CC BY
65DOI: 10.25712/ASTU.2072-8921.2019.01.016 УДК 664
STUDY ON PHYSICO-CHEMICAL AND TEXTURE PROPERTIES OF GELATIN-FREE JELLY DESSERTS
N.V. Nepovinnykh, O.N. Kliukina, N.M. Belova, N.M. Ptichkina, A. Bostan
The aim of this investigation is to address the technological challenge of producing jelly desserts by replacing gelatin (overcome religious and ethical constraints) by non-starch polysaccharides (PS) of plant, bacterial or algal origin - individually (PS-1) or in binary mixtures (PS-1 - PS-2), to study the texture of desserts, responsible for gel network formation of dessert. Hydrocolloids are widely used in many food formulations to improve quality attributes and shelf-life. The polysaccharides assessed included alginate, pectin, konjac glucomannan, xanthan and guar gum, singly or in binary mixtures. The polysaccharides and their optimal concentrations were determined (konjac glucomannan 0.4%: xanthan gum 0.6%; locust bean gum 0.2%: xanthan gum 0.8%; iota-carrageenan 0.4%) as structuring agents for the production of desserts without gelatin.
Organoleptic quality of trial products was evaluated by subjective assessment of taste, consistency, aroma and appearance. Analysis of texture indicators of desserts was carry out. Probable shelf-life was assessed by measurements of moisture content and water activity.
Several organoleptically-acceptable and economically-viable new formulations were identified; one of these successfully reproduces the essential attributes of a well-established and widely-consumed traditional dessert.
Keywords: Non-starch polysaccharides; Gelatin; Alginate, Pectin, Konjac glucomannan, Xanthan gum; Guar gum.
1. INTRODUCTION
Traditionally jelly desserts mainly are produced with edible gelatin, milk or milk cream and sugar. The issue of gelatin replacement has been around for many years for the vegetarian, halal and kosher markets, but has recently gained increased interest worldwide with the emergence of the bovine spongiform encephalopathy virus [1]. Hydrocolloids are widely used in many food formulations to improve quality attributes and shelf-life. The one main of using hydrocolloids is gelling effect. Hydrocolloids form gels by means of physical association of their polymer chains through hydrogen bonding, hydrophobic association and cation mediated cross-linking. Hence, hydrocolloid gels are often referred to as "physical gels" [2, 3].
Mechanism and the resulting supramolecular structures forming a macroscopically homogeneous and sufficiently stable gel network are important in polysaccharide-protein systems.
The aim of this investigation is to produce gelatin-free jelly desserts, by replacing gelatin (overcome religious and ethical constraints) by polysaccharides (PS) of plant, bacterial or algal origin - individually (PS-1) or in binary mixtures (PS-1 - PS-2), to study the texture of desserts, responsible for gel network formation of dessert.
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2. MATERIALS AND METHODS
2.1. Materials
Commercial samples of the following food hydrocolloids were used for preparation of dessert gels: konjac glucomannan, xanthan gum (Danisco, France); iota carrageenan, guar gum (Sarda Starch Pvd. Ltd. India); locust bean gum from Ceratonia siliqua seeds (Sigma-Aldrich Co. LLC, USA); sodium alginate (DuPont Nutrition & Health, France); pectin (ZPOW Pektowin, Poland); gelatin (Russia, Krasnodar).
As recipe components for production of desserts beet sugar (Russia, Krasnodar); milk with 3.5 % of fat or milk cream with 20 % of fat (Russia, Saratov); vanillin (Russia, Moscow) were used.
Distilled water was used for dissolution of food hydrocolloids.
2.2. Methods
The sensory evaluation was performed in Sensory Laboratory of Food Science and Technology Department, Agrarian University. Desserts in quantity 10 g were poured in plastic dish, coded under a specific number and presented to 9 trained panelists. Organoleptic quality of products was evaluated by subjective assessment of appearance, consistency, smell, taste and colour. Each attribute was rated by a 5-point scale (0-1 for very bad, 1-2 for bad, 2-3 for fair, 3-4 for good and 4-5 for excellent), and individual scores were combined to receive a
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total score of product quality. Each dessert was evaluated three times by each panelist.
