The effects of kefir grain and starter culture on kefir produced from cow and buffalo milk during storage periods

Abstract The present study was aimed to determine the effect of different types of milk and kefir grains or starter cultures on the chemical properties, and microorganism counts of kefir samples. The type of milk had a significant effect on the acidity, dry matter, protein, and CO2 values. Acidity and CO2 values increased during storage period, while dry matter, fat and protein contents decreased. However, the type of milk had no significant effect on Lactobacillus, Leuconostoc and yeast counts. In the samples produced using starter culture microorganism counts except those of L. acidophilus of the samples increased (p < 0.05) during the 14 days of storage. Higher Lactobacilli (8.52 log cfu/ml) and Lactococci (8.84 log cfu/ml) was found in kefir produced using buffalo milk and starter culture in 21 days of storage, while higher L. acidophilus (6.41 log cfu/ml) was found in kefir produced using cow milk and starter culture. In general, due to the higher dry matter and protein content and yeast population, kefir made from buffalo milk may be preferred.摘要 本研究旨在探究不同乳类、开菲尔粒（kefir grains）与发酵剂（starter cultures）对开菲尔样品的化学特性及微生物计数的影响。乳类种类对开菲尔的酸度、干物质、蛋白质及二氧化碳（CO₂）含量具有显著影响。贮藏期间，样品的酸度与CO₂含量逐渐升高，而干物质、脂肪及蛋白质含量则呈下降趋势。但乳类种类对乳杆菌属（Lactobacillus）、明串珠菌属（Leuconostoc）及酵母菌计数无显著影响。在使用发酵剂制备的样品中，除嗜酸乳杆菌（L. acidophilus）外，其余微生物计数在14天贮藏期内均显著升高（p < 0.05）。贮藏21天时，使用水牛乳与发酵剂制备的开菲尔中乳杆菌（8.52 log cfu/ml）与乳球菌（8.84 log cfu/ml）含量均为最高；而使用牛乳与发酵剂制备的开菲尔中嗜酸乳杆菌含量最高，达6.41 log cfu/ml。总体而言，由于水牛乳制备的开菲尔具备更高的干物质、蛋白质含量及更优的酵母菌种群量，因此更具应用价值与推广潜力。