Process of Cheese Making
Cheese
making is a complicated process which varies extensively with the different
types of cheeses available. The basic
principle behind all natural cheese production is the curdling and coagulation
of milk so that it forms into curds and whey (what Ms. Muffet ate!). Rather than the accidental curdling of
un-refrigerated forgotten milk, today’s methods encourage the curdling process
by the addition of a starter culture, which is a living colony of microscopic
organisms, typically bacterial, that produces lactic acid. Milk will naturally
sour and form into an acid curd; however, the addition of the starter culture
promotes the acidification of the milk.
It is possible to make cheese without a starter, but the starter is one
of the components that gives different cheeses their
distinctive flavor. A coagulating
enzyme, called rennet is also used to speed up the separation of the curds
(solid) and whey (liquid). The solid
curds are what will eventually become what we know as cheese. In a way cheese is just a tasty way of
preserving milk for a long period of time; the cheese-making process solidifies
milk proteins and fat and preserves them.
The following diagram shows the basic stages of the
cheese making process.
Here the basic process of cheese making will
be outlined. However, keep in mind that
the cheese making process is diverse and intricate when considering the broad
spectrum of cheese varieties.
To
begin, you need the basis of all cheese – milk.
Variation in the quality of cheese occur
depending on the type of milk used. A
variety of types of milk are used to make different types of cheeses as well,
ranging from cow, goat, sheep, and even buffalo milk. Milk must also be carefully selected to make
sure there are no antibiotic or harmful against that could affect the
process. After the milk is prepared,
usually pasteurized, the starter culture is added. As aforementioned the starter can determine
the distinct taste of the cheese. There
are two basic categories of starter cultures.
Mesophilic starter cultures, the type typically used by amateur cheese
makers, have microbes that cannot survive at high temperatures and thrive at
room temperatures. Cheddar and 
product
lowering the pH. If there is too much
acid in the milk the cheese will be crumbly; however, not enough and the curd
will be pasty. After acidification, coagulation begins to 
produce curds and whey. As the pH of the milk lowers, the structural
nature of the casein proteins present in milk changes leading to the formation
of a curd that entraps fat and water.
Like with the fermentation of milk, coagulation would occur naturally if
the milk was left alone; however, the more common method utilizes enzymes from
a number of sources: animals, plants,
and fungi. The traditional source of
enzyme is rennet. Rennet is a
preparation made from the lining of the fourth stomach of calves. The most important enzyme in rennet is chymosin
which causes particles of milk protein (casein) to clump together. When the solid gel-like clump is cut in a
precise process called cutting, a liquid called whey is allowed to escape. The purpose of cutting the curd is to begin
the water/whey removal process by increasing the surface area of the
curds.
Casein micelle.
Casein micelle.
After cutting the curds, salt is
added to ensure the cheese will not spoil as it cures as well as playing a key
role in the formation of the cheese’s rind and to provide flavor. Now the curds are pressed in a cheese press,
lightly at first to allow the escape of the remaining whey, the severely (up to
a ton of pressure!) to solidify the cheese.
The next stage is bandaging where the cheese
is wrapped in an absorbent sterile bandage (i.e. cheesecloth) and allowed to ripened. During the
ripening stage, bacteria continue to grow in the cheese and change its chemical
composition, resulting in flavor and texture changes in the cheese. It is also during this period that the rind
of the cheese is formed. The rind’s
basic function is to protect the interior of the cheese and allow it to ripen
harmoniously. The maturation/ripening
period can take only two weeks for some cheese, and as long as 7 years for
others. The type of bacteria active at
the maturation stage and the length of time the cheese is aged determine the
type and quality of cheese being made.
Now all that’s left
is to enjoy the variety of cheeses available.
References:
www.ebs.hw.ac.uk/SDA/cheese2.html