UNIVERSITY OF NAIROBI

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1 UNIVERSITY OF NAIROBI COLLEGE OF AGRICULTUREfVETERINARY MEDICINE INDUSTRIAL PROJECT 2005 MANUFACfUREOF AN ACCEPfABLEJAMFROMBAOBABFRUIT (Adansonia digitata) NGURA J. W. A24/0155/01 15 TH JULY 2005 (Undergraduate program: Food Science & Technology) SUPERVISOR: DR. SEHMI

2 NOTE OF APPRECIATION My gratitude extends to au the personalities involved in the development of this project. In particular, I would like to thank my supervisor, my parents and Joram who assisted me in typing of this project. My success reflects on you and your great assistance wid forever be appreciated.

3 INTRODUCTION The production of sugar preserves has been done from a variety of fruit found allover world. It was however been observed that most of these preserve are made from common fruit as opposed to the less known fruit (wild). There is a particular bias to tropical fruit like oranges, pine apples, plums and strawberries while less known fruits are ignored. The Baobab fruit is one of the less known as far as fruit processing is concerned despite it has high level of vitamin C, fructose, sacchrose and glucose content. Fruit pulp is also acidic and this is due to the presence of organic acid including citric acid, tartariqrnalic, succinic as well as ascorbic acid. The level of pectin is also high in the fruit. The Baobab fruit is a wild fruit, which are obtained from baobab tree (Adansonia digitata). These trees are found mostly in low altitude areas, especially semi- arid region. In Kenya is found in coastal region and some parts of Eastern province. throughout the year. The plant comes in several varieties, common in Kenya. The main uses of this plant are: Leaves: the Being a dry fruit it is found A. digitata, L being the most Young fresh leaves are cut into pieces and cooked in a sauce. Sometimes they are dried and powdered and used for cooking. The powder is called Labo in mjwtand village markets in Western Africa. Fruit pulp. The dry pulp is either eaten fresh or used to add gruels on cooling after cooking. is sold in many A good way of preserving the vitamin content. It can also be ground to make a refreshing drink with a pleasing wine - gum flavour. In Tanzania, it is added to aid fermentation of sugar cane for beer making. Seeds. In general, seeds are used as a thickening agent in soup but they can be fermented and used as flavouring agent, or roasted and eaten as snacks. The knowledge of chemical composition of the fruit and in particular the sugar, acid and pectin show that thus fruit can be tried to manufacture of quality and an acceptable Jam. So it was this in mind that this study was carried out to investigating the feasibility of making an acceptable quality of Baobab jam. Effective pulp extraction was facilitated by removing of fibres and seed by kneading in cold water, the resulting emulsion is sieved. After appropriate adjusting of the PH the pulp ~ " the sugar mix of different ratio were mixed together with 1% of pectin of total mass, the mixture 1

4 was then cooked for sometime until a jam of above 65 brix was formed. The physical characteristics of Jam were analyzed. Changes in the characteristic of jam after cooking were investigated in addition to the effect of storage at different storage conditions. Objectives: and sub - objectives: Overall objective: To manufacture an acceptable Jam from baobab fruit. Sub-objectives. 1. Determination of total solid, total sugar, total titratatable acidity, PH, and the pectin level of the baobab fruits. 2. To determine the ascorbic acid content of the fruit pulp. 3. To manufacture the an acceptable Jam from baobab fruit. 4. To perform a sensory evaluation to determine the level of acceptability. 5. To determine the shelf life of the product. Hypothesis. The Baobab fruit pulp can be used for the manufacture of an acceptable Jam in terms of strength, colour, flavour, rigidity, continuity and appearance. Justification The baobab fruit is a very abundant fruit especially th~e areas that the baobab trees are found. Baobab tree is a drought resistant plant, which are usually found in semi - arid areas. So baobab fruit can be used as a measure of food safety in those areas. It's structure and composition allows for its effective pulping resulting in a large percentage of the raw material as pulp. This ljulp contains all the fruit ingredient except those found on the skin and the seed and the amount has bearing on the quantity of pulp that can be produced. The fruit has a total soluble solid content of 13 brix and acidity as low as PH 2.7. This means it is well guarded against microbial spoilage due to that its high acidity. However during Jam manufacture, one has to increase the total solid content and decrease the acidity to give a Jam of the required continuity. Lastly, but most important the use of this fruit has not been exploited so by making Jam from this fruit, your are increasing the utilization of this fruit and you are also diversifying the use of tree product or market by manufacturing of an acceptable Jam from baobab fruit. It is for this reason basically that my project proposal has come into being. It is my aim to prove that the baobab fruit has an appreciable nutritive value especially vitamin and can be used to make various food product. Jam being my choice offood product. 2

