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What is kefir?
Kefir or kéfir - or kephir or kefyr - is a milk-based fermented dairy product - or better, fresh milk. More precisely, the vaccine can be used in the production of kefir, or sheep's milk and / or goat's milk
Originally from the Russian territory, kefir has gradually spread throughout the Caucasus - even to the south - where it has been produced and consumed in large quantities for millennia. Its nutritional content and the "theoretical" probiotic power - due to the presence of Lactobacillus acidophilus and Saccharomyces kefir - have made it a cornerstone of local nutrition.
Did you know that ...
Various meanings are attributed to the noun "latticino"; the most widespread, between the common language and the technical one, are three:
- Milk-based foods - common language
- Foods derived from milk with a high percentage of lactose; includes all those fresh obtained by thermal coagulation of whey proteins, and those in which probiotics (necessary for lactic coagulation) and maturing have not been sufficiently effective in disaccharide catabolism - technical, but obsolete
Foods that do not undergo the coagulation of caseins, such as ricotta, butter, cream and yogurt. The cheeses would therefore not be considered dairy products, regardless of the concentration of lactose - technical, currently most quoted.
Kefir is a derivative of milk, maintains a small part of the initial lactose and is not produced by coagulation of casein proteins; it is therefore considered a dairy product in all respects. It is part of the II fundamental group of foods - milk and derivatives - and is a good source of high biological value proteins, calcium phosphorus and vitamins - especially of group B, in particular vit B2 (riboflavin), and vitamin / provitamine A. Produced from whole milk, it also has a modest amount of saturated fat and cholesterol. It should be specified that the chemical profile of this food changes substantially also based on: level of milk skimming, composition of the granules - in the section on production we will find out better what they are - and processing technology.
Kefir is generally considered suitable for most diets; some cases that are part of clinical nutrition or are linked to particular conditions are exceptions, such as: lactose intolerance, allergies to milk proteins, phenylketonuria and severe histamine intolerance - milk is an istamino-liberating food. The elimination of kefir can be useful to lower the percentage of saturated fats and the intake of cholesterol in the diet - even if, comparing it to other foods certainly richer, this cannot be considered an intervention of primary importance.
Kefir is eaten raw, fresh (not preserved) and cold, often associated with honey and fruit. It replaces, for instance, yogurt - which is shared by different organoleptic and taste characteristics. A valid but recent alternative to various dairy or non-seasoned dairy products, kefir is not part of the Italian gastronomic tradition. Currently, thanks to globalization, to cultural intertwining but above all to the internet, some recipes have been spread that see kefir as the protagonist or simple ingredient.
Nutritional Properties
Nutritional properties of kefir
Whole milk kefir provides an average caloric quantity, supplied mainly by lipids, followed by proteins and finally by a few carbohydrates. Fatty acids have a saturated prevalence, peptides are of high biological value - with a high percentage of tryptophan - and soluble glucides (lactose disaccharide).
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High biological value of proteins means that they contain all the essential amino acids in the right quantities and proportions with respect to the human protein model.
Kefir does not contain fiber, but has a low concentration of cholesterol. It provides traces of lactose, few purines and a significant level of phenylalanine. It is a product derived from milk, a liberating istamino food, and moreover it is subjected to microbial fermentation - which can raise the amount of histamine.
Among the most abundant kefir vitamins we mention: riboflavin (vit B2), niacin (vit PP), pyridoxine (vit B6), cobalamin (vit B12), retinol (vitamin A) and carotenoids (provitamine A - RAE); some sources also report a good level of vitamin D, but this is not a certain fact. As far as mineral salts are concerned, the most abundant are: calcium and phosphorus
Kefir VS yogurt: differences
At first sight, kefir may seem quite similar to yogurt; despite appearances, kefir is derived from the fermentative action of quite different bacterial and yeast strains; for this reason, it has quite different organoleptic-taste characteristics.
In particular, kefir is distinguished from yoghurt by the slight content of ethyl alcohol, which fluctuates roughly between 1 and 2%, and carbon dioxide. These compositional differences are the result of a different microbial metabolism; while yogurt is formed exclusively (or almost) by lactic fermentation, kefir also uses an alcoholic process.
| Kefir | Yogurt | |
| Lactic acid | - | + |
| Carbon dioxide | + | - |
| Ethyl alcohol | + | - |
Diet
Kefir in the diet
Kefir is more digestible than milk, not only for the reduction of lactose, but also for the partial hydrolysis of proteins. This does not mean that it can be drunk freely, under any circumstances, and with very abundant portions - especially by those who suffer from disorders or discomfort of the digestive system. It should instead be greatly reduced in the case of hyperchlorhydria and hypochloridria, stomach acid, gastritis, ulcer and gastroesophageal reflux disease - almost always associated with hiatal hernia. It can also alter the level of people with irritable bowel and colitis.
