植物乳杆菌发酵对大麦β-葡聚糖的结构及营养特性作用解析

Whole grain food has a recognized healthy function, through the fermentation of lactic acid bacteria can give it a higher nutritional value. Barley, which is rich in beta glucan, is an important resource of whole grains. Our previous research showed that barley fermentation with lactic acid bacteria could significantly improve the regulating effect on blood glucose and blood lipid. In this project, the effects of Lactobacillus plantarum dy-1 fermentation on the structure and nutritional characteristics of barley β-glucan are systematically studied for the first time. With gas chromatography (GC), nuclear magnetic resonance (NMR) and high performance anion exchange chromatography with pulsed amperometric detector (HPAEC-PAD) technology, the influence of the physical and chemical properties and fine structure details of β-glucan from aqueous extract of barley by Lactobacillus plantarum dy-1 fermentation are studied. And its rheological and solution conformation characteristics are detected by TA rotational rheometer and more detector combined HPSEC equipment. Regulation on blood glucose and lipid synthesis of barley β-glucan is investigated by animal test. This project could make an assessment on the key scientific problem that whether fine structural changes of β-glucan is the main factor for the nutritional variation of Lactobacillus plantarum dy-1 fermented barley extract，and provide technological support to barley food processing.

全谷物食品具有公认的健康功能，通过乳酸菌发酵能赋予其更高的营养价值。大麦富含β-葡聚糖，是重要的全谷物资源。申请人前期研究证实，乳酸菌发酵大麦能显著增强体内血糖血脂调节功能。在此基础上，本课题采用GC、HPLC、核磁共振以及HPAEC-PAD等仪器分析手段，研究植物乳杆菌dy-1（前期筛选）发酵对产物中β-葡聚糖理化性质及精细结构特征的影响；利用旋转流变仪、多检测器联用HPSEC仪等结构学分析方法，研究其流变和溶液构象特征变化；同时，从血糖水平及脂质合成角度，探讨发酵前后大麦β-葡聚糖对大麦营养特性的影响。进而解析大麦乳酸菌发酵过程中β-葡聚糖结构与功能的变化规律，构建发酵过程参数-葡聚糖结构-理化性质-营养特性间的量化关联，回答“大麦β-葡聚糖结构变化是否为大麦植物乳杆菌发酵产物营养特性发生变化的主要因素”这一科学问题，为大麦在健康食品工业应用提供技术支撑。

大麦富含β-葡聚糖，是重要的全谷物资源。申请人前期研究证实，乳酸菌发酵大麦能显著增强体内血糖血脂调节功能，然而其物质基础尚不清楚。本研究采用植物乳杆菌Dy-1发酵大麦，并对未发酵大麦β-葡聚糖（RBG）及发酵大麦的β-葡聚糖（FBG）的理化性质、精细结构及营养特性的变化进行了对比分析，结果表明：（1）发酵后大麦 β-葡聚糖的分子量降低，β-(1→3)糖残基与 β-(1→4)糖残基的比值范围发生了改变；（2）发酵前后大麦β-葡聚糖的溶解性、溶胀性、持水性和持油性增强，表观粘度、弹性模量和粘性模量无显著差异；（3）秀丽隐杆线虫模型研究结果表明，RBG 和 FBG 均能显著提高线虫的运动行为能力，增加线虫的能量消耗，减少线虫体内脂肪沉积，其中 FBG 效果更为显著；（4）RBG 和 FBG 对线虫 nhr-49 介导的信号通路、TGF-daf-7 途径、5-羟色胺介导的信号通路以及 TOR 和氨基己糖介导的信号通路均有一定程度的调控作用，但是二者对部分基因表达的调控作用有显著性差异；（5）RBG和FBG都能显著降低线虫在氧化应激条件下的ROS水平，并对SOD和CAT酶活性均有显著影响，且FBG处理能显著降低氧化胁迫下线虫体内MDA含量；（6）FBG和RBG预处理可以延长线虫在氧化胁迫下的平均寿命，其通过Daf-2/Daf-16途径参与抗氧化应激防御。本项目研究结果解析了大麦乳酸菌发酵过程中β-葡聚糖结构与功能的变化规律，揭示了大麦植物乳杆菌发酵产物营养特性发生变化的重要物质基础，为大麦在健康食品工业应用提供了理论基础。