Rennet (pronounced /ˈrɛnɪt/) is a natural complex of enzymes produced in any mammalian stomach to digest the mother's milk, and often used in the production of cheese. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following Cheese is a Food made from Milk, usually the milk of cows, Buffalo, Goats or sheep, by coagulation. Rennet contains a proteolytic enzyme (protease) that coagulates the milk, causing it to separate into solids (curds) and liquid (whey). Proteolysis is the directed degradation ( digestion) of Proteins by cellular Enzymes called Proteases or by intramolecular digestion A protease is any Enzyme that conducts Proteolysis, that is begins protein Catabolism by Hydrolysis of the Peptide bonds that link Curd is a Dairy product obtained by curdling (coagulating Milk with Rennet or an edible Acidic substance such as Lemon juice Whey or milk plasma is the liquid remaining after Milk has been Curdled and strained it is a By-product of the manufacture of Cheese The active enzyme in rennet is called chymosin or rennin (EC 3.4.23.4) but there are also other important enzymes in it, e. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Chymosin (or rennin) is an aspartic acid protease Enzyme found in Rennet. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. g. , pepsin or lipase. Pepsin is a digestive Protease ( released by the chief cells in the Stomach that functions to degrade food Proteins into A lipase is a Water-soluble Enzyme that Catalyzes the Hydrolysis of Ester bonds in water–insoluble Lipid There are non-animal sources for rennet substitutes.

Contents 1 Uses 2 Production of natural calf rennet 2.1 Traditional method 2.2 Modern method 3 Alternative coagulants 3.1 Vegetable rennet 3.2 Microbial rennet 3.3 Genetically engineered rennet 3.4 Acid coagulation 4 See also 5 References 6 External links

Uses

The chief use of rennet is in the making of cheese, curd, and junket. Cheese is a Food made from Milk, usually the milk of cows, Buffalo, Goats or sheep, by coagulation. Curd is a Dairy product obtained by curdling (coagulating Milk with Rennet or an edible Acidic substance such as Lemon juice Junket is a Milk -based dessert made with sweetened milk and Rennet, the digestive Enzyme which Curdles milk Chymosin reacts specifically with κ-casein, cleaving the protein between the amino acids phenylalanine(105) and methionine (106), producing two fragments. See Casein paint for information about casein usage in artistic painting In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Phe redirects here For the BitTorrent feature see PHE. For the constellation see Phoenix (constellation. Methionine ( abbreviated as Met or M) is an α- Amino acid with the Chemical formula HO2CCH(NH2CH2CH2SCH3 The soluble fragment (residues 106-169), which becomes part of the whey, is known as glyco macro peptide and contains the glycosylation sites for κ-casein. Peptides (from the Greek πεπτίδια, "small digestibles" are short Polymers formed from the linking in a defined order of α- Amino The other component (residues 1-105) is insoluble, and in the presence of calcium ions causes the coagulation of the casein micelles to form a curd. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20

Production of natural calf rennet

Natural calf rennet is extracted from the inner mucosa of the fourth stomach chamber (the abomasum) of young calves. A calf (kɑːf plural calves, /kɑːvz/ is the young of various species of Mammal. The mucous membranes (or mucosae; singular mucosa) are linings of mostly endodermal origin covered in Epithelium, which are involved in These stomachs are a by-product of veal production. A by-product is a secondary or incidental product deriving from a Manufacturing process a Chemical reaction or a biochemical pathway and is not the primary product Veal is the Meat of If rennet is extracted from older calves (grass-fed or grain-fed) the rennet contains less or no chymosin but a high level of pepsin and can only be used for special types of milk and cheeses. Grass is the common word that generally describes Monocotyledonous green Plants The family Gramineae ( Poaceae) are the "true grasses" and include Milk is an opaque white liquid produced by the Mammary glands of female Mammals (including Monotremes. Cheese is a Food made from Milk, usually the milk of cows, Buffalo, Goats or sheep, by coagulation. As each ruminant produces a special kind of rennet to digest the milk of its own mother, there are milk-specific rennets available, such as kid goat rennet especially for goat's milk and lamb rennet for sheep milk. Physiologically a ruminant is a Mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first stomach known "Mom" "Mum" and "Mommy" redirect here The domestic goat ( Capra aegagrus hircus) is a subspecies of goat Domesticated from the Wild goat of Southwest Asia and Eastern Europe Rennet or digestion enzymes from other animals, like swine-pepsin, are not used in cheese production. (Swine-pepsin is, however, used in the analysis of disulfide bonds of proteins. In Chemistry, a disulfide bond is a single Covalent bond derived from the coupling of Thiol groups )

