Effects of incubation temperature, starter culture level and total solids content on the rheological properties of yogurt

Abstract

The effects of incubation temperature (35-45oC), starter culture level (0.003-0.006%, w/v), and milk total solids content (12.32-15.68%, w/v) on the rheological properties of yogurt were investigated using central composite rotatable design (CCRD) and response surface methodology (RSM). Gelation time during milk fermentation and apparent viscosity of yogurt stored for 3 days were the rheological parameters studied. The results revealed that the gelation time and apparent viscosity of yogurt were significantly affected (P < 0.1) by incubation temperature, starter culture level, and total solids. Incubation temperature had the greatest influence on the gelation time. Higher temperature led to shorter gelation time, but resulted in lower apparent viscosity of yogurt. Apparent viscosity of yogurt was mainly affected by total solids. Higher apparent viscosities were also obtained at lower incubation temperature