Effect of Linseed (Linum usitatissimum L.) hydrocolloid as edible coating on decreasing oil absorption in potato chips during Deep-fat frying

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1 International Journal of Agriculture and Crop Sciences. Available online at IJACS/2013/6-2/63-69 ISSN X 2013 IJACS Journal Effect of Linseed (Linum usitatissimum L.) hydrocolloid as edible coating on decreasing oil absorption in potato chips during Deep-fat frying Forough Tabibloghmany 1 *, Mohammad Hojjatoleslamy 2, Fahimeh Farhadian 1 and Elham Ehsandoost 3 1. Department of Food Science and Technology, Young Researchers Club, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran. 2. Department of Food Science and Technology, shahrekord Branch, Islamic Azad University, Shahrekord,Iran 3. Department of food science and Technology, Young Researchers Club, Kazerun Branch, Islamic Azad University, Kazerun, Iran. *Corresponding author ftloghmany20@yahoo.com ABSTRACT: The objective of this research was to study the effect of Linseed (Linum usitatissimum L.) hydrocolloid on some physico-chemical properties of fried potato chips such as moisture content and oil uptake, acidity, peroxide value, texture and color during Deep-fat frying. The slices of potato were immersed in 1.5%, 2% and 2.5% aqueous solution of Linseed hydrocolloids at room temperature for five minutes. A control treatment was immersed in water and a Xanthan treatment was immersed in aqueous solution of Xanthan hydrocolloid in a same condition. The results of experiment showed that all three concentrations of Linseed hydrocolloid (1.5%, 2% and 2.5%) were effective in decreasing oil absorption but the highest effect was showed by treatment of 1.5% Linseed hydrocolloid solution. The investigation revealed that treatment with 1.5% Linseed hydrocolloid was the best in decreasing oil uptake, acidity and peroxide value of extracted oil, increasing moisture content of potato chips with no changes in texture compared to control sample. Sensory evaluation of treated potato chips did not show significant differences (p 0.05) compared to Control samples. The results point out the suitability of using residue Linseed hydrocolloid as edible coating for decreasing oil absorption in potato chips from both nutritional and economical aspects. Keywords: Linseed, oil absorption, potato chips, hydrocolloid INTRODUCTION Frying is one of the oldest cooking processes of food, inducing chemical and physical properties changes including starch gelatinization, protein denature, water vaporization and crust formation. This process affects heat and mass transfer, causing oil movement into the product as well as water movement from the product into the oil. (BeMiller and Whistler, 1996) Deep-fat frying is a widely used method for preparing foods. The aim of deep-fat frying is to seal the food surface by immersing food pieces in the hot oil so that all flavors and juices are retained inside.the high temperature causes partial evaporation of water, which moves away from the food and through the surrounding oil. The soft and moist interior along with the porous crispy crust provides increased palatability to foods.moreover, interest in low fat products has recently increased. Fried foods also contain high amount of fat, yet remain popular. One of the main problems associated with fried food is its high oil content; as a result, owing to its association with the high incidence of diseases. Interest in low fat product has recently increased as excess fat consumption is considered to heighten blood cholesterol, high blood pressure and coronary heart disease. Thus, research in reducing oil absorption during deep-fat frying has been intense in recent years. Recently, many investigations were carried out with the aim of lowering oil intake during deep fat frying. They were mostly focused on ingredients addition (chemical compounds) that could lower oil absorption, cooking

2 technology (time and temperature) and pre-treatment procedures. (Koelsch, 1994; Krochta and de Mulder- Johnston, 1997; Williams and Mittal, 1999). Among these, hydrocolloids are another factor that can play a leading role for oil reduction.