Traditional method

Dried and cleaned stomachs of young calves are sliced into small pieces and then put into saltwater or whey, together with some vinegar or wine to lower the pH of the solution. In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following Vinegar is an acidic liquid processed from the Fermentation of Ethanol in a process that yields its key ingredient Acetic acid (also called ethanoic acid Wine is an Alcoholic beverage made from the fermentation of Grape juice After some time (overnight or several days), the solution is filtered. The crude rennet that remains in the filtered solution can then be used to coagulate milk. About 1 gram of this solution can normally coagulate 2000 to 4000 grams of milk. For other uses of the words gram or gramme see Gram (disambiguation.

Today this method is used only by traditional cheese-makers in central Europe: Switzerland, Jura, France, Romania, and Alp-Sennereien in Austria. Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation Jura is a department in the east of France named after the Jura mountains (not to be confused with the Swiss canton of Jura This article is about the country For a topic outline on this subject see List of basic France topics. Romania ( dated: Rumania, Roumania Austria (Österreich ( officially the Republic of Austria (Republik Österreich

Modern method

Deep-frozen stomachs are milled and put into an enzyme-extracting solution. In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following The crude rennet extract is then activated by adding acid; the enzymes in the stomach are produced in an inactive preform and are activated by the stomach acid. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following Gastric acid is one of the main Secretions of the Stomach, together with several Enzymes and Intrinsic factor. After neutralization of the acid, the rennet extract is filtered in several stages and concentrated until reaching the required potency: about 1:15000 (1 kg of rennet would have the ability to coagulate 15000 litres of milk). The litre or liter (see spelling differences) is a unit of Volume.

In 1 kg of rennet extract there are about 0. 7 grams of active enzymes and no other organic material – the rest is water and salt and sometimes sodium benzoate, E211, 0. For other uses of the words gram or gramme see Gram (disambiguation. Sodium benzoate ( E211) also called benzoate of soda, has Chemical formula NaC6H5CO2 Sodium benzoate ( E211) also called benzoate of soda, has Chemical formula NaC6H5CO2 5% - 1% for preservation. Typically, 1 kg of cheese contains about 0. 0003 grams of rennet enzymes.

Alternative coagulants

Because of the limited availability of proper stomachs for rennet production, cheesemakers have always looked for other ways to coagulate the milk. Artificial coagulants are a useful alternative, especially for cheap or lower-quality cheeses.

As the proper coagulation is done by enzymatic activity, the task was to find enzymes for cleaving the casein that would result in a taste and texture similar to animal-based rennet.

Vegetable rennet

Many plants have coagulating properties. Some examples include fig tree bark, nettles, thistles, mallow, and Creeping Charlie. Ficus is a Genus of about 850 Species of woody Trees Shrubs Vines Epiphytes and hemi-epiphytes in the family Nettle is the common name for between 30-45 species of Flowering plants of the genus Urtica in the family Urticaceae, with a cosmopolitan though This article is about the plant for other uses see Thistle (disambiguation. Glechoma hederacea ( Ground-ivy; syn Nepeta glechoma Benth, Nepeta hederacea ( L Enzymes from thistle or cynara are used in some traditional cheese production in the Mediterranean. Cynara is a Genus of about 10 Species of thistle-like Perennial plants in the family Asteraceae, originally from the Mediterranean

These real vegetable rennets are also suitable for vegetarians. Vegetarianism is the practice of a diet that excludes Meat (including game and slaughter by-products Fish (including Shellfish and other sea Vegetable rennet might be used in the production of kosher cheeses but nearly all kosher cheeses are produced with either microbial rennet or GM rennet. The term " vegetable " generally means the edible parts of Plants The definition of the word is traditional rather than Scientific, however See also Kashrut Kosher foods are those that conform to the regulations of Jewish religion Worldwide, there is no industrial production for vegetable rennet. Commercial so-called vegetable rennets usually contain rennet from the mold Mucor miehei - see microbial rennet below. WikipediaManual_of_Style#National_varieties_of_English --> Molds (or

