The benefits of fermented milk kefir

Milk kefir is a fermented dairy product. Kefir ‘grains’ are placed into milk where the colony of microbes digest the lactose (milk sugar) and produce a carbonated beverage with a sour yoghurt taste and thin consistency. Due to the digestion of lactose by the colony of microbes, people who are lactose intolerant can usually tolerate kefir (do not consume if you have a milk allergy). Kefir grains can be removed when the consistency is of thin yoghurt or left until the milk splits. Once split the whey is then poured off and the curds drained to make kefir cream cheese.

Milk kefir and health

Although kefir may taste like a thin yoghurt there are vastly more microbes present in kefir than in yoghurt. Yoghurt usually consists of no more than 2-3 different types of lactobacillus bacteria strains whereas kefir can have up to 50 different types of bacteria, yeast and fungi present. This diversity of microbes benefits your gut health by regulating microbial composition and contributes to kefirs role as a functional food by providing a vast array of bioactive compounds that confer health benefits. The bacteria Lactobacillus kefiranofaciens is responsible for the formation of kefir grains (3). However, the fermentation of the milk is due to a combination of microorganisms that live in symbiosis with the kefir grains. These include lactose fermenting and nonfermenting yeast species (Kluyveromyces, Pichia, and Saccharomyces), lactic acid bacteria (Lactobacillus, Lactococcus, Leuconostoc, and Streptococcus) and acetic acid bacteria (4).

The bioactives that make kefir a functional food include: kefiran, exopolysaccharides, bioactive peptides, and organic acids (4). These bioactives provide antimicrobial, anticancer, and immune-modulatory activities. In addition to these benefits studies have demonstrated the ability of lactobacilli found in kefir to inhibit the growth and/or toxic effects of a wide variety of pathogenic bacteria and to reduce levels of cholesterol, particularly LDL or the ‘bad cholesterol’ (5).

Home made or store bought?

Milk kefir can be purchased at some supermarkets, however when produced commercially kefir is often produced from starter cultures or a serial fermentation process that begins with kefir produced from grains that are then used as a natural starter culture for milk fermentation. This process is called the “Russian method” (1). These kefir type beverages do not have the same diversity of microbes as those artisanal kefir beverages made with milk kefir grains. The microbes in kefir made with grains have shown increased survival through the gastrointestinal tract compared to industrial cultures (2). Investing in the grains is also much cheaper in the long run. Milk kefir grains last indefinitely if well looked after and at a cost of between $8 and $9 (as of February 2023) for a 1kg bottle of milk kefir at the supermarket you will recover your cost in a short space of time.

Like all ferments the warmer the temperature the faster the milk will ferment. For this reason, I prefer to make kefir cream cheese in the warmer months. In the cooler months of the year the kefir produced is slightly thicker consistency, is less likely to split and the ferment is easier to control.

If you prefer to consume kefir as a beverage undertaking a secondary fermentation process can improve the flavour. The second ferment is undertaken after the grains have been removed, when the kefir is at the consistency you like. Transfer the kefir to a sealable vessel, add a couple of pieces of citrus peel to the kefir then leave for a couple of hours before refrigerating. Other ingredients like berries can also be added.

How to use

Milk kefir can be added to smoothies, used in salad dressings, made into ice cream or drunk straight up.

Storing kefir grains

Kefir grains can be stored in a glass jar covered in milk in the fridge when not in use. Refreshing the milk once a week if not using regularly is necessary to keep the microbes fed and stop them from dying out.

Interested in learning more

Come along to a fermentation workshop and learn how to make fermented food and beverages. Click here to find out more

The information provided on this website is for information purposes only and is not meant to be nor should be considered medical advice.

References

1)     Azizi, N. F., Kumar, M. R., Yeap, S. K., Abdullah, J. O., Khalid, M., Omar, A. R., Osman, M. A., Mortadza, S. A. S., & Alitheen, N. B. (2021). Kefir and Its Biological Activities. Foods (Basel, Switzerland), 10(6), 1210. https://doi.org/10.3390/foods10061210

2)     Vieira, C. P., Rosario, A. I. L. S., Lelis, C. A., Rekowsky, B. S. S., Carvalho, A. P. A., Rosário, D. K. A., Elias, T. A., Costa, M. P., Foguel, D., & Conte-Junior, C. A. (2021). Bioactive Compounds from Kefir and Their Potential Benefits on Health: A Systematic Review and Meta-Analysis. Oxidative medicine and cellular longevity, 2021, 9081738. https://doi.org/10.1155/2021/9081738

3)     Georgalaki, M., Zoumpopoulou, G., Anastasiou, R., Kazou, M., & Tsakalidou, E. (2021). Lactobacillus kefiranofaciens: From Isolation and Taxonomy to Probiotic Properties and Applications. Microorganisms, 9(10), 2158. https://doi.org/10.3390/microorganisms9102158

4)     Vieira, C. P., Rosario, A. I. L. S., Lelis, C. A., Rekowsky, B. S. S., Carvalho, A. P. A., Rosário, D. K. A., Elias, T. A., Costa, M. P., Foguel, D., & Conte-Junior, C. A. (2021). Bioactive Compounds from Kefir and Their Potential Benefits on Health: A Systematic Review and Meta-Analysis. Oxidative medicine and cellular longevity, 2021, 9081738. https://doi.org/10.1155/2021/9081738

5)     Slattery, C., Cotter, P. D., & O'Toole, P. W. (2019). Analysis of Health Benefits Conferred by Lactobacillus Species from Kefir. Nutrients, 11(6), 1252. https://doi.org/10.3390/nu11061252