(mellema, 2003). Hydrocolloids have been used as multifunctional additives in food processing. They are added to control and to improve physical properties like viscosity, water binding capacity and emulsion stability. It was also reported that some hydrocolloids, mainly long chain polysaccharides, could reduce oil absorption during deep fat frying. (Ang, 1993; Koelsch and Labuza,1992; Mallikarjunan et al., 1997; Nelson and Fennema, 1991; Williams and Mittal,1999) There are two main ways of applying hydrocolloids in fried products. The first is as an aqueous solution forming what is generally known as edible coating on the food to be fried. Its main purpose, although not the only one, is to reduce oil absorption. The second is as a batter ingredient in battered or breaded foods. This is a field which has seen spectacular development in recent decades. (Fiszman and Salvador, 2003) Some of the most useful hydrocolloids are cellulose derivatives such as methyl cellulose (MC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC) and carboxyl methyl cellulose (CMC). (Albert and Mittal, 2002) All these cellulose derivatives are water soluble with good film-forming properties. Alginate and pectin are widely used in food systems to stabilize and to modify the rheology of food. Linseed or flax(linum usitatissimum L.) is an annual crop belonging to the family linaceae(s).this plant grows to a height up to 60 cm, with slender and very fibrous stems, lanceolate leaves having three veins, up to 4 cm long and 4 mm wide, and its bright blue flowers are up to 3 cm in diameter. The fruit contains a seed known as flax seed or linseed.fig1. Linseed is considered a functional food or source of functional ingredients, because it contains alpha-linolenic acid, lignans and polysaccharides (other than starch), all of which have positive effects in disease prevention. Although scientific evidence supports linseed consumption, many people are still unaware of the benefits provided by this product and its possible applications in the production of foodstuffs. (Bunney, 1992). The aim of this study was to investigate the influence of Linseed (Linum usitatissimum L.) as new hydrocolloids on decreasing oil absorption in potato chips. To our knowledge this is the first study on the feasibility of employing Linseed as edible coating on decreasing oil absorption in potato chips during Deep-fat frying. Figure1. Linseed or Flax (Linum usitatissimum L.) MATERIALS AND METHODS MATERIALS Potato tubers (Solanum tuberosum) and Linseed (Linum usitatissimum L.) were purchased from a local market (Kazerun,Iran). Edible oils (sun flower oil, soy bean, Cottonseed) for frying were purchased from Behshar industrial company in Iran. N-hexane solution (C 6 H 14 ) with a purity of 95% (with Molecular mass gram /mol and free acid less than %), acetic acid with a purity of 98-99%, pure chloroform, pure starch and phenolphthalein were obtained from Merck Germany. (MERCK, Germany).Xanthan gum was purchased from Canco Canada company. Sodium thiosulphate (with Molecular mass gram /mol and with purity more than 64

3 95%) were obtained from Ghatranshimi Company of Iran and refined iodized salt with purity more than 99.2% was purchased from Iran ArossShahr Company. Extraction of Gum Initially distilled water at 85 was added to cleaned Linseed with ratio of 1:14 and for 3 hours was left under mixing with rpm (Eurostar IKA -WERKE) and degrees centigrade, subsequently extracted gum was separated by Auto Juicer/ Extractor (Sanyo electric co.ltd.japan, model SJ 5400) and separated gum was purified with the addition of 96% ethanol in a ratio of 1: 3. Purified gum was dried in vacuum oven (Fabrikstrasse2.D-79312emmendingen Germany) at 39 and pressure gauge 0.6 bar subsequently was grinded (IKA -WERKE Germany) and was sieved by sifter (mesh 60). Finally the obtained gum was packaged in Poly- Amid bag. Potato slices preparation The potato tubers were washed, hand-peeled and cut to slices with a thickness of 1.5 mm by a operated potato-slicing device, then prepared slices of potato were casted by steel mold with diameter 3 cm as all of slices were uniformed circles with diameter of 3 cm and thickness of 1.5 mm. The prepared slices of potato were blanched in brine 3% at 85 for 3.5 min. After blanching, the slices of potato immersed in 1.5%, 2% and 2.5% aqueous solution of Linseed hydrocolloids at room temperature for five minutes.also a control treatment was immersed in water and a Xanthan treatment was immersed in aqueous solution of Xanthan hydrocolloid in the same condition.subsequently, the slices were drained and dried in oven (WT-binder) at 150 for 10 min to reduce the surface water. Frying Frying was carried out in a thermostatically temperature-controlled fryer (HOME KING Germany) having a capacity of 1L of oil. The slices were fried at150± 10 for 10 minute in frying oil with a constant product weight/oil volume ratio of 1:5. Because we had 5 different batches of treated slices potato, the oil was changed after each batch of treated slices. All fried samples were allowed to cool to room temperature and analyzed for solid matter, as well as oil content. In industry the most common frying temperature for potato product is 180 we selected a medium (150. In this study, ) frying temperature.because Previous findings show that acrylamide (a possible carcinogen in humans) formation in potato chips could be reduced significantly by decreasing the frying temperature (Haase et al.,2003; Pedreschi