5 LITERATURE NUTRITIVE REVIEW VALUE No scientific information is available on the nutritive value of the fruit. However information from the Internet shows that it is suspected to have large amount of ascorbic acid. Quote. "the fruit mg/loog shows it has large amount of vitamin C. JAM. Jam is defined as semi - solid food product made by not less than 45 part of fruit pulp to which 55 part of sugar have been added to obtain a soluble solid content of not less than 65 Brix. 4'1) The main component involved ~Jam manufactures are a) Fruit pulp - for product identity. b) Sugar - for preservation/ inversion! Jam rigidity. c) Pectin - for continuity, network structure. d) Acid - for rigidity, preservation. It has been scientifically analyzed and proven that pectin level and acidity value of the fruit pulp have an effect on the various attribute of the Jam made from the fruit pulp especially its hq,~ strength in terms of rigidity and continuity pectin ahi BliMo effect on the rigidity while acidity has effect on continuity. Acidity is measured in terms of PH and titratable acidity. The most important acid in fruit q}re citric acid, tartaric, malic, succinic as well as ascorbic acid. The pre-dominant fruit is citric acid. acid in baobab The taste and flavour of the fruit mainly depend on the sugar: acid ratio and the buffer effect. Another importance attached on acidity is the stability given to the fruit against microbial degradation and vitamin oxidation. Endogenous acid could be insufficient or in excess in which case supplementation and neutilization is required respectively. The sugar in the fruit gives the sweetness of the product. The sugar includes fructose, sucrose, SYiJQ6e and glucose content. Sucrose is an important sugar, which result into invert sugar on heating in presence of an acid. Supplementation preserve. is required most cases to make the sugar 3

6 RESEARCH DESIGN & METHODOLOGY Materials. Baobab fruit were obtained from Kibwezi. Sugar was bought from the supermarket. Chemicals. The chemical used in the laboratories stones within and without Nairobi. were obtained from various chemical industries and PROCESS FLOW DIAGRAM Baobab fruit C~g ~ of the fruit, removal of the outer cover ~ Fruit PtP (powder) soaked in water Fibres and seeds were removed by sieving the fruit pulp using muslin cloth ~ FruitP!P Mix fruit pulp with 75% sugar ~ Adjust the PH accordingly ~ Mix the rest of the sugar with appropriate pectin amount. Cook J,P - sugar mix fur sometime + Add sugar - pectin mixture Cook until Jam acquire a 67.5 brix ~ Fill hot.-..a;.in glass jar 4

7 + Cool in cold running water ~. At room tern 2 days I Scientific analysis & sensory evaluation accelerate storage 55 c for some Days I shelf life determination SCIENTIFIC ANALYSIS Fruit pulp Total soluble solids The abbe refractometer was used and Tss expressed as 0 brix. Total sugar (The luff- schoorl method; method no. 4 of the international federation of fruit juice producers, 1968) was used and the result given as percentage. Total titratable acidity. 10ml of the fruit pulp are pipetted into a conical flask. The pulp is heated till boiling start. 50 ml of carbon dioxide - free distilled water are added. 1ml of phenolphthalein solution is added. The mixture is titrated with 0.1 N NaoH up to appearance of a distinct red colour calculation. 1ml or O.lN NaoH represent 10m! mill equivalent of acid in 1 litre or 0.64g acid per litre, calculated as citric acid. Ascorbic acid content. Sml fruit pulp was mixed which 15m! of the 20% trichloroacetic acid solution and filtered. Sml of the filtrate was taken and Sml of the 4% KH solution was added and soon drops of the starch solution. This was then titrated with N - bramosuccinimide solution Calculation: vitamin C = VC. 176/178 mg. Where V = Volume of bramosuccinimide (ml) C = concentration of the N - bromosuccimide (mg/ml) The final result was expressed as mg/l00g. PH A PH meter was used. JAM SAMPLES Total soluble solids. The Abbe refractometer was used and the Tss express as ~rix. 5

