21 Fruit the fruit that is used also influences the gelling process, depending on the type of fruit, how ripe it is and on the storage conditions. the most important factors are the sugar and acid contents as well as the minerals and other fruit-specific substances contained. with increasing ripeness, enzymes within the fruit degrade the fruit-inherent pectin and the flesh becomes softer. during ripening, the fruit-inherent acid decreases and the sugar content increases. Acid content the optimum ph-value for the gelling process during jam production is achieved by adding edible acids and their salts. In addition to the physico-chemical effects of the acids, the flavour-enhancing factors are also of great importance. However, the legal regulations also have to be taken into account. the following additives are permitted for regulating the ph-value: lactic acid e 270 citric acid e 330 tartaric acid e 334 calcium lactate e 327 sodium citrate e 331 calcium citrate e 333 sodium tartrate e 335 In order to guarantee uniform gelation, the use of a ph-meter in the production of jams and other fruit spreads is an absolute necessity. the edible acid originally present in the fruits or added to the product tends to suppress the dissociation of free carboxyl groups in pectin. while the dissociated carboxyl groups repel each other because of their similar negative charges, the non-dissociated carboxyl groups form a network structure in which water is bound. Lactic acid lactic acid is commercially available as a 50%, 80% or 90% aqueous lactic acid solution. Its specific acid value is lower than that of tartaric or citric acid. In order to obtain a defined ph-value the dosage of lactic acid must be higher than that of tartaric or citric acid. Tartaric acid tartaric acid is a crystalline product which dissolves well in water. It has the highest specific acid value of all the acids used for this purpose. tartaric acid requires the smallest dosages. It is added during the cooking process either directly or in a 50% aqueous solution. However, tartaric acid is rarely used in the production of jams as its acidic characteristic is relatively tart. 21 JAMS and Other Fruit Spreads

22 lactic acid tartaric acid citric acid EEC number E 270 E 334 E 330 Basic formula C 3 H 6 O 3 C 4 H 6 O 6 C 6 H 8 O 7 Molar mass Acid dissociation constant pka pka pka ph-value (0.1 n solution) Table 3: Important data on lactic acid, tartaric acid and citric acid Source: Genusssäuren und Salze [Edible acids and salts]: Anwendung und Wirkung in Lebensmitteln [Application and effect in food] / Publisher: Fachgruppe Lebensmittelchemie und Gerichtl. Chemie i.d. GDCh. (Editor: G. Wieder).-Hamburg: Behr, 1989 (Lebensmittelchemie, Lebensmittelqualität [Food chemistry, food quality]; volume 14) 22 Citric Acid citric acid is naturally present in a great number of fruits. It is crystalline and dissolves well in water. citric acid is weaker than tartaric acid, but stronger than lactic acid. citric acid tastes naturally sour and harmonious. this acid, too, is preferably added as a 50% aqueous solution. lemon juice concentrate is often used as a natural source of citric acid. If the acid value is too high (ph-value below 2.8) the gel elasticity increases and the gels become firm and brittle. with a low acid value (ph-value above 3.3) the gel structures are soft. when a certain ph limit is exceeded, gelation is no longer possible. the presence of buffer salts in fruit, e.g. salts of citric and malic acid, suppresses the extent of the ph modification due to the added fruit acids, thus offsetting part of the effective acid value. to obtain the desired ph-value, the acid dosage must be raised. on the other hand, if the ph-value in the fruit is too low, it can be increased in order to prevent pre-gelation. If the aim is to stabilise the ph-value within strict limits, as is the case, for example, with jams, the specific properties of edible acids in forming excellent buffer systems with their salts can be used, e.g. in the combination citric acid and sodium citrate. as a rule, fruit acids are added to the cooking batch towards the end of the cooking process. this prevents pre-gelling, which can occur with the optimum ph-value if the temperature of the cooking batch drops below the setting temperature due to the blending in of the sugar or the pectin solution. even if all parameters are at their optimum setting and the temperature is higher than the setting temperature, excessively long processing after the addition of acid can lead to pregelation.

23 Low Methylester Pectins Gelling Behaviour the gel formation of low methylester pectins can be pictured as follows: when a small amount of calcium ions is added, the pectin chains start to bond over calcium bridges. as the calcium ion concentration increases, gelation sets in. with an increasing calcium dosage, the gels become firmer and increasingly elastic and brittle until an optimal point is reached. as of a certain calcium dosage, which is dependent on the soluble solids content, the gel strength drops rapidly, resulting in pre-gelled products, but not in gels. the amount of calcium ions required for proper gelation largely depends on the concentration of soluble solids, the type of sugar, the ph-value of the product and the buffer substances. 23 JAMS and Other Fruit Spreads

24 Breaking strength % tss 50% tss 40% tss 30% tss 20% tss calcium ion concentration [mg ca 2+ /g pectin] Fig. 8: Sucrose gel with increasing TSS content (low methylester pectin, DE 40%, 0.1m citric acid / potassium citrate buffer solution, ph-value 3.0) 24 Concentration of Soluble Solids figure 8 shows how the breaking strength of a gel changes as the calcium dosage is increased, for various soluble solids contents. whereas with a soluble solids content of 60%, practically no calcium ions are required to form a firm gel, considerable amounts of calcium become necessary with a soluble solids content of 20 30%. the lower the soluble solids content in a gel, the higher the calcium requirement in order to achieve proper gelation. the gel strength in these samples was determined with the Herbstreith Pectinometer by testing the breaking strength. Influence of the Sugar Type not only the concentration, but also the type of sugar or sugar substitute used will affect gelation. thus, the amount of calcium required to achieve optimal gelation is, for example, usually much higher with a sugar substitute than with sucrose. fructose gels also require more calcium ions. Influence of the Product s ph the higher the ph-value in the gel the higher the amount of calcium ions required in the gel to achieve comparable gel strengths.

25 the increase in the ph-value leads to an increase in the charged particles in the gel, which dissociates the pectin molecules even more strongly. the reaction between the calcium ions and the other charged buffer substances is thus enhanced, which in turn reduces the number of calcium ions available for reactions with pectin. an increased concentration of calcium ions creates more bonding points between the pectin molecules and thus keeps the gel strength intact. Influence of the Buffer Ions the type and concentration of buffer ions present in the gels, which originate largely from the fruit that is used and can differ in accordance with the type of fruit, have a decisive impact on the calcium ions required to achieve sufficiently firm gels. an increase in the concentration of buffer substances, in particular when these have a strong binding effect on calcium, such as e.g. the salts of citric acid, requires, just like an increase in the ph-value, an increase of the calcium dosage. the amount of calcium required for gelation is influenced not only by the formulation parameters, as already described, but also by the production technology and in particular by how high the filling temperature is. the higher the filling temperature, the more calcium ions can be incorporated into the gel network without causing pre-gelation. the amount of the calcium dosage controls not only the firmness of the gel, but also its rheological and sensory properties. 25 JAMS and Other Fruit Spreads

26 Breaking strength I II III IV Calcium ion concentration Fig. 9: Breaking strength of pectin gels as a function of the concentration of the added calcium ions (sections I IV) 26 Rheology and Sensory Analysis With a pre-defined formulation (i.e. type of sugar and sugar concentration, pectin concentration and type and quantity of fruit are constant), gels become increasingly firmer as the calcium concentration increases. The firmness can be assessed by testing the breaking strength with the Herbstreith Pectinometer. However, an increase in the calcium concentration not only raises the breaking strength of the gels but also affects the rheological and sensory properties such as spreadability, stability, tendency to syneresis, regeneration potential, yield point of the gels and "mouth feel". These properties are described below in sections I IV, which are also shown on the graph in Fig. 9. These sections represent specific ranges with varying calcium-pectin ratios. Section I The calcium concentration in section I is very low: fruit preparations in this range are highly viscous to slightly gelled. Section II Gels in this range have only just started gelation or are already gelled. The gels are smooth and spreadable. Rheologically speaking, they can be distinguished by their viscoelasticity: Pectin gels have viscoelastic properties, i.e. both elastic and viscous properties. The elastic component is responsible for a high breaking strength, even reaching brittle gel textures, for low mechanical stability together with poor spreadability and for a tendency to syneresis. The viscous component, on the other hand, prevents brittleness, produces good spreadability and a low tendency to syneresis.

