Effects of Dioscorea opposita mucilage addition on the physicochemical properties, texture, and stability of set-type yogurt

Abstract

Dioscorea opposita mucilage (DOM), a polysaccharide-protein polymer with antioxidant activity, can be served as a natural ingredient in nutritional yogurts. The effects of DOM addition at different concentrations (2%, 4%, 6%, 8%, 10% and 12% w/w) on the total number of lactic acid bacteria, pH, titratable acidity, syneresis, viscosity, texture, color and sensory evaluations of full-fat yogurts and skimmed yogurts during 21 days storage at 4 °C were investigated. The results suggested that DOM could improve the growth of LAB, strengthen the network and gelation of yogurt, and thicken the dispersion, which led to the significant decrease in pH and cohesiveness, and drastic increase in the syneresis, firmness and adhesiveness. Additionally, sensory evaluation revealed that the overall liking scores of full-fat yogurts (8.1–8.7) were higher than those of skimmed yogurts (7.9–8.3), which exhibited strong correlations with firmness and viscosity of set-type yogurts. Although DOM addition affected the sensory undesirably, such as creaminess, the thickness and overall liking were improved, especially for the skimmed yogurts. In summary, 8% w/w DOM could effectively improve the texture, quality and stability of set-type yogurts. This study provides new applications in functional dairy products and promotes the value of the by-products of D. opposita.