Calorie content of desserts was determined using chemical composition according equation (1):
Calorie content = 9 * Х1 + 4 * Х2 + 4 * Хз (1)
where Х1 - mass fraction of fat in the product, g / 100 g; Х2 - mass fraction of protein in the product, g / 100 g; Хз - mass fraction of carbohydrate in the product, g / 100 g [4].
Water activity (aw) of desserts was determined by cryoscopic method using AWC water activity meter (AWC, Saratov, Russia). The experiment was performed at room temperature (22 °C) using 10 g of sample. Average value of three replicate measurements was taken. A distinctive feature of the cryoscopic method of determining the activity of water in food products in comparison with other methods (hygrometric and "dewpoint") is the elimination of the influence of external factors, primarily temperature and humidity of the environment, since only the temperature of product is measured. This ensures high accuracy and reproducibility of results, especially in the upper range of water activity (above 0.9) [5].
Water activity was determined using equation (2):
-ln aw = 27.622 - 528.373*T - 4.579 ln T (2)
where T - cryoscopy temperature, K.
Moisture content (W) of desserts was determined using a moisture analyzer MX 50 (A&D, Japan). Three grams of sample was loaded on an aluminium plate and heated at 160 °C for 5 min. Average of three replicate measurements were done [6].
pH of systems was determined using the pH-meter Checer (Hanna, USA), which was calibrated using the standard pH buffer solution.
Analysis of texture indicators (hardness, adhesion, strength of adhesion, cohesion, index of elasticity, elasticity) was carry out using a texture analyzer CT 3 (Brookfield, USA). Probe TA5 (diameter cylinder probe is 12.7 mm) was used. Weight of dessert was 10 g. All experiments were carry out at room temperature (22 °C ± 1 °C).
Gel strength of desserts was examined by Valenta device is intended for measurement of gel strength of jellies products on basis of hydrocolloids with delivery of results of measurements in grams [7, 8]. Limit measurement of gel strength is from 100 g to 3000 g. Error limits not more than 10 %. Gel strength (Pk, g) - minimum weight of load, which break surface of gel by means of plunger with hemispherical nozzle of determined size (diameter 16 mm, height 10 mm). The surface of gel (weight of gel was 40 g) on which this nozzle presses has an area of 2 cm2.
3. RESULTS AND DISCUSSION
Technology of dessert preparation includes following stages.
Take ingredients (g): gelatin (after swelling) or polysaccharide, vanillin, beet sugar according recipe. Mix up ingredients, gets a dry mixture (if gelatin replace by polysaccharide). Take required amount of milk or milk cream, according recipe. Mix up. Get a liquid base. Heat the liquid base to 60 °C. Put a dry mixture into a liquid base at constant stirring. Heat until almost boiling, but do not boil. Put hot dessert into a mould, cool it.
Data of recipes and sensory evaluation of desserts are presented in Table 1.
Hydrocolloids Concentration of hydrocolloids, % Cream, g Milk, g Vanillin, g Beet sugar, g Water, g Sensory evaluation, total score
gelatin (control sample) 3.5 34.7 17.3 35.0 5.0
guar gum : xanthan gum 0.4:0.6 34.7 44.8 10.0 4.8
LBG: xanthan gum 0.2:0.8 34.7 44.8 10.0 5.0
konjac glucomannan : xanthan gum 0.4:0.6 34.7 44.8 1.2 8.3 10.0 5.0
iota carrageenan 0.4 34.7 51.4 4.0 5.0
pectin 0.7 34.7 48.1 7.0 4.9
alginate 0.7 34.7 48.1 7.0 4.5
Table 1 - Recipes and sensory evaluation of desserts (yield of dessert 100 g)
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As follows from Table 1 desserts with polysaccharides (LBG : xanthan gum; konjac glucomannan : xanthan gum; iota carrageenan) had best sensory characteristics. Total score of sensory evaluation was 5.0.