27 With the gels in section II the viscous influences predominate; the gels are spreadable and stable, with a high regeneration potential following mechanical stress and they show very little tendency to syneresis. In the sensory respect, too, the viscous components influence the perception of taste. These are gels that melt in the mouth and have a very pronounced sweet, fruity, taste. The reaction of the pectins with calcium ions increases the setting temperature and results in a yield point at a higher temperature: In resting state, when the jams have been filled into their containers and are no longer being stirred or pumped, but are still hot and liquid, they have an infinitely high viscosity and behave like solids. This has the advantage that fruit pieces will neither rise nor settle, but remain cast in position in the gel. This is then known as good fruit retention. Fruit pieces that are regularly distributed in the gel are considered a quality feature of jams. High viscosity cannot replace the yield point. A high viscosity delays the rising of the fruit, but it cannot prevent it. JAMS and Other Fruit Spreads

28 Section III In section III the calcium ion concentration is very high and there are a lot of calcium bridges which densely concentrate the pectin molecules. The pectin network becomes very tight, originally bound water molecules are readily squeezed out of the gel network. The gel texture is predominantly elastic, the viscous phase is suppressed. This lends to a very high breaking strength, but makes the gel unstable against mechanical processing. Once they have been processed, e.g. stirred or pumped, they do not regenerate or they require a long time to do so. The tendency to syneresis thus increases. The yield point or the fruit retention property continues to rise and the setting temperature also increases. Low Methylester, Amidated Pectins Gelling Behaviour Influence of Calcium Ion Concentration In the case of low methylester, amidated pectins, too, the calcium ion concentration, which is necessary for gelation, depends on various product parameters such as the soluble solids content, the ph-value of the product and the buffer ion concentration. Even with a low calcium ion concentration the pectin chains cluster via calcium bridges. Here the calcium ion concentration that is needed for gelation can originate from the natural calcium content that is contributed by the fruit or the drinking water contained in the product formulation. 28 Section IV In this section, the calcium ion concentration is too high and at the given filling temperature pre-gelling will occur. The gel strength decreases, the consistency becomes mushy, syneresis occurs and the yield point also drops. The texture of the products is not very appealing. This range is not recommended for jams or other fruit spreads. By increasing the filling temperature it is possible to prevent pre-gelling up to a certain point. The gels then remain very firm, but they are brittle with a high tendency to syneresis. The amid groups stabilise the network by hydrogen bridge bonds, so that even with a low calcium ion concentration elastically set gels are formed Not only the degree of esterification, but also the number of amid groups determines the sensitivity and hence the calcium required for the formation of a gel network and the resulting setting temperature. When the calcium ion concentration is increased, the gels become firmer until an optimal point is reached and the texture of the gels becomes more elastic and brittle.

29 As the bondings are additionally stabilised due to the presence of acid amid groups and with that by the formation of hydrogen bonds, low methylester, amidated pectins are able to gel homogeneously and relatively independently of the calcium ion concentration over a wide range. If the calcium dosage is raised intensely, pre-gelation, i.e. an over-reaction between the pectin molecules and the calcium ions, ensues. Fine gel particles are formed, the gel structure loses its elastic character, the texture becomes pasty, thus lowering the gelling strength. Confronted with mechanical stress the gel loses water and syneresis occurs. This process of pre-gelation is reversible. If pre-gelled gels are heated again to a temperature that is higher than their melting temperature and then cooled down again, a firm, elastic gel forms. Natural calcium content of the fruit Gel strength Low methylester amidated pectin Low methylester Classic Apple pectin 29 Calcium ion concentration Fig. 10: Gelation of low methylester, amidated pectins as a function of the calcium ion concentration JAMS and Other Fruit Spreads

30 Gelling Properties of Low Methylester, Amidated Pectins with Differing Calcium Sensitivity The gelling properties of low methylester, amidated pectins, i.e. the setting time / setting temperature and the formation of a defined gel texture, are essentially determined by the calcium sensitivity. Therefore the behaviour of low methylester, amidated pectins as a function of the calcium ion concentration is not only influenced by the given formulation parameters such as soluble solids content, ph-value of the product and the amount of buffer salts present/added, but also by the calcium sensitivity of that particular pectin. Thanks to this feature, low methylester, amidated pectins can be specifically selected so as to ensure that they gel homogeneously and relatively independently of the calcium ion concentration and produce the desired texture in the respective final product.

31 Sensitivity levels of low methylester, amidated pectins: Low sensitivity: e.g. Pectin Amid AF 005, Pectin Amid CF 005 Medium sensitivity: e.g. Pectin Amid AF 010, Pectin Amid CF 010 High sensitivity: e.g. Pectin Amid AF 020, Pectin Amid CF 020 For special applications H&F pectins with very high sensitivity are also available. Furthermore, H&F offers made-to-order low methylester, amidated pectins that are already standardised with specific buffer substances to a defined gelling behaviour. a) Setting time / setting temperature of low methylester, amidated pectins with differing calcium sensitivity The higher the calcium sensitivity of the low methylester, amidated pectin, the faster the setting time and the higher the setting temperature in a gel preparation that is produced with this pectin. b) Gelling properties of low methylester, amidated pectins with differing calcium sensitivity at different filling temperatures The texture and the firmness of the final product can be influenced significantly by the selected filling temperature. Using the example of two low methylester, amidated pectins with differing calcium sensitivity, Fig. 12 (page 32) shows, how under comparable formulation parameters the firmness and texture of the final product changes, when the product is filled at different temperatures. If a product, such as a fruit preparation (e.g. 45% TSS, ph-value 3.3) is produced and filled with a calcium-sensitive pectin, elastic gels with a constantly high gelling strength will be obtained as long as the filling temperature is higher than the setting temperature of the fruit preparation. If the filling temperature is lowered and finally falls below the setting temperature, pre-gelation will occur, resulting in the partial loss of the maximum gelling strength that could have been achieved. At the same time, the lower the selected filling temperature, the increasingly liquid the texture of the pre-gelled fruit preparation becomes. 31 Increase in calcium sensitivity Increase in setting time/setting temperature Pectin Amid AF 005 Pectin Amid CF 005 Pectin Amid AF 010 Pectin Amid CF 010 Pectin Amid AF 020 Pectin Amid CF 020 Fig. 11 JAMS and Other Fruit Spreads

