益生菌发酵对胡萝卜多糖结构特征及其营养特性的影响

Fruit and vegetable fermentation by probiotics is an important method to solve problems encountered in their modern manufacturing. Structure and nutrition of fruit and vegetable are usually affected in processing. It is significant to explore material base of the nutritional variation of fruit and vegetable by analyzing their structural difference. Our previous research showed that carrot fermented by probiotics was better in regulating blood sugar. Carrot is rich in polysaccharide (dietary fibre), and many reports confirm that it is good for blood sugar regulation by taking appropriate amount of bioactive polysaccharide. Therefore, carrot before and after probiotic fermentation is subjected for study in this research. Polysaccharides are extracted from the carrot and purified by chromatography. Then, methods such as partial acid hydrolysis, methylation and NMR are applied to characterize polysaccharide structure. Modern rheological techniques, atomic force microscope, dynamic and static light scattering, combing with theory of polymer solution, are used to analyze the rheological and conformational characteristics. Finally, effects of polysaccharide on blood sugar regulation and immunomodulation are investigated by animal studies, respectively. According to these results, the differences of polysaccharides from carrot before and after fermentation on the structural characteristics and their nutrition could be compared. Then, we could make an assessment on key scientific problems that whether structural changes are main factors for the nutritional variation of carrot before and after fermentation by probiotics. The study would also guide researches on effects of probiotic fermentation on structure and function of edible polysaccharide from other resources.

益生菌发酵是果蔬现代加工的一种重要手段。果蔬在加工过程中其结构特征和营养价值容易受到影响，从结构特征变化角度探讨其营养特性变化的物质基础，具有重要的科学意义。前期研究显示益生菌发酵胡萝卜具有更好的血糖调节功能，胡萝卜中富含多糖类膳食纤维，大量研究已证实摄入适量活性多糖有利于调节体内血糖水平。因此本课题拟选取益生菌发酵前后的胡萝卜为研究对象，通过溶剂萃取结合色谱技术纯化多糖，再采用部分酸水解、甲基化、NMR等方法表征多糖结构，并借助现代流变技术、原子力显微镜、动静态光散射仪以及高分子溶液理论解析多糖流变、溶液构象特征，最后利用动物实验分别研究胡萝卜多糖对血糖和免疫功能的调节作用。通过综合比较益生菌发酵前后胡萝卜多糖结构特征及其营养特性变化情况，明确胡萝卜多糖结构变化是否是胡萝卜营养特性改变的主要因素这一关键科学问题。本研究还可为益生菌发酵对其他食源性多糖结构和功能的影响提供方法学参考。

益生菌发酵是果蔬现代加工的一种重要手段，果蔬在加工过程中其结构特征和营养价值容易受到影响，因此从结构特征变化角度探讨其营养特性变化的物质基础，具有重要的科学意义。本课题选取益生菌（植物乳杆菌NCU 116）发酵前后的胡萝卜为研究对象，分析益生菌发酵对胡萝卜多糖结构特征及其营养特性的影响。益生菌发酵胡萝卜果浆PFCP拥有更高的表观粘度以及更低的离心沉淀率、可溶性固形物水平，使得它比未发酵胡萝卜果浆NFCP拥有更好的稳定性，同时可能由于益生菌的新陈代谢作用以及加工过程的影响使得PFCP和NFCP在营养成分上存在一定差异；发酵前后的胡萝卜水溶性多糖WSP、酸溶性多糖CSP和碱溶性多糖NSP在结构和构象上也存在一定差异；发酵前后胡萝卜水溶性多糖（WSP-n，WSP-p）进一步纯化后，分别获得了3种果胶类多糖（RG-I、HG型），构象特征有一定差异，但精细结构差异相对较小；WSP-n和WSP-p多糖组分均能够有效的改善II型糖尿病的健康情况，同时也能增强免疫抑制小鼠免疫调节功能，而WSP-p的作用效果相对较好，这种差异可能源自两者的构象特征不同。通过比较益生菌发酵前后胡萝卜中多糖结构、溶液构象特征的差异，以及在血糖调节和免疫功能活性方面的作用，明确了益生菌发酵对胡萝卜多糖结构特征的改变及其营养特性的影响，从而阐明发酵前后胡萝卜营养特性发生变化的重要物质结构基础，为乳酸菌发酵胡萝卜及其相关系列相关产品开发与应用提供了理论依据。