Formation of gel network in desserts is due to complex interaction of hydrocolloids, milk lipids and sugar.
Data of nutritional value and calorie content of desserts are presented in Table 2.
Table 2 - Nutritional value and calorie content of desserts (yield of dessert 100 g)
Hydrocolloids Concentration of hydrocolloids, % Hardness, MPa Adhesion, MJ Strength of adhesion, N Cohesion, MJ Index of elasticit y Elasticity, N
gelatin (control sample) 3.5 4.5 4.1 11.7 - 0.39 102±2
guar gum : xanthan gum 0.4:0.6 2.3 5.0 13.2 0.69 0.52 109±2
LBG: xanthan gum 0.2:0.8 2.3 5.0 13.2 0.69 0.52 109±2
konjac glucomannan : xanthan gum 0.4:0.6 2.3 5.0 13.2 0.69 0.52 109±2
iota carrageenan 0.4 2.5 5.3 13.2 0.28 0.57 112±2
pectin 0.7 2.4 5.2 13.3 0.48 0.54 110±2
alginate 0.7 2.4 5.2 13.3 0.48 0.54 110±2
It could be seen from Table 2, calorie content of desserts does not change when gelatin is substituted by non-starch polysaccharides since in these recipes the amount of milk was increased (see Table 1).
It should be noted that desserts (LBG: xanthan gum; konjac glucomannan : xanthan gum; iota carrageenan) had best sensory characteristics (see Table 1) as well as data of
gel strength. Results well corroborate with knowledge about synergetic effect between some hydrocolloids. Non-gelling agents (xanthan gum and galactomannans), and gelling agent carrageenan are commonly combined to improve properties of gels, such as elasticity [3, 9-11].
Data of physico-chemical properties of desserts are presented in Table 3.
Table 3 - Physico-chemical properties of desserts
Hydrocolloids Concentration of hydrocolloids, % Protein, g Fat, g Carbohy drate, g Dietary fibre, g Ash, g Calorie content, kcal
gelatin (control sample) 3.5 4.5 4.1 11.7 - 0.39 102±2
guar gum : xanthan gum 0.4:0.6 2.3 5.0 13.2 0.69 0.52 109±2
LBG: xanthan gum 0.2:0.8 2.3 5.0 13.2 0.69 0.52 109±2
konjac glucomannan : xanthan gum 0.4:0.6 2.3 5.0 13.2 0.69 0.52 109±2
iota carrageenan 0.4 2.5 5.3 13.2 0.28 0.57 112±2
pectin 0.7 2.4 5.2 13.3 0.48 0.54 110±2
alginate 0.7 2.4 5.2 13.3 0.48 0.54 110±2
As follows from Table 3, all samples could be put into the group of perishable products, their water activity being more than 0.9.
Desserts with polysaccharides (LBG: ПОЛЗУНОВСКИЙ ВЕСТНИК № 1 2019
xanthan gum, konjac glucomannan : xanthan gum and iota carrageenan) had the best strength characteristics compared to desserts with pectin and alginate. Desserts with polysaccharides
(LBG: xanthan gum, konjac glucomannan : xanthan gum and iota carrageenan) were selected for further study and production.
Texture data of desserts are presented in Table 4.
Table 4 - Texture data of desserts
Interaction of konjac glucomannan with xanthan gum does not absolutely require long sections of contiguous unsubstituted D-mannose residues but rather sections where all the galactosyl residues are located on one side of the main chain and may also serve as "junction zones" [3, 12]. Mixtures of xanthan gum and galactomannans with low galactose contents, e.g., carob galactomannan, form gels at total carbohydrate concentrations as low as 0.2 %. However, galactomannans with higher galactose contents, e.g., guar galactomannan, show only a slight degree of interaction with xanthan gum. Thus, it has been proposed that long sections of contiguous, unsubstituted mannose residues at the "junction zones" are required for interaction of galactomannans with xanthan gum and other polysaccharides [3, 13-16].
