乳酸菌发酵对脱脂米糠中糖和酚类物质含量的影响

本文比较不同乳酸菌发酵对脱脂米糠中糖和酚类物质的影响。采用半干法酶解工艺提高脱脂米糠中可发酵糖的含量,向灭菌的半干法酶解后的脱脂米糠中分别接入5种乳酸菌(保加利亚乳杆菌、乳酸链球菌、植物乳杆菌、干酪乳杆菌和肠膜明串珠菌),比较发酵过程中乳酸菌活菌数、总糖、还原糖、可溶和不溶性酚类物质含量的变化。结果表明,采用半干法酶解工艺,脱脂米糠中还原糖提高到155.08 mg/g,相比于原料中提高了6倍左右。5种乳酸菌均能在脱脂米糠中生长,但进入对数生长期后生长速率存在显著差异。5种乳酸菌中嗜酸乳杆菌降糖能力最强,其发酵72 h后脱脂米糠中总糖和还原糖分别下降了31.33%和60.76%。嗜酸乳杆菌发酵脱脂米糠24h时可溶性酚类物质含量最高,提高了33.00%,发酵72 h后不溶性酚类物质下降了20.32%,均显著优于其它四种菌。

Effects of Lactic Acid Bacteria Fermentation on the Content of Sugars and Polyphenols of Defatted Rice Bran

This study investigated the influence of fermentation by different lactic acid bacteria on the sugar and polyphenol content of defatted rice bran. Semi-dry enzymatic hydrolysis was used to increase the fermentable sugar content in defatted rice bran. After being treated with semi-dry enzymatic hydrolysis and sterilization, the defatted rice brans were inoculated with Lactobacillus bulgaricus, Streptococcus lactis, L. plantarum, L. casei, and Leuconostoc mesenteroides, respectively. Changes in the viable count of lactic acid bacteria, and the content of total sugar, reducing sugar, soluble polyphenols, and insoluble polyphenols during the fermentation were studied. The results showed that semi-dry enzymatic hydrolysis increased the content of reducing sugar in defatted rice bran to 155.08 mg/g, almost six times higher than that of the untreated defatted rice bran. All five lactobacilli grew in the defatted rice bran, but significant differences were found among their growth rates after entering the logarithmic phase. Among the five lactobacilli, L. acidophilus exhibited the strongest sugar transformation capacity; after 72-hour fermentation by L. acidophilus, the content of total sugar and reduced sugar decreased by 31.33% and 60.76%, respectively. The highest content of soluble polyphenols (33% increase) was observed after 24-hour fermentation by L. acidophilus; after 72-hour fermentation, the insoluble polyphenol content decreased by 20.32%, significantly better than those of other four stains.