Asian J. Dairy & Food Res., 32 (3) : 228-234, 2013 AGRICULTURAL RESEARCH COMMUNICATION CENTRE www.arccjournals.com / indianjournals.com NUTRITIONAL SUPPLEMENTATION OF LOW-FAT FROZEN YOGHURT INCORPORATED WITH CARROT PULP Stuti Agarwal and Ranu Prasad Halina School of Home Science (Foods and Nutrition), SHIATS, Allahabad-211 002, India Received: 20-02-2012 Accepted: 26-06-2013 ABSTRACT Yoghurt is a fermented milk product which is produced by adding a mixed culture of Lactobacillus bulgaricus and Streptococcous thermophilus. Fermentation of milk sugar produce lactic acid, which acts on milk protein to give yoghurt its texture and its characteristics taste. The present study was carried out with different levels (2%, 3%, 4% and 5%) of carrot pulp. Frozen yoghurt mix was standardisation to 12 % sugar, 12 % SNF, @ 2% culture, Fat (0.5%, 1.5% and 3.0%) and Stabilizer (0.5%) adjusted to 26% total solids for frozen yoghurt. The low fat frozen yoghurt samples of different treatments were analyzed for organoleptic characteristics (flavour, body & texture, general appearance and overall acceptability) and nutritional characteristics (moisture, ash, fat, protein, acidity, ph & total solids). The data obtained on various parameters were statistically analyzed. Based on the results, it was concluded that the low fat frozen flavoured yoghurt with 3% carrot pulp, 0.5%, 3.0% fat ) are high as comparable with other treatments in the organoleptic characteristics (Flavour & taste, Body & texture, Colour & appearance and Overall acceptability) and nutritional characteristics (moisture, ash, fat, protein, acidity, ph & total solids). Key words: Carrot pulp, Frozen yoghurt, Sensory quality, Yoghurt. INTRODUCTION Yoghurt is coagulated milk product obtained by lactic acid fermentation through the action of Lactobacillus Bulgaricus and Streptococcuc Thermophillus, form milk and milk products (pasteurized or concentrated milk) with or without optional additions (milk powder, skim milk powder, whey powder etc.). The micro organisms in the final products must be viable and abundant (F.A.O/ W.H.O, 1977). (Shahani and Chandan, 1979). Anticarcinogenic effect of yoghurt has been demonstrated by Ayebo and Sahani, (1980). Frozen yoghurt is best viewed somewhere between real yoghurt and ice cream while it contains protein, the protein found in frozen yoghurt is often as little as a third the amount found in regular yoghurt and roughly equivalent to that found in ice cream. While ice cream is quite high in fat between 10 & 18% fat by weight-frozen yoghurt varies more widely. It usually has been fat than a comparable ice cream, but higher amount of fat and substantially more calories than comparable yoghurt. Fat free frozen yoghurt exists, but they often have even more added sugar than other varieties. (Tsang, 2009). Yoghurt is one of the most popular fermented milk products worldwide and has gained widespread consumer acceptance as a healthy food (Mckinley 2005). Frozen yoghurt has been the fastest growing product in the frozen dessert market in recent years (Opdahl and Baer, 1991, Guinard et al., 1994). Carrot (Dascus carota L.) is rich in Vitamin Yoghurt is more nutritious than several other A, B 1, B 2, C, E, Folic acid, beta carotene, fermented milks because of its higher milk solids carbohydrate, calci um, phosphorous, iron, content. Yoghurt is valued for its therapeutic value potassium, magnesium, copper, manganese and being known to have antibiotic and curative sulphur, besides having potent antioxidant property properties. Yogurt is also useful for controlling the, but lacks in protein and fat. Thus, carrot juice was growth of harmful bacteria and in curing intestinal found to be suitable for incorporation in the disease like constipation, diarrhoea, dysentery production of nutritionally rich yoghurt food. This * Corresponding author s e-mail Id: agrawalstuti159@gmail.com, eshu_chic@yahoo.co.in
