Effect of Trisodium Citrate on Rheological and Physical Properties and Microstructure of Yogurt

Acid-base buffering curves of milks containing different levels of trisodium citrate (TSC): a) 0, b) 5, c) 10, d) 20, e) 25, f) 30, and g) 40mM TSC (arrows indicate direction of titration).

Storage modulus (G′) (a) and loss tangent (LT) (b) as function of pH for yogurts made from milk with 0 (○), 5 (▴), 10 (●), 20 (▵), 25 (■), 30 (□), and 40mM (×) added trisodium citrate. Means of triplicates, error bars indicate SD.

Relationship between the removal of casein-bound Ca from micelles and the loss tangent value at pH 5.1 in yogurt gels made from these trisodium citrate (TSC)-treated milks. Values are means of triplicates.

Whey separation of yogurts made from milk with different levels of trisodium citrate (TSC). Whey separation was measured when gels reached at pH 4.6. Means of triplicates, error bars indicate SD. ^a–eColumns with different letters are significantly different (P<0.05).

Microstructure of yogurt gels made from milk treated with 0 (a), 5 (b), 10 (c), 20 (d), 25 (e), 30 (f), or 40 (g) mM trisodium citrate (TSC). 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.