DEVELOPMENT OF YOGURT FROM CAMEL MILK USING EXOPOLYSACCARIDE PRODUCING LACTIC ACID BACTERIA

Abstract

This research was conducted with the objective of developing yogurt from camel milk using exopolysaccharides producing lactic acid bacteria, starch and camel milk powder to improve the texture and other quality characteristics of the product and to evaluate the sensory values of consumer’s acceptability. The experiment was conducted as Completely Randomized Design with one way Analysis of Variance. Physicochemical properties of raw camel milk and yogurt, viscosity, syneresis, textural profile analysis and sensory evaluation were analyzed and discussed. The result of this study has shown significant differences (p<0.05) in physico-chemical composition of protein, lactose, total solid, solid not fat and moisture between the treatments without stabilizers and treatments with the addition of stabilizers (yogurt with starch, yogurt with camel milk powder & yogurt with combination of both starch and camel milk powder). Yoghurt with non-EPS released more whey than yogurt with EPS, however, the level of syneresis of yoghurt with EPS and starch was significantly (p<0.05) less than the other yoghurt samples. Yogurt with EPS & starch had the highest viscosity and the lowest syneresis value (36.17s, 36.67% respectively) among the treatments. The highest level of syneresis was observed on the yoghurt treated with camel milk powder (68.33%) when compared with the yogurt treated with starch alone (36.67%) and starch with camel milk powder (54.67%), the amount of starch added to the yogurt showed a significant effects (p<0.05) on reducing syneresis and increasing viscosity, especially cow milk yogurt produced with starch showed very high viscosity. Therefore, the viscosity of camel and cow milk yogurt was improved and syneresis was decreased by the addition of starch to the milk. However, addition of camel milk powder to cow and camel milk did not contribute for reducing syneresis, increasing viscosity and improving the texture. In texture profile analysis, yogurt produced with starch had significantly higher (p<0.05) firmness, elasticity, cohesiveness and adhesiveness in both camel and cow milk yogurt. The firmness, elasticity, cohesiveness and adhesiveness were relatively higher in yogurt with exopolysaccharides than the yogurt without exopolysaccharides. Nevertheless, the aforementioned properties were not improved by the addition of camel milk powder. The sensory values of camel and cow milk yogurt were evaluated for colour, taste, aroma, texture, and overall acceptability. Yogurt with starch alone and yogurt with starch & camel milk powder were rated highest for texture (5.66±0.20 and 5.70±0.00 respectively). In general, there was no significant difference (p>0.05) in the average mean scores of all treatments in camel milk yogurt. On the other hand, cow milk yoghurt produced with non-EPS was rated highest in color and significantly different (p<0.05) from the other samples. Camel milk yogurt produced with exopolysaccharides and starch was accepted higher for overall acceptability. In conclusion, using of exopolysaccharides producing lactic acid bacteria and starch could improve physico-chemical and textural qualities of the product.