Kefir is a fascinatingly complex fermented product which appears like a slightly fizzy yogurt. The beverage has a strong following with those seeking a healthier lifestyle because it is a classic probiotic product. It has long been drunk throughout the ages and is a part of folklore for its numerous benefits. The food has always been popular throughout Asia but is now part of the established health food culture in Europe, North America and Japan.
Where does kefir originate from?
The drink originates from the Caucasus mountains that straddle Russia and the middle Asian states such as Kazakhstan and Kyrgyzstan. It derives from the word ‘kef’ that means pleasant taste in Turkish. It is also known variably as kefyr, kephir, kefer, kiaphur, knapon, kepi or kippi. There are many similarities with that other popular fermented drink, kombucha.
The flora of traditional kefir consists of two species of yeasts called Saccharomyces kefir and Torula kefir, and certain lactobacilli named Lactobacillus caucasicus. There are also certain lactic streptococci and aroma producing Leuconostoc sp. associated with kefir
granules. A number of suppliers offer defined cultured grains containing typical kefir bacteria. Depending upon the level of sanitation used in straining and storing of granules, kefir grains may be contaminated with undesirable bacteria such as micrococci, coliforms, and spore forming bacilli.
A good freeze-dried Kefir Mild 01 starter culture is available from Dansisco. It is composed of the following bacteria: Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis biovar diacetylactis, Leuconostoc mesenteroides subsp. mesenteroides, Streptococcus thermophiles, Lactobacillus acidophilus.
How is it made?
It is produced by the incubation of kefir ‘grains’ with either a dairy feedstock or just water. The fermentation combines lactic acid production with the alcoholic fermentation of lactose present in milk. The taste is mildly acidic because of the combination of lactic acid and ethanol with flavours from the milk, produced by the bacteria and yeast such as acetaldehyde and acetoin. It is also lightly carbonated. A variety of milks can be used although ideally full fat milk is preferred because it creates such a creamy texture. For many goat’s milk kefir has a slightly less viscous texture than the type produced from a cow. For vegans, a ‘kefir’ prepared from nut and oat milk or variants is suitable.
Kefir grains are small, irregularly shaped, yellowish-white, hard granules that resemble miniature cauliflower blossoms (Vedamuthu, 1977).
If the kefir is produced using ‘grains’ in only water than it is best described as a fizzy drink. The feedstock is fruit juice or water containing just sugar. To be honest, its the dairy based products which have caused most of the excitement. It is often used in place of drinking yogurt or as an ingredient in its own right. Some folks prepare smoothies with it and it certainly goes very well with acid fruits like raspberries, blueberries and strawberries.
The grains look rather like cottage cheese with a rubbery texture. These ‘grains’ contain at least 50 species of probiotic bacteria which are mainly lactic acid bacteria and yeasts. There is more microbial variety in the dairy versions than in the water-based products.
Overview of Health Benefits
The therapeutic benefits are well known and these are being examined in great detail (Zeynap et al., 2011; Arslan, 2014). It is certainly the case that kefir has antibacterial, antifungal and even anticancer effects amongst the many others which are listed later on.
Kefir including the microorganisms that it contains act like most probiotics. Indeed it is a long-standing member of this group of foods and can modulate gut microbiota and mycobiota. The modulation is associated with its many health benefits but unfortunately there are still too few studies to establish the exact mechanisms of the benefits imparted (Kim et al., 2018).
Antimicrobial Benefits
Kefir shows inhibitory activity against mostly gram-positive bacteria such as Staphylococcus, Coccus and Bacillus. The ‘grains’ are more potent than kefir itself.
Antifungal Benefits
Kefir acts against a variety of moulds especially yeasts. The moulds include Candida, Microsporum, Saccharomyces, Rhodotorula, Trichopyton, and species (Cevikbas et al., 1994).
Anticancer And Antimutagenic Effects
Kefir has been shown in mice studies to reduce tumor size and necrosis associated with this disease (Cevikbas et al., 1994).
Other notable benefits include the following:-
- antioxidants
- antiobesity
- anti-hepatic steatosis
- antiallergenic including reduction of lactose intolerance syndrome
- anti-inflammatory
- stimulation of the immune system
- reduces cholesterol
- relieves constipation
The Role of Postbiotics: Kefiran
The recent trend in postbiotics has not gone unnoticed with kefir (Barros et al., 2021). Kefiran is the prebiotic/postbiotic from kefir that promotes potential beneficial effects on food allergies. It’s impact can be linked to the fundamental benefits of the overall intestinal microbiome through to the immune system.
Kefiran is a branched polysaccharide produced by Lactobacillus.
Preparation Of Kefir
Ingredients:
- kefir grains
- milk from a cow, sheep or goat but officianadoes also claim horse and camel are probably the most realistic.
You will need a glass or plastic jar with a secure lid and of sufficient volume to hold the fermenting drink. The sieve (plastic) is used to filter out the culture before drinking.
Directions:
Given its richness, the recipe below should generate about 100ml.
- A teaspoon of ‘grains’ is added to a jar containing about 100ml of milk. Adding more grains produces a more sour tasting kefir.
- Put the lid on and leave the jar in a room for 24 hours at room temperature.
- The following day, strain the product through a lined plastic sieve to remove as much of the culture as possible. The product should be relatively free of cloud and retain some of its fizziness. The lining should be muslin or coffee filter paper.
- Keep the ‘grains’ by placing in a clean jar and adding further milk to prepare the next batch. If the kefir is too thin, some of the watery component can be sieved off through a fine mesh.
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References
Arslan, S. (2015). A review: chemical, microbiological and nutritional characteristics of kefir. CyTA-Journal of Food, 13(3), pp. 340-345 (Article)
Barros, S.É.L., Rocha, C.D.S., de Moura, M.S.B., Barcelos, M.P., da Silva CHTP, Hage-Melim LIDS. (2021) Potential beneficial effects of kefir and its postbiotic, kefiran, on child food allergy. Food Funct. May 11;12(9) pp. 3770-3786. doi: 10.1039/d0fo03182h. PMID: 33977950.
Cevikbas, A., Yemni, E., Ezzedenn, F. W., Yardimici, T., Cevikbas, U., & Stohs, S. J. (1994). Antitumoural antibacterial and antifungal activities of kefir and kefir grain. Phytotherapy Research, 8(2), pp. 78-82 (Article).
Guzel-Seydim, Z. B., Kok-Tas, T., Greene, A. K., & Seydim, A. C. (2011). Functional properties of kefir. Critical Reviews in Food Science and Nutrition, 51(3), pp. 261-268 (Article).
Kim, D. H., Jeong, D., Kim, H., & Seo, K. H. (2018). Modern perspectives on the health benefits of kefir in next generation sequencing era: improvement of the host gut microbiota. Critical Reviews in Food Science and Nutrition, pp. 1-12 (Article)
Rodrigues, K. L., Caputo, L. R. G., Carvalho, J. C. T., Evangelista, J., & Schneedorf, J. M. (2005). Antimicrobial and healing activity of kefir and kefiran extract. International Journal of Antimicrobial Agents, 25(5), pp. 404-408.
. (1977). Exotic fermented dairy foods. J Food Protect. 40 pp. 801–2. .
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