What is Biotechnology?
is one that uses
various branches of
industry, agriculture and
Outline of cheesemaking proces
The basic source for cheesemaking is milk obtained from
cows, goats, sheep etc.
There are the main stages cheesemaking:
2. Coagulation -separating the milk into solid curds
3.Maturing of cheese
Microorganisms are used in each step of this
process and determine the flavor and texture of the
The 1st step of cheesemaking –
The milk is contaminated with bacteria such as E. coli,
Salmonella, Listeria that are dangerous for human
Pasteurisation is the process of heating up milk and
cooling it back down in an effort to minimize the bacterial
risk of that product.
The key to pasteurisation is to heat the milk to 72 degrees
for no more than 15 seconds and then quickly cooling it to
The second and the main step of
cheese making– Coagulation
Cheesemaking involves separating the milk into solid
curds and liquid whey by coagulating the casein
protein in milk. Acidifying (souring) milk helps to
separate the curds. For this purpose the lactic acid
bacteria is added.
Curds and whey
Bacteria acidify milk
Acidifying (souring) milk helps to separate the curds
and whey and control the growth of undesirable
bacteria in cheese.
Usually special ‘starter’ bacteria are added to milk
to start the cheesemaking process. These bacteria
convert the lactose (milk sugar) to lactic acid and
lower the milk’s pH.
Starter bacteria and type of cheese
Now it is important how we are going to produce cheese.
Now, depending on the type of cheese are added to the
corresponding lactic acid bacteria.
There are two types of bacteria used for this process:
Mesophilic bacteria thrive at room temperature but die at
higher temperatures. They are used to make mellow
cheeses, such as Cheddar, Gouda and Colby.
Thermophilic bacteria thrive at higher temperatures,
around 55 °C, and are used to make sharper cheeses such
as Gruyère, Parmesan and Romano.
Why are there holes in cheese ?
Starter bacteria produce lactic acid, as well as aromatic
compounds and carbon dioxide, which is responsible for the
formation of cheeses mesh
Enzymes speed up coagulation
Some cheeses are curdled only by acidity. For example,
paneer cheese is made using lemon juice to curdle the
milk and cottage cheese is made using mesophilic
bacteria. However, for most cheeses, rennet
(podpuszczka) is also added to the milk after a starter
Rennet is a mixture containing the active enzyme
chymosin. Rennet speeds up the coagulation of casein and
produces a stronger curd. It also allows curdling at a
lower acidity, which is important for some types of cheese.
Rennet is an extract from a calf’s stomach. It nowadays
can be synthetically made
The 3rd step of cheesemaking –
maturing of cheese. Further action of
As cheese matures, bacteria break down
the proteins, altering the flavour and
texture of the final cheese. The proteins
first break into medium-sized pieces
(peptides) and then into smaller pieces
Other microorganisms in
cheesemaking- fungus and yeats
During maturing, some cheeses are inoculated with a
fungus such as Penicillium.
Inoculation can be either on the surface (for example, with
Camembert and Brie) or internally (for example, with blue
vein cheeses). During ripening, the fungi produce
digestive enzymes, which break down large protein
molecules in the cheese. This makes the cheese softer,
runny and even blue.