8 Total titratable acidity loml of the fruit pulp was put in a conical flask was titrated with 0.1 ml of phenolphthalein was added. The mixture was titrated with NaoH up to the appearance of a distinct red colour. Total sugar. (The luff - schoorl method; method No. 4 of the international federation of fruit juice producers, 1968) was used and the result given as a percentage. Invert sugar. (The luff - schoorl method; method No. 4 of the international federation of fruit juice producer, 1968) was used and result given as a percentage Sucrose content Sucrose content = (total sugars - invert sugars) x 0.95 and the result given is a percentage. Shelflife. The Jam sample was stored at accelerated storage i.e. 55 C for some day and analysed for any physical changes. PH A PH meter was used. STUDY DESIGN Pectin 1% of the total mass PH is adjusted to 3~.l.- Sample Fruit pulp % 50% 55% 60% Sugar 60% 55% 50% 45% 40% "Brix Titratatable acidity Reducing sugar Non - reducing sugar Organoleptic analysis Hedonic -9 --point rating will be used to asses the sensory quality. The 5 samples were each 'iibq[~7 -a.placet.on a table. 14 panelist were each called over at different times to taste the product and give their opinion by filling in the score sheet. The samples were spread on bread. Tea was served to aid in swallowing. 6

9 SCORE SHEET FOR SENSORY EVALUATION Name Date. Please eat and taste free sample presented to you and indicate your degree of liking for colour, taste or flavour, texture or appearance, spread ability, mouth feel or smoothness, appearance and overall acceptability of each sample on the basis of the following scale. 9 - like extremely 8 - like vel)' much 7 - like moderately 6 - like slightly 5 - neither like nor dislike 4 - dislike slightly 3 - dislike moderately 2 - dislike vel)' much 1 - dislike extremely Please place the number matching your degree of liking for each quality attribute in the corresponding box for each sample. Sample code Colour Taste / flavour / aroma Viscosity / appearance Spreadabili ty Mouth feel/texture Overall acceptability Comment:. Ngura. 7

10 RESULTS & DISCUSSION RESULT a) Fruit pulp analysis Parameter Total soluble solid Total sugar Total titratable acidity Value 13 v brix 9.7 mg/l l.6% PH 2.7 Ascorbic acid content 12.62mg/l00mg The fruit has a high acidity hence its low PH. It has a substantial though slightly less than was expected i.e. 16mg/l00m amount of ascorbic acid b). Jam sample analysis Sample code Attribute PH Total soluble solid (brix) Titratable acidity (%) Total sugar 4l Much sugar Sucrose content Sample code Fruit pulp % Sugar % After making Jam making various parameters tested changed. Though PH does not change too much, the titratable acidity is greatly reduced. The total sugar are higher than before because of exogenous sugar was added. Most the total sugar was inverted leaving behind a little un-inverted sucrose. 8

11 (c) Storage At room temperature, the result were as recorded in the scientific and organoleptic analysis. At accelerated storage after 18 days all the sample turned dark brown and become more rigid, and sample 275 solidify completely. (d). Organoleptic - analysis. Sample code Attribute Colour Mean Std dev Taste/ flavour/ aroma Mean Std Dev Viscosity/ appearance Mean Std Dev Mouth feel/texture Mean Std Dev Overall acceptability Mean l Std dev

12 Hedonic (rating on a point scale) Variable Mean Std dev Colour Taste! flavour Viscosity! appearance Spreadability Texture/ mouth fell Overall acceptability :#-' From the 1st table the various samples showed variatio\ and 280 were regarded the best. Sample 291 was the least acceptable. In the second table all the means were above 5 meaning all the characteristics of the Jam were acceptable to the consumer. The overall acceptability showed that the consumer liked the Jam generally. Lcompare individual attributes from each sample. (1) COMPARING INDIVIDUAL ATTRIBUTES FROM EACH SAMPLE a) colour Source of df ss ms f-ratio variation Calculated tabulated Total Treatment /\ Residual b) Taste/flavour/ aroma Source of df ss ms f-ratio variation Calculated tabulated Total Treatment Residual

13 c) Viscositv/aooearance Source of df ss ms f-ratio variation Calculated tabulated Total 17 l Treatment 4 2l Residual l d) Soread abilitv Source of df ss ms f-ratio variation Calculated tabulated Total 17 14l.649 Treatment 4 22, Residual e) Texture/mouth feel Source of df ss nu f-ratio variation Calculated Tabulated Total Treatment Residua j) Overall acceptability Source of df ss ms f-ratio variation Calculated tabulated Total Treatment 4 2l Residual l

