Whey-based Ingredients 189
to form lumps. Neutralization, prior to
drying, is therefore recommended.
Whey powders are used in bakery prod-
ucts, dry mixes, process cheese foods and
spreads, frozen desserts, sauces, meat emul-
sions, confections, soups, gravies, snack
foods, yogurts, and beverages (Chandan
1997 ).
Demineralized Whey Powder
Demineralization of whey began around
- Monovalent ions (Na^ +^ , K^ +^ , Cl - ) in whey
powders result in negative sensory proper-
ties, whereas divalent ions (Ca^2 +^ , Mg^2 +^ ) con-
tribute to the health image of the product
(Bargeman et al. 2005 ). The removal of min-
erals to various degrees is achieved with ion
exchange, electrodialysis, and nanofi ltraton.
Typical demineralization levels are 50%,
70%, and 90%. With a demineralization level
of 90% it is possible to produce a whey
powder with a mineral content of less than
1%. Demineralized whey powders are ingre-
dients in infant formula with a gross compo-
sition close to that of human milk.
Ion exchange is the most mature of the
demineralization technologies. It has the
ability to remove nearly all the minerals
(both monovalent ions and divalent ions)
present in whey and whey permeates (Hoppe
and Higgins 1992 ). Electrodialysis is recom-
mended for demineralization levels up to
50% to 60%. The process is ion - type selec-
tive, resulting in a higher loss of monovalent
ions.
Nanofi ltration is a relatively recent devel-
opment. A crucial factor in the commercial
viability of nanofi ltration was the develop-
ment of membranes with high lactose reten-
tion that allows effective salt removal. With
nanofi ltration the same level of demineraliza-
tion as with electrodialysis is achieved, but
at a lower rate of removal of divalent salts
(Table 8.3 ) (Hoppe and Higgins 1992 ,
Bargeman et al. 2005 ). An added advantage
- Cheese or casein fi nes recovery from
whey. Cheese or casein fi nes impact
negatively on fat separation and must be
removed fi rst (Bylund 1995 ). Centrifugal
separators are commonly used.
- Fat separation. Fat is recovered in cen-
trifugal separators as whey cream con-
taining 25% to 30% fat.
- Concentration. Concentration is gener-
ally achieved by falling fi lm evaporation
under vacuum to a maximum of 65%
solids. When energy costs are high,
reverse osmosis is often considered as an
option for the pre - concentration of whey
(Storms et al. 1980 ). It will not fully
eliminate the evaporator because it is
limited to concentrations of less than
25% whey solids.
- Crystallization. If whey concentrate is
dried conventionally following evapora-
tion, the fi nal product will contain a large
proportion of amorphous lactose. This
leads to a very hygroscopic powder that
may cake on storage. It is necessary to
convert a high percentage of the lactose
to its α - monohydrate crystalline form.
Either lactose crystallization can be
completed in the concentrate prior to
drying or a two - stage dryer process that
allows for crystallization prior to fi nal
drying may be used. When a crystallizer
is used, the concentrate is cooled to 15 ° C
to 20 ° C (59 ° F to 68 ° F) and kept under
constant stirring for 6 to 8 hours to obtain
the smallest possible crystals. Lactose
crystallization is also promoted by
rapidly cooling to less than 100 ° C
(212 ° F) as the product is removed from
the dryer (Morr 1992 , Pearce 1992 ,
Bylund 1995 ).
- Drying. Whey is conventionally dried in
a spray dryer. Care is taken with preheat-
ing conditions to ensure a good - quality
product. According to Bylund (1995) ,
acid whey from cottage cheese and
casein is diffi cult to dry because it tends
