518 Chapter 20
tion. However, their high costs of manufac-
ture along with insuffi ciently defi ned clinical
benefi ts have thus far prevented their wide-
spread use in commercial formulas.
Efforts have been made to produce some
of the more esoteric proteins (especially lac-
toferrin) via fermentation of genetically mod-
ifi ed microorganism species, but these are not
yet commercially viable. Greater research
into fractionation of milk and further experi-
ence in alternate production avenues will
ultimately enable exploration of the poten-
tially unique properties of these proteins.
Some examples include β - casein with bio-
logical functionality related to its phosphory-
lation state and κ - casein with bacterial
adhesion modifi cation and other functional-
ity, dependent on its glycosylation state.
Furthermore, α - lactalbumin has calcium -
and zinc - binding properties, and with no free
thiols the pure form does not form gels upon
denaturation or acidifi cation. β - lactoglobulin
forms a unique stable foam and has useful
gelation properties. Lactoferrin is potentially
bactericidal with structural similarities to the
lysozymes. It is evident that the exploitation
of these proteins is just beginning.
Byproduct streams from production of
major food ingredients from milk are another
important source of interesting ingredients.
Most notable among these are the byproductsmother ’ s milk may still be reduced or absent
from formula, though that is changing.
Human milk proteins differ from bovine
milk in several important ways. Human milk
is whey dominant, with approximately 60%
of the protein from whey, while cow ’ s milk
is casein dominant, with approximately 80%
of the protein from casein. Breast milk casein
contains mostly β - casein with some κ - casein
(glycosylated with sialic acid) and virtually
no α - casein. Also in contrast to bovine whey,
the human whey fraction contains no β -
lactoglobulin and relatively high levels of
lactoferrin. Lactoferrin is a multifunctional
protein with antimicrobial activity that pro-
vides immune functionality as well as signifi -
cant and biologically functional iron - binding
capacity.
Standard commercial formulas usually
have a combination of bovine caseins, pre-
dominately β - lactoglobulin in the whey
protein, and only trace amounts of lactofer-
rin. While casein - dominant formulas were
prevalent 20 to 30 years ago, a more balanced
delivery of whey and casein is now the norm.
Advances in protein separation technologies
resulted in commercial availability of frac-
tions of milk proteins such as bovine β -
casein, lactoferrin, and bovine whey protein
enriched in α - lactalbumin, which may be
used to mimic human milk protein composi-
Table 20.4. Major protein components of human milk and major
commercial infant formulas.
Protein (g/liter) Breast milk Commercial
formulas * *
Total protein Apprx. 6.9 – 9.2 * 14.0
α - s caseins 0 2.7
β - casein 3 – 3.4 2.2
κ - caseins Apprx. 0.5 0.7
β - lactoglobulin 0 3.5
α - lactalbumin 2.7 – 3.3 1.2
Lactoferrin 1.4 – 1.9 0
Glyco - macro peptide 0 1.4
Other proteins 1 – 2 2.3
* Amount of protein decreases over time; excludes non - protein nitrogen
* * Milk base enriched with demineralized whey protein, data provided by Paul
Johns, Abbott Laboratories.