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All samples characterized by low elasticity as a comparison with control sample (Fig. 1). Despite reduced elasticity, sensory characteristics of samples are high, that was confirmed by data presented in Table 6 by indices of adhesion. Apparently, adhesion data in systems with polysaccharides is higher than in systems with gelatin.
This is also confirmed by high total scores of sensory evaluation. Adhesion data correlate with creamy and pleasant consistency of desserts with polysaccharides.
a b
с d
Figure 1 - Desserts: control sample gelatin 3.5 % (a), LBG 0.2 : xanthan gum 0.8 (b), konjac glucomannan 0.4 : xanthan gum 0.6 (c), iota carrageenan 0.4 % (d)
Desserts with non-starch polysaccharides do not show syneresis and do not change texture properties for a long time (during 48 hours).
4. CONCLUSIONS
Technologies of gelatin-free jelly desserts were developed by replacing in recipes of desserts gelatin with non-starch polysaccharides.
Sensory, physico-chemical and textural properties of desserts were studied. Obtained data indicate that properties of desserts are comparable with properties of control sample, and exceed it by adhesion index. It was confirmed by good sensory properties of desserts (creamy and pleasant consistency during chewing) [17].
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Hydrocoll oids Concen trationo f hydroc olloid, % Pk,g aw W, % pH
gelatin (control sample) Ю CO О 4 8 0.9646 ±0.003 2 70.83± 0.39 6.908± 0.016
guar gum : xanthan gum 0.4:0.6 о ю 0.9636 ±0.003 2 70.82± 0.39 6.933± 0.008
LBG: xanthan gum 0.2:0. 8 о ю 2 0.965 1±0.0 006 71.87 ±0.15 6.918 ±0.02 V
konjac glucoma nnan : xanthan gum 0.4:0.6 0 О 2 0.9643±0. 0006 71.56±0.0 9 6.928±0.0 25
iota carragee nan ■чг o о 6 СП 0.9636 ±0.003 2 70.82± 0.39 6.925± 0.026
pectin O 0 ю 0.9649±0 .0032 71.60±0. 61 6.935±0. 025
alginate O о 0 0.9648 ±0.003 2 71.62± 0.61 6.933± 0.025
ACKNOWLEDGEMENT
This investigation was carried out within of the joint scientific agreement named «Development of Reduced Calorie Dessert with Improved Quality Attribute Using Hydrogels» between scientific group from Saratov State Agrarian University, Russia and scientific group from Research Institute of Food Science and Technology, Iran.
This study was financially supported by the Grant of President of Russian Federation for young scientists (number MD-2464-2018.8).
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Nepovinnykh Nataliia Vladimirovna, Doctor of Technical Sciences, Professor, Department of Food Technology, Faculty of Veterinary Medicine, Food and Biotechnology, Saratov State Agrarian University named after N.I. Vavilov, nnepovinnykh@yandex.ru, tel: 8-917-209-309-4.
Klukina Oksana Nikolaevna, PhD, Associate Professor, Department of Food Technology, Faculty of Veterinary Medicine, Food and Biotechnology, Saratov State Agrarian University named after N.I. Vavilov,oksanaklukina@yandex.ru, tel: 8-919-82345-07.
Belova Nina Mikhailovna, graduate student, assistant professor, Department of Food Technology, Faculty of Veterinary Medicine, Food and Biotechnology, Saratov State Agrarian University named after N.I. Vavilov,nina 131191@.gmail.com, tel: 8-937-966-00-98.
Ptichkina Nataliia Mikhailovna, Doctor of Chemical Sciences, Professor, Department of Food Technology, Faculty of Veterinary Medicine, Food and Biotechnology, Saratov State Agrarian University named after N.I. Vavilov, n.ptichkina@.gmail.com, tel: 8-905-034-71-34.
Aram Boston, PhD, Department of Food Nanotechnology, Research Institute of Food Science and Technology, Km 12, Mashhad-Quchan Highway, Mashhad, Iran, arambostan@yahoo. com.
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