Effect of Tetrasodium Pyrophosphate on the Physicochemical Properties of Yogurt Gels

Acid-base buffering curves of milks containing different levels of tetrasodium pyrophosphate (TSPP): a) 0, b) 0.05, c) 0.10, d) 0.125, e) 0.150, and f) 0.2% TSPP (arrows indicate direction of titration).

Effect of different levels of tetrasodium pyrophosphate (TSPP) on a) turbidity (absorbance at 700nm) and b) particle size (where τ is turbidity, γ is the wavelength of light) of casein micelles. Means of triplicates; error bars indicate S; the dotted line in panel (a) indicates that an increase in turbidity was observed with time.

Storage modulus (G′, •) and loss tangent (LT, ○) as a function of time for yogurts made from milk treated with tetrasodium pyrophosphate (TSPP): a) 0, b) 0.05, c) 0.10, d) 0.125, e) 0.150, and f) 0.2% TSPP. Note the different scale for the G′ axis in Figures 3e and f. Means of triplicates; error bars indicate SD.

Whey separation of yogurts made from milk with different levels of tetrasodium pyrophosphate (TSPP). Whey separation was measured when gels reached at pH 4.6. Means of triplicates; error bars indicate SD. ^a–eBars with different letters are significantly different (P<0.05).

Microstructure of yogurt gels made from milk treated with a) 0, b) 0.05, c) 0.10, d) 0.125, e) 0.150, or f) 0.2% tetrasodium pyrophosphate (TSPP). Yogurt gels were formed at 42°C and examined at pH 4.6. The protein matrix is white and pores are dark. Scale bar = 20μm.