et al., 2004).All experiments were run in triplicate and the present results are the average of the obtained results. ANALYTICAL METHODS Moisture content was determined by drying in oven at 105 until constant weight was reached. After 3 hours; all samples were weighed every 5 minute until a constant weight was attained. The oil content was determined by a sample and rapid method that consists of weighting, crashing of slices chips and immersing in a 250 ml beaker containing 200 ml of Hexane per 100gr slices at 28 for 45 minute. Then, beaker content was screened by filter paper (Wattman no.50), subsequently Hexane was removed by evaporation at 45 in rotary evaporator (Heidolph model no Laboro TA4000) and the extracted oil which remained in the Distillation flask was weighed in an analytic balance. Moisture and oil contents of samples were expressed as percentage of original samples (w/w). Peroxide Determination 5-4 gram of extracted oil was weighted in Erlenmeyer flask and 30 ml mix of Acetic Acid-Chloroform was added to it. Then 5 ml saturated Potassium Iodine aqueous solution was added to it and was left in dark conditions 65

4 for 1 minute.after This 30 ml distilled water was added to it and a few drop starch aqueous solution was poured and then was titrated by Sodium Thiosulphate (0/01 molar) to disappeared blue color Peroxide value is calculated according to mili equivalents oxygen in kilogram extracted oil: P= V=milliliter of volume used Sodium ThioSulphate solution (0/01 molar) in titration N=normality of Sodium ThioSulphate solution W=weight of oil P=peroxide value Acidity of extracted oil gram extracted oil was weighted in Erlenmeyer flask and was added 30 ml neutralized solution of Ethanol and 2 milliliter phenolphthalein in to it and then was titrated with sodium hydroxide (0/01 molar) aqueous solution to appear pale pink color. Free Fatty Acid is calculated according to oleic acid per 100 gram oil: Q = V = milliliter of volume used Sodium hydroxide aqueous solution (0/01 molar) in titration N = normality of Sodium hydroxide aqueous solution W=weight of oil Q= Free Fatty Acid according to oleic acid Texture measurement Texture measurements of potato chips were performed at room temperature (20 ) by a puncture test performed in a Texture Analyzer (Brookfield). Samples were punctured with a cylindrical plunger. Depth of penetration was 1 mm, thickness and diameter of samples was 0.8 mm and 2.5 cm respectively. Force vs. distance curves were generated with the puncture test. Maximum force at rupture was determined from the force deformation curves. The punch diameter was 1 mm. The parameter maximum force (MF) was obtained from the force vs. Color determination The color of slices chips samples was measured by image processing plus software (Fig.1). In order to Photography using a camera (Sony.Cyber-shot, 16.2 Mega Pixel) was performed in specific box under angle light. Since the color surface of a potato chip is highly heterogeneous due the complex distribution of water, starch, reducing sugars, principally, it is generally important to compute the average color which is representative of the complete surface. Each sample was measured in ten different locations to determine L*, a* and b* values where L*(lightness) was the quantity of reflected light and chromatic-ordinates, a* (redness) and b* (yellowness). The results were expressed as mean in the L*a*b* by image pro-plus software. Figure1.Schematic representation of the image acquisition and processing system used to measure the potato chip color in L*, a* and b* units. 66

5 Sensory evaluation A panel of 15 assessors with experience in sensory evaluation was selected to evaluate the samples of potato chips. The intensities of sensory attributes odor, taste, color, texture, and flavor. Fried slices was immediately after production, presenting five samples of four slices to the panel in random order to be scored for intensity using an ordinal scale and a five-point hedonic scale from 1 (like extremely) to 5 (dislike extremely). The procedure and analysis of results were carried out following standard methods. Statistical analysis All measurements were performed at least in triplicate and mean values were reported. All statistical analyses were performed using SPSS software program statistics. Analysis of variance (ANOVA) was performed to study differences in quality parameters of deep-fat fried potato slices coated with hydrocolloid of different formulations. When significant differences were found the Duncan comparison test was applied to determine the difference among means. Statistical significance was expressed at the 5% level. RESULTS AND DISCUSSION Comparison of the moisture content and oil uptake of coated and uncoated fried products Statistical analysis have shown that use of hydrocolloid coatings has a