Principles of Cheese Technology 235the white appearance of milk of water buf-
faloes, goats or sheep. Titanium dioxide and
chlorophyll based - colorants are permitted in
many countries.
Certain enzymes are used as ripening
supplements. These are generally lipases and
proteases developed from starter cultures,
which are used to accelerate cheese ripening.
Other enzyme preparations are derived from
the buccal cavity of young goats and sheep,
which consist of concentrates of esterases.
When cow ’ s milk is substituted for goat or
sheep milk, these enzyme preparations simu-
late the development of traditional fl avors of
feta, Romano, and parmesan cheeses.Starter
Milk is normal habitat of several lactic acid
bacteria that may cause spontaneous souring
under favorable conditions. Specially pre-
pared lactic acid bacteria called starters are
used for cheese production control (Broome
et al., 2003 ; Powell, 2003 ; Hill, 2009 ). A
starter consists of harmless microorganisms
that impart desirable and predictable charac-
teristics to a given variety of cheese upon
culturing in milk and cheese curd. The starter
bacteria are non - motile, Gram - positive, non -
sporeforming, catalase, and nitrate negative,
and are microaerophilic (prefer low oxygen
concentration) in nature. They are generally
inactivated at refrigeration temperature.
Under microscope, the lactococci appear
round/elliptical (cocci) shaped with diameter
of approximately 1 μ M. The lactobacilli are
rod shaped, 1 μ M in width and 2 to 3 μ M
length. Depending on the cheese, the starters
contain mesophilic or thermophilic cultures.
They are distinguished by their optimum
growth temperature, which is approximately
30 ° C to 35 ° C (86 ° F to 95 ° F) for mesophilic
cultures, and 39 ° C to 50 ° C (102 ° F to 122 ° F)
for thermophilic cultures. As the starter
culture grows, its metabolic end products
lead to acidifi cation of milk and curd.
Furthermore, evolution of CO 2 can form
holes (eyes) as in Swiss cheese. Productionsafety reasons, most of the world ’ s cheese is
produced with pasteurized milk. Some plants
use thermization treatment to prevent spoil-
age of stored raw milk over weekends; the
technique involves heating raw milk at 63 ° C
to 65 ° C (145 ° F to 149 ° F) for a few seconds.
Nevertheless, milk still must be pasteurized
prior to cheese making.
Pasteurization inactivates heat - labile
enzymes and reduces bacterial load. Pasteur-
ized milk must test phosphatase negative.
Generally, in the United States, FDA regula-
tions require pasteurization of milk at 71.7 ° C
(161 ° F) for 15 seconds for cheeses consumed
fresh. If milk is not pasteurized for cheese
making, the cheese must be held for at least
60 days at 1.67 ° C (35 ° F) or higher prior
to consumption. The equivalent heat treat-
ment is 63 ° C (145 ° F) for 30 minutes. Heat
treatment of milk at a higher temperature -
time regime has deleterious effects on milk
coagulation and the physical quality of
cheese.
Additives in Cheese Milk.
Calcium chloride is added to milk at
approximately the 0.02% level to accelerate
coagulation and to improve cheese yield.
Cheese color is added to produce certain
cheeses of consistent color throughout the
year. One example is annatto dye, an oil
extract of seeds of the Bixa orellana plant.
Annatto contains two apocaroteinoid pig-
ments, bixin and norbixin, that do not have
vitamin A activity. The color is red to yellow
and is pH dependent. The yellow coloration
is more pronounced at higher pH and changes
to a reddish hue at the normal pH of cheese.
At a pH of under 4.8, it turns light pink and
eventually colorless. Bleaching and pink col-
oration in cheese is due to oxidation of
annatto caused by heat treatment, ultraviolet
light, iron, copper, and chlorine. β - carotein,
another colorant used in cheese, imparts too
much yellow hue.
Bleaching agents are used in some
cheeses made from cow ’ s milk to simulate