Dairy Ingredients for Food Processing

188 Chapter 8

Ingredients containing whey proteins

range from whey powder with an average of

12.5% protein to whey protein isolates with

a minimum of 90% protein.

Whey Powder

Whey powder is produced either by drying

defatted fresh whey from rennet casein or

cheese manufacture (dry sweet whey) or

from cottage cheese, casein, or fresh cultured

cheese types (dry acid whey). Sweet whey

powder provides a mild and sweet fl avor,

whereas acid whey powder is a source of

lactic acid fl avor and dairy calcium. The

increased content of calcium in acid whey is

due to the colloidal calcium released from

casein micelles during acidifi cation. In

general approximately 30% of the calcium in

milk is in its free, ionic form. Table 8.4 gives

the typical composition of sweet and acid

whey powders.

The main steps in the processing of whey

powder are as follows:

are 30% to 40% of the total running costs of
the process. Leakages at the gaskets between
membranes may also cause signifi cant losses
of product. System improvements are con-
tinuously being developed to overcome these
diffi culties.
Table 8.3 highlights the differences
between electrodialysis, nanofi ltration, and
ion exchange for the reduction of whey
minerals.

Whey Products and Ingredients

Drying Whey

Dairy products are dried primarily to extend
storage stability, reduce transportation costs,
and provide an ingredient that is easily incor-
porated in food formulations. Dehydration is
an energy - intensive process. Water removal
is generally more cost effective in an evapo-
rator than in a spray dryer: a single - stage
spray dryer requires six times the energy con-
sumed by a conventional triple - effect evapo-
rator (Goel et al. 1979 ).
Falling fi lm evaporators are widely used
for concentrating dairy products under
vacuum. Whey ingredients may be concen-
trated to 30% to 60% solids with two or more
stages. By adding more stages to the evapora-
tor, the steam consumption/kilogram of water
evaporated is reduced. In practice, the number
of stages is determined economically by a
balance of steam savings against capital
outlay (Pearce 1992 ). Mechanical or thermal
vapor compression may be introduced to
further reduce evaporation costs.

Table 8.3. Reduction of minerals in whey, partially or fully demineralized by electrodialysis ( ED ),
nanofi ltration ( NF ), and ion exchange ( IE ).

Ions 60% ED

reduction (%)

45% NF

reduction (%)

40% ED

reduction (%)

IE reduction

(%)

K^ +^ , Na^ +^64    65    42    98

Ca^2 +^35    6    24    92

Cl - 89 54 71 95

Adapted from Hoppe and Higgins (1992) , Bargeman et al. (2005)

Table 8.4. Typical composition of sweet whey

powder and acid whey powder.

Sweet whey

powder

Acid whey

powder

% Protein 12.8 ± 1.8 12.3 ± 1.3

% Lactose 69.0 ± 6.0 66.0 ± 4.0

% Fat 1.3 ± 0.3 1.0 ± 0.5

% Ash 8.5 ± 0.3 11.0 ± 1.3

% Moisture 4.3 ± 0.8 4.3 ± 0.8

% Calcium 0.7 ± 0.1 2.2 ± 0.2

Adapted from Renner (1992) , Chandran (1997)