Microbial rennet

Some molds such as Rhizomucor miehei are able to produce proteolytic enzymes. WikipediaManual_of_Style#National_varieties_of_English --> Molds (or These molds are produced in a fermenter and then specially concentrated and purified to avoid contamination with unpleasant side products of the mold growth. Fermentation has many important uses in industry Though the word fermentation can have stricter definitions when speaking of it in industrial fermentation it more loosely At the present state of scientific research, governmental food safety organizations such as the EFSA deny QPS (Qualified Presumption of Safety) status to enzymes produced especially by these molds. The European Food Safety Authority ( EFSA) is an Agency of the European Union that provides independent scientific advice and clear communication on existing and emerging WikipediaManual_of_Style#National_varieties_of_English --> Molds (or

The flavor and taste of cheeses produced with microbial rennets tend towards some bitterness, especially after longer maturation periods. ^[1] These so-called "microbial rennets" are suitable for vegetarians, provided no animal-based alimentation was used during the production. Vegetarianism is the practice of a diet that excludes Meat (including game and slaughter by-products Fish (including Shellfish and other sea

Genetically engineered rennet

Because of the above imperfections of microbial rennets, some producers sought further replacements of natural rennet. With the development of genetic engineering, it suddenly became possible to use calf genes to modify some bacteria, fungi or yeasts to make them produce chymosin. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described Chymosin (or rennin) is an aspartic acid protease Enzyme found in Rennet. Chymosin produced by genetically modified organisms was the first artificially produced enzyme to be registered and allowed by the FDA in the USA. In 1999, about 60% of U. Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) S. hard cheese was made with genetically engineered chymosin^[2]. One example of a commercially available genetically engineered rennet is Chymax, created by Pfizer. Chymax is a bio-engineered Rennet substitute used in Cheeses developed by Pfizer. Pfizer Incorporated ( is a major Pharmaceutical company, which ranks number one in the world in sales

Today the most widely used genetically engineered rennet is produced by the fungus Aspergillus niger. Aspergillus niger is a Fungus and one of the most common species of the genus Aspergillus. The problems of destroying the aflatoxins or the antibiotic-resistant marker genes seem to be solved. Aflatoxins are naturally occurring Mycotoxins that are produced by many species of Aspergillus, a Fungus, most notably Aspergillus Antibiotic resistance is the ability of a Microorganism to withstand the effects of Antibiotics. A marker gene is used in Molecular biology to determine if a piece of DNA has been successfully inserted into the host organism

Cheese production with genetically engineered rennet is similar to production with natural calf rennet. Genetic rennet contains only one of the known main chymosin types, either type A or type B. Other chymosin types found in natural rennet do not exist in genetic rennet. This is also the reason why special analysis can determine what kind of coagulant has been used by analyzing what bonds have and haven't been cleaved. Flocculation is a process where a Solute comes out of Solution in the form of floc or flakes

Often a mixture of genetically engineered chymosin and natural pepsin is used to imitate the complexity of natural rennet and to get the same results in coagulation and in development of flavour and taste.

The so-called "GM rennets" are suitable for vegetarians if there was no animal based alimentation used during the production in the fermenter—but only for vegetarians who are not opposed to GM-derived foods.

Acid coagulation

Milk can also be coagulated by adding some acid, e. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are g. citric acid. Citric acid is a weak organic Acid. It is a natural Preservative and is also used to add an acidic or sour taste to foods and Soft drinks This form of coagulation is sometimes used in cheap mozzarella production without maturation of the cheese. Mozzarella is a generic term for several kinds of originally Italian Cheeses that are made using spinning and then cutting (hence the name the Italian verb Cream cheese, paneer, and rubing are also made this way, see Category:Acid-set cheeses for others. Cream cheese is a sweet soft mild-tasting white Cheese, defined by the US Department of Agriculture as containing at least 33% Milkfat (as marketed Paneer ( Hindi: पनीर panīr, from Persian پنير panir) is the most common Persian and South Asian Cheese Rubing ( 乳饼 pinyin rǔbǐng is a firm fresh Goat Milk Cheese made in the Yunnan Province of China by people of the The acidification can also come from bacterial fermentation such as in cultured milk. Fermented milk products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented

See also

• Pepsin
• A recipe for homemade Quark without rennet

References

External links

• Fankhauser's Page on Rennet history and use
• EFSA and Qualified Assumption of Safety
• FDA-registration of recombinant chymosin
• Recombinant Chymosin
• Cheese Yield Experiments and Proteolysis by Milk-Clotting Enzymes
• Validation of recombinant and bovine chymosin by mass spectrometry
• Mass spectrometric characterisation of proteins in rennet and in chymosin-based milk-clotting preparationstae

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