Cheddar. Swiss. Gouda. Goat. Brie. Blue. What do they have in common? They all are CHEESE! But this simple, delicious 5 letter word comes from a complicated process.....

Cheese is: a fresh or ripened product obtained after coagulation and separation of a selective concentration of milk.

But cheese is not a naturally found food.. it is created from the coagulating, or clotting of milk with added enzymes (proteins that help to lower the energy needed to start a reaction; a cataylst in a chemical reaction). These enzymes are important in all dairy production for they bring texture, flavour, extended shelf life and disguise the bitterness of products.
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The most populat enzyme used to curdle milk is called proteases. It works to break down a protein in milk called kappa casein in order to start milk's clottining.
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Another important enzyme is rennet. Rennet is a lactic acid, used to help speed up the process with proteases, but is found in the membrane of the stomach of a calf! It comes in many different forms deriving from animals, vegtables, and genetically enginnered ones! The active enzyme within rennet is called chymosine, and that together, once added to milk, start its clotting.

  • Transformation of casein, broken down from proteases to paracasein under the influence of rennet
  • Precipitation of paracasein in the presence of calcium ions.

All these take place due to specific temperatures, acidicity and calcium, because of its ionic nature, in the milk. However, the best temperature for rennet's reaction t is 40°C, but lower temperatures are normally used in the practice, basically to avoid excessive hardness of the clotting.

The whole process looks something like this:

Fun Fact:
Lactase™ can be applied to cheese in the beginning coagulation session, for people who are lactose intolerant!

After the milk clotts, we cut the coagulum (product made from the clotted milk) to break up the curd. Then, like in the figure below (B) we start to stir the curd again, to decrease the chance of lumps. After this we add heat once we have drained the whey (juices produced). Then, we add heat to kill off bacteria produced in the clotting of the milk
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A : during stirring B : during cutting C : during whey drainage D : during pressing
Source : Dairy Processing Handbook, Tetrapak Sweden

Fast Fact: Different cheeses like Emmenthal and Parmesan need higher temperatures to be warmed at for their textures!

Stir the soon-to-be cheese again, and then, the process through which the new whey is removed from the cheese, also helps determine its type. After this, we can put it into a press or mould for shaping, and then salt the cheese to help it ripen. After this, the cheese goes through a process of utlizing enzymes again called **//Lactose and Protein decomposition.//** This is where rennet again is used a paracasein molecule in the cheese into polypeptides. Rennet here makes decomposition of the casein quickly as a bacterial enzyme.
external image enz_sub.jpg Lactose decomposition uses the enzyme lactase to act upon the substrate group of lactose to make glucose and galactose, that is usually closely monitored by producers to make textures of cheeses with holes.

Finally, the cheeses will be stored to control the ripening cycle; aged cheeses, like blue cheese, for example go through enlonged cycles. Different temperatures and humidities must be kept in different conditions for every type of cheese during their ripening stages.

Enzymes, and all types of rennet, comes in many forms from powders, pastes, and liquid concentrations that can be bought online even, at sources like here. These include speciali bioenginnering enzymes like DairyHOX™ that can even whiten cheese to make it look more appetizing!
Enzyme Origin
Availbale Form
Customer Benefit
Danisco Rennet
Natural Extract of animal rennet
powder concentrated liquid paste
Kappa Casein Hydrolysis
milk clotting

Fun Facts: Rennet is still Controversial….
"Animal rights activists argue that it is inhumane to kill calves for their stomach enzymes, [rennet] especially when there are several alternative coagulants available to make cheese. These activists would argue that if you eat cheese, then purchase one that is made using cloned or microbial enzymes."

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So, back to Cheddar. Swiss. Gouda. Goat. Brie. Blue. All are cheeses, and are great, maybe because there are so complicated to make!
By Kaylee