Transcript BIOTECHNOLOGY IN MANUFACTURING CHEESE What is

BIOTECHNOLOGY IN
MANUFACTURING CHEESE
What is Biotechnology?
Biotechnological process is
one that uses microorganisms
in various branches of
industry, agriculture and
medicine.
Outline of cheesemaking proces
The basic source for cheesemaking is milk obtained from cows,
goats, sheep etc.
There are the main stages cheesemaking:
1.Pasteurisation
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 final cheese
The 1st step of cheesemaking –
pasteurisation
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 4°C.
.
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 bacteria.
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 bacteria
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
(amino acids).
Other microorganisms in cheesemakingfungus 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.