292 Chapter 11
curd is adequately cooked when a handful
of water - chilled curd springs apart when
squeezed together with moderate pressure.- Washing. After completion of cooking, the
jacket water is drained. The whey is
removed until the curd begins to surface.
Wash water, acidifi ed with phosphoric acid
and glucono - δ - lactone to pH 4.6 and chlo-
rinated to 10 to 20 ppm, is then added equal
to the volume of the whey removed. The
temperature of the curd should drop to
27 ° C to 30 ° C (81 ° F to 86 ° F). After agita-
tion for 10 minutes, the water is drained.
Washing is continued two more times with
chilled water to drop the temperature of the
curd to 13 ° C to 16 ° C (55 ° F to 61 ° F) and
fi nally to 5 ° C (41 ° F) or lower. The curd is
trenched and allowed to drain for 30 to 60
minutes before creaming. - Creaming. The curd is blended with cream
dressing in a blender or the vat itself. The
dressing is formulated to contain 12.5%
fat, 8.5% solids - not - fat (SNF), 2.7% salt,
and 0.25% stabilizer. The stabilizer is espe-
cially designed for the dressing to display
high viscosity and to avoid wheying off.
The dressing is pasteurized at 75 ° C to 77 ° C
(167 ° F to 171 ° F) with a holding period of
30 minutes and homogenized at 57 ° C
(135 ° F) at a pressure of 136 atm (2,000 psi),
single - stage followed by cooling to 4 ° C
(39 ° F) or below. One part of the dressing
is blended with two parts of the curd to
yield a minimum of 4% fat in creamed
cottage cheese. The dressing can be further
treated to enhance the shelf life of cottage
cheese to control the growth of spoilage
psychrotrophic organisms, yeasts, and
molds. Use of sorbic acid is allowed. The
typical shelf life of cottage cheese pack-
aged in moisture - barrier containers is three
to four weeks at a storage temperature of
4 ° C (39 ° F).
Cottage cheese curd yield is typically
around 15.5% kg/100 kg of skim milk of 9%cooled to 32 ° C (89.6 ° F) and pumped into
a cheese vat where the jacket temperature
is adjusted to maintain the milk tempera-
ture at 32 ° C (89.6 ° F). Bulk culture con-
taining Lactococcus lactis ssp. lactis/
cremoris is added at the rate of 5% to 7%
and mixed thoroughly. The TA/pH is mea-
sured at this point. The stirring is continued
at intervals of 30 minutes for a period of
1.5 hours. The increase in acidity at this
point should be 0.05% to 0.07%. If it is not,
1% more culture is added for each 0.01%
increment below 0.05%. Next, rennet is
added after diluting 1 part of rennet with
40 parts of water. Rennet is used at the rate
of 1 ml for large curd and 0.3 to 0.5 ml per
454 kg (1,000 lbs) of skim milk. After
mixing the rennet thoroughly, the vat is
covered for about two hours for fermenta-
tion and the pH should drop to 4.6 to 4.7.- Cutting. When the curd is ready, it is cut
fi rst along the length of the vat using
appropriate horizontal knives to get the
desired small - or large - curd product. Wire
knives of 0.62 cm (1/4 inch) opening are
used to for small - curd, and wire knives of
1.86 cm (3/4 inch) opening give a large -
curd product. Next, the second cut is made
lengthwise with the vertical knife. The
third cut is made with the same vertical
knife crosswise across the vat. - Cooking. After cutting, the curd is allowed
to heal for 10 minutes. The jacket water
temperature is raised to 44 ° C to 50 ° C
(111 ° F to 122 ° F) to initiate cooking of the
curds. The temperature of the curd is raised
slowly to 54 ° C (129 ° F) in 1.5 hours. The vat
is hand - stirred every fi ve to 10 minutes and
a mechanical agitator is used after the tem-
perature of the vat reaches 38 ° C to 41 ° C
(100 ° F to 106 ° F). The agitation speed is
increased slowly to avoid matting the
curd. Small curd cooks faster than large
curd. The agitation is continued until
the curd becomes reasonably fi rm. The