32 Due to the relatively high setting temperature of the fruit preparation manufactured with reactive pectin, the final gelling strength decreases relatively quickly as the filling temperature drops. If this fruit preparation is finally filled at a low temperature (e.g. 60 C), this results in a pasty texture with a higher tendency to syneresis due to the pre-gelation. If the same fruit preparation is manufactured using a pectin with a lower calcium sensitivity, the gelling strength will be constant across a wider temperature range, as this fruit preparation has a lower setting temperature. Products that are manufactured using pectins with a low calcium sensitivity, can therefore also be processed and filled at lower temperatures. The products show only a very low tendency to syneresis. c) Gelling properties of low methylester, amidated pectins with differing calcium sensitivity at different product ph-values The product ph-value has a significant influence on the gelling behaviour of low methylester, amidated pectins. Using the example of two pectins with differing sensitivity, Fig. 13 on page 34 shows the breaking strength as a function of the calcium dosage for two different product ph-values of the gel preparation. The breaking strength that is achieved when using the pectin with low calcium sensitivity subject to the calcium dosage increases in the case of the two product ph-values as the calcium ion concentration increases. LMA Pectin with high sensitivity LMA Pectin with low sensitivity 32 Gel strength Falling filling temerature Fig. 12: Texture of gels manufactured with low methylester, amidated pectins with differing calcium sensitivity as a function of the filling temperature

33 With a comparable calcium ion concentration the gel strength decreases from ph 3.2 to ph 3.6, which means that the gels become softer as the ph-value rises and the viscous shares increase. As the ph-value of the final product rises, the calcium requirement increases, i.e. to obtain comparably firm gels, gels with a higher ph-value need more calcium ions than gels with lower ph-value. temperature of this gel preparation is so high that pre-gelation occurs under the given conditions. As a result, the texture loses its elasticity and becomes more and more viscous. In contrast to this, elastic gels are formed over a wide range at a ph-value of ph 3.6 by when the high-sensitive pectin is used. The curve form is flat, which means that the breaking strength of these gels hardly changes when the calcium dosage is increased. The breaking strength of the gels that are manufactured using a high-sensitivity pectin also increases initially as the calcium ion concentration rises. In comparison, the absolute values measured in this range are higher than for the pectins with low sensitivity. At the same time, the texture of the gels that are manufactured with a more reactive pectin, are more elastic with a comparable ph-value. Starting from a defined calcium ion concentration, however, the gel strength of the gels with a ph-value of 3.2 drops, since the setting For the user, a flat curve shape means that there is a wide operating range under these conditions, as the gels are very tolerant towards fluctuations in the calcium content. This guarantees high flexibility and a reliable production process. Low methylester, amidated pectins with a high sensitivity, such as Pectin Amid AF 020 or Pectin Amid CF 020, are therefore especially well suited for use with higher product ph-values, whereas pectins with a lower sensitivity, such as Pectin Amid AF 005 or Pectin Amid CF 005, are used for products with a lower ph-value. 33 JAMS and Other Fruit Spreads

34 Breaking strength LMA pectin with high sensitivity LMA pectin with low sensitivity Calcium ion concentration ph 3.2 ph 3.6 Fig. 13: Breaking strength (Herbstreith Pectinometer Mark IV) of gels (40% TSS, 1.0% pectin), manufactured at different ph-values with low methylester, amidated pectins with differing calcium sensitivity as a function of the calcium ion concentration 34 d) Gelling properties of low methylester, amidated pectins with differing calcium sensitivity at different soluble solids content Not only the ph-value of the product but also the soluble solids content is an important parameter in the selection of low methylester, amidated pectins. When the soluble solids content changes, low methylester, amidated pectins show different gelling properties subject to their calcium sensitivity. Depending on the product and its soluble solids content, the desired gelling behaviour can be achieved by selecting the appropriate pectin type. Using the example of three pectins, each with a different sensitivity, the following diagrams show the breaking strength of gel preparations as a function of the calcium dosage with different soluble solids ranges (20%, 40%, 60% TSS). Gelling behaviour at 20% TSS As the calcium ion concentration rises, the breaking strength measured with the Herbstreith Pectinometer Mark IV increases and the texture of the gels becomes firmer and more elastic. Over the entire range that was investigated, the high-sensitivity pectin produces firmer gels with a comparable calcium ion concentration than pectins with medium or low sensitivity.

35 Breaking strength In order to achieve a comparable breaking strength, pectins with medium or low sensitivity require higher calcium dosages than pectins with a high sensitivity. For the formation of elastic gels, gel preparations that are manufactured with pectins with medium and low sensitivity require a certain amount of calcium ions, whereas gels that are manufactured with a high-sensitive pectin, already form an elastic gel when a small amount of calcium ions is added, which can originate e.g. from the fruit or the water used. With low soluble solids contents (0 20% TSS) the high-sensitive pectin requires a certain amount of calcium ions for gelation, but then demonstrates high tolerance towards fluctuations in the calcium content, resulting in homogenous gelation over a wide working range. As a result, low methylester, amidated pectins with a high calcium sensitivity, such as Pectin Amid AF 020 or Pectin Amid CF 020, are eminently suitable for use in products with a low sugar content such as sugar-reduced fruit preparations or delicatessen products. In contrast to pectins with low and medium sensitivity, the curve shape for the pectin with high sensitivity is flat and the breaking strength of the gels shows very little change over a wide range. Pectins with a very high sensitivity such as Pectin Amid CF 025 or Pectin CF 025-G are suitable for glazes, spray glazes and fruit jellies, among others. 20% TSS 35 LMA pectin with high sensitivity LMA pectin with medium sensitivity LMA pectin with low sensitivity Calcium ion concentration Fig. 14: Breaking strength of gels (20% TSS, 1.0% pectin, ph-value 3.2) manufactured with low methylester, amidated pectins with differing calcium sensitivity as a function of the calcium ion concentration JAMS and Other Fruit Spreads

36 40% TSS Breaking strength LMA pectin with high sensitivity LMA pectin with medium sensitivity LMA pectin with low sensitivity Calcium ion concentration Fig. 15: Breaking strength of gels (40% TSS, 1.0% pectin, ph-value 3.2) manufactured with low methylester, amidated pectins with differing calcium sensitivity as a function of the calcium ion concentration 36 Gelling behaviour at 40% TSS If the soluble solids content is raised to 40% TSS, low methylester, amidated pectins with medium and higher calcium sensitivity will form elastic gels even with a low calcium ion concentration. In particular with gels that are manufactured with the medium-sensitivity pectin, the breaking strength is consistently high over a very wide range and relatively independent of the calcium ion concentration. With a defined, relatively high calcium ion concentration the gel strength of gels that are manufactured with the high-sensitivity pectin drops slightly, as here the setting temperature is so high that under the given conditions pre-gelation already sets in. The texture then becomes more and more viscous, resulting in declining breaking strength values. At comparable gel strength the pectin with high calcium sensitivity forms elastic-brittle gel textures, whereas gels manufactured with a pectin with low sensitivity are elastic-viscous and smooth. As, with a soluble solids content of 40%, the pectins with high calcium sensitivity and in particular the pectins with medium calcium sensitivity demonstrate homogeneous gelation over a wide range and thus high tolerance towards calcium ions, these medium sensitive pectins are eminently suitable for use in products in this soluble solids range. For example, in applications with gelling sugar (2:1) with a soluble solids content of 40 45%, many different types of fruit are used; these differ primarily in their calcium and acid content. The pectin with the low calcium sensitivity, on the other hand, requires a certain amount of calcium ions to form elastic gels. The breaking strength values then rise as the calcium ion concentration increases and the gels become firmer. In addition, the production conditions in the home vary from user to user. Nevertheless, products with homogeneous gelation and satisfactory firmness are expected. Low methylester, amidated pectins with medium sensitivity guarantee success with these preparations.

