How is RENNET to be used?

Question

How does one use a microbial rennet tablet. In what proportion should it be added to milk. Do please let me know. Thanks.

Answer 1

The chief use of rennet is in the making of cheese 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. This in the presence of calcium ions causes the coagulation of the casein micelles to form a curd.

Answer 2

Rennet Tablets

A product used to thicken milk when making custard, ice cream and cheese. Rennet tablets contain the natural coagulating enzyme, rennet. Rennet is used to curdle milk or separate curds from whey. When making custard, the rennet tablet is generally crushed and then dissolved in water before it is added to a lukewarm milk mixture. It is quickly stirred into the milk mixture and then allowed to stand for a short period of time in which it will quickly thicken the mixture into a smooth thickened custard.

USE OF JUNKET TABLETS: One tablet will clabber 5 gallons of inoculated milk. To use it, you dissolve the tablet in a small amount of water (1 tablet in 1/4 cup fresh clean water). The solution will be slightly cloudy . Look for and crush undissolved chunks at the bottom of the glass. The dissolved rennet is then stirred into the inoculated milk .

Answer 3

I use vegetarian rennet to make cottage cheese, custard and cream cheese. It can be tricky to work with. The box usually contains detailed recipes. I dont know about using the tablets, but would think the liquid is easier to work with. If it is traditional rennet, it is made with the digestive juices of slaughtered baby calves, so I prefer the vegetarian version which is derived from plants.

Answer 4

rennet substance containing rennin, an enzyme having the property of clotting, or curdling, milk. It is used in the making of cheese and junket. Rennet is obtained from the stomachs of young mammals living on milk, especially from the inner lining of the fourth, or true, stomach (abomasum) of milk-fed calves. The preparation of rennet was formerly a part of the domestic function of making cheese; the inner membrane was kept in salt, dried, and, when rennet was needed, soaked in water. Now extract of rennet is made and sold commercially. It is usually prepared by soaking the tissues in warm, slightly salted water and straining and preserving the resulting liquid. Heat interferes with the action of rennet.
http://www.encyclopedia.com/doc/1E1-rennet.html

Answer 5

The chief use of rennet is in the making of cheese 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. This in the presence of calcium ions causes the coagulation of the casein micelles to form a curd.

[edit] Production of natural calf rennet

Natural rennet is produced in the inner mucosa of the fourth stomach of young ruminants. These stomachs are a by-product of veal production.

[edit] Traditional method

Today this method is only used by traditional cheese-makers in central Europe, e.g. in Switzerland, Jura in France, or Alp-Sennereien in Austria.

Dried and cleaned stomachs of young calves are sliced into small pieces and then put into saltwater, together with some vinegar or wine to get a lower pH. After some time – overnight or several days - this solution has to be filtered. This crude rennet can then be used for coagulation of the milk. 1 gram of this solution should then coagulate 2000 to 4000 grams of milk.

[edit] Modern method

Deep-frozen stomachs are milled and put into an extracting solution – in this solution the enzymes are extracted. 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 - e.g. 1:15.000 (1 kg of rennet would have the ability to coagulate 15,000 litres of milk).

1 kg of rennet extract contains about 0.7 grams of active enzymes and no other organic material – the rest is water and salt and sometimes some sodium benzoate, E211, 0.5% - 1% for preservation. 1 kg of cheese contains about 0.0003 grams of rennet enzymes.

[edit] 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.

[edit] 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.

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 also no industrial production for vegetable rennet. Commercial so-called vegetable rennets usually contain rennet from the mold Mucor miehei - see microbial rennet below.

[edit] Microbial rennet

There are some moulds like Rhizomucor miehei that have the capability to produce proteolytic enzymes. These moulds are produced in a fermenter and then especially concentrated and purified to avoid contamination with unpleasant side products of the mould growth. At the present state of scientific research institutes like the EFSA deny the QPS-status - Qualified Presumption of Safety - to enzymes produced especially by these moulds.

The flavour and taste of cheeses produced with microbial rennets tend towards some bitterness, especially if longer maturation is wanted. These so-called "microbial rennets" are suitable for vegetarians if there was no animal-based alimentation used during the production in the fermenter.

[edit] Genetically engineered rennet

Because of the above imperfections of microbial rennets, some big companies 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]

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.

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. Some of the other chymosin types found in genetic rennet do not exist in natural rennet. This is also the reason why special analysis can determine what kind of coagulant has been used.

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.

[edit] 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 bacteria as happens in soured milk.

Answer 6

Follow the instruction on the package.