Food Chemistry

538 10 Milk and Dairy Products

Table 10.36.Protein, lactose and mineral contents of
whey productsa

Product DMb Protein Lactose Minerals
(%) (%) (%) (%)

Skim milk 9 .03653 7

Whey (from
coagulating
with rennet) 6.0–6.413 75 8
Whey (from
coagulating
with acid) 5.8–6.212 67 14

Demineralized whey
powder 12–13 85 1–2
Whey protein powderc
I47449
II 74 20 6
aAverage values are expressed as % of dry matter.
bDry matter.
cAfter one (I) and two (II) ultrafiltrations.

• Preliminary concentration of the whey to
  50–55% dry matter in falling-film evaporating
  systems (thermal or mechanical vapor com-
  pression), followed by spray drying (one step
  or two step with subsequent vibraton fluid
  bed).


• Preliminary concentration of the whey to 21–
  25% dry matter by reverse osmosis (hyper-
  filtration), followed by concentration to 50–
  55% dry matter via falling-film evaporators
  and spray drying.

The composition of whey powder is presented in
Tables 10.27 and 10.36.

10.2.10.2 Demineralized Whey Powder

In the applications of whey powder, the miner-
als can interfere with the taste. The production

of demineralized whey powder proceeds via ion
exchange or, preferentially, electrodialysis (1.5–
4 .5V/cell; current density 5–20 mA/cm^2 mem-
brane area, Fig. 10.31). The course of deminer-
alization is shown in Fig. 10.32.

Fig. 10.31.Principle of electrodialysis of whey. 1 cath-

ode, 2 cation membrane, 3 anion membrane, 4 anode

Fig. 10.32.Whey demineralization. Ions ofachloride,

bsodium,cpotassium,dcalcium,ephosphate,flac-

tate,gcitrate, andhmagnesium

10.2.10.3 Partially Desugared Whey Protein

Concentrates

In the ultrafiltration of whey, protein concen-

trates depleted of lactose to various extents are

obtained, depending on the number of stages

and amount of wash water. Another, less gentle

method involves the heating of whey (95◦C,

3–4 min) by direct steam injection, followed

by precipitation of the denatured proteins at

pH 4.5, separation in a sedimentation centrifuge

(2000–4000 min−^1 ), and drying.