37 Low methylester, amidated pectins with medium calcium sensitivity, such as Pectin Amid AF 010 or Pectin Amid CF 010, continue to be used, for example, in reduced-calorie fruit preparations, fruit preparations for yoghurt or to stabilise fruit cream. Gelling behaviour at 60% TSS With a soluble solids content of 60% pectins with high and medium calcium sensitivity gel even without the addition of calcium ions. When calcium ions are added, the breaking strength values initially increase, the texture of the gel becomes firmer and more elastic-brittle. With a further increase in the calcium ion concentration, pre-gelation will occur relatively quickly, leading to a decrease in the gel strength. With a soluble solids content of 60% TSS the setting temperature of these pectins increases so intensely as the calcium ion concentration increases, that gelation sets in already during the boiling process and the gel can no longer be filled without being destroyed. The gels that result from this pre-gelation are pasty with a decreasing firmness and an increased tendency to syneresis. The higher the sensitivity of the low methylester, amidated pectin is, the lower the calcium ion concentration at which pre-gelation sets in since the setting temperature of gels increases with increasing sensitivity of the pectins. The pectin with low sensitivity gels at a soluble solids content of 60% TSS even without a separate dose of calcium. In contrast to pectins with high and medium sensitivity, the curve shape for the pectin with low sensitivity is flat and the breaking strength of the gels shows very little change over a wide range. Even with high calcium dosages pre-gelation will not occur. As a result, low methylester, amidated pectins with a low calcium sensitivity, such as Pectin Amid AF 005 or Pectin Amid CF 005, are eminently suitable for use in products with a high sugar content such as jams and marmalades. 60% TSS Breaking strength LMA pectin with high sensitivity LMA pectin with medium sensitivity LMA pectin with low sensitivity 37 Calcium ion concentration Fig. 16: Breaking strength of gels (60% TSS, 1.0% pectin, ph-value 3.2) manufactured with low methylester, amidated pectins with differing calcium sensitivity as a function of the calcium ion concentration JAMS and Other Fruit Spreads

38 SynereSiS behaviour Syneresis is an undesired phenomenon in jams and other fruit spreads that depends on many factors. It is described more closely in the following. Pectin is supposed to immobilize the free water in the product. If the desired water binding effect is not completely achieved during gel production or during further processing of the gel, gels show a tendency to "shrink" and to release fluid: this is known as syneresis (the pectin chains approach each other too closely and squeeze the originally bound water out of the gel network). Syneresis must be examined separately for high and low methylester pectins because of their different gelling mechanisms. High Methylester Pectins (HM Pectins) Gelled products with HM pectins generally have a soluble solids content of at least 60%. With these high soluble solids, products manufactured under optimum conditions show no signs of syneresis, as long as the gel is still intact. Syneresis can occur to a lesser extent during normal usage of gelled products (e.g. in the household) but especially when the gel is stirred or pumped. HM pectin gels are not able to regenerate their gel texture after mechanical destruction. Once the texture of these gels has been damaged, syneresis sets in and becomes more pronounced during a longer storage period. 38 Jelly without tendency to syneresis Jelly with tendency to syneresis

39 Pectins form visco-elastic gels, i.e. gels with elastic as well as viscous phases. The higher the elastic and the lower the viscous phase in a gel, the more susceptible the gel textures are to mechanical processing and the greater their tendency to syneresis. The ratio of elastic and viscous phases is determined by the degree of esterification of the pectins and their sensitivity to multivalent ions. Very high methylester pectins form very elastic gels with high setting temperatures. Medium methylester pectins form elastic gels with higher viscous phases and lower setting temperatures. Due to the elevated viscous phase, medium methylester pectins are less sensitive to mechanical stress, show less tendency to syneresis and result in more spreadable gels. Another reason for high gel elasticity is ion sensitivity, which occurs also in high methylester pectins dependent on the raw material and the production method. Ion sensitivity is probably also influenced by the way the free carboxyl groups are distributed in the pectin molecule. A clustered occurrence of free carboxyl groups, caused by the corresponding enzyme activity in the raw material, results in high ion sensitivity. This makes gels highly elastic to brittle with an intensified tendency to syneresis. High methylester Classic Apple Pectins are comparatively insensitive to ions since the carboxyl groups are statistically distributed throughout the molecule due to the production method. Enzymes, which cause clustered demethoxylation, are not active in the raw material pomace, in contrast to other raw materials, e.g. citrus peel. The most frequent causes of syneresis are unsuitable production conditions, which can be summarised using the term pre-gelling. Pre-gelling always occurs if the selected filling temperature for the gel is too low. Reasons for this (with correct pectin dosage) can be: the sugar concentration is too high the acid dosage (which causes the ph-value in the product to be too low) is too high an unsuitable type of pectin, e.g. a pectin that sets too fast This can be remedied by correcting the sugar and acid concentrations, and by aligning the filling temperature and the pectin type. Another reason for syneresis could be inadequate sugar exchange between the fruit and the liquid medium, which may be due to too short a cooking time for fruit with very hard skins or firm fruit pulp. Discharge of fluid also occurs if the selected pectin dosage is too low or the pectin has not been completely dissolved. This means that the water that is present cannot be sufficiently immobilized. 39 JAMS and Other Fruit Spreads

40 Low Methylester Pectins (LM Pectins) Whether or not syneresis occurs in gels with low methylester pectins depends on the ratio of pectin to calcium. An appropriate dosage of low methylester pectin and relatively few calcium ions result in thixotropic gels with a high regeneration rate. This means that if a gel is handled mechanically, e.g. jam is spooned out of a jar, the destroyed gel can regenerate quickly and liquid does not seep out of the gel network; the tendency to syneresis is relatively low in these gels. An increase in the amount of calcium in proportion to the selected pectin dosage renders the gels more elastic, reduces the viscous phase, at the extreme the texture becomes brittle and is no longer spreadable, resulting in thixotropic gels with a very low regeneration rate. If the gels are destroyed it takes a very long time for the texture to regenerate and liquid can escape. The occurrence of strong syneresis in jams and other fruit spreads looks unappealing and for this reason is considered by jam manufacturers and consumers alike to be a quality defect that is to be avoided. 40

41 41 Fig. 17: Determination of syneresis behaviour of fruit preparations JAMS and Other Fruit Spreads

42 StandardiSation of H&F Pectins Fig. 18: Ridgelimeter (USA-Sag Method) 42 As pectin is extracted from natural, plant raw materials, its properties can differ depending on the quality of the raw materials used. For this reason the pectins are analysed and standardised to their defined functionality to ensure that a constant texture is obtained every time the pectin is deployed. Different standardisation methods are used depending on the intended use of the pectins. The standardisation of high methylester pectins to constant grade value is performed all over the world using a Ridgelimeter according to the "USA-Sag method". For more information watch our application film "Determining the gelling strength according to the USA-SAG method" on: or at

43 A sugar-pectin-water gel with 65% soluble solids and a ph-range of about 2.0 is made for this purpose. The gel is cooled under defined conditions (25 C [77 F] 24 hours). After cooling, the gel is released from its mould and the percentage of sagging under its own weight is measured with the so-called Exchange Ridgelimeter after exactly 2 minutes. A gel that sags 23.5% is considered a standard gel. The grading of pectin is calculated according to the following formula: To determine the breaking strength and the texture with the Herbstreith Pectinometer a random gel is subjected to stress up to the point where the gel network is destroyed. The force needed to do this is measured as a function of time. The advantages of this method are simple handling, good reproducibility and above all the great flexibility regarding the formulation. Thus it is possible to assess gels that are exactly adjusted to their specific application. USA-Sag = F x a b F = correction factor a = amount of pectin sugar in the gel (650 g) b = amount of pectin in the gel (4.33 g in this example) With a sagging of 23.5% factor F = 1 and the USA-Sag = 150. For gels that sag distinctly (weaker gels) correction factors < 1 are used; for gels that sag less distinctly correction factors > 1 are used. The method described above has served as a commercial basis for high methylester pectins for many years. However, this method is not undisputed; critics say that the very low ph-value in the gel lacks practical relevance. This means that the pectin is assessed by the gelation of a product that in practice would not be produced this way. The internal strength, also termed breaking strength, correlates better with the sensory perception of stability than the USA-Sag values do. Therefore, there are increasing efforts to assess high methylester pectins not only according to the USA- Sag method, but also by way of their breaking strength. However, the measurement of fruit spreads containing fruit components can only be reproduced if the fruit is finely ground or at least distributed homogeneously in relatively small pieces. To determine the breaking strength and the texture with the Herbstreith Pectinometer the gel preparation (sol) is filled into a standardised measuring beaker with shear insert. After a defined gelling time this shear insert is pulled out of the gel and the force needed to do this is measured. The following information is obtained from the resulting force-time diagram: The maximum force is equivalent to the force that is needed to destroy the gel and is called the breaking strength. This breaking strength or internal strength correlates very well with the firmness that is perceived in the sensory assessment when the gel is first chewed or taken up with a spoon. 43 JAMS and Other Fruit Spreads

