Principles of Cheese Technology 245Hooping and Pressing
In soft and semi - soft cheeses, the curd and
whey are dipped into perforated molds and
hoops of selected shapes and sizes. As whey
drains, the curd settles. The hoops should be
turned upside down at regular intervals to
ensure better draining of whey and formation
of a smooth plastic mass of uniform shape.
The molds and hoops are selected to form
discs of various sizes of small wheels or slabs
of cheese. The cheese forms are removed
from the molds and hoops and immersed in
brine for cooling and salting.
In Swiss and Dutch type cheeses, prior to
draining, the curd is pressed under whey to
eliminate trapped air and liquid, to obtain a
smooth texture. For certain cheese varieties
(Brick, Muenster), the curd is washed with
water to reduce the lactose content. After
draining up to 67% of the whey, fresh water
is added to the vat to replace the drained
whey and the curd - water mixture is agitated
for about 15 minutes. The washing step
results in higher moisture retention in
cheese while achieving a pH of 5.0 to 5.2.
The water temperature infl uences the mois-
ture retention in cheese curd. Gouda cheese
curd is washed with hot water to dry out
the curd.
The curd is fi lled into hoops; in hard
cheese varieties it is subjected to hydraulic
pressure to fuse the curd into a single block.
For cheddar, traditionally 170 kPa of pressure
is applied for several hours. Warmer curd
requires lower pressure. Little or no pressure
is needed for soft cheeses. A small amount
of whey may be expelled at this stage.
Vacuum treatment can be applied before
or after pressing to reduce/eliminate mechan-
ical openings in the blocks.Salting the Curd
Salt (sodium chloride) incorporation in
cheese curd is another key step in cheese
production. Sutherland (2003) has describedments rapidly without the buffering capacity
of calcium and phosphorus. Thus, the curd
develops an acidic fl avor and the body
becomes weak and pasty.
Draining the Whey and Milling
the Curd
When the cooking step has been completed
and the desirable acidity has been recorded
(pH of whey 6.1 to 6.4), the whey is physi-
cally removed from the vat. The curd is
allowed to settle to the bottom of the vat and
a screening device is fi tted in the discharge
end of the vat. On opening the valve, clear
whey exits from the vat, leaving a heap of
curd behind. The draining time from all vats
(typically 20 minutes) should be fairly uni-
form to maintain quality of the cheese. The
curd is trenched on the sides of the vat to
facilitate further draining. The curd is allowed
to stick together (matting) to form loaves,
while acidity builds and whey acquires near -
clear character. In cheddar, American, and
pasta fi lata cheese varieties, the fi nal pH
should be 5.2 to 5.4. When the proper acidity
level is attained, the cheddar cheese loaves
are ready for milling into small cuts and
salting. The pasta fi lata cheese loaves are fed
into hot water stretching and molding equip-
ment, where the curd is softened, melted, and
stretched in hot water and then exits in a
particular shape. These forms are immersed
in cold brine for cooling and salting.
Whey separation in automated cheese vats
is carried out by pumping curd along with
whey onto a draining and matting conveyer
belt, where it is allowed to reach proper
acidity. The fused curd mat is then mechan-
ically cut, salted, and conveyed to the hoop-
ing station for shaping into cheddar blocks
and barrels. Salting occurs after hooping
and pressing in several other cheese vari-
eties. Whey is processed further to manufac-
ture important ingredients such as dry whey,
lactose, and whey protein concentrates
(Kilara, 2008 ).