Dairy Ingredients for Food Processing

Fermented Dairy Ingredients 339

cerned and to prevent whey separation. The

milk solids can be raised by boiling milk to

evaporate the water, adding milk powder,

and concentrating the milk membranes.

Boiling is traditional; however, it is not cost

effective because it uses excess steam in pro-

cessing. Addition of milk powder, usually

skim milk powder, is incorporated into either

whole milk, skim milk, or water, and then

mixed thoroughly. A variety of mixers or

blenders are avalable for this purpose. They

are designed to provide complete dispersion

of the dry milk powder into an aquoeus

phase, complete hydration of the dry ingredi-

ent so the residual lump produced is minimal,

heat treatment, inoculation and fermentation,
mixing of fruits and sweeteners, packaging,
and storage (Figure 13.1 ). Standardization of
milk fat is essential in yogurt manufacture
due to variations in the fat content of milk
sourced from different breeds and seasons as
well as to comply with regulations in particu-
lar countries. This step is carried out by
pumping whole milk into a milk separator to
remove excess fat and produce skim milk
with a certain fat content to conform to stan-
dards in different countries (Tamime and
Robinson 2007 ).
Milk solids also are fortifi ed to comply
with the regulations of various countries con-

Figure 13.1. Flow process chart for set and stirred yogurt manufacture. Adapted from Walstra et al. (2006).

Incubating

(2.5 h)

Cooling

(6°C)

Cooling

(30–32°C)

Packaging

Packaging

Homogenizing

(55°C 20 MPa)

Pasteurizing

(5min 85°C)

Cooling

(45°C)

Incubating

(16–20 h)

Stirring

Cooling

(6°C)

Milk

Set

yogurt

Stirred

yogurt

Packaging

Cooling

(6°C)

Starter

(2.5%)

Starter

(0.025%)

Fortifying

Standardizing

Milk

Solids