Rhizomucor miehei as enzyme source for microbial rennet cheese: culture and molecular identification

Information 16/02/09.


The cheeses are a diverse group of food products with a variety of flavors, shapes and textures, made worldwide, based on milk, mainly from cow, goat, sheep and buffalo.

All cheeses contain the coagulated milk protein (casein) and fats of this. To achieve coagulation proteins should acidified milk for adding a natural enzyme complex (rennet), obtained from the gastric mucosa of young animals, casein clotting occurs, separating the curd from whey. Acidification can be accomplished by adding vinegar or lemon, but also some bacteria when using milk sugars produce lactic acid. For the preparation of some soft cheeses, Indian cheese (paneer) or mozarellas reduced cost, it is used only the acid coagulation with citric acid. Contine chymosin rennet enzyme, which is produced by the stomach of any animal species to digest breast milk. In addition, rennet containing other enzymes like pepsin and lipase.

Today there are alternatives to animal rennet, either to be consumed by cheeses or dairy-vegetarian to reduce the cost of obtaining natural rennet.

To use a natural non - animal rennet, the main alternative is to use enzymes produced by the filamentous fungus (mold) Rhizomucor miehei (United Fungi, Order Mucorales, Mucoraceae Family, Genus Rhizomucor). This fungus produces proteolytic enzymes which are obtained by culturing the fungus in fermenters and then concentrating and purifying the enzymes generated. The flavor and aroma of cheeses made by this microbial rennet tends to be somewhat bitter (bitternes), especially after long periods of maturation. Other vegetable alternatives as a source of proteolytic enzymes are used juice figs, nettles, thistles, mallows or ground ivy.

To reduce the cost of obtaining animal rennet, the use of genetically modified organisms was introduced, cloning the genes coding animals enzyme chymosin rennet bacteria, yeasts or filamentous fungi, then, separating the enzyme from the cultures of these organisms. In 1999, the American FDA accepted this enzyme as the first enzyme produced artificially. In 2008, 80 to 90% of the cheese produced in the US and UK, using this enzyme generally produced by Aspergillus niger (A. currently brasiliensis) genetically modified.

Tests in IVAMI:

  • Qualitative or quantitative culture for planting Rhizomucor miehei microbial rennet.
  • Morphological identification of growth of filamentous fungi (molds) to verify the existence of Rhizomucor miehei and exclude contamination with other species.
  • Molecular identification of the species of filamentous fungus Rhizomucor miehei (mold) cultivated.

Recommended types of samples:

  • Rennet milk microbial origin (about 100 g).

Shipping and storage conditions:

  • Refrigerated for less than 2 days and shipping within cork white box pack (frigolín) frozen.

Delivery time :

  • Culture and morphological identification: 5 to 7 working days.
  • Culture and molecular identification: 5 to 7 working days.

Cost of testing:

  • Culture and morphological identification of filamentous fungi cultivated genus level (Rhizomucor spp, or other.): Consult ivami@ivami.com .
  • Culture and molecular identification of filamentous fungi (mold) cultivated species level (Rhizomucor miehei, or others. Consult ivami@ivami.com .