44 A relatively low value for the texture constant K is obtained from the ratio of breaking strength, i.e. the maximum force, and the integral of the force-time curve. From a sensory point of view these gels are assessed as very easy to spread and homogeneously firm with a high mouthfeel. 44 Fig. 19: Herbstreith Pektinometer The so-called texture constant K is determined on the basis of the ratio of the maximum force and the integral of the resulting force-time-curve. This value gives information on the spreadability of the gels and on the behaviour of a gel preparation in the mouth when chewed and swallowed. The Herbstreith Pectinometer Mark IV is used to determine the two parameters breaking strength and texture constant K and to distinguish different types of pectin gels: Elastic-viscous gels, for example, only need a low force to be destroyed or broken and therefore have a relatively low breaking strength. As elastic-viscous gels have an inner cohesion, a low but steady exertion of force is needed after destruction to pull the shear insert out of the gel. This results in a relatively large integral area in the force-time curve. Elastic gels have high breaking strength values, which means that a high exertion of force is needed to break them. Elastic gels break into individual fragments when destroyed. Therefore, after breaking only a low force needs to be exerted to pull the shear insert out of the gel, resulting in a comparatively small area in the force-time curve. The calculated texture constant K is then higher than for viscous, spreadable gels. From a sensory point of view, elastic-brittle gels are often assessed as less spreadable and slightly rough with less mouthfeel. Determination of Setting Time/Setting Temperature In addition to the desired texture, the setting temperature is a particularly important parameter for the manufacturer of fruit preparations. The higher the setting temperature, the faster the product starts to gel and the higher the filling temperature in the production process has to be set. If the setting temperature of the product is higher than the specified filling temperature, pre-gelation will occur, i.e. the product already starts gelling before filling begins. The mechanical stress during the filling process irreversibly destroys the gel network already formed, resulting in a partial loss of the final gel strength in the end product. For more information watch our application film "Determining the breaking strength of gels with the Herbstreith Pectinometer Mark IV" on: or at

45 On the other hand, products that contain whole fruits or pieces of fruit require a relatively high setting temperature, as these products are intended to gel quickly after the filling process in order to prevent the fruit or fruit pieces from floating and from separating from the gel. The setting time and the setting temperature are influenced on the one hand by formulation parameters such as soluble solids content, ph-value of the product, buffer substances and pectin dosage, and on the other hand by the degree of esterification, the raw material used as the basis for the pectin and the pectin production technique. Determining the setting time according to Joseph and Bayer has proved to be an easy method to perform without any technical effort. Joseph, G.H., Bayer, W.F. (1949): Food Technol. 3, With this method a gel preparation is produced according to the Ridgelimeter method and the setting process observed under defined cooling conditions. The time up to the start of gelation is measured and defined as setting time. As the formulation parameters lack practical relevance (no buffer substances, ph-value approx. 2.2) the measured values correlate only to a certain extent with practical experience. This becomes particularly clear when definite reactions with ions, mostly bivalent cations such as calcium ions, are already anticipated due to the low degree of esterification or due to the raw material (as with citrus pectins by clustered distribution of carboxyl groups). To determine the setting temperature H&F has developed a rheometric method using an oscillating rheometer. With this method, the sample is subjected to a force during the cooling phase in the form of a sinusoidal, oscillating motion and the likewise sinusoidal response motion of the sample measured. The sample is not destroyed with this measurement. If the sample is in a liquid state, the viscous share is dominant and the phase displacement between the applied force and the response motion (deformation) measures approx. 90. If the sample has become a firm gel, the elastic shares predominate and the resulting phase displacement is virtually 0. If the viscous and elastic shares are equal H&F speaks of a sol-gel-transition or gel point. The displacement angle will then measure 45 and H&F defines the appertaining temperature as the setting temperature. High methylester pectins are usually divided into the following groups based on the setting time / setting temperature: rapid set (rs) medium rapid set (mrs) slow set (ss) extra slow set (xss) As up until now there is no official method for determining the setting time and the setting temperature of pectin gels, this classification is arbitrary and can fluctuate from manufacturer to manufacturer. 45 JAMS and Other Fruit Spreads

46 ClaSSiC, Combi PluS and amid PeCtinS and their Application 46 Customised Pectins for Systematic Control of Sensory and Rheological Properties of Jams and Other Fruit Spreads Increased quality demands on jams and other fruit spreads are not limited only to the gel strength, but also increasingly extend to include consistency, texture and syneresis behaviour. What is regarded as the optimal consistency by consumers in one country and for a certain product, may be quite different in other places. In some countries, for example, very firm and more brittle gels are required for special products; other countries prefer gels that are particularly spreadable (Swiss consistency). In general, consumers expect a firmer consistency of "extra jam" than of e.g. compote or jellied fruit desserts. Pectins are the preferred gelling and thickening agents for jams and other fruit spreads, because these are already naturally present in fruit and thus provide a natural texture. Apple and citrus pectins with different degrees of esterification are commercially available; each of these pectins forms a typical gel texture based on its specific raw material and degree of esterification. Citrus pectins generally have highly elastic to brittle gelling properties with a relatively high tendency to syneresis. Apple pectins, on the other hand, form elastic gels with a certain amount of viscosity, to which they owe their good spreadability with a low tendency to syneresis and which also influences the taste of the gels. Apple pectin gels melt in the mouth, and the fruity-sweet flavour is perceived intensively. Based on these properties, H&F supplies Classic Apple and Citrus Pectins for a great variety of product requirements. In addition, for fruit applications H&F has also developed Combi Pectins (apple/citrus), which differ from traditional pectins on account of their production method and properties. To produce Combi Pectins, pomace and citrus peel are extracted jointly in a defined mixing ratio, which is dependent on the desired end product.

