Whey from traditional cheese production contains about
0.8% protein corresponding to 13% of the dry matter. These proteins are known
as serum proteins or whey proteins. As the nutritive value is considered very
high and as human milk contains more whey proteins than cow's milk, numerous
attempts have been made to separate these proteins from the whey, especially
for use in baby food powders.
How to produce whey protein
concentrate
The most accepted and widely used
process is ultrafiltration. The solids content and the composition of
the whey protein concentrate, also known as retentate, from the ultrafiltration
can be varied to meet special requirements for the final product.
Commercially, whey proteins are available with three different protein
contents: 35% WPC, 60% WPC, and 80% WPC or higher.
What do you get from 100 kg
of whey?
If 100 kg of normal sweet whey with 6 %
solids is used, approx. 20 kg of 35 % WPC is discharged from the
ultrafiltration module with a solids content of about 10 %, which is increased
by evaporation
to 45 % before spray
drying. Approx. 8 kg of 60 % WPC is discharged with a solids content of
about 15 %, evaporated to 42 % before spray drying. High protein
concentration results in high viscosity and it is necessary to add water
(diafiltration) during the final filtration if 80 % WPC is produced. 3 kg of 80
% WPC is discharged with a solids content of about 28-30 %. Due to the high
protein content it is dried directly.
Spray drying of whey protein
concentrate
Spray drying of whey protein
concentrates is easy, but to maintain a good solubility of the product, it is
essential to use low outlet air temperatures to avoid denaturation. Two-stage drying
is therefore recommended. As the solids content of the concentrate is low
due to the high protein content, the spray drying plants are always equipped
with bag
filters.
Today, there is a tendency to produce
agglomerated instant whey proteins. Due to the lack of lactose as binder,
especially in 80 % WPC,
agglomeration is difficult. However, by selecting the
Multi Stage Dryer
MSD™, it is possible to obtain sufficient agglomeration. As the proteins
are very hydrophilic, they will absorb water instantaneously at first
contact with water, which makes the dispersion difficult. By agglomeration and
lecithination, water absorption is delayed long enough to allow
the powder to be dispersed in the water before the final dissolution. The
powder has the same applications as the concentrates, but has the supreme
advantage of an almost infinite keeping quality.