462 Part IV: Milk
homogenized milk, stabilized mainly by a surface
layer of adsorbed casein micelles, can become struc-
tural elements of the final acid gel.
The relative proportion of caseins and whey pro-
teins in yogurt has a significant influence on the
structure of the gel (Puvanenthiran et al. 2002).
Hydrocolloid stabilizers (polysaccharides or pro-
teins) may be added to the mix to modify the viscos-
ity and/or prevent syneresis (Fizsman et al. 1999,
Tamime and Robinson 1999). Sweetening agents
(e.g., natural sugars or synthetic sweeteners such as
aspartame) may be added to the mix, and fruit
purees or fruit essence may be added either at the
start or end of fermentation.
Figure 20.2.Principles of manufacture of (a)acid-coagulated and (b)rennet-coagulated cheese.