Transcript production ofcheese

MISS : SALSABEEL ALJOUJOU
I. Introduction
 Cheddar cheese is a semi-hard cows milk
cheese.
 It can vary in taste from mild to extra sharp.
 The cheese is one of the most well known
cheeses in the world, and many countries
produce regional versions of cheddar cheese,
especially Britain and former colonies.
 Because of the fame of the cheese, it is
readily available in most markets, and it
varies widely in quality.
 Cheese is a highly proteinaceous food
made from the milk of some herbivores.
 Cheese is believed to have originated in
the warm climates of the Middle East some
thousands of years ago, and is said to have
evolved when milk placed in goat stomach
was found to have curdled.
 The scientific study and manipulation of
milk for cheese manufacture is however
just over a hundred years old.
 About a thousand types of cheese have been
described depending on the properties and
treatment of the milk, the method of production,
conditions such as temperature, and the
properties of the coagulum, and the local
preferences.
II. Stages in the manufacture of cheese
II.1 Pasteurize/Heat Treat Milk
Depending on the desired cheese, the milk may be
pasteurized or mildly heat-treated to reduce the
number of spoilage organisms and improve the
environment for the starter cultures to grow.
Some varieties of milk are made from raw milk so
they are not pasteurized or heat-treated.
 Raw milk cheeses must be aged for at least 60
days to reduce the possibility of exposure to
disease causing microorganisms (pathogens)
that may be present in the milk.
II.1.1 Cool Milk
Milk is cooled after pasteurization or heat
treatment to 90°F (32°C) to bring it to the
temperature needed for the starter bacteria to
grow.
If raw milk is used the milk must be heated
to 90°F (32°C).
II.1.2 Inoculate with Starter & Non-Starter Bacteria
and Ripen
For cheese prepared at temperatures less than
40°C strains of Lactococcus lactis are
used.
For those prepared at higher temperatures the
more thermophilic Streptococcus
thermophilus, Lactobacillus bulgaricus, and
Lact. helveticus are used.
Lactic acid has the following effects:
 It causes the coagulation of casein at pH 4.6,
the isoelectric point of that protein, which is
used in the manufacture of some cheeses,
e.g. cottage cheese.
 It provides a favorably low pH for the action of
rennin the enzyme which forms the curd from
casein in other types of cheeses.
 The low pH eliminates proteolytic and other
undesirable bacteria.
 It causes the curd to shrink and thus promotes
the drainage of whey.
 Metabolic products from the lactic acid bacteria
such as ketones, esters and aldehydes
contribute to the flavor of the cheese.
II.1.3 Adding of rennet for coagulum formation
Chymosin, rennet, and rennin are often used
interchangeably to refer to this enzyme.
The latter, rennin, should not be confused with
renin, which is an enzyme associated with
kidneys and does not clot milk.
The rennet is the enzyme that acts on the milk
proteins to form the curd which is derived from
the fourth stomach, abomasum of freshly
slaughtered milk-fed calves
Besides those of calves, the abomasum of kids
(young goats), lamb or other young mammals
have been used.
II.1.3.2 Some commercial microbial rennets
and their microbial sources
Substitutes from microbial sources have been
very successful and continue to be used.
Many act like trypsin and have an optimum pH
activity between 7 and 8.
Microorganisms, including Bacillus subtilis, B.
cereus, B. polymyxa, and Mucor pusillus t (also
known as Rhizomucor pusillus) and Rh. miehei
have been extracted for their proteasenzymes.
The bacilli enzyme preparations were not suited
for cheese making because of excessive
proteolytic activity while the fungal-derived
enzymes gave good results, but not without off
flavors such as bitter.
III. Cut Curd and Heat: The curd is allowed to ferment until it reaches pH
6.4. The curd is then cut with cheese knives into
small pieces and heated to 100°F (38°C).
 The heating step helps to separate the whey from
the curd
IV. Drain whey
The whey is drained from the vat and the curd
forms a mat.
V. Texture curd
 The curd mats are cut into sections and piled on top
of each other and flipped periodically. This step is
called cheddaring. Cheddaring helps to expel more
whey, allows the fermentation to continue until a pH
of 5.1 to 5.5 is reached, and allows the mats to "knit"
together and form a tighter matted structure.
 The curd mats are then milled (cut) into smaller
pieces.
VI. Dry Salt or Brine
For cheddar cheese, the smaller, milled curd
pieces are put back in the vat and salted by
sprinkling dry salt (1% and 3% by weight) on
the curd and mixing in the salt.
VII. Form Cheese into Blocks
The salted curd pieces are placed in cheese
hoops and pressed into blocks to form the
cheese.
.
VIII. Store and Age
The cheese is stored in coolers until the desired age is reached.
Depending on the variety, cheese can be aged from several months
to several years.
IX. Package
Cheese may be cut and packaged into blocks