辛烯基琥珀酸淀粉酯与肠道发酵性及肠道菌群多样性的构效关系研究

Octenyl succinic anhydride modified starch (OSA starch) is a chemically modified starch that has been approved for food use in China. OSA starch is widely used as an emulsifier in the food industry. Recently, it has been found that OSA starch is high in slowly digestible starch and resistant starch, and it has good fermentability in colon. OSA starch as an emulsifier may have nutrition functions and exert physiology benefits. In our previous research, it has been found that OSA starch could increase the butyrate content in mice feces. Mice feeding high fat diet with 10% OSA starch had higher percentage of good bacteria Bacteroides and Alistipes content in their feces as compared with mice consuming high fat diet. Our research suggests prebiotic effect of OSA starch, however little is known about the factors that affecting the fermentability of OSA starch. In this research, we are planning to prepare OSA starch with different structure characteristics, including origin of starch, degree of substitution, crosslinking combining OSA substitution. Fermentability of OSA starch will be investigated by in vitro fermentation and in vivo animal experiment. Short chain fatty acid content and composition in the ferementation media as well as mice feces will be analyzed by GC-FID. The gut microbiota composition of rat feces will be analyzed by 16S rRNA method. Structure of OSA starch after in vitro and in vivo digestion will be evaluated. We are hoping the research will provide more information on the structure functionality of OSA starch on its fermentability and understand the potential of using OSA starch as a functional food ingredient.

辛烯基琥珀酸淀粉酯（OSA淀粉）是重要的乳化剂和可食用改性淀粉。OSA淀粉慢消化和抗性淀粉含量高、肠道发酵性好，有望成为具有营养价值的功能性乳化剂。前期研究发现，高脂饲料中添加OSA淀粉显著增加了小鼠粪便中丁酸的含量和拟杆菌门的相对丰度，肠道菌群结构与高脂饲料对照组显著不同。但影响 OSA淀粉肠道发酵性及肠道菌群多样性的因素尚不清楚。本项目计划从原淀粉来源和取代度两方面制备OSA淀粉，研究揭示OSA淀粉消化产物的结构特征与肠道发酵性的作用关系。通过体外实验和动物模型，明确发酵产物短链脂肪酸的含量及组成；通过16S rRNA法测定小鼠粪便中肠道微生物群落的组成。通过体内和体外法获得OSA淀粉上消化道消化产物，测定其分子量分布、支链长度、淀粉颗粒表面形貌等结构特征，检测细菌对淀粉颗粒的粘附率。本项目有望明确OSA淀粉与其发酵性的构效关系，为开发其营养功能及拓宽应用领域提供科学依据和理论基础。

辛烯基琥珀酸（OSA）淀粉酯是常用的食品添加剂。采用新方法制备OSA淀粉，原淀粉的来源不同，OSA的反应效率不同。在3%的改性水平上，高直链玉米（HAM）淀粉的反应效率最高，显著高于蜡质玉米淀粉和马铃薯淀粉。随着OSA添加量的增加，反应效率降低。OSA改性并没有显著改变淀粉颗粒的表观形貌和晶体类型。但OSA淀粉的结晶度降低，糊化温度降低，吸收晗降低。新型OSA改性方法并没有显著增加HAM淀粉的抗性淀粉的含量。我们将OSA淀粉对大鼠进行灌胃，2小时后收集大鼠回肠内容物，大鼠回肠内未见淀粉颗粒，OSA淀粉经小肠消化后，淀粉颗粒结构消失。我们研究了新方法和传统方法制备OSA淀粉对高脂饮食小鼠肥胖的预防效果以及对肠道发酵产物短链脂肪酸（SCFA）和粪便微生物群落结构的影响。研究结果显示新型OSA淀粉显著减少了由高脂饮食诱导的小鼠体重的增加，改善了血糖应答。新型OSA淀粉具有良好的肠道发酵性，显著增加高脂膳食小鼠粪便中丙酸、丁酸和戊酸的含量，特别是丁酸的含量。同时，OSA淀粉改变了小鼠肠道菌群的结构，降低了厚壁菌门与拟杆菌门的比值，增加了有益菌以及与SCFA产生有关的菌群丰度，并抑制了潜在有害菌的生长。传统方法制备的OSA淀粉也具有预防高脂饮食诱导小鼠肥胖的作用。OSA淀粉和HAM淀粉显著增加了高脂饮食小鼠粪便中乙酸、丙酸、丁酸和总短链脂肪酸的含量。传统OSA淀粉和HAM淀粉改变了小鼠粪便中菌群的结构和丰度，显著降低了高脂饮食小鼠粪便中粪便中潜在有害菌属如Desulfovibrio的相对丰度，增加了有益菌属Faecalibaculum和Bacteroides的相对丰度。我们还研究了抗性糊精的制备条件对其分子结构和消化性的影响。随着反应条件加剧，淀粉溶解度的增加，粘度和分子量降低，在反应过程中产生了新的糖苷键，包括α-1,6、β-1,6、α-1,2和β-1,2。分支度随着反应条件的加剧而增加，并最终保持稳定。反应条件的加剧导致了RS含量的增加，且RS含量与分支度呈正相关。本项目有助于明确OSA淀粉的生理功能，为拓展OSA淀粉的应用提供了科学依据。