香蕉果肉对乳酸菌在冻干和贮存中活性的影响

Effects of banana pulp on the viability of lactic acid bacteria during freeze-drying and storage

为开发香蕉-益生菌冻干产品及探索益生菌保护技术,以不同成熟度香蕉泥混合乳酸菌并真空冷冻干燥,通过测定香蕉-乳酸菌冻干粉在冻干、贮藏和模拟胃酸胁迫下的活菌数、冻干粉的微观形貌及香蕉的理化指标,探讨不同成熟度香蕉对乳酸菌在冻干和贮藏中的保护作用。结果表明,香蕉对乳酸菌在冻干和贮存中的保护效果与可溶性固形物含量、可溶性糖含量、淀粉含量有显著相关性(P<0.01);随着成熟度提高,香蕉对乳酸菌冻干的保护效果增强,对乳酸菌贮藏的保护效果减弱;但总体而言,成熟度越高,在冻干、贮存、和胃酸胁迫后的活菌数也越高。其中,三级香蕉组冻干后活菌数6.67×10^(6) CFU/mL与脱脂乳组6.20×10^(6) CFU/mL无显著差异;在贮藏28 d后乳酸菌存活率101.95%,是空白组的21.42倍;在模拟胃酸胁迫后活菌数仍保持在106 CFU/mL以上。结果显示,3级以上成熟度香蕉不仅是良好的乳酸菌载体,同时能为乳酸菌冻干和贮存提供有效保护。

In order to develop banana-probiotic freeze-dried products and explore probiotic protection technology,the lactic acid bacteria(LAB)were mixed with banana puree of different maturity and vacuum freeze-dried.Then the protective effect of bananas of different maturity on LAB during freeze-drying and storage was discussed through the viable count of banana-LAB freeze-dried powder under freeze-drying,storage and gastric acid stress,the microscopic morphology of freeze-dried powder and the physical and chemical indicators of bananas.The results showed that the protective effect of banana on LAB during freeze-drying and storage was significantly correlated with the content of soluble solids,soluble sugar and starch(P<0.01).With the improvement of maturity,the protective effect of bananas on freeze-drying of LAB was enhanced,and the protective effect on storage of LAB was weakened.But in general,the higher the maturity,the higher the viable count was determined after freeze-drying,storage,and gastric acid stress.Among them,the viable count in the 3-grade banana group after freeze-drying was 6.67×10^(6) CFU/mL,which was not significantly different from the 6.20×10^(6) CFU/mL in the skim milk group(P<0.05).The survival rate of LAB after 28 d of storage was 101.95%,which was 21.42 times that of the blank group.And the viable count remained above 106 CFU/mL after simulated gastric acid stress.In conclusion,bananas with maturity level of 3 or above were not only good carriers of LAB,but also provided effective protection for freeze-drying and storage of LAB.