47 Classic Pectins The Classic Pectins of interest in this area have the letter coding "AF" in their nomenclature, whereby A stands for apple as raw material and F for the application area fruit, correspondingly C stands for citrus as raw material. The high methylester Classic Pectins are intended for jams and other fruit spreads with more than 60% soluble solids content. Which type is suitable in a specific case depends on: As the degree of esterification declines, the setting temperature of these gels also drops, if they are manufactured under the same conditions and according to the same formulation. Pectin Classic AF 201 is a very rapid set pectin and Pectin Classic AF 401 a medium-rapid set pectin. As the degree of esterification declines, the texture will also change: the smoothness and hence the spreadability of the pectin gels increases. the formulation the production technology the texture requirements KONFITÜREN und andere Fruchtaufstriche

48 Herbstreith&FoxKG Pectin Classic AF 401 has a medium-rapid setting time and the resulting gels are characterised by a distinctive smoothness, spreadability and full flavour. Recipe Product: Jam Extra Pectin: Classic AF g Pectin solution 5% (= 0.25%) 450g Fruit 420g Sucrose, crystalline 200g Glucose syrup (15% dextrose, 15% maltose, 13% maltotriose) x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 63% ph-value: Procedure: A For the production of the pectin solution see Application Information. B Mix fruit, glucose syrup and sucrose and heat to approx. 90 C. C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 85 C (185 F). Pectin Classic AF 504 is a rapid-set pectin that results in good spreadability and excellent fruit distribution. Herbstreith&FoxKG Recipe Product: Jam Extra 48 Pectin: Classic AF g Pectin solution 5% (= 0.4%) 450g Fruit 420g Sucrose, crystalline 200g Glucose syrup (15% dextrose, 15% maltose, 13% maltotriose) x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 63% ph-value: Procedure: A For the production of the pectin solution see Application Information. B Mix fruit, glucose syrup and sucrose and heat to approx. 90 C. C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 85 C (185 F).

49 The particular feature of Pectin Classic AF 504 is that even during the manufacturing process an adequate yield point is formed at very high temperatures. Whole fruit or large pieces of fruit remain floating resulting in an optimal distribution of the fruit. That is why this pectin is particularly suitable for products in which good fruit retention is important, e.g. cherry jam with large pieces of fruit. The setting temperature of this slow setting pectin is comparatively low. Bubbles of air that incorporated into the product during cooking can escape before gelation sets in, allowing a clear gel to develop. Higher methylester pectins form gels with a rather firm, sometimes brittle gel texture, because fruit pieces or fruit fibres that contribute to the gel s smoothness, are missing. Gels that are produced with Pectin Classic AF 504 show a very spreadable texture and an extremely low tendency to syneresis. For jelly with a soluble solids content of more than 60%, all of the high methylester pectins listed here can also be used, but Classic AF 501 and Classic CF 501 are particularly recommended. Herbstreith&FoxKG Recipe Product: Jelly Extra Pectin: Classic AF 501/Classic CF 501 4g Pectin (= 0.4%) 450g Fruit juice, approx. 12% TSS 410g Sucrose, crystalline 200g Glucose syrup (15% dextrose, 15% maltose, 13% maltotriose) x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 63% ph-value: Procedure: A Mix the pectin with approx. 100 g sucrose from total sucrose amount. B Stir mixture A into fruit juice and boil until the pectin has dissolved completely. C Add the remaining sucrose and the glucose syrup and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 85 C (185 F). 49 JAMS and Other Fruit Spreads

50 H&F offers low methylester classic apple and citrus pectins, e.g. Pectin Classic AF 710, for use in low-calorie jams and other fruit spreads. These pectins are standardised to a constant calcium sensitivity and as a rule are generally used with calcium salts. With the calcium dosage it is possible to influence the product properties, e.g. firmness and spreadability (see p. 35 for more details). In addition to these standard pectins, H&F develops specially customised pectins in close cooperation with its customers. Combi Plus Pectins Special extraction conditions have been designed to produce Combi Plus Pectins with very specific properties. With regard to their gelling properties, these pectins lie somewhere between the classic apple and the classic citrus pectins. The pronounced viscous properties, characteristic for apple pectins, are complemented by the higher elasticity of citrus pectins. This results in pectins that form gels with high elasticity, but that at the same time are spreadable and have a relatively low tendency to syneresis. Amidated Pectins Amidated, low methylester pectins are used to produce fruit spreads with a smooth, elastic gel texture. In comparison to low methylester Classic Pectins, it is mostly not necessary to add extra calcium when amidated pectins are used. In order to achieve optimal gelling properties, the addition of calcium may become necessary for fruit spreads below 40% TSS, depending on the type of fruit, the pectin and process parameters.

51 Herbstreith&FoxKG Recipe Product: Jam Extra Pectin: Combi Plus g Pectin solution 5% (= 0.25%) 450 g Fruit 420 g Sucrose 200 g Glucose syrup (15% dextrose, 15% maltose, 13% maltotriose) x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 63% ph-value: approx Procedure: A For the production of the pectin solution see Application Information. B Mix fruit, glucose syrup and sucrose and heat to approx. 90 C (194 F). C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 85 C (185 F). Herbstreith&FoxKG Recipe Product: Jam Extra Pectin: Amid AF 005-K 100 g Pectin solution 5% (= 0.5%) 500 g Fruit 420 g Sucrose, crystalline 100 g Glucose syrup (15 % Dextrose, 15 % Maltose, 13 % Maltotriose) x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 56% ph-value: approx Procedure: A For the production of the pectin solution see Application Information. B Mix fruit, glucose syrup and sucrose and heat to approx. 90 C (194 F). C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 85 C (185 F). 51 JAMS and Other Fruit Spreads

52 Herbstreith&FoxKG Recipe Product: Fruit Spread Pectin: Amid AF 005-N 160 g Pectin solution 5% (= 0.8%) 450 g Fruit 350 g Sucrose, crystalline 60 g Water x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 40 % ph-value: approx Procedure: A For the production of the pectin solution see Application Information. B Mix fruit, sucrose and water and heat to approx. 90 C (194 F). C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 80 C (176 F). Herbstreith&FoxKG Recipe Product: Fruit Spread Pectin: Classic AF g Pectin solution 5% (= 0.9%) 500 g Fruit 240 g Sucrose, crystalline 120 g Water 0.35 g tricalcium dicitrate x 4 H 2 O x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 30% ph-value: approx Procedure: A For the production of the pectin solution see Application Information. B Mix fruit, sucrose, water and calcium citrate and heat to approx. 90 C (194 F). C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. E Filling temperature approx. 85 C (185 F).

53 Herbstreith&FoxKG Recipe Product: Organic fruit spread Pectin: Classic AF g Pectin (= 0.8%) 600 g Fruit* 580 g agave syrup*, approx. 75% TSS x ml lemon juice concentrate* to adjust the ph value Input: approx g Output: approx g TSS: approx. 50% ph-value: approx Procedure: A Mix the pectin with approx. 50 g agave syrup (from total quantity). B Mix fruit and mixture A and heat to approx. 90 C (194 F). C Add remaining agave syrup and cook to final soluble solids. D Add the lemon juice concentrate to adjust the ph-value. E Filling temperature approx. 80 C (176 F). * from organic production Herbstreith&FoxKG Recipe Product: Fruit Spread Pectin: Amid AF g Pectin solution 5% (= 0.6%) 450 g Fruit 450 g Sucrose, crystalline x ml Citric acid solution 50% to adjust the ph-value Input: approx g Output: approx g TSS: approx. 50% ph-value: approx Procedure: A For the production of the pectin solution see Application Information. B Mix fruit and sucrose and heat to approx. 90 C. C Add the hot pectin solution and cook to final soluble solids. D Add the citric acid solution to adjust the ph-value. 53 E Filling temperature approx. 85 C (185 F). JAMS and Other Fruit Spreads

