莲子抗性淀粉体外消化的结构变化对短双歧杆菌增殖的影响

Effect of Structural Changes of Lotus Seed Resistant Starch through Digestion in Vitro on Bifidobacterium breve Proliferation

抗性淀粉是一类重要的结肠微生物碳源,研究其构效关系,有助于了解其在体内的转化过程。以用微波法和水浴法制备的莲子抗性淀粉(MP-LRS3和WB-LRS3)为原料,通过体外消化,测定其在消化过程中结构的变化,建立与内源性短双歧杆菌的营养互作关系。结果表明:体外消化后MP-LRS3和WB-LRS3的结构均发生改变,其中结晶度显著升高(P<0.05),形态由表面粗糙的叠层结构逐步解聚为粒径较小且棱角圆润的颗粒,晶体结构仍为B型,双螺旋结构更加紧密,淀粉分子的排列更加有序。MP-LRS3和WB-LRS3因制备方式不同,故消化处理前、后的晶体特性均存在差异。相同消化阶段,MP-LRS3较WB-LRS3的解聚程度高。此外,MP-LRS3和WB-LRS3对短双歧杆菌的促增殖能力均随消化进程逐渐增强,在同一消化阶段前者的促增殖能力更强,这可能与消化环境对莲子抗性淀粉的解聚程度不同造成的结构差异有关。黏附结果与促增殖能力呈正相关,推测黏附水平也受莲子抗性淀粉结构变化的影响,并可能是影响莲子抗性淀粉与短双歧杆菌营养互作关系的重要因素之一。本研究结果可为完善抗性淀粉的体内代谢和益生作用提供理论依据。

Resistant starch is a kind of important carbon source for colonic microorganisms.The study of its structure-function relationship is helpful to understand the mechanism of dietary nutrition in the body.In this paper,lotus seed resistant starch prepared by microwave-power method(MP-LRS3)and water-bath method(WB-LRS3)were used as raw materials.With digestion in vitro,MP-LRS3 and WB-LRS3 were used to determine the structural changes and established their nutritional interactions of Bifidobacterium breve.The results showed that after digestion in vitro,the crystallinity of MP-LRS3 and WB-LRS3 changed significantly(P<0.05),the layered structure with rough surface gradually depolymerizated into smaller particles with rounded corners,and both of their crystal structure still were B type.After recrystallization,the double helix structure was compacter and the arrangement of starch molecules was more orderly.However,due to the different preparation methods,the crystal properties were different after digestion.At the same digestion stage,the depolymerization degree of MP-LRS3 was higher than that of WB-LRS3.In addition,MP-LRS3 and WB-LRS3 showed a better adhesion reaction to Bifidobacterium breve with the process of digestion,but the level of the former was higher at the same digestion stage,which might be related to the different depolymerization degree in the digestion environment of lotus seed resistant starch caused by the structural differences.There was a positive correlation between the adhesion reaction and the ability to promote proliferation.It was speculated that the structural difference caused by the different degree of depolymerization made that MP-LRS3 was stronger than WB-LRS3 on adhesion ability and proliferative effect.The results of this study could provide a theoretical basis for improving the metabolism and probiotic action of resistant starch in vivo.