How are kefir microbial communities and product characteristics maintained in industrial production?

Kefir, a millennia-old symbiotic fermented dairy product, has emerged as a focal point of research in the global functional foods sector owing to its distinctive organoleptic properties and extensive health-promoting effects. Kefir grains, serving as the natural starter culture for traditional kefir, constitute a complex symbiotic consortium comprising lactic acid bacteria, acetic acid bacteria, and yeasts, whose stratified spatial distribution and metabolic synergistic interactions determine the characteristic flavor profile and probiotic functionality of kefir. Nevertheless, contemporary kefir production faces fundamental challenges stemming from the incompatibility between traditional fermentation methodologies and modern industrial manufacturing processes, resulting in commercial kefir products exhibiting deficiencies in core functional microbial populations, flavor homogenization, and suboptimal functional efficacy claims. This review analyzes the current research landscape concerning kefir grains and kefir microbial communities, while providing a comprehensive overview of the organoleptic characteristics, nutritional composition, and functional properties of kefir. Through a systematic examination of three distinct fermentation production methodologies and principal challenges confronting commercial development, this study proposes synthetic microbial communities and kefir grain-like starter cultures as innovative production strategies for advancing kefir manufacturing.