significant effect on the moisture content of slices chips (p 0.05).As samples treated with 1.5% Xanthan had the highest moisture content. Also, it can be seen that all three concentrations of Linseed hydrocolloids were effective increasing moisture content. So the highest moisture content was treatment of 1.5% Linseed hydrocolloid.in addition the results have shown that immersion in 1.5% Xanthan hydrocolloid solution has a significant effect on the oil uptake (p 0.05). The results of experiment showed that all three concentrations of Linseed hydrocolloid (1.5%, 2% and 2.5%) were effective in decreasing oil absorption but the highest effect was showed by treatment of 1.5% Linseed hydrocolloid solution. It is known that hydrocolloid treatment may alter the water holding capacity and consequently affect oil uptake (Rimac-Brncic et al.2004). This result may attributed to the presence of hydrocolloid coatings acting as lipid barriers, particularly 1.5% Xanthan and 1.5% Linseed hydrocolloids due to its thermal gelation properties. The moisture content and oil uptake of coated and uncoated potato chips are shown in Table1. These results were in good agreement with the study of Laboratory production of low fat potato chips with application hydrocolloid coatings who found that hydrocolloid coatings (such as different concentrations of pectin, sodium alginate and CMC) increases the moisture content and decreases oil uptake in potato chips. Similar findings were also observed by Rimac-Brncic et al, 2004 in increasing moisture content and decreasing oil uptake with application of 1% solution of CMC coating on strip chips. Table 1. Moisture content and uptake oil in different treatments of potato chips Treatment Moisture content Uptake oil Blank 2.85 a a 1.5% linen 6.52 b b 2% linen 5.41 c c 2.5% linen 4.52 d d 1.5% Xanthan e e Results have been expressed as mean. Means that have been shown in a column with different letters, according to Duncan test at level p 0.05havesignificant difference together. Evaluation and Comparison of the hydrocolloid coatings on acidity and peroxide value of extracted oil of potato chips Peroxide value (PV) is milli equivalent peroxide in per 1000gram oil or fat sample that according to Lee method in fats and oils should be less than 5 ml and according to International unit should be less than 10 ml. Application of selected hydrocolloid coatings at level of p 0.05 is caused decreasing significantly in peroxide value. The investigation showed that the lowest PV was related to the treatment of 1.5% Xanthan and 1.5% Linseed hydrocolloid solutions.also, treatment of 2.5% and blank had no significant difference (Table 2) 67

6 .Acidity is expressed according to free fatty acid (Oleic acid) per 100 gram oil.acidity of treatments and blank at level of p 0.05 had no significant difference (Table 2). Table 2. Peroxide value and acidity in different treatments of potato chips. Treatment PV Acidity Blank 1.83 c a 1.5% linen 1.04 a a 2% linen 1.22 b a 2.5% linen 1.92 c a 1.5% Xanthan 1.03 a a Results have been expressed as mean. Means that have been shown in a column with different letters, according to Duncan test at level of p 0.05 have significant difference together. Texture analysis In this study, the force required to break the chips (hardness) was increased by decreasing moisture content of potato chips.as the highest hardness was related to blank sample and the lowest hardness was related to Xanthan treatment.however among treatments of 2%, 2.5% and blank at level of p 0.05 had no significant difference (Table 3). The texture in the treatments of coated by Xanthan was very leathery and had no notable hardness, but other treatments were much more brittle. Table 3. Hardness in different treatments of potato chips. Treatment Hardness Blank c 1.5% linen b 2% linen bc 2.5% linen c 1.5% Xanthan a Results have been expressed as mean. Means that have been shown in a column with different letters, according to Duncan test at level p 0.05have significant difference together. Color measurement In defining and quantifying color, a color system must be selected, usually among four alternatives: L*a*b*, RGB (Red, Green, Blue), XYZ and CMYK (Cyan, Magenta, yellow, black). Color of fried potatoes has been measured usually in units L*a*b* using either a colorimeter or specific data acquisition or image processing systems. L*a*b* is an International standard for color measurements, adopted by the Commission International ed Eclairage (CIE) in This color model creates a consistent color regardless of the device used to generate the image (e.g., monitor, printer or scanner). L* is the luminance or lightness component, which ranges from 0 to 100, and parameters a* (from green to red) and b* (from blue to yellow) are the two chromatic components, which range from 120 to 120. In