study aimed at development and optimization of low fat frozen flavoured yogurt and to evaluate the organoleptic and nutritional characteristics of low fat frozen flavoured yogurt. MATERIALS AND METHODS The experimental work was carried out in the research laboratory of Warner School of Food and Dairy Technology, Sam Higgionbottom Institute of Agriculture, Technology and Sciences, Allahabad. Raw materials Milk: Milk was procured from Students Training Dairy, Sam Higgionbottom Institute of Agriculture, Technology and Sciences, Allahabad. Skimmed milk powder was purchased from the local market of Allahabad. Culture: Freeze dried culture of Lactobacillus bulgaricus and Streptococcus thermophilus were obtained from the Dairy Microbiology Division of N.D.R.I Karnal (Haryana). Other materials: Fresh carrot and sugar were purchased from the local market of Allahabad. Plastic cups of 100ml capacity also purchased from the local market of Allahabad. Stabilizer (Sodium alginate) was obtained from dairy technology. Culture propagation Mixed Culture: Mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus were propagated in sterile skim milk test tubes by inoculation and incubation at 37 0 C.After incubation the culture were stored at 50 0 C. Bulk culture: Bulk culture was routinely propagated in sterile skimmed milk for this purpose 2% of the active culture was introduced into skimmed milk and incubated at 37 0 C. After setting the culture were transferred and stored at 5 0 C until further use. Analysis of milk Determination of milk Fat: Fat percentage of milk was determined by Gerber method as per procedure given in ISI: 1224 part I (1977). Determination of Solid Not Fat: The SNF content of milk was determined by Richmond s formula as per the procedure laid down by Indian Standard: 2311(1973) Hand Book of Food Analysis. Standardization of milk SNF: Milk SNF 12%was standardized by using skimmed milk powder. Vol. 32, No. 3, 2013 229 Preparation of carrot pulp: Carrots were washed with warm water after removing top, bottom and surface layers to avoid surface contamination and blanched in hot water for 5 min to inactivate pectinase and peroxidise enzymes and also to tenderize it. Carrot was blended by using a food processor for carrot pulp (INALSA, INDIA) and evaluated for total solids (AOAC, 1990) and titratable acidity (Ranganna, 1979). The ph of the samples was measured by using digital ph meter (Century Digital ph meter, India). The carrot juice had 6.82% total solids, 2.67 (% of citric acid) titratable acidity and a ph of 5.79. Preparation of low-fat frozen yoghurt (lffy): Mix was prepared by using skim milk wi th standardization of fat 0.5% (F 1 ), 1.5% (F 2 ) and 3.0% ( ) and 12% milk solid not fat. With the addition of 12% sweetening agent and 0.5% stabilizer in different concentration. The mix was standardized to a total solid content of up to 12% by addition of skim milk powder. The mix was homogenized and then pasteurized and cooled to 42 o C. Yogurt starter culture was added at the rate of 2% and carrot pulp was added in 2% (T 1 ), 3% (T 2 ), 4% ) and 5% (T 4 ) concentration. The mix was incubated at 42 o C till we achieve an acidity of 0.45%. The mix was aged at 5 o C and frozen in a batch freezer to overrun of 70%. TREATMENTS: Carrot pulp T 1 : Addition of 2 percent of carrot pulp T 2 : Addition of 3 percent of carrot pulp T 3 : Addition of 4 percent of carrot pulp T 4 : Addition of 5 percent of carrot pulp Fat F 1 : 0.5 percent fat F 2 : 1.5 percent fat : 3.0 percent fat Nutritional analysis of prepared yoghurt: Fat, total solids, moisture, ash, titratable acidity, protein content (kjeldahl method), titartable acidity and ph of the samples were determined as per BIS (1989). The ph of samples was determined by using a digital ph meter. Sensory evaluation: The yoghurt sample was evaluated for the sensory attributes of colour and appearance, body and texture, flavour and over all acceptability by a panel of 5 judges selected from
230 ASIAN JOURNAL OF DAIRY & FOOD RESEARCH Mix liquid ingredients-milk Standardization of fat (0.5%, 1.5% and 3.0% F 1, F 2, and, SNF up to 12%) Addition of sugar (12%) & Stabilizer (0.5%) Heated to (60-62 o C) Blending in mixer grinder Heating (85 o C) Holding for 30 min Addition of carrot pulp (2%, 3%, 4% and 5%) Cooling to (42 to 43 o C) Addition of flavour and colour Inoculation with Lactobacillus bulgaricus and Streptococcus thermophilus (2%) Incubation (42 o C for 3-4hr up to LA 0.8%) Freezing (-3 to -5 o C) Hardening (-16 to -23 o C) Fig: Flow diagram for the preparation of Low-fat frozen yoghurt incorporated with carrot pulp
