Rennet (IPA pronunciation: [ˈɹɛnɪt]) is a natural complex of enzymes produced in any mammalian stomach to digest the mother's milk. Rennet contains a proteolytic enzyme (protease) that coagulates the milk, causing it to separate into solids (curds) and liquid (whey). The active enzyme in rennet is called rennin or chymosin (EC 3.4.23.4) but there are also other important enzymes in it, e.g., pepsin or lipase. There are non-animal sources for rennet substitutes.. Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. ... Proteases (proteinases, peptidases, or proteolytic enzymes) are enzymes that break peptide bonds between amino acids of proteins. ... Curdled is also the name of a Quentin Tarantino film. ... Percentages are relative to US recommendations for adults. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Rennet, also called rennin or chymosin (EC 3. ... The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. ... Pepsin is a digestive protease (EC 3. ... A computer-generated image of a type of pancreatic lipase (PLRP2) from the guinea pig. ...

Uses

The chief use of rennet is in the making of cheese, curd, and junket. Chymosin reacts specifically with κ-casein, cleaving the protein between the amino acids phenylalanine(105) and methionine (106), producing two fragments. 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. 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. Cheese is a solid food made from the milk of cows, goats, sheep, and other mammals. ... Curd is a dairy product obtained by curdling (coagulating) milk with rennet or an edible acidic substance such as lemon juice or vinegar and then draining off the liquid portion (called whey). ... Junket is a milk-based dessert, made with sweetened milk and rennet, the digestive enzyme which curdles milk. ... Casein is the most predominant phosphoprotein found in milk and cheese. ... Phenylalanine is one of the standard amino acids. ... Phenyl alanine is an α-amino acid with the formula HO2CCH(NH2)CH2C6H5. ... Methionine is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2SCH3. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Standard atomic weight 40. ...

Production of natural calf rennet

Natural calf rennet is extracted from the inner mucosa of the fourth stomach chamber (the abomasum) of young calves. These stomachs are a by-product of veal production. 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. 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 goats' milk and lamb-rennet for sheep-milk. 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.) The mucous membranes (or mucosa) are linings of ectodermic origin, covered in epithelium, that line various body cavities and internal organs. ... A by-product is a secondary or incidental product deriving from a manufacturing process or chemical reaction, and is not the primary product or service being produced. ... Veal is the meat of young calves (usually male) appreciated for its delicate taste and tender texture. ... 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. 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. Vinegar is sometimes infused with spices or herbs—as here, with oregano. ... A glass of red wine This article is about the alcoholic beverage. ...

Today this method is used only by traditional cheese-makers in central Europe: Switzerland, Jura, France, Romania and Alp-Sennereien in Austria. For other uses, see Europe (disambiguation). ... Jura is a department in the east of France named after the Jura mountains (not be confused with the Swiss canton of Jura). ...

Modern method

Deep-frozen stomachs are milled and put into an enzyme-extracting solution. The crude rennet extract is then activated by adding acid – the enzymes in the stomach are produced in an inactive pre-form and are activated by the stomach acid. After neutralisation 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). Neutralization is a chemical reaction in which an acid and a base react and produce salt and water. ...

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, 0.5% - 1% for preservation. Typically, 1 kg of cheese contains about 0.0003 grams of rennet enzymes. Sodium benzoate (E211), also called benzoate of soda, has chemical formula C6H5COONa. ... Sodium benzoate (E211), also called benzoate of soda, has chemical formula C6H5COONa. ...

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 taste and texture similar to what animal-based rennet produces.

Vegetable rennet

Many plants have coagulating properties. Some examples include fig tree bark, nettles, thistles, mallow, and Creeping Charlie. Rennet from thistle or cynara is used in some traditional cheese production in the Mediterranean. Species About 800, including: Ficus altissima Ficus americana Ficus aurea Ficus benghalensis - Indian Banyan Ficus benjamina - Weeping Fig Ficus broadwayi Ficus carica - Common Fig Ficus citrifolia Ficus drupacea Ficus elastica Ficus godeffroyi Ficus grenadensis Ficus hartii Ficus lyrata Ficus macbrideii Ficus microcarpa - Chinese Banyan Ficus nota Ficus obtusifolia Ficus palmata... Species See text Nettles are members of the genus Urtica in the family Urticaceae. ... Milk thistle flowerhead Thistledown a method of seed dispersal by wind. ... Mallow is the common name of several closely related genera of plant in the family Malvaceae: Althaea – Marsh mallow Callirhoe – Poppy mallow Kosteletzkya – Seashore mallow Lavatera – Tree mallow or rose mallow Malacothamnus – Santa Cruz Island bush-mallow Malva – Mallow Malvaviscus – Turks cap mallow Sidalcea – Greek mallow Sphaeralcea – Globemallow Plants... Binomial name Glechoma hederacea L. Creeping Charlie (Glechoma hederacea), also called Ground Ivy, of the Mint family (Lamiaceae), is a viney, invasive plant considered a weed in lawns. ... Species Cynara alba Cynara algarbiensis Cynara auranitica Cynara baetica Cynara cardunculus Cynara cornigera Cynara cyrenaica Cynara humilis Cynara hystrix Cynara scolymus Cynara syriaca Note that this list may include some synonyms Cynara is a genus of about 10 species of thistle-like perennials in the family Asteraceae, originally from the... The Mediterranean Sea is an intercontinental sea positioned between Europe to the north, Africa to the south and Asia to the east, covering an approximate area of 2. ...

