Comparison of traditional and backslopping methods for kefir fermentation based on physicochemical and microbiological characteristics

Backslopping method for large-scale production of kefir drink was established to scale up the production of kefir beverage containing original kefir microbiota. The microbiological, nutritional, physiochemical, and sensory properties of novel backslopped kefir (BK) were compared with those of traditional kefir (TK). Application of backslopping method in kefir production increased production yields by 50-folds, and the microbiological, nutritional, and physicochemical characteristics of BK were not significantly different from those of TK except the numbers of Lactobacillus kefiri and yeast, % carbohydrate, and pH. In cold storage, the number of lactic acid bacteria remained constant at 9 log CFU/mL in both TK and BK; however, yeast population increased from 4.7 to 6.5 log CFU/mL of BK, and from 4.8 to 7.5 log CFU/ml of TK (p < 0.05). The pH decreased throughout the storage period. In sensory evaluation, the scores of taste/flavor in TK were significantly lower than those of BK from storage day 7-11. In addition, whey separation was observed in TK and BK at day 5 and 9, respectively, consistent with the scores of texture/consistency. The novel method could be applied for the convenient scale-up production of kefir with good yield, improved sensory properties, and prolonged shelf-life.