Say "Cheese!"
Microbes and the cheese they make
Because there are 2000 distinct varieties of cheese in about 20 differnt types.
The first bacterium listed makes the lactic acid that thickens the milk; the second bacterium is generally the flavor producer.


Type of Cheese
Bacteria Responsible

Streptococcus lactis, Leuconostoc cremoris


S. cremoris, S. diacetylactis, S. thermophilus


S. lactis, S. cremoris, Penicillium camemberti, P.candidum


S. thermophilus, Lactobacillus bulgaricus

Monterey Jack

S. lactis, S. cremoris


S. lactis, S. cremoris, Brevibacterium linens

Bleu (Roquefort)

S. lactis, S. cremoris, Penicillium roqueforti


S. lactis, S. cremoris, S. durans, L. casei, L. plantarum


S. lactis, S. cremoris


S. lactis, S. cremoris, S. diacetylactis


S. lactis, L. helveticus, S. thermophilus, P. shermanii

Parmesan (goat milk)

S. lactis, S. cremoris, S. thermophilus, L. bulgaricus


S. lactis, S. cremoris, S. thermophilus, L. bulgaricus

Type of Cheese
Bacteria Responsible


Cheese Characteristics
Soft cheeses: Fresh, unripened cheeses; these are
cheeses which do not age and include Cottage, Cream and Ricotta.
In taste they are the mildest. They are usually not salted.
Double and Triple cremes: Lots of cream has been added to the cheese in process. The double
cremes have a fat content of 60%, and the triple cremes a 75% fat content.
Some of them do not undergo a ripening process, so they can also be classed as
unripened cheeses.
Bland and buttery: These are essentially mild tasting,
stable, all-purpose table cheeses. These cheeses
are unpronounced in flavor and aroma. This group includes Edam, Gouda, and Fontina.
Swiss-style cheeses: Swiss-style cheeses usually have tough
hard rinds and interiors dotted with holes. These holes are caused by expansion of
gas within the cheese curd during the ripening period.
Cheddar-style cheeses: Cheeses that are 'cheddared' undergo a step in
the making process which involves them being cut into pieces and stacked
and turned at the bottom of the cheese vat for a period. The familiar
cheddar cheese is firm textured, yellow with a clean, mellow taste which
develops a sharp and tangy bite the further it matures. Vermont is one of the
best-known American types.
Extra-hard cheeses: They have an exceptionally hard, brittle texture which makes
them suitable for grating and are known for their sharp flavor. Cheeses of this
type can be matured for up to three years.
Blue veins: These cheeses are characterized by the veins of blue, blue-black or green,
and their pungent aromas and tangy flavors. All blue-vein cheeses are internally
ripened after being inoculated with a Penicillium spore.
Smoked cheeses: Smoked cheese is simply a cheese variety, often Cheddar,
which has been treated and flavored with smoke. Most of this type of
cheese is processed. In most cases the smoke flavor is produced by chemicals.
Processed cheese: All processed cheese has its ripening process stopped
at a given point by heat treatment. It is usually made from one or two
cheese types blended together For many people processed cheeses taste
'plastic' but are very popular partly because they don't spoil quickly,
are cheap and have a very mild taste.
Adapted from "The Cheese Book," by Richard
Widcome. Chartwell Books (Seacaucus, NJ),
Basic Cheese making
Cheese is made from any kind of milk; the basic principle involved in making all natural cheese is to curdle the
milk so that it forms into curds (milky white lumps) and whey (a thin liquid). As
anyone knows who has left milk unrefrigerated for a period, milk will curdle quite
naturally. The milk sours and forms into an acid curd. Today's methods help the curdling process by the addition of a starter (a bacterial culture which produces lactic acid) and rennet (a substance obtained from the stomach linings of young calves that contains a coagulating enzyme which speeds the separation of liquids and solids).
Cheeses that do not require a ripening process under go the following steps:
  1. warming the milk and letting it stand,
  2. treating it with a lactic starter to help the acid development
  3. cutting and draining the whey from the cheese.
  4. The cheese is then packed and marketed without further ripening.
Cheeses that undergo a ripening process (also known as a curing, maturing or ageing
process) are all treated with rennet. Before the ripening process begins, they undergo the following steps:
  1. Milk is warmed
  2. A starter culture and rennet are added
  3. The milk coagulates into a single huge curd
  4. The curd is stirred and cut to drain off whey
  5. The curd is heated, sometimes pressed, to remove more whey
  6. The curd is molded and shaped into a cheese, salting taking place before or after this process
  7. The cheese is matured under controlled conditions
During the ripening period, the two most important factors are the length of the
maturing time ( two weeks to seven years) and the temperature at which
the cheese is matured.
It is during this time that the microorganisms play their part. They may be present
naturally in the milk or in the atmosphere of the curing room, or they can be artificially
Adapted from "The Cheese Book," by Richard Widcome. Chartwell Books
(Seacaucus, NJ), 1978.
Info. for this page found at CheeseNet
  New England Cheese Company
American Cheese Society
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