Cheese ripening
Encyclopedia
Cheese ripening or alternatively cheese maturation is a process in cheesemaking
. It is responsible for the distinct flavour of cheese
, and through the modification of "ripening agents", determines the features that define many different varieties of cheeses, such as taste, texture, and body. The process is "characterized by a series of complex physical, chemical and microbiological changes" that incorporate the agents of: "bacteria
and enzymes of the milk
, lactic culture, rennet
, lipases, added moulds or yeast
s, and environmental contaminants." The majority of cheese is ripened, save for fresh cheese.
Roquefort, which is required to be ripened in designated caves in south-eastern France
. However, with invention of refrigeration
in the 20th century, the process today has evolved considerably, and much more efficient at producing a consistent quality of cheese, at a faster pace and a lower cost, depending on the type of cheese.
Ripening is influenced by a variety of factors, ranging from the microflora to the curd, and others. The enzymatic process is the most crucial process for all cheeses, although bacteria
plays a role in many varieties. The most important agents in this process include four the following elements: "Rennet
, or a substitute for rennet, starter bacteria
and associated enzymes, milk enzymes, second starter bacteria and associated enzymes, and non-starter bacteria". Each of these factors affect the cheese ripening process differently, and has been the subject of much research. It is important for manufacturers to understand how each of these elements work, so that they are able to maintain the quality of the cheese, while producing the cheese at an acceptable investment of time and cost. These agents contribute to the three primary reactions that define cheese ripening: glycolysis
, proteolysis
, and lipolysis
.
By taking the cheese through a series of maturation stages where temperature and relative humidity are carefully controlled, the cheese-maker allows the surface mould to grow and the mould-ripening of the cheese by fungi to occur. Mould-ripened cheeses ripen faster than hard cheeses, in weeks as opposed to the typical months or even years. This is because the fungi used are more biochemically active than the starter bacteria. Where the ripening occurs is largely dependent on the type of cheese, some cheeses are surface-ripened by moulds, such as Camembert and Brie
, some are ripened internally, such as Stilton
. Surface ripening of some cheeses, such as Saint-Nectaire
cheese, may also be influenced by yeast
s which contribute flavour and coat texture. Others are allowed by the cheesemaker to develop bacterial surface growths which give characteristic colours and appearances. The growth of Brevibacterium linens, for example, creates an orange coat to cheeses.
In contrast to cheddaring, making cheeses like Camembert
requires a more gentle treatment of the curd. It is carefully transferred to cheese hoops and the whey is allowed to drain from the curd by gravity, generally overnight. The cheese curds are then removed from the hoops to be brined by immersion in a saturated salt solution. This is because the amount of salt
has a large effect on the rate of proteolysis
in the cheese, stopping the bacteria from growing. If white mould spores have not been added to the cheese milk the cheese-maker applies them to the cheese either by spraying the cheese with a suspension of mould spore
s in water or by immersing the cheese in a bath containing spores of, e.g., Penicillium candida.
gas that is produced by bacteria
in the cheese.
In Swiss-type cheeses, the eyes form as a result of the activity of propionic acid bacteria
(propionibacteria), notably Propionibacterium freudenreichii
subsp. shermanii. In Dutch-type cheeses, the CO2 that forms the eyes results from the metabolisation of citrate
by citrate-positive ("Cit+") strains of lactococci.
, fat
, brine
, and many other elements. Brine, as an example, mixes with saliva
, delivering the flavour of the cheese to the taste buds and determining the cheese's moistness. Many of these elements are specific to the type of cheese. For instance, proline
is more abundant in Emmental
than in any other type of cheese, and gives the cheese its much sweeter taste.
Cheesemaker
A cheesemaker is a person who makes cheese.The craft of making cheese dates back at least 4,000 years. Archaeological evidence exists of cheesemaking by the ancient Egyptian civilizations....
. It is responsible for the distinct flavour of cheese
Cheese
Cheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms....
, and through the modification of "ripening agents", determines the features that define many different varieties of cheeses, such as taste, texture, and body. The process is "characterized by a series of complex physical, chemical and microbiological changes" that incorporate the agents of: "bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and enzymes of the milk
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
, lactic culture, rennet
Rennet
Rennet is a complex of enzymes produced in any mammalian stomach to digest the mother's milk, and is often used in the production of cheese. Rennet contains many enzymes, including a proteolytic enzyme that coagulates the milk, causing it to separate into solids and liquid...
, lipases, added moulds or yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
s, and environmental contaminants." The majority of cheese is ripened, save for fresh cheese.
History
Cheese ripening was not always the highly industrialised process it is today, in the past, cellars and caves were used to ripen cheeses instead of the current highly regulated process involving machinery and biochemistry. Some cheeses still are made using more historical methods, such as the blue cheeseBlue cheese
Blue cheese is a general classification of cow's milk, sheep's milk, or goat's milk cheeses that have had cultures of the mold Penicillium added so that the final product is spotted or veined throughout with blue, blue-gray or blue-green mold, and carries a distinct smell, either from that or...
Roquefort, which is required to be ripened in designated caves in south-eastern France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
. However, with invention of refrigeration
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...
in the 20th century, the process today has evolved considerably, and much more efficient at producing a consistent quality of cheese, at a faster pace and a lower cost, depending on the type of cheese.
