Technology of Blueberry Incorporated Goat Milk based High Protein Dessert
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Date
2022
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ICAR-NDRI, KARNAL
Abstract
Goat milk is preferred over bovine milk due to its unique nutritional composition and there has been renewed interest in therapeutic and nutritional characteristics of goat milk because of higher amount of short and medium chain fatty acids (better digestibility) and lower α-s1 casein (less allergenic). Further, goat milk can be efficiently utilized by converting into value-added products incorporated with natural bioactive such as blueberry. Blueberries have great potential for inclusion in dairy dessert owing to their high antioxidant capacity and several health benefits. However, fermentation of goat milk has always been a challenge for the processors due to lesser firm curd and weaker gel. Certain physical interventions, involving an increase in the total solids or protein content, can be attempted for the preparation of fermented goat milk products. In this study, goat milk based high protein dessert was developed using ultrafiltration technique at different concentration factors and optimizing its formulation using blueberry, sugar and inulin. Ultrafiltered goat skim milk 3X was used for preparation of blueberry dessert as it showed higher protein (%) (8.91 ± 0.15) and total solids (%) (15.58 ± 0.22) than 1X and 2X. Protein curd mass (PCM) obtained after fermentation was further optimized for the incorporation of blueberry crush (BC) (PCM: BC::70:30, 80:20, 90:10), sugar ( 5%,10%,15%) and inulin (2%, 3%, 4%). Based on sensory analysis and rheological characteristics, PCM: BC with 80:20 ratio, 10% sugar and 4% inulin was optimized and selected for further characterization. The optimized blueberry dessert (OBD) had pH, acidity (% lactic acid), fat (%), protein (%), ash (%) and total solids (%) with the value corresponding to 4.23, 1.37, 1.01, 13.55, 0.93 and 48.79, respectively. Color values of high protein blueberry dessert were significantly (p < 0.05) affected with the addition of blueberry crush. The L*and b* values of the optimized product significantly decreased (p<0.05) with the blueberry addition while, a* values significantly (p<0.05) increased. The antioxidant activity (DPPH, FRAP) and total phenolic content of OBD were significantly higher (p<0.05) than control. Control and optimized samples were further stored in polypropylene packaging material and subjected to in-package thermization. Acidity increased significantly (p<0.05) with storage for both control and OBD non-thermized and thermized samples. Rheological attributes showed that storage modulus was higher than loss modulus indicating viscoelastic behavior. α –Lactalbumin, β – Lactoglobulin, α, β, Kappa caseins, αs₁-casein were the major protein fractions identified in non-thermized and thermized samples. Storage studies depicted the spoilage of non-thermized control and OBD samples on 7th day and 14th day of storage, respectively while, thermized control and OBD were found to be acceptable upto 28 days under refrigerated condition.