米谷蛋白对挤压淀粉复合物结构及性质的影响

Effect of glutelin on structure and properties of extrusion starch complex

以大米淀粉及米谷蛋白为原料,通过双螺杆挤压技术制备了不同比例的大米淀粉/米谷蛋白复合物,利用FTIR、1HNMR、XRD、DSC、快速黏度计、低场核磁(LF-NMR)、流变仪和SEM对复合物的形成机制、结构变化、理化性质以及微观形态进行了表征。结果表明,大米淀粉发生降解、α-1,6-糖苷键断裂,分支化减弱,并与米谷蛋白发生化学相互作用(包括美拉德反应),形成均匀致密的片层微观结构,从而增强对水分子的束缚能力。挤压后复合物表现为较低的热稳定性、结晶特性、糊化特性以及黏弹性。这些特性随着米谷蛋白添加量的提高得到改善,尤其在米谷蛋白添加量(以淀粉质量为基准,下同)为13%时,复合物的相对结晶度由2.10%(米谷蛋白添加量为9%)增加至3.51%(米谷蛋白添加量为13%),峰值黏度增加至376.51 Cp(1000 c P=1 Pa·s),崩解值提升为362.20 Cp,回生值增加至87.14 Cp,剪切应力随之增大,储能模量与损耗模量明显升高。

Rice starch/glutelin complexes with different proportions were prepared by twin-screw extrusion technology.The formation mechanism,structural changes,physiochemical properties,and micromorphology of the complexes obtained were then analyzed by FTIR,1HNMR,XRD,DSC,rapid viscosimeter,low-field nuclear magnetic resonance(LF-NMR),rheometer,and SEM.The results showed that rice starch was degraded,theα-1,6-glycoside bond was broken,and the branching was weakened as well.Meanwhile,a uniform and dense lamellar structure were formed by chemical interaction(including the Maillard reaction)with glutelin,which led to improved binding capacity for water molecules.The complexes being extruded displayed low thermal stability,crystallization,gelatinization and viscoelasticity,all of which were improved as the content of glutelin increased.When the protein addition(based on the mass of rice starch,the same below)was 13%,the relative crystallinity increased from 2.10%,which was obtained when the amount of glutelin added was 9%,to 3.51%,the peak viscosity increased to 376.51 Cp,the disintegration value increased to 362.20 Cp,and the retrogradation value increased to 87.14 Cp.The shear stress and storage modulus as well as loss modulus were also significantly improved.