the Halina School of Home Science and Warner School of Food and Dairy Technology. 9 point Hedonic Scale score card was used for the purpose. Statistical analysis: The data obtained for different parameters was analysed statistically using Factorial randomized block design (ANOVA) and critical difference technique with three replications. (Imran and Coover, 1983) RESULT AND DISCUSSION Moisture & ash content: As shown in Table 1, the moisture content of the samples ranged from 75.0 81.7 per cent. T 3 had the average percent of moisture content (77.94 %). This justified its thickness which the panellists averagely rated very good. The ash content of the frozen yoghurt samples had a range between 0.62 1.96 percent is shown in Table 2. There were significant variation in moisture and ash content due to carrot pulp and fat content. Protein: The frozen yoghurt ) contained 3.24 percent protein (Table 1). The value compares well with that reported by Tamine & Robinson (1985) who reported 3.9 percent protein for the typical full fat plain yoghurt and Bakhru (1986) who stated 3.4 percent protein in good quality yoghurt made of whole milk. Laxminarayana and Shankar (1980), Kosikowski (1981), Sharma (1981), Speak and Hansen (1983), Uzonyl and Gyetare (1983) reported protein content of 2.25 to 5.5 percent in yoghurt. The critical examination of table 1 indicates that addition of carrot pulp and fat resulted in significant decreases in protein content of yoghurt from 4.29 2.89 percent at percent level of carrot pulp. Fat: Fat content of frozen yoghurt ) was 2.57 percent. The results are more or less in agreement with the values reported by Tamine & Robinson (1985), Bakhru (1986), Desai et al. (1994) and Baig and Prasad (1996). The perusal of Table 1 reveals that the addition of carrot pulp at different levels decreases the fat content of frozen yoghurt. The variation due to carrot pulp was non-significant. Total solid: Total solid content in frozen yoghurt ) was found to be 31.2 percent. This is obviously due to very high total solids content of fat. These results are in agreement with those of Yaygin (1980) who reported that total solids content of yoghurt was increased with the addition of different Vol. 32, No. 3, 2013 231 amount of fat content. The total solids content of yoghurt showed significant increasing trend with the increase in the level of carrot pulp with the values of 28.03 30.96 percent at levels of carrot pulp, respectively. Titartable acidity and ph: Titartable acidity of ) was observed to be 0.19 percent. The finding is in accordance with the minimum level of 0.11 percent. According to ISI (1974), the maximum lactic acid acidity should be 0.8 percent. The significant difference in acidity (0.11-0.19 % L.A) due to addition of carrot pulp. Titratable acidity found increased and ph decreased with increased levels of carrot pulp is mainly due to sugar fermentation and conversion of lactose to lactic acid. Similar findings were reported O Neil et al.1979; Tamine and Robinson, 1985; Shin et al. 1991 and Salwa et al. 2001 for yoghurt. General appearance: Good quality yoghurt was a gel like coagulation and porcelain like surface without wheying off. It has natural milk colour and fresh appearance (Ranganadham and Gupta 1987). The frozen yoghurt T 3 recorded highest mean score of 8.6 for general appearance. There was significant variation due to fat and carrot pulp on the general appearance of yoghurt (Table 2). Flavour: Good quality yoghurt has pleasant milky to slight sour taste with natural yoghurt flavour. Variation in the score for flavour due to different treatments was found to be significant. The data regarding average score for fat and carrot pulp was T 3 (8.7) indicating that flavour of all the samples was good irrespective to treatments (Table 2). The characteristics flavour of yoghurt is due to production of lactic acid, acetaldehyde and other carbonyl compounds during fermentation of lactose by yoghurt culture (Pette and lolkeme, 1950). In another study no acidic yoghurt taste was observed in yoghurt ice cream (Caisip and Resubel 2001). Body and texture: Good quality plain yoghurt should have custard like body with a smooth texture. Variation in the score for body and texture due to different treatments was found to be significant. The average score for carrot pulp and fat level was 8.2 ) indicating that body and texture of all samples was good irrespective of the treatments. Chawla and Balachandran (1994) stated that incorporation of SNF in milk contribute to refinement in taste of yoghurt
