530 Chapter 20
- There can be an optimum pH region for
maximum heat stability with milk or prod-
ucts primarily comprised of milk. The
ionic strength and concentration of cat-
ions (primarily divalent) can infl uence
heat stability and the pH optimum region
dramatically. - For long - term shelf stability in liquid prod-
ucts, typically the higher the homogeniza-
tion pressures, the better. The goal is to
have the fat globules as small as possible
to prevent the natural rise (creaming) in
sterilized product over time. However, the
protein must not only adequately cover the
fat globules, but provide some charge to
cause electrostatic repulsion of the other
particles. Without adequate electrostatic
repulsion, the protein - covered globules
will adhere to each other, forming a distinct
cream or sediment layer depending on the
amount of protein covering the globules
and their resulting buoyancy. - Ultra - high - temperature - short - time
(UHTST) treatments are an excellent way
of reducing microbial counts, and can be
instrumental in binding the whey protein to
casein to afford the whey protein greater
retort stability. - Protein fouling on equipment can be a
great nuisance and a signifi cant cause of
unacceptably short continuous process run
times. Fouling is termed as either type A or
type B. Type A is the building up of a pro-
teinacous layer that restricts heat transfer
and product fl ow. Type B is a mineral
build - up that can be diffi cult to remove by
CIP (cleaning in place) procedures, but
otherwise does not affect processing. If
fouling is problematic during process
development, its resolution could involve
prior preheating or forewarming the protein
mixture, better balance of the minerals
such as ratio of citrates and phosphates to
soluble magnesium and calcium ions, and
selection of the proper pH. It rapidly
becomes clear that resolving processing
common to all nutritional products that
contain dairy proteins:
- How well do the ingredients mix together?
- Is there a unique sequence of mixing them
that promotes better physical stability of
the formulation? - What are the ideal temperatures of mixing?
- What is the optimum pH or acceptable pH
range? - Do the proteins incorporate a lot of air
during mixing, requiring deaeration prior
to homogenization? - What is the ideal homogenization pressure?
- Is additional heat treatment required, such
as ultra - high - temperature - short - time? - Does the protein(s) foul the equipment?
If the product is to be retorted, the mixing,
pH, and processing requirements can have
huge effects on the product ’ s retort and shelf
stability. One the other hand, if the product
is to be spray dried, its concentration and the
selection of carbohydrates during liquid pro-
cessing can substantively infl uence the fi nal
powder quality.
Examples for Manufacturing
Considerations
The following are some examples of the
manufacturing questions, above.
- Typically, the proteins are blended together
with the fat or oil, minerals, and some or
all of the carbohydrates. Some proteins
hydrate well in water, whereas others
require high - shear mixing for total disper-
sion. With caseinates, especially calcium
caseinate, prior dry blending with a carbo-
hydrate helps disperse the caseinate parti-
cles and aid in their dissolution and
hydration. In some cases, a protein - in - oil
suspension is the preferred processing. - As has been noted, native whey proteins
are heat sensitive, while caseinates are
not.