Recent developments in dairy kefir-derived lactic acid bacteria and their health benefits

Kefir is one of the most consumed traditional fermented dairy products and it has a complex probiotic and nutritional composition. Kefir grain contains casein and other milk solids together with the yeasts and lactobacilli that cause the characteristic kefir fermentation and serve as a starter to induce this fermentation when introduced into fresh milk. Both kefir and kefir grains have a rich microbiota and their composition is affected by many parameters like kefir origin, production method (artisanal or industrial), kefir grain: milk ratio, type of milk, fermentation conditions, inoculum source, equipment used in production and storage conditions. Lactic acid bacteria (LAB) are a significant part of the kefir's microbial composition and the health-promoting effects. Kefir-derived LAB have beneficial effects on colorectal cancer, cardiovascular diseases, type 2 diabetes mellitus, obesity, kidney diseases, modulation of the immune system as well as intestinal microbiota through different biological mechanisms. In addition, bioactive peptides and metabolic products of kefir have shown promising results as health beneficial components along with certain antiviral effects including COVID-19. Therefore, this article is up-to-date information about the production, processing as well as health benefits of dairy kefir-derived LAB with future prospect of work.