232 ASIAN JOURNAL OF DAIRY & FOOD RESEARCH Moisture Level of carrot pulp F 1 78.5 79.2 81.05 81.7 80.11 F 2 77.3 78.4 79.4 80.8 78.97 75.0 76.8 77.94 78.5 77.06 Mean 76.93 78.13 79.46 80.33 78.71 CD 0.05 Carrot pulp : 0.39 : S, Fat : 0.344 : S Ash Level of fat F 1 0.62 1.07 1.12 1.7 1.12 F 2 0.67 1.15 1.18 1.77 1.19 0.72 1.29 1.46 1.96 1.35 Mean 0.67 1.17 1.25 1.81 1.22 CD 0.05 Carrot pulp : 0.07 : S, Fat : 0.06 : S Protein F 1 4.2 3.96 3.24 2.89 3.57 F 2 4.26 3.94 3.24 2.94 3.59 4.29 3.96 3.28 2.96 3.62 Mean 4.25 3.95 3.25 2.93 3.59 CD 0.05 Carrot pulp : 0.403 : S, Fat : 0.349: S Fat F 1 0.43 0.42 0.43 0.43 0.42 F 2 1.23 1.2 1.32 1.28 1.25 2.45 2.58 2.57 2.6 2.55 Mean 1.37 1.4 1.44 1.43 1.88 CD 0.05 Carrot pulp : NS, Fat : 0.25: S Total solids F 1 26.7 27.7 28.7 29.7 28.20 F 2 27.8 28.7 29.8 30.8 29.27 29.6 30.6 31.2 32.4 30.95 Mean 28.03 29.0 29.9 30.96 29.47 CD 0.05 Carrot pulp : 0.39 : S, Fat : 0.344: S Titartable Acidity TABLE 1: Effect of nutritional analysis of fat and carrot juice incorporated in low fat frozen yoghurt. Level Level of of Carrot carrot pulp pulp F 1 0.16 0.12 0.16 0.15 0.147 F 2 0.13 0.17 0.16 0.18 0.16 0.11 0.15 0.19 0.17 0.15 Mean 0.13 0.14 0.17 0.16 0.15 CD 0.05 Carrot pulp : 0.0034 : S, Fat : NS with improved consistency, viscosity and reduced whey separation. Fat levels had significant effect on body and texture of yoghurt. The highest score of 8.2 was recorded for 3.0 percent level of fat indicating that the frozen yoghurt at 3.0 percent fat was the best quality product with firm body and smooth texture. Overall acceptability: The overall acceptability of yoghurt was determined on the basis of the average of the total score obtained for different sensory
General appearance Vol. 32, No. 3, 2013 F 1 6.4 6.7 7.2 7.2 6.87 F 2 6.6 7.4 7.9 7.6 7.37 7.0 7.8 8.6 8.6 8.0 Mean 6.66 7.3 7.9 7.8 7.4 CD 0.05 Carrot pulp : 0.137 : S, Fat : 0.119 :S Flavour T 1 T 2 T 3 T 4 Mean F 1 6.7 7.0 7.2 7.2 7.02 F 2 6.7 6.9 7.8 7.6 7.25 6.9 7.4 8.7 7.5 7.62 Mean 6.76 7.1 7.9 7.43 7.29 CD 0.05 Carrot pulp : 0.143 :S, Fat :0.124 :S Body and texture F 1 6.3 6.2 6.5 6.3 6.32 F 2 6.7 6.6 6.8 7.4 6.87 7.8 7.5 8.2 8.1 7.9 Mean 6.93 6.76 7.16 7.03 7.22 CD 0.05 Carrot pulp : 0.15 :S, Fat : 0.13 :S Overall acceptability TABLE 2: Influence of Fat and Carrot pulp on organoleptic quality of yoghurt. F 1 6.45 6.63 6.96 6.9 6.73 F 2 6.66 6.8 7.66 7.53 7.16 7.33 7.63 8.57 8.56 8.02 Mean 6.81 7.02 7.73 7.66 7.30 CD 0.05 Carrot pulp : 0.34 :S, Fat : NS 233 attributes viz. general appearance, flavour and body and texture. From the average figures of overall acceptability in Table 2, it is seen that highest overall acceptability score was recorded for yoghurt with 4 percent of carrot pulp and 3.0 percent of fat 8.5 ). The critical examination of data indicates that from all the carrot pulp levels are highly significant. It is concluded that the low-fat frozen yoghurt containing 3% fat and 4% carrot pulp ) was high as comparable with other treatments in organoleptic and nutritional characteristics. T 3 S 3 showed significant difference in organoleptic characteristics (flavour and taste, body and texture, colour and appearance & overall acceptability) and nutritional characteristics (protein, ph, acidity, total solids), When the highest amount of fat and carrot pulp were added. It is quite obvious from the results that the total solids percent significantly increased with the increase in fat and carrot pulp. The quality of sample T 3 S 3 (3% fat and 4% carrot pulp) is very well comparable to that of the other treatments. REFERENCE AOAC., (1990), Official methods of Analysis. (5 th edn.) Association of Official Analytical Chemists. Washington, D.C. Arbuckle, Wendell Sherwood, (1986), Ice Cream. 4th ed. AVI Publishing. Ayebo, A.D. and Sahani K.M., (1980), Cultured Dairy prod. J. 15:21. Baig, R.K. and Prasad, V., (1996), Indian J. Dairy Sci. 49(9): 585. Chawla, A.K. and Balachandran, R., (1994), Indian J.Dairy Sci. 47(9): 762. Davidson, R.H., Duncan, S.E., Hackney, C.R., Eigel, W.N. and Boling, J.W., (2002), Probiotic culture survival and implications in Fermented Frozen Yoghurt Characteristics. Journal of Dairy Science, 83:666-673. Desai, S.R. et al., (1994), Indian J. of Dairy Sci. 47(10): 870.
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