54 production methods for Jams and Other Fruit Spreads 54 How to Incorporate Pectins into the Product Batch The best way of adding standardised pectin to the cooking process is to produce pectin solutions using suitable equipment. If slow-speed mixers are the only equipment available, the pectin is mixed with about 5 times the amount of sugar and this mixture is dissolved in water at a temperature of at least 80 C (176 F). This way, 3 5% pectin solutions can be produced. If a dissolver with high-speed mixer is available (more than rpm), pectin is added at a water temperature of at least 80 C (176 F) while the mixer is running, sprinkled directly into the mixer flux and dissolved. Depending on the type of pectin, pectin solutions of 5 7% can be produced this way. Nowadays, 7 10% pectin solutions can be produced using modern injection mixers. Fig. 20 on page 55 shows a flow chart for a modern high-speed dissolving unit. When such high-percentage pectin solutions are used, the water volume that evaporates during the cooking process is clearly lower than when 3 5% pectin solutions are used. If liquid sugars or sugar syrups are used, the pectin can also be suspended in 10 times the amount of liquid sugar/sugar syrup while the mixture is slowly stirred. This suspension can then be incorporated into hot water with a Temperature of at least 80 C (176 F), resulting in a 3 5% pectin solution. If pectin is to be added directly to the product batch, i.e. not as pectin solution, this is best achieved with the above-mentioned pre-mix of pectin and 5 10 times the amount of sugar or a suspension with liquid sugar or sugar syrups. In this case it is important to ensure that the soluble solids content in the batch during the dissolving of pectin is not higher than 30%, otherwise the solubility would be hindered. For more information watch our application film "Techniques used for adding pectin to the product batch" on: or at

55 Incorporation of powdered pectin into the product batch Incorporation of dispersed pectin into the product batch pectin powdered ingredients pectin liquid sugar pre-mixing mixer approx. 500 min -1 pre-mixing mixer approx. 500 min -1 productbatch productbatch Production of pectin solutions pectin ingredients pre-mixing mixer approx. 500 min -1 water pectin mixer approx min -1 pectin mixer approx min water water Fig. 20: Incorporating pectin into the product batch/flow chart of high-speed dissolving equipment JAMS and Other Fruit Spreads

56 Reduction by Boiling The objective of making jams and other fruit spreads is to create an end product with a long shelf-life and the required soluble solids content as well as the other product features aimed for. During cooking, an adequate exchange of sugar between the liquid medium and fruits is achieved, which prevents water loss in the end product during storage. When fruits preserved with SO 2 are used, it is important to ensure that the maximum admissible level of sulphur dioxide is not exceeded. The Cooker In the large-scale production of jams and other fruit spreads using cooking kettles differentiation is made between two basic types of reduction processes: Cooking in an open kettle under atmospheric pressure and Cooking in a closed vacuum system with reduced pressure. The flat construction necessitates a low filling level, which in turn shortens the path of the steam bubbles from the heated floor to the surface of the liquid, thus reducing the risk of overheating. In-built baffles which appropriately override the agitator from above, interrupt the agitated flux and improve distribution and diffusion during cooking, while preserving the integrity of the fruit pieces. A high dome on closed cooking systems prevents foam overflow from the cooking contents. Modern cooking systems are equipped with automatic metering devices for glucose syrup, acid solution and pectin solution. The integration of a process refractometer and a ph measuring sequence enable automatic monitoring of the soluble solids content and ph-value. Continuous vacuum cooker systems are also available and used to produce jams and other fruit spreads. 56 The container material for modern cookers is a V2A special steel. The construction of cookers is determined by various factors: A flat construction provides a large surface for the cooking contents and thus reduces cooking time and provides a large evaporation area. A flat, spacious kettle floor with adjoining steam jacket provides a large heating surface. A slow-speed anchor mixer with scrapers guarantees gentle treatment of the fruit and prevents burning on the cooker walls. Cooking in an Open System Cooking in an open kettle is practiced nowadays in only a few, small manufacturing companies. The reminiscence of artisanal tradition is spawning a certain renaissance of this system. Pre-Heater In the pre-heater, the prepared fruits and added sugars are heated to C ( F) and thoroughly mixed with an anchor mixer with scrapers. Berry fruits often require pre-cooking with water in order to get the hard skins of the fruits to burst and enable an adequate sugar exchange.

57 Cooking in Vacuum Systems Cooking in vacuum systems is done in closed kettles under reduced pressure. The great benefit of this cooking method lies in the low cooking temperatures and short cooking times. Both criteria are crucial for an optimal end product as regards appearance, colour, flavour and vitamins, since the raw materials are exposed to a minimum amount of stress. The short cooking times and relatively large cooking batches also make the process highly efficient. Vacuum cooking is divided into the following steps: Vacuum Kettle The pre-heated fruit/sugar mixture is drawn from the pre-heater into the kettle by vacuum and boiled down under vacuum, under constant stirring and the addition of steam. In order to prevent foaming, edible oils and fats as well as mono- and diglycerides of edible fatty acids can be added during cooking. The pectin solution is then added and further reduced by boiling under vacuum until the desired final soluble solids content is reached. Once the final soluble solids content is reached, the batch is vented and the acid added. Filling is often done at temperatures of C ( F) in order to minimise the risk of germs. Sophisticated cooking systems with flavour recovery condense the volatile aroma components from the water vapours and return them to the cooking batch before it is discharged. This cooking process is not only suitable for the production of jams, jellies and marmalades, but also for fruit preparations for the dairy and baking industries. JAMS and Other Fruit Spreads

58 Filling process of Jams and Other Fruit Spreads The jams and other fruit spreads are discharged from the vacuum kettle by way of pumps or, even gentler, by gravity into heated filling troughs with agitators, from which they are drawn into the filling machines. The temperature of the cooking batch at the time of filling is about C ( F). Not only the relatively high filling temperature but also treatment of the packaging, e.g. by vaporisation or radiation, guards against microbial contamination. After filling and capping, the jars pass through a tunnel cooler and are sprinkled with cold water, which lowers their temperature to C ( F). The rapid lowering of the temperature prevents caramelisation and colour changes in the filled article (centre burning) and brings the product into a temperature range at which gelation sets in and an optimal gel texture can slowly form. After cooling the products are labelled and then packed. Before distribution, however, the jars should be stored until the product has thoroughly set. 58

59 Liquid sugars, glucose syrups fruit sugar pre-heater steam pectin solution acid solution cooling water H 2 O cooler vakuum vessel steam H 2 O vakuum pump filling bowl 59 storage dispatch filling machine + cap closer tube cooler labelling machine final packaging Fig. 21: Boiling equipment JAMS and Other Fruit Spreads

60 General calculation and Design of Formulations Soluble Solids Content and Refractometry The soluble solids contents of raw materials and end products are important parameters for the calculation and design of jam and other fruit spread formulations. They indicate what amounts of dissolved solids (sugar, acids, pectins, salts, etc.) are contained in anhydrous form in 100 g of the mass. Thus an anhydrous substance, for example, consists of 100% TSS, a fruit with 10% soluble solids and 90% water has a soluble solids content of 10%. A refractometer is used to measure the TSS content. c1 α Medium 1 Modern jam cookers have digital display refractometers with temperature compensation installed in the vessel walls, which allows the development of the soluble solids content to be monitored throughout the entire cooking process. β c1 = sin α =n c2 sin β c2 60 Fig. 22: Refraction of light Medium 2

61 Visual field in the Abbe refractometer Ray path on the Abbe refractometer 1 1. Ocular lens 2. Objective lens 3. Reflecting prism 4. Amili prisms 5. Objective lens 6. Scale 7. Reflecting mirror 8. Illumination prism 9. Measuring prism 10. Reflecting mirror Fig. 23: Abbe refractometer JAMS and Other Fruit Spreads

