不同聚合度魔芋葡甘低聚糖的酶解制备及其体外益生功能

以魔芋葡甘聚糖（konjac glucomannan，KGM）为原料，研究β-甘露聚糖酶酶解后魔芋葡甘低聚糖（konjac oligoglucomannan，KOGM）的制备流程对聚合度（polymerization degree，DP）的影响，探讨不同聚合度KOGM 与原料KGM 在理化性质、微观结构上的差异以及对5 种乳酸菌的增殖、产酸、总糖利用及短链脂肪酸的影响。结果表明，采用酵母发酵去除单糖以及随后的离心和灭菌工艺对KOGM 聚合度无明显影响。制备得到的3 种KOGM 的聚合度分别为16.74、12.74 和11.13。3 种KOGM 与原料KGM 具有相似的主链结构，其中2 种低聚合度KOGM（low polymerization konjac oligoglucomannan，KOGM-L）（KOGM-L1 的DP 为12.74，KOGM-L2 的DP 为11.13）有更低的黏度特征，且存在相似的微观形态，呈现更加明显的碎片化和孔洞结构。与KGM 和中聚合度KOGM（medium polymerization konjac oligoglucomannan，KOGM-M）（DP 为16.74）相比，低聚合度KOGM-L 更有利于促进乳酸菌增殖、产酸及总糖分解，但2 种低聚合度KOGM-L 之间没有显著差异（P>0.05）。低聚合度KOGM-L2与长双歧杆菌培养时总菌数最高（OD600=2.13），但是低聚合度KOGM-L1 与鼠李糖乳杆菌培养时增殖倍数最高（4～5 倍）。短链脂肪酸总产量及各组分含量显示低聚合度KOGM-L 要显著高于中聚合度KOGM-M、原料KGM 和菊糖（P<0.05）。综上所述，不同聚合度的KOGM益生功能差异明显，低聚合度KOGM 效果最佳。聚合度相近的KOGM 益生功能相似，聚合度11～13 对长双歧杆菌和鼠李糖乳杆菌有更好的益生效果。

Enzymatic Preparation of Konjac Oligoglucomannan with Different Polymerization Degrees and Their in vitro Probiotic Functions

The effect of the preparation process of konjac oligoglucomannan（KOGM）after β-mannanase hydrolysis on the degree of polymerization（DP）was studied by using konjac glucomannan（KGM）as raw material.The differences of physicochemical properties and microstructure between KOGM with different DPs and raw material KGM were investigated.Their effects on the proliferation，acid production，total sugar utilization and short-chain fatty acids of five kinds of lactic acid bacteria were also discussed.The results showed that the technology steps of monosaccharides removal method by yeast fermentation，subsequent centrifugation and sterilization had no significant effects on the DP of KOGM.The DPs of the prepared three kinds of KOGMs were 16.74，12.74 and 11.13，respectively.The backbone structure of these KOGMs was similar to that of the raw material KGM，and the two low polymerization konjac oligoglucomannan KOGM-L（the DP of KOGM-L1 was 12.74，and that of KOGM-L2 was 11.13）had lower viscosity characteristics and similar microscopic morphology，showing more obvious fragmentation and pore structure.Compared with KGM and medium polymerization konjac oligoglucomannan（KOGM-M，DP was 16.74），KOGM-L was more conducive to promoting the proliferation of lactic acid bacteria，acid production and total sugar decomposition，but there was no significant difference between the two KOGM-L（P>0.05）.KOGM-L2 cultivated with Bifidobacterium longum reached the maximum colonies in total count（OD600=2.13），but KOGM-L1 cultivated with Lactobacillus rhamnosus had the highest proliferative ratio values（4-5 times）.The total output and each component content of short-chain fatty acids showed that KOGM-L was significantly higher than KOGM-M，raw material KGM and inulin（P<0.05）.In summary，KOGM with different DPs had significant differences in prebiotic functions，in which KOGM with low DP gained the best effect.KOGM with similar DPs had similar probiotic functions，and the DP 11-13 had better probiotic effects on B.longum and L.rhamnosus.