利用示踪粒子及膨胀流变学研究β-乳球蛋白聚集体的界面行为

Interfacial Behavior ofβ-Lactoglobulin Aggregates Evaluated by Using Particle Tracking Microrheology and Interfacial Dilatational Rheology

在热加工过程中,蛋白易形成聚集体,不同聚集形态蛋白质的界面结构、流变学特性对乳液体系的稳定性及油脂消化特性具有显著影响。为探究β-乳球蛋白聚集体的界面行为,本研究通过调节pH值和加热时间制备了β-乳球蛋白(β-lactoglobulin,β-lg)的不同聚集体,包括β-lg、纳米颗粒聚集体(β-lg NP)和纤维状聚集体(β-lg F),并对这3种形态蛋白质的形貌进行了表征;利用示踪粒子微流变学及膨胀流变学对不同质量分数的β-lg、β-lg NP、β-lg F在油-水(癸烷-水)界面的吸附过程及胆盐取代行为进行研究,并通过体外消化模型实验研究了3种形态蛋白质乳液的消化特性。结果表明,质量分数越高,蛋白向界面扩散越快,形成界面黏弹性越强;蛋白质聚集体比β-lg向界面吸附更快,且形成界面膜弹性更高;在胆盐取代界面蛋白过程中,发现β-lg NP抵抗胆盐取代能力最强,β-lg最弱,与乳液的体外消化模型实验结果一致。

Proteins are easily self-assembled into different aggregates during thermal processing.The surface structure and rheological properties of different protein aggregates have significant effects on the stability and digestibility of emulsions stabilized by them.To explore the interfacial behavior ofβ-lactoglobulin aggregates,in this study,β-lactoglobulin(β-lg)aggregates,β-lg nanoparticle aggregates(β-lg NP)andβ-lg fibrillar aggregates(β-lg F)were prepared by controlling the heating temperature and pH,and their morphology was evaluated.The adsorption kinetics and the displacement behavior of protein films by bile salts(BSs)at the oil(decane)/water interface were studied using particle tracking microrheology and interfacial dilatational rheology.The digestion characteristics of emulsions stabilized by these protein aggregates were studied using an in vitro digestion model.It was found that protein diffusion to the interface became faster and the interfacial viscoelasticity became stronger with increasing protein concentration.β-lg NP andβ-lg F could be adsorbed faster than nativeβ-lg onto the interface,forming interfacial films with higher elasticity.In the case of protein displacement,β-lg NP had the strongest ability to resist bile salt substitution,while nativeβ-lg had the weakest ability,which was consistent with the results from in vitro digestion experiments.