|Two main methods are used to separate
the protein from the rest of the whey, namely,
filtration or ion exchange.
Processing whey protein by
filtration can be done using a filter with a pore size
of about one micro, i.e., microfiltration, or using a
filter with a pore size about 250 nanometres (0.25
microns) large, i.e. nanofiltration.
In ion exchange, proteins are separated based on
their electrical charge. Hydrochloric acid and sodium
hydroxide are used during this process. Because of this,
whey protein fractions that are sensitive to pH are
denatured, e.g. glycomacropeptides, immunoglobulins,
lactoferrin, and alpha lactalbumin. This means that the
structure of the protein is changed, so that its
biological activity is reduced or completely eliminated.
Ion exchange is considerably cheaper than
microfilatration or ultrafiltration, and it is very
effective in getting rid of fats and carbohydrates.
However, some beneficial protein fractions, as mentioned
above, are lost, which is not the case for filtration
methods. Whey protein isolates obtained by
microfiltration also retains more calcium, phosphorus,
and potassium than those obtained by ion exchange.