CaCl_(2)作用下核诱导形成乳清蛋白纤维聚合物特性研究

Properties of CaCl_(2)on Nucleation-induced Whey Protein Fiber Polymer

在低pH值、低离子强度、长时间高温加热条件下乳清蛋白可以自组装形成纳米纤维聚合物。纤维的形成主要有自发和核诱导2种方式,对改善乳清蛋白的功能性质具有重要作用。通过界面性质与纤维结构的关系探究CaCl_(2)对核形成、核诱导以及成熟纤维的影响。结果表明:核诱导方式比自发方式对CaCl_(2)的耐受性更强,CaCl_(2)浓度为50 mmol/L时,均相核诱导、二次核诱导乳清蛋白形成的纤维聚合物较自发方式样品乳化稳定性指数分别降低了30.92%、34.09%,泡沫稳定性指数分别降低了68.18%、78.59%。加入20~50 mmol/L CaCl_(2)能提高蛋白质的聚合速率,同时降低反应的活化能,但这种快速聚合破坏了纤维有序组装的过程,核诱导方式由于加快了纤维聚合物的形成速度,与自发方式相比,核诱导对CaCl_(2)的耐受程度更高。

Whey protein concentrate(WPC)is capable of self-assembling into amyloid fibril aggregates under certain denature conditions,such as high temperature with low pH and low ionic strength.There are two pathways for WPC to form amyloid fibril aggregates with spontaneous pathway and nucleation-induction pathway,which play an important role in improving the functional properties of WPC.The effect of CaCl_(2)on nucleation formation,nucleation-induction and mature fibrils was investigated through the relationships between interface properties and fibrils structure.The results showed that the nucleation-induction method was more resistant to CaCl_(2)than the spontaneous mode.When the CaCl_(2)concentration was 50 mmol/L,the emulsification stability of the fibrous polymer formed by homogeneous nucleation-induction and two nucleation-induced whey protein was decreased by 30.92%and 34.09%,respectively,and the foam stability was decreased by 68.18%and 78.59%,respectively.The addition of 20~50 mmol/L CaCl_(2)can increase the polymerization rate of protein and reduce the activation energy of the reaction.However,the rapid polymerization destroyed the orderly assembly process of fiber.Compared with the spontaneous mode,the nucleation-induction mode was more tolerant to CaCl_(2)because it accelerated the formation of fiber polymer.