Due to the high content of essential amino acids, such as milk and yogurt, kefir also lends itself to the diet of those who have a higher protein requirement. This is especially the case for growing subjects, pregnant women or nurses, subjects with poor intestinal absorption - for example in digestive disorders or intestinal resections or in the third age - or who, for various reasons, find themselves in deficit of these nutrients - incorrect habits, fasting, anorexia nervosa etc. Sportsmen who practice extreme endurance activities and those who practice strength sports in which muscle growth (hypertrophy) is essential may have a higher protein requirement.
Kefir, in the right portions and with adequate consumption frequency, is suitable for any diet. In case of hypercholesterolemia it may be advisable to prefer skimmed milk or to reduce consumption. It has no relevant effects on other replacement pathologies.
Kefir is harmless for celiac disease and hyperuricemia, while it would be eliminated in the diet against phenylketonuria, histamine intolerance and milk protein allergy. It is suitable for the diet for lactose intolerance only of modest entity; serious hypersensitivities, on the other hand, also require the exclusion of this food.
Did you know that ...
As a result of fermentation, in kefir, as well as decreasing lactose, an enzyme called β-galactosidase also increases. It is a hydrolytic catalyst that deals with the hydrolysis of β-D-galactose terminal residues in polysaccharides known as β-galactosides, through the rupture of terminal β-glycosidic bonds. Some β-galactosidases are also able to hydrolyze α-L-arabinosides, β-D-fucosides and β-D-glucosides.
Due to the high content of calcium and phosphorus, constituents of bone hydroxyapatite, kefir is a valid ally during growth and in old age; the need for these minerals also increases during pregnancy and lactation. It is also rich in water-soluble B vitamins - coenzymatic factors vital for the metabolism of all tissues - and the liposoluble A - necessary for cell differentiation, visual function, reproductive function, etc.
Suitable for the latto ovo vegetarian diet, it is instead contraindicated for the vegan diet. It is pertinent to the Muslim and Jewish diet, provided it is derived from animals considered "pure".
Kitchen
Description of kefir
For color and density, kefir vaguely resembles "diluted" yogurt. The aroma is characteristic, and mainly due to the presence of diacetyl and acetaldehyde, respectively produced by particular microorganisms.
How to eat kefir?
Kefir is consumed mainly by itself; it is appreciated fresh or at room temperature, mainly as a drink.
Kefir is more frequently associated with foods such as: honey, sweet and / or sour fruit and pickles - for example gherkins and other fermented vegetables such as sauerkraut.
Kefir is preserved by refrigeration and should not be extended beyond 7 days.
Home-made Kefir
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Introduction to kefir production
The traditional production of kefir takes place by adding 2-10% of the granules in the fresh milk (sheep, goat or cow) composed of:
- Selected colonies of bacteria and yeasts
- Water-soluble complex carbohydrates (called kefiran and produced by the same bacteria and yeasts of kefir, especially: Lactobacillus kefiranofaciens subsp. Kefiranofaciens and Lactobacillus kefiranofaciens subsp. Kefirgranum ).
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The biological starters contained in the kefir granules are based on both bacteria and yeasts; among the various bacteria stand out the Genera: Acetobacter, Lactobacillus ( kefiri, parakefiri, kefiranofaciens subsp. kefiranofaciens and subsp. kefirgranum ), Lactococcus and Leuconostoc, while among the yeasts there are Genera: Candida, Kluyveromyces and Saccharomyces . These are mutually symbiotic microorganisms held together by coagulated proteins. At the industrial level, granules are not used, but rather specific standardized mixes of bacteria and yeasts, in order to minimize production times and keep the nutritional composition and organoleptic characteristics of the food constant. The industrial kefir are also distinguished by a lower alcohol content, often below the threshold of one percent or in some cases even nothing.
The ideal temperature for the production of kefir is around 20-25 ° C, while the duration of the process is about 24/48 hours, during which the mixture is placed in a semi-closed container, away from sunlight, and shaken from time to time.
The production of kefir perpetuates in a similar way to yogurt, sourdough or sourdough; that is, the granules - which continue to grow and develop inside the kefir - are filtered and re-used to the bitter end.
Curiosity
It seems that the probiotic flora of kefir is the same contained in the digestive tract of goats. It is interesting to learn that - besides having the possibility of producing kefir from animal milk at home - the bacterial and yeast colonies present in the granules are able to ferment also vegetable milks such as: soy milk, rice milk, oat milk, coconut milk, etc. Water kefir (also known as Tibicos) is a slightly alcoholic and sparkling drink obtained from the fermentation, by addition of kefir granules, of a sugary liquid containing a 3-10% sucrose added to fruit juices (lemon, grapes, orange etc.) and flavoring (ginger, mint, fennel, anise, etc.).