14 (11) COMPARING SAMPLES A) OveraU acceptability Source of df ss ms f-ratio variation Calculated tabulated Block Treatment Residual l.035 Total B) Spread-ability Source of df ss ms f_r~tln "~n~tlnn Calculated tabulated Block 1 l ,51 Treatment Residual Total (111) COMPARING PANELIST EFFECT Overall acceptability Source of df ss ms.r. r~+~" variation Calculated tabulated Sample Panelist Residual Total B) Spreadability Source of df Ss ms f-ratio variation Calculated Tabulated Block l Treatment 13 64, Residual l.299 Total

15 DISCUSSION Fruit pulp analysis A total soluble solid content of 13 Brix was reported, arising from any dissolved substances found in the pulp. This showed about 13% soluble solid per loogm. A direct indication that a lot of dissolved nutrient found in the pulp of the dissolved which is low for jam manufacture. This necessitated supplementation solids, 9.7mgll was total sugar, of sugar. This sugar contributes to the sweetness and firmness of the Jam. The main sugar includes glucose, fructose and galactose. A total titratable acidity of 1.6% was reported. The PH showed that the fruit pulp was about 2.6. Thus low PH showed the fruit pulp was microbially stable. The acid - sugar ratio has a direct effect on the flavour of the pulp. The acid taste depends on this ratio and the resultant buffer effect. The main acid of concern are citric, malic and tartaric acid, citric acid being the predominant acid. Acidity also contribute to the firmness of the Jam. The vitamin content of the pulp was studied showing that the pulp was a good source of vitamin C. the ascorbic acid content of pulp was 12.62mg/l00g. showed that the fruit contained about 16mg/l00g On average, literature ascorbic acid and was termed as a very good source of the vitamin. This vitamin is important for collagen synthesize and as an antioxidant and it also gives the fruit pulp quality. It helps to prevent scurvy. It is labile to heat, air, alkalis and catalys~ ::> JAM MANUFACfURE. Process \ The fruit were sorted to remove any bruised fruit, which could lead to spoilage of the whole batch. These bruised fruit could also lead to contamination of the pulp. The fruit was crushed to remove the outer cover, then the fruit pulp was soaked in water for 3 hours to loosen the powder. The fruit pulp was then sieved using muslin cloth to remove seed and fibres. Care was taken to ensure the seeds were not crushed to prevent astringency resulting from better tannin found on the seed. The NaHC03 was used to adjust the PH according to the sample to be studied. Some sugar was added to the pulp while the rest was mixed with the pectin for proper 13

16 dispersion. The pulp - sugar mixture was cooked. During cooking, the sugar was absorbed into the fruit pulp. This being facilitated by the water in the pulp. This caused an increase in brix. Sugar hydrolysis occurred resulting in the inversion of sucrose.. In addition, cooking resulted in sugar - sugar reactions giving the brown to the Jam. This is known as caramelization - some of the water evaporated while rest was absorbed within the matrix of the Jam. The jam was then filled hot into glass jars. INGREDIENTS. The major ingredients are sugar and fruits pulp ingredients. To form a pectin gel, water, sugar and acid are needed. The level of ingredients is specific to give a good quality product. Pectin, sugar and acid are responsible for jam quality. Jam is a 3 - dimensional network where water and dissolved material and pulp are immobilized. Pectin is responsible for the network. This network is influenced by sugar and acid. For best quality, optimal levels of sugar, acid and pectin should be used. Optimal levels are shown in figure below: - Jam strength ~.. Continuity Concentr tion of pectin 1.5% 1.0% 0.5 Yo ~ Hard/ firm Jam ~. Optimum ~ No Jam ~. 1:---- Acid PH I RIg,. td' ity 2.7~6 bri~;:j~m+ N:;am 3.2 Optimum Sugar " 64% Weak jam 67.5% Optimum 70.0% Crystal Jam The quality of jam refers to jam strength, which consists of two components (i.e.) jam continuity and jelly rigidity. Influence on Jam strength by pectin, sugar and acid a). Role of pectin. Pectin is high molecular carbohydrate, which act as unifying, galling, stabilizing and thickening agents. 14

