Safety and Biological Aspects of Kefir Production

Kefir is a fermented drink which contains lactic acid (by lactic acid bacteria) as well as ethanol and carbon dioxide produced by lactose fermentation (by yeasts). The aim of this study is investigation of kefir constituents and their clinical roles to declare its valuable effects in daily or even weekly consumption by human. So whey as raw material, substrates, producing microorganisms, their balance of co-culture and produced products, as well as health beneficial effects, mechanism of action against oxidative agents together with threats, production of biogenic compounds are described. Kefir manufacture is done by various microorganisms. Mixed culture of lactic acid bacteria and yeasts resulted in the slow production of lactic and acetic acids compared to their pure cultures. So, acid production is controllable. Unique characteristics of kefir are related to microbial synergism in kefir grains that lead to its special benefits. The most important health effects are: nervous system improvement, anti-carcinogenic effect, lowering blood pressure and hypo-cholesterolaemic effect, treating of tuberculosis, atherosclerosis, fatigue, depression and gastrointestinal disorders, improvements of kidney function due to vitamin B production, anti-diabetic effect and so on. Healthy effect of kefir consumption indicated that all constituents including microorganisms as starter cultures and also final product induce human health. With regard to non-distributed consumption of kefir in Iran, use of educational strategies can lead to its increasing daily consumption.