Dairy Ingredients for Food Processing

Chemical, Physical, and Functional Characteristics of Dairy Ingredients 51

be used to determine effi cient ultra - high -

temperature (UHT) milk pasteurization

because alkaline phosphatase is only par-

tially inactivated.

Lysozyme

Lysozyme is an antimicrobial enzyme that

cleaves the glycosidic linkages between N -

acetylmuramic acid and N - acetylglycosamine

of bacterial cell walls, ultimately leading to

cell lysis. Gram - positive bacteria are more

susceptible to the activity of this enzyme due

to their simpler cell walls.

Plasmin

The activity of plasmin is important in cheese

ripening and the stability of casein micelles

in products such as UHT milk and milk

protein isolates.

Minerals and Salts

Minerals and salts contribute to the chemical

equilibrium, nutritional value, and shelf life

of milk. They infl uence several processes

including heat stability, alcohol coagulation,

age - thickening of sweetened condensed

milk, rennin coagulation, and the clumping

of fat globules during homogenization.

Growth Factors

Growth factors are potent hormone - like

polypeptides that modulate growth and dif-

ferentiation of a variety of cell types,

mammary development, and neonatal devel-

opment in the gastrointestinal tract. Growth

factors in milk include epidermal growth

factor, transforming growth factor, insulin,

and prolactin.

Vitamins

Milk is a source of both fat - soluble vitamins

(A, D, E, and K) and water - soluble vitamins

(B and C). The B vitamins in milk include

milk. The precipitation or coagulation of
casein micelles can be achieved in various
ways including isoelectric precipitation,
rennet coagulation, polyvalent ion precip-
itation, alcohol precipitation, and heat
coagulation.
Caseins contain signifi cant amounts of the
essential amino acids required in the body,
especially valine, leucine, isoleucine, phenyl-
alanine, tyrosine, and proline. They contain
high amounts of proline residues, which
result in a lack of secondary and tertiary
structures. They also are rich in lysine and
can be used as a supplement in lysine -
defi cient foods such as cereal and other plant -
based foods. All three major casein proteins
have been shown to have immunomodulatory
properties (Gill et al., 2000 ).
Functional enzymes in milk have antimi-
crobial properties and are used in processing
applications including lactoperoxidase, alka-
line phosphatase, lysozyme and plasmin.

Lactoperoxidase

Lactoperoxidase catalyzes the oxidation of
thiocynate by hydrogen peroxide to hypo-
thiocynate, which is a potent antimicrobial
agent against a wide range of Gram - positive
and Gram - negative microorganisms includ-
ing Escherichia coli, Lactobacillus planta-
rum, Pseudomonas fl ouorescens, Listeria
innocua , and Staphylococcus aureus. The
lactoperoxidase system forms the basis for
applications as an antimicrobial agent in oral
health care products and to enhance the shelf
life of perishable foods. It also can be used
to determine the presence of mastitis.

Alkaline Phosphatase

Alkaline phosphatase is used commercially
as an indicator for the effectiveness of the
pasteurization process and the contamina-
tion of pasteurized milk because its activity
is destroyed by the pasteurization process,
which kills pathogens. However, it cannot