Process
After the initial manufacturing process of the cheese is done, the cheese ripening process occurs. This process is especially important, since it defines the flavour and texture of the cheese, which differentiates the many varieties. Duration is dependant on the type of cheese and the desired quality, but "three weeks to two or more years" is the general requirement for most cheeses.Ripening is influenced by a variety of factors, ranging from the microflora to the curd, and others. The enzymatic process is the most crucial process for all cheeses, although bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
plays a role in many varieties. The most important agents in this process include four the following elements: "Rennet
Rennet
Rennet is a complex of enzymes produced in any mammalian stomach to digest the mother's milk, and is often used in the production of cheese. Rennet contains many enzymes, including a proteolytic enzyme that coagulates the milk, causing it to separate into solids and liquid...
, or a substitute for rennet, starter bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and associated enzymes, milk enzymes, second starter bacteria and associated enzymes, and non-starter bacteria". Each of these factors affect the cheese ripening process differently, and has been the subject of much research. It is important for manufacturers to understand how each of these elements work, so that they are able to maintain the quality of the cheese, while producing the cheese at an acceptable investment of time and cost. These agents contribute to the three primary reactions that define cheese ripening: glycolysis
Glycolysis
Glycolysis is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+...
, proteolysis
Proteolysis
Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...
, and lipolysis
Lipolysis
Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into free fatty acids followed by further degradation into acetyl units by beta oxidation. The process produces Ketones, which are found in large quantities in ketosis, a metabolic state that occurs when the liver...
.
By taking the cheese through a series of maturation stages where temperature and relative humidity are carefully controlled, the cheese-maker allows the surface mould to grow and the mould-ripening of the cheese by fungi to occur. Mould-ripened cheeses ripen faster than hard cheeses, in weeks as opposed to the typical months or even years. This is because the fungi used are more biochemically active than the starter bacteria. Where the ripening occurs is largely dependent on the type of cheese, some cheeses are surface-ripened by moulds, such as Camembert and Brie
Brie
Brie is a historic region of France most famous for its dairy products, especially Brie cheese. It was once divided into two sections ruled by different feudal lords: the western Brie française, corresponding roughly to the modern department of Seine-et-Marne in the Île-de-France region; the...
, some are ripened internally, such as Stilton
Stilton
Stilton is a village in Cambridgeshire, England, and within the historic county boundary of Huntingdonshire.-Geography:Stilton lies south of the city of Peterborough. It lies on the old Great North Road, from London and was an important coaching stop in the days before motorised transport. It...
. Surface ripening of some cheeses, such as Saint-Nectaire
Saint-Nectaire
Saint-Nectaire is a French cheese made in the Auvergne region of central France. The cheese has been made in Auvergne since at least the 17th century. Its name comes from the Marshal of Senneterre , who served it at the table of Louis XIV...
cheese, may also be influenced by yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
s which contribute flavour and coat texture. Others are allowed by the cheesemaker to develop bacterial surface growths which give characteristic colours and appearances. The growth of Brevibacterium linens, for example, creates an orange coat to cheeses.
In contrast to cheddaring, making cheeses like Camembert
Camembert
Camembert is a commune in the Orne department in north-western France.It is most famous as the place where camembert cheese originated.Camembert has been called "The largest small village in France." This is because the area of the commune itself is out of proportion to the center of the village...
requires a more gentle treatment of the curd. It is carefully transferred to cheese hoops and the whey is allowed to drain from the curd by gravity, generally overnight. The cheese curds are then removed from the hoops to be brined by immersion in a saturated salt solution. This is because the amount of salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
has a large effect on the rate of proteolysis
Proteolysis
Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...
in the cheese, stopping the bacteria from growing. If white mould spores have not been added to the cheese milk the cheese-maker applies them to the cheese either by spraying the cheese with a suspension of mould spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s in water or by immersing the cheese in a bath containing spores of, e.g., Penicillium candida.
Eyes
The round holes that are a characteristic feature of Swiss-type cheese (e.g. Emmentaler cheese) and some Dutch-type cheeses are called "eyes". They are bubbles of carbon dioxideCarbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
gas that is produced by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
in the cheese.
In Swiss-type cheeses, the eyes form as a result of the activity of propionic acid bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
(propionibacteria), notably Propionibacterium freudenreichii
Propionibacterium freudenreichii
Propionibacterium freudenreichii is a Gram-positive, nonmotile bacterium that plays an important role in the creation of Emmental cheese, and to some extent, leerdammer. Its concentration in Swiss-type cheeses is higher than in any other cheese. Propionibacteria are commonly found in milk and dairy...
subsp. shermanii. In Dutch-type cheeses, the CO2 that forms the eyes results from the metabolisation of citrate
Citrate
A citrate can refer either to the conjugate base of citric acid, , or to the esters of citric acid. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate.-Other citric acid ions:...
by citrate-positive ("Cit+") strains of lactococci.
Taste
The process of cheese ripening affects the taste of the final product. If the product is not ripened, the resulting cheese is tasteless, and so, all cheese is ripened except for fresh cheeses. Different factors define taste in cheese, including caseinCasein
Casein is the name for a family of related phosphoprotein proteins . These proteins are commonly found in mammalian milk, making up 80% of the proteins in cow milk and between 60% and 65% of the proteins in human milk....
, fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
, brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
, and many other elements. Brine, as an example, mixes with saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
, delivering the flavour of the cheese to the taste buds and determining the cheese's moistness. Many of these elements are specific to the type of cheese. For instance, proline
Proline
Proline is an α-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that the human body can synthesize it. It is unique among the 20 protein-forming amino acids in that the α-amino group is secondary...
is more abundant in Emmental
Emmental
For the cheese made in the region, see Emmental .The Emmental is a region in west central Switzerland, forming part of the canton of Bern. It is a hilly landscape comprising the basins of the Emme and Ilfis rivers. The region is mostly devoted to farming, particularly dairy farming...
than in any other type of cheese, and gives the cheese its much sweeter taste.