contrast with other color models such as RGB and XYZ, in the L*a*b*space the color perception is uniform. This means that the Euclidean distance between two colors corresponds approximately to the color difference perceived by the human eyes. (Pedreschi et al. 2002). In this study the L * value of all treatments at level of p 0.05 had significant difference. So that the lightest and the darkest treatment were related to samples of chips coated with1.5% and 2.5% Linseed hydrocolloid solutions, respectively (82.54 vs ).The lowest and highest a * was related to Xanthan and blank treatments respectively ( vs ). The b * value of all treatments at level of p 0.05 had significant difference. The b * values was ranged from The highest yellow was seen in treatment of 2.5% Linseed. Due to effect of coating hydrocolloid on enzymatic browning reactions were decreased. The results showed that increasing hydrocolloid concentration effect on the chips tissue and lead to get more yellow and less red. 68

7 Sensory evaluation Descriptive sensory evaluation showed five attributes identified in the taste, odor, flavor, texture and color potato chips samples. Exception of Xanthan treatments, all potato chip samples were generally liked and consumer sensory evaluation indicated that there was no clear preference of one sample over the others, despite of differences observed through descriptive sensory analysis and physico-chemical characteristics. Among three treatments of Linseed and blank sample, all of sensory parameters at level of p 0.05 no significant difference was seen. However Xanthan treatment was the most unfavorable because of leathery texture and unpleasant appearance.this treatment at level of p 0.05 had significant difference with others. CONCLUSION AND SUGGESTION The present work is considered as the first report demonstrating the suitability of using Linseed (Linum usitatissimum L.) as new hydrocolloid on decreasing oil absorption in potato chips.the results of this experiment showed that application of Linseed as coating hydrocolloid in preparation of potato chips cause to decrease oil uptake, acidity and peroxide value of extracted oil, increase moisture content of potato chips with no changes in texture compared to blank treatment. The investigation revealed that the treatment with 1.5% Linseed was the best in above cases.although, Xanthan treatment potato chips had highest moisture content and lowest oil uptake. This Treatment was evaluated the most unfavorable for sensory and texture evaluations. Therefore application of residue Linseed hydrocolloid as edible coating is acceptable for decreasing oil uptake potato chips from both nutritional and economical aspects. REFERENCES Albert S, Mittal GS Comparative evaluation of edible coatings to reduce fat uptake in a deep-fried cereal product. Food Research International 35: Ang JF Reduction of fat in fried batter coatings with powdered cellulose. Journal of American Oil Chemistry Society 70: BeMiller JN, Whistler RL Carbohydrates. In O. W. Fennema (Ed.), Food chemistry, (3rd ed.). New York: Marcel Dekker, Inc. Bunney S The Illustrated Encyclopedia of Herbs (Their Medicinal and Culinary Uses). Chancellor Press, London, p Fiszman SM, Salvador A Recent developments in coatings batters. Trends in Food Science & Technology14: Haase NU, Mattha us B, Vosmann K Minimierungsan- sa tze zur Acrylamid-Bildung in pflanzlichen Lebensmitteln-aufge- zeigt am Beispiel von Kartoffelchips. Deutsche Lebensmittel-Rundschau, 99: Koelsch C Edible water vapor barriers: properties and promise. Trends in Food Science and Technology 5: Koelsch CM, Labuza TP Functional, physical and morphological properties of methyl cellulose and fatty acid based edible barriers. Lebensmittel Wissenschaft und Technologie 25: Krochta JM, de Mulder-Johnston C Edible and biodegradable polymer films: challenges and opportunities. Food Technology 51: Mallikarjunan P, Chinnan MS, Balasubramaniam VM Edible coatings for deep fat frying of starchy products. Food Science and Technology 30: Mellema M Mechanism and reduction of fat uptake in deep-fat fried foods. Trends in Food Science & Technology 14: Nelson KL, Fennema OR Methylcellulose films to prevent lipid migration in confectionary products. Journal of Food Science 56: Pedreschi F, Aguilera JM Some changes in potato chips during frying observed by confocal laser scanning microscopy (CLSM). Food Science and Technology International, 8(4): Pedreschi F, Kaack K, Granby K Reduction of acrylamide formation in fried potato slices. Lebensmittel- Wissenschaft und Technologie 37: Rimac-Brncic S, Lelas V, Rade D, Simundic B Decreasing of oil absorption in potato strips during deep fat frying. Journal of Food Engineering, 64: Williams R, Mittal GS Low fat fried foods with edible coatings: modeling and simulation. Journal of Food Science 64: