益生菌Lactobacillus casei Zhang与商业益生菌对胃肠转运耐受性及发酵特性的比较

Comparison of Transit Tolerance and Fermentation Properties of Probiotic Lactobacillus Casei Zhang with Commercial Probiotic Strains

比较益生菌干酪乳杆菌Zhang(L.casei Zhang)与商业化益生菌嗜酸乳杆菌NCFM(NCFM)、鼠李糖乳杆菌GG(LGG)、干酪乳杆菌Shirota(LcS)、动物双歧杆菌Bb12(Bb12)对人工胃肠液的耐受性及发酵特性。将各菌置于人工消化液及含3.0g/L牛胆盐的MRS培养基中,37℃培养,分别于3h和8h时测定人工胃液和肠液中各菌株的存活率,同时每小时测定MRS培养基的浊度,以延迟时间评价各菌株对胆盐的耐受性。对由各菌株制得的发酵乳在发酵及贮藏期间酸度与活菌数的变化进行了测定,结果表明,在pH2.5的人工胃液消化3h后,干酪乳杆菌Zhang存活率低于NCFM(p<0.05),高于其它3株对照菌(p<0.05);在pH3.0和pH4.0的人工胃液消化3h后,干酪乳杆菌Zhang的存活率与4株对照菌无显著差异(p>0.05);在pH8.0的人工肠液消化8h后,干酪乳杆菌Zhang的存活率高于Bb12(p<0.05),低于NCFM(p<0.05),与其它2株对照菌无差异(p>0.05)。干酪乳杆菌Zhang对3.0g/L牛胆盐的耐受性与LcS差异不显著(p>0.05),而高于其它3株对照菌(p<0.05)。脱脂乳37℃发酵24h后,接种干酪乳杆菌Zhang的样品的酸度低于4株对照菌。4℃贮藏28d内,各益生菌在发酵乳中继续生长,其中干酪乳杆菌Zhang发酵乳的pH值变化(降低0.55)显著高于4株对照菌(p<0.05);贮藏28d后干酪乳杆菌Zhang活菌数为1.0×109cfu/g,显著高于4株对照菌(p<0.05),说明干酪乳杆菌Zhang具有良好的胃肠转运耐受性和极佳的贮藏稳定性。

The simulated gastric tolerance and fermentation properties of LactobaciUus casei Zhang were assayed and compared with the four selected commercial probiotics： L. acidophilus NCFM, L. rhamnosus GG, L. easel Shirota and Bifidobacterium animalis Bbl2. The strains were inoculated into simulated gastric juice, intestine juice and MRS broth with 0.3 g/100 g bile salts. Total viable counts of strains were determined after incubated 3 h and 8 h at 37℃ in the simulated gastric juice and intestine juice, respectively. And studied the effect of bile salts on the growth rate of the strains by determining the absorbance at every one hour. Then, the pH values, TA and viable counts of fermented sampies were determined during the fermentation and the refrigerated storage. Results showed that：After the incubation at pH 2.5 for 3 h, the survival rate of L. casei Zhang in simulated gastric juice was lower than L. acidophilus NCFM, but was higher than the other three probiotic strains （p〈0.05）. After the incubation at pH 3.0 and pH ,4.0 for 3 h, the survival rates of L. easel Zhang in simulated gastric juice were not significant difference with the selected probioties（p〉0.05）. After the 8 h incubation in the simulated intestine juice, the survival rate of L. casei Zhang was no considerable difference with L. rhamnosus GG and L. easel Shirota （p〉0.05）. The tolerance of L. casei Zhang to bile salts was not significant difference with L. casei Shirota, but was higher than the other three probiotic strains （p〈0.05）. The defatted milk inoculated with L. casei Zhang showed higher pH and lower TA than those of the samples. All the tested strains of probitics showed continuing growth in the defatted milk, and the pH value decreased significantly in the sample inoculated with L. casei Zhang was higher than those inoculated with the selected commercial probiotics during 28 d of refrigerated storage at 4 ℃（p〈0.05）. After the storage, the sample fermented with L. casei Zhang exhibited higher viable count （1.0×10^9cfu/ g） than the other samples （p〈0.05）. These results indicated that L. casei Zhang has a good transit tolerance and storage stability.