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 Gouda are two common cheese make from these mesophilic bacterium.  Thermophilic starter cultures, on the other hand, can survive at scorching temperatures.  These heat-loving bacteria are used when the curd is cooked to as high as 132ºF and account for many Swiss and Italian cheeses.  The bacteria start off the cheese making process with the acidification of milk. Bacteria feed on the lactose in milk and produce lactic acid as a waste Lc. cremoris on Reddy's mediumproduct 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 Text Box: Lactococci lactis.  A common starter culture bacteria.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. 

 

           

 

 

Text Box: Decanting the whey.

Casein micelle.

 

Text Box: Cutting the Curd – factory style.

                                                     

 

 

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.

 

New cheese pressCheese frame

 

Text Box: A maturing cheese

 

Text Box: Modern Cheese Press

 

 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

 

 

History of Cheese

The Cheese Process

Contributing Microorganisms

Making Cheese

Recipes

Fun Facts

Quiz