These real vegetable rennets are also suitable for vegetarians. 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. 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. For animals adapted to eat primarily plants, sometimes referred to as vegetarian animals, see Herbivore. ... Kosher foods are those that meet certain criteria of Jewish law. ... It has been suggested that Toxic mold be merged into this article or section. ...

Microbial rennet

Some molds, such as Rhizomucor miehei are able to produce proteolytic enzymes. These molds are produced in a fermenter and then especially concentrated and purified to avoid contamination with unpleasant side products of the mold growth. 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. Moldy cream cheese Molds (British English: moulds) are various fungi that cover surfaces as fluffy mycelium and usually produce masses of asexual, sometimes sexual spores. ... This article is about industrial fermentation. ... Location: Parma, Italy Formation: - Signed - Established July 2002 Superseding pillar: European Communities Director: Website: efsa. ...

The flavor and taste of cheeses produced with microbial rennets tend towards some bitterness, especially after longer maturation periods. These so-called "microbial rennets" are suitable for vegetarians, provided no animal-based alimentation was used during the production.

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, fungus or yeast to make them produce Chymosin. 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.S. hard cheese was made with genetically engineered Chymosin.^[1] Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Subkingdom/Phyla Chytridiomycota Blastocladiomycota Neocallimastigomycota Glomeromycota Zygomycota Dikarya (inc. ... Typical divisions Ascomycota (sac fungi) Saccharomycotina (true yeasts) Taphrinomycotina Schizosaccharomycetes (fission yeasts) Basidiomycota (club fungi) Urediniomycetes Sporidiales Yeasts are a growth form of eukaryotic microorganisms classified in the kingdom Fungi, with approximately 1,500 species described. ... Rennet, also called rennin or chymosin (EC 3. ... The United States Food and Drug Administration is the government agency responsible for regulating food, dietary supplements, drugs, cosmetics, medical devices, biologics and blood products in the United States. ... This article is about the year. ...

Today the most widely-used genetic rennet is produced by the fungus Aspergillus niger. The problems of destroying the aflatoxins or the antibiotic resistant marker genes seem to be solved. ... Chemical structure of Aflatoxin B1 Aflatoxins are naturally occurring mycotoxins that act as carcinogens and are produced by two types of mold, Aspergillus flavus and Aspergillus parasiticus. ... Antibiotic resistance is the ability of a microorganism to withstand the effects of an antibiotic. ... 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 genetic 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.

Often a mixture of genetic 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.g. citric acid. This form of coagulation is sometimes used in cheap mozzarella production without maturation of the cheese. Paneer is also made this way. The acidification can also come from bacterial fermentation such as in cultured milk. For other uses, see Acid (disambiguation). ... Citric acid is a weak organic acid found in citrus fruits. ... This article or section does not cite any references or sources. ... Making paneer Paneer (Hindi: पनीर , from Persian پنير sometimes spelled Panir or Paner), is the most common Indian form of cheese. ... Fermented milk products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria such as Lactobacillus, Leuconostoc, Pediococcus, Lactococcus, and Streptococcus. ...

See also

• Pepsin
• Rennet is the name of a character in the 1932 satire Cold Comfort Farm
• A recipe for homemade Quark without rennet

Pepsin is a digestive protease (EC 3. ... Year 1932 (MCMXXXII) was a leap year starting on Friday (the link will display full 1932 calendar) of the Gregorian calendar. ... Cold Comfort Farm is a comic novel by Stella Gibbons, published in 1932. ...

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 preparations

References

Carroll, Ricki. Making Cheese, Butter, & Yogurt. Storey Publishing 2003. Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 226th day of the year (227th in leap years) in the Gregorian calendar. ...

"Biotechnology and Food: Leader and Participant Guide," publication no. 569, produced by North Central Regional Extension. Printed by Cooperative Extension Publications, University of Wisconsin-Extension, Madison, WI, 1994. Publication date: 1994.

Tom Zinnen, biotechnology specialist, University of Wisconsin-Extension and UW Biotechnology Center, UW-Madison; and Jane Voichick, professor, Nutritional Sciences, UW-Madison and UW- Extension.