Kefir

Kefir or kephir is a fermented milk drink similar to a thin yoghurt that is made from kefir grains, a specific type of mesophilic symbiotic culture.

Kefir products contain nutrients in varying amounts from negligible to significant, including dietary minerals, vitamins, essential amino acids, and conjugated linoleic acid, in amounts similar to an unfermented cow, goat, or sheep milk. kefir is composed mainly of water and by-products of the fermentation process, including carbon dioxide and ethanol.

Typical of milk, several dietary minerals are found in kefir, such as calcium, iron, phosphorus, magnesium, potassium, sodium, copper, molybdenum, manganese, and zinc in amounts that have not been standardized to a reputable nutrient database.Also similar to milk,kefir contains vitamins in variable amounts, including vitamin A, vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6 (pyridoxine), vitamin B9 (folic acid), vitamin B12 (cyanocobalamin), vitamin C, vitamin D, and vitamin E.[26] Essential amino acids found in kefir include methionine, cysteine, tryptophan, phenylalanine, tyrosine, leucine, isoleucine, threonine, lysine, and valine.

Probiotic bacteria found in kefir products include: Lactobacillus acidophilus, Bifidobacterium bifidum, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, Lactobacillus kefiranofaciens, Lactococcus lactis, and Leuconostoc species. Lactobacilli in kefir may exist in concentrations varying from approximately 1 million to 1 billion colony-forming units per milliliter, and are the bacteria responsible for the synthesis of the polysaccharide kefiran.

In addition to bacteria, kefir often contains strains of yeast that can metabolize lactose, such as Kluyveromyces marxianus, Kluyveromyces lactis, and Saccharomyces fragilis, as well as strains of yeast that do not metabolize lactose, including Saccharomyces cerevisiae, Torulaspora delbrueckii, and Kazachstania unispora.