鼠李糖乳杆菌发酵豆乳贮藏稳定性及菌体肠道耐受性分析

Storage Stability and Intestinal Tolerability of Soymilk Yogurt Fermented by Lactobacillus rhamnosus

研究了鼠李糖乳杆菌纯种发酵豆乳在-20,4,7℃和25℃条件下贮藏28 d的产品稳定性。定期测量不同温度下发酵豆乳的p H值、滴定酸度和活菌数,并对发酵豆乳进行感官品评。结果表明:发酵豆乳产品在低温(-20,4,7℃)条件下贮藏18 d,活菌数含量仍在3.8×10~8CFU/m L以上,p H值降至4.64,豆乳质地细腻,无乳清析出,由此确定发酵产品低温贮藏期为18 d;发酵豆乳室温(25℃)贮藏8 d,活菌数达9.8×10~8CFU/m L,pH值降至4.2,豆乳质地细腻,无乳清析出,确定发酵产品室温贮藏期为8 d。此外,研究了发酵豆乳中鼠李糖乳杆菌在不同浓度的胆汁和人工消化液中的耐受性。分别在0,0.1%,0.2%,0.3%的胆盐溶液中处理3 h,鼠李糖乳杆菌活菌数均维持在10~6CFU/m L以上。在人工肠液中处理24 h后活菌数仍在10~6 CFU/m L。本试验为鼠李糖乳杆菌纯种发酵豆乳产品安全贮藏以及菌体对肠道的耐受性研究提供了理论依据。

The stability of soybean yogurt fermented by Lactobacillus rhamnosus stored at-20, 7, 4 ℃ and 25 ℃for four weeks were investigated. The p H value, titratable acidity and viable cell count of fermented soymilk were regularly measured at different temperatures. Sensory evaluation was carried out with fermented soymilk storaged at different temperatures. Under low temperatures（-20, 4, 7 ℃）, the viable cell count number of the soybean yogurt was still 3.8×10~8 CFU/m L above and the p H value decreased to 4.64 after 18 d. It had fine and smooth texture which tasted good.Under room temperature（25 ℃）, the best storage time was 8 d; the viable number was 9.8×10~8 CFU/m L and the pH value decreased to 4.2. This study also focused on survival of probiotics in soybean yogurt fermented by Lactobacillus rhamnosus at different concentration of bile and artificial digestive juice, the viable counts of it was 1×106 CFU/m L after 3 h in different concentration of bile and 1×10~6 CFU/m L after 24 h in artificial intestinal juice. It well showed tolerance to artificial digestive juices in the fermented soymilk. This study provided a scientific basis for the quality control and the safe storage of the soybean yogurt.