62 The solid ingredients content in a simple solution is determined by the refraction index n ; this method of determination is known as refractometry. The refraction index n is the ratio of the velocity of light in the medium under examination and air. The physical principle at the basis of this method is Snellius Law, which says that during the refraction of monochromatic light (light of a uniform wavelength) at the boundary line of two media, the angle of incidence alpha is to the angle of refraction beta as is the velocity of light in these media. The refractometric determination of the soluble solids content is performed at 20 C (68 F). The refraction index is dependent on the temperature; a thermostatic refractometer should be used for accurate measuring. With increasing temperature and decreasing density, the refraction index becomes smaller. The Abbe refractometer directly displays the refraction index; instruments calibrated to sugar solution show the soluble solids content in percentage of sugar. The measuring accuracy of refractometric soluble solids readings is ± 1%. The most important parts of a refractometer are: A binocular prism to take in the liquid to be measured, which can be rotated around its horizontal axis A telescope to observe the boundary line of total reflection An adjustable compensator for colour contrasting of the boundary line A scale window fixed in the telescope, on which the refraction index or the soluble solids scale is displayed. sample small refraction 62 large refraction prism lens scale lens Fig. 24: Optical construction of a small handheld refractometer

63 Handheld Refractometer Handheld or pocket refractometers are very handy and easy to use. These instruments are slightly less accurate in their measurements than an Abbe refractometer, however, they are quite adequate for most applications. The optical construction of a small handheld refractometer is shown in Fig. 24 on page 62. The weighed-in volume of purée, pulp, juice or aqueous fruit extract, as set down in the German Fruit Jams Regulation, and the refractometrically determined minimum content of soluble solids of more than 55% form the basis for the design of formulations. How to calculate formulations and yield is shown on the basis of a general example (see Table 4): The batch size is determined by the total volume of all raw materials. The batch consists of 60 kg soluble solids and 41.5 kg water. To achieve a soluble solids content of e.g. 63%, a certain amount of water needs to be evaporated. The amount of water to be evaporated is determined by calculating the difference between the batch size and the theoretical yield (101.5 kg 95.2 kg = 6.3 kg water). When designing formulations, it is frequently assumed that the average soluble solids content of fruits amounts to 10%. However, in reality these values fluctuate considerably. Table 5 shows the most important types of fruit and their average soluble solids content as well as the range in which this may fluctuate. Raw Material Volume TSS Content Soluble Solids Fruit 45.0 kg approx. 10% 4.5 kg Sugar 51.0 kg approx. 100% 51.0 kg Glucose syrup 80% TSS 5.0 kg approx. 80% 4.0 kg Pectin 0.3 kg approx. 100% 0.3 kg Acid 0.2 kg approx. 100% 0.2 kg Total kg 60.0 kg Table 4: Calculation of formulation and yield kg TSS total x 100% 60kg x 100% = = 95.2kg theoretical yield set TSS [%] 63% Raw Material Average soluble solids content [%] Range of Variation [%] Apples Cherries, sweet Plums Peaches Apricots Strawberries Raspberries Blackberries Red Currants Gooseberries Table 5: Soluble solids content of fruits (source: Souci-Fachmann-Kraut: Composition of foods, nutritional tables 1989/90 (Wissenschaftliche Verlagsgesellschaft mbh Stuttgart 1989) JAMS and Other Fruit Spreads

64 Jams and other fruit spreads Pectin type DE [%] A [%] Characteristics + properties Main application 64 Classic AF Apple pectin, rapid set Classic AF Apple pectin, medium rapid set, smooth gel texture Classic AF Apple pectin, slow set, spreadable gel texture Classic AF Apple pectin, optimum fruit distribution also at high filling temperature, smooth gel texture Classic AF Apple pectin, smooth, spreadable texture Classic AF Apple pectin, very good solubility even with higher soluble solids content Classic CF 207 > 70 Citrus pectin, rapid set Classic CF Citrus pectin, medium rapid set Classic CF Citrus pectin, slow set Classic CF Citrus pectin, extra slow set Amid AF 005-K amidated Apple pectin, low calcium sensitivity, anti-floating effect Amid CF 005-B amidated Citrus Pectin, very low calcium reactivity jams, marmalades, fruit preparations, TSS > 58%, ph jams and marmalades in jars or large trading units, fruit preparations, TSS > 58%, ph jams, marmalades and jellies TSS > 58%, ph jams, marmalades, fruit preparations, TSS > 58%, ph jams, marmalades, fruit preparations TSS > 60%, ph household gelling agent jams, marmalades, fruit preparations TSS > 58%, ph jams, marmalades, fruit preparations TSS > 58%, ph jams, marmalades, fruit preparations TSS > 58%, ph jams, marmalades, fruit preparations TSS > 58%, ph jams, marmalades, fruit preparations TSS 50 60%, ph jams, marmalades and fruit preparations TSS > 55 %, ph Table 6: DE = Degree of esterification A = Degree of amidation

65 Jams and other fruit spreads Pectin type DE [%] A [%] Characteristics + properties Main application Classic AF Apple pectin, medium calcium sensitivity low-calorie jams and fruit preparations TSS < 55%, ph fruit purees TSS 15 25%, ph fruit sauces TSS < 55%, ph Classic AF Apple pectin, high calcium sensitivity, elastic texture low-calorie jams and fruit preparations TSS 10 50%, ph TSS > 40% gels without addition of calcium TSS < 40 % requires small addition of calcium Classic CF Citrus pectin, low calcium sensitivity Classic CF Citrus pectin, high calcium sensitivity Amid AF 005-N amidated Apple pectin, medium calcium sensitivity, anti-floating effect Amid AF 005-Q amidated Apple pectin, medium calcium sensitivity, optimum berry distribution, smooth gel texture Amid AF amidated Apple pectin, medium calcium sensitivity Amid AF amidated Apple pectin, high calcium sensitivity Amid CF 010-D amidated Citrus pectin, medium calcium sensitivity Amid CF 020-C amidated Citrus pectin, high calcium sensitivity Amid CF 025-D amidated Citrus pectin, very high calcium sensitivity low-calorie jams, fruit spreads and jellies TSS 40 60%, ph low-calorie jams, fruit spreads and jellies TSS < 45%, ph low-calorie jams and fruit spreads TSS 35 50%, ph cranberry preparation TSS 35 50%, ph low-calorie jams and fruit spreads TSS %, ph 3,0 3,6 fruit preparations, jellies TSS 10 40%, ph low-calorie jams, fruit spreads and jellies TSS 30 55%, ph low-calorie jams, fruit spreads and jellies TSS 15 45%, ph low-calorie jams, marmalades, fruit preparations and fruit spreads (TSS %, ph ) 65 Table 7: DE = Degree of esterification A = Degree of amidation JAMS and Other Fruit Spreads

66 individuality is our Strength Pectins by Herbstreith & Fox have enjoyed a worldwide reputation over many decades. Continual improvement of our production methods and high quality standards have contributed significantly to our success today in the world market. This development has always been characterised by innovative hinking and farsighted research. We also supply users with formulations and production solutions, e.g. for the manufacture of high-quality jams, jellies and marmalades. For this purpose, our technical experts integrate specific pectins into the composition and optimisation of formulations in order to get the most out of them. Today, we are in a position to offer pectins which can be used in all areas of application that are currently conceivable. Consistent production and quality controls using state-ofthe-art analytical equipment guarantee the constant high quality of our pectins. This positive and continuous progressive approach has not only been upheld in the face of challenges, which our staff in research and development have repeatedly and successfully set themselves, but also by the great variety of requirements brought to us by our customers, the users. Analysis of your finished product also contributes to assuring the high and consistent quality of your product, and can even shed light on potential improvements regarding your end product. New, promising product ideas should not fail because of formulation or production problems. This is what we stand for. In the interests of the manufacturer, the product and the consumer. 66 An essential component of this successful cooperation with our users is, of course, the transfer of our know-how. Our analysis can provide valuable assistance even early on in the assessment and control of raw materials.

67 JAMS and Other Fruit Spreads