超高压诱导β-乳球蛋白-壳聚糖共价复合物及其稳定乳状液的制备与表征

Preparation and Characterization of β-Lactoglobulin-Chitosan Covalent Conjugate under High Pressure Processingand Emulsion Stabilized by It

目的:探究超高压处理对美拉德反应的影响,通过蛋白质-多糖共价复合物反应,开发更高效的油-水界面膜以提高乳液稳定性。方法:以不同质量比(1∶1、1∶2、1∶4)的β-乳球蛋白和壳聚糖为原料,经不同压力(200、400、600 MPa)处理后,进行干法美拉德反应,以β-乳球蛋白和壳聚糖的物理混合物为对照,研究产物的褐变程度、荧光光谱和圆二色光谱图,以及制备的乳液粒径、Zeta-电位、物理稳定性等。结果:蛋白与多糖质量比为1∶1和1∶2时,随压力增加,褐变程度先升高后降低;蛋白与多糖质量比为1∶4时,褐变程度随压力增加持续升高。超高压诱导的美拉德反应使蛋白质荧光发生猝灭,壳聚糖比例越高,猝灭程度越大。在蛋白与多糖不同质量比(1∶1、1∶2、1∶4)时,共价复合物的α-螺旋相对含量分别由19.5%、21.1%、22.5%(物理混合物)降至18.7%、16.9%、15.9%,共价复合物α-螺旋相对含量均在400 MPa达到最大值,分别为19.6%、19.0%、16.6%。蛋白与多糖共价复合物制备的乳液粒径(399.1、481.5、584.4 nm)以及4 h时稳定性动力学指数(1.60、2.31、0.49)均比其物理混合物要小,而Zeta-电位更高(46~48 mV),乳液更稳定。结论:超高压诱导美拉德反应对其产物乳液的乳化稳定性有积极影响。

Objective:To explore the impact of ultra-high pressure(UHP)treatment on the Maillard reaction,and to develop a more efficient oil-water interface membrane for improving emulsion stability through protein-polysaccharide covalent complexation.Methods:The Maillard reaction betweenβ-lactoglobulin(β-Lg)and chitosan(CS)at different mass ratios(1:1,1:2 and 1:4)was initiated under dry-heating conditions after preprocessing at different pressures(200,400 and 600 MPa).Their physical mixtures were used as a control for comparison.The resultant conjugates were characterized by the degree of browning,fluorescence spectroscopy,and circular dichroism spectroscopy,and the particle size,zeta-potential,and physical stability of the emulsions prepared with the conjugates were measured.Results:When the mass ratio ofβ-Lg to CS was 1:1 and 1:2,as the pressure increased,the degree of browning first increased and then decreased;when the ratio was 1:4,the degree of browning continued to increase.The fluorescence ofβ-Lg was quenched after the Maillard reaction,and the higher the CS ratio,the stronger the degree of quenching.Theα-helix content ofβ-Lg was reduced from 19.5%,21.1%and 22.5%to 18.7%,16.9%and 15.9%,respectively after the Maillard reaction atβ-Lg to CS ratios of 1:1,1:2 and 1:4,and theα-helix content reached the maximum value of 19.6%,19.0%and 16.6%,respectively under 400 MPa.The particle size(399.1,481.5 and 584.4 nm)and 4 h turbiscan stability index(1.60,2.31 and 0.49)of the emulsions prepared with the covalent conjugates were smaller than those with the physical mixtures,and the former had higher zeta-potential(46–48 mV).Conclusion:UHP-induced Maillard reaction had a positive effect on emulsion stability.