Dairy Chemistry And Biochemistry

CHEMISTRY AND BIOCHEMISTRY OF CHEESE AND FERMENTED MILKS 431

Preparation of the basic mix

Homogenization I

Cooling .1

Incubation *

in retail cartons

Cooling to <4'C

Set yoghurt I

lncuhation in hulk

Agitition to hlrak

coagulum

Adjition ol'huit

Packaging^1

I

Cooling J to <ST

Stirivd yoghuri

Figure 10.32 Protocol for the manufacture of yoghurt. *, Sucrose and/or fruit (fruit flavours)
may be added at this point. (From Robinson and Tamime, 1993.)

Fermented milk products exhibit thixotropic rheological properties, i.e.
the viscosity (resistance to flow) decreases as the rate of shear increases; a
typical relationship is shown in Figure 10.33. The rheological properties are
major parameters of quality and are controlled by varying the total solids
content of the milk, the heat treatment and homogenization of the milk and
the use of hydrocolloids, e.g. gelatin or carageenan.