17 Food chemistry codex definition. "Pectin is a hydrophilic colloidal carbohydrate consisting chiefly of partially methoxylated polygalaturonic acid units - a linear galaturonoglycan of x-i,4, linked and galactopyano- syluronic acid" They are found in cell walls and middle lamella of tissue of plant. The commercial pectin is mainly extracted from citrus peel, apple pomace and beet pulp using hot dilute acids ph 1 to 3.5, temp. 70 C to 90 C.its precipitated form extract with ethanol or isoproponal or metal salts e.g. copper and aluminium. The precipitate is purified, dried and pulverized to form a yellowish, whitish powder. Commercial available pectin are classified according to their degree of methoxylations ( esterification of methoxy content) Two classes include low ester and high ester pectin. The low ester pectin are important for jam manufacture because they have more non-methoxylated group these nonmethoxylated groups and undissocited group are more important. The dissociated groups are more hydrophilic then the undissociated groups. The pectin-water bonding results in hydration/solubility of the pectin by hydrogen bonding while pectin-pectin bonding results in continuity of the Jam. In a solution of pectin, pectin-water bonding is favoured. Two type of pectin are used. The slow set pectin, which sets at 55'C is ideal for jellies only while rapid set pectin(sets at 85'C) is used for jams- and marmalades though it can also be used Jelly. b) Role of acid In a pectin solution, non-methoxylated groups appear as dissociated carboxyl ions. Acids influence dissociation of the pectin molecule. High acid levels cause a shift in equilibrium to the left to form-undissociated carboxyl groups, which bind much less water. This causes exudation of the water molecules from the matrix of the Jam resulting in the 'weeping of Jam The Jam becomes more and more rigid due to increased pectin-pectin bonding. 15

18 r~ c) Role Sugar ( In a pectin solution, the pectin-water bond is favored over pectin-pectin bonds. This is the reason why the pectin stays in solution. A stearic effect is created when water molecules cluster around the carboxylic molecules. The water separates pectin a molecule so linking to form pectin-pectin bonds is inhibited. When sugar is introduced, sugar-water bonds are preferred to both pectin-pectin bonds and pectin-water bonds. The net effect is that water is withdrawn from the vicinity of the pectin. The sugar acts as a dehydrant. The pectin molecules can then move and link up to form pectin - pectin bonds. Sugar promotes the formation of these bonds resulting in a firm Jam. The proportion of sugar which pectin will form into a firm jam, gives the Jam grade-jam breaking strength, elasticity and extent of sag. Organoleptic Analysis From the ANOV A tables produced for each of the attributes showed that there was no significant difference in attributes in the different samples. The calculated F-value was less than the tabulated F-value. This means that the differences were due to error not necessarily showing a difference in the samples as far as the Jam characteristics studied are concerned. From ANOVA tables produced by comparing the samples, both the overall acceptability and spreadability showed no significant difference indicating that the samples were the same and the various treatments did not affect the Jam quality. From the ANOV A tables produced by comparing the panelist effect, the results showed very significant effects. The differences noted from this study were highly significant. 16

19 c ~ n ~~ I.;->-J CONCLUSION AND RECOMMENDATION ~,..; v? Conclusion The Baobab fruit pulp has high ascorbic content and is termed to be a good source at ~"t4-::-.the vitamin-it is also high acidic and therefore microbially stable. The pulp can be used to [.ef ~ manufacture a good j am at acceptable quality. The study showed that there was no significant effects fruit pulp and sugar level on strength of the jam. According to the rating of sensory evaluation there was need to improve on appearance and spreadability. This is because they had a smaller mean relative to other sensory parameter. This can be due to the choice of panelists for sensory evaluation who could have given erroneous conclusions -They could have been influence by the 1st sample tested and used to that t1udge the rest of the samples. Recommendation All in all this was a challenging project that required a great deal of study. I would recommend that more research be carried out in this fruit -Baobab.It can very well change the attitude people have about it.1 would also like to recommend the development of other food products from fruit e.g. wines, sauces. aroma extracts, etc The seed can also be used to extract oil for further product development. 17

20 REFERENCES 1. Considine P-E. Foods and Food Production Encyclopaedia Van Nostrad Reinhold Company 1982 New York. 2. Desrosier IW. Technology of food preservation AVI Publishing Co. 1977(4 th edition) Westport, Connecticut 3. Gisela Jellinek Sensory evaluation of food Ellis Horwood International Publishers 1985 Chichester, England. 4. Sophie & Sehmi Fruits and vegetables & techniques of food analysis lectures University of Nairobi 5. Ranganna, S. Manual of Analysis of Fruit &Vegetable products. Tata McGraw-Hill Publishing Co. Ltd Samson IA. Tropical fruits Longmann Singapore Publishers 1986(2 nd edit ion) Singapore 7. Watts B.M. et. al. Basic sensory methods for food evaluation International Development Research Centre