β-乳球蛋白对VE热稳定性的影响

Effect ofβ-Lactoglobulin on the Thermal Stability of Vitamin E

为改善超高温瞬时灭菌(ultra-high temperature instantaneous sterilization,UHT)乳中VE的热稳定性,以β-乳球蛋白(β-lactoglobulin,β-LG)和VE为材料制备复合物,探究β-LG对VE热稳定性的影响。通过浊度、粒径、Zeta电位、扫描电子显微镜、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、红外光谱和荧光光谱研究β-LG与VE的结合情况;利用生物膜干涉技术进一步分析β-LG与VE之间的结合程度;通过高效液相色谱法测定普通强化乳(添加VE)和复合物强化乳(添加β-LG/VE复合物)中UHT前后的VE含量并计算VE热损失率,以确定β-LG对VE热稳定性的影响。结果表明,β-LG可以通过氢键和疏水相互作用与VE结合形成复合物,β-LG与VE结合后,可以减少VE在水溶液中的聚集,使VE的溶解性增加;生物膜干涉技术也证明β-LG与VE之间存在结合,亲和力常数为7.493×10^(-2) mol/L;复合物强化乳中VE损失率为(4.01±0.18)%,显著低于普通强化乳((10.90±0.17)%)(P<0.05)。以上说明,β-LG可以显著提高VE的热稳定性,为开发维生素强化乳制品提供理论基础。

In order to improve the thermal stability of vitamin E(VE)in ultra-high temperature sterilized(UHT)milk,a complex ofβ-lactoglobulin(β-LG)with VE was prepared.Turbidity,particle size,zeta potential,scanning electron microscopy,sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE),infrared spectroscopy and fluorescence spectroscopy were used to explore whetherβ-LG combined with VE.The degree of binding was further analyzed by bio-layer interferometry.The contents of VE in common fortified milk(with VE)and complex fortified milk(withβ-LG/VE complex)before and after ultra-high temperature sterilization were determined by high performance liquid chromatography(HPLC)and the loss rate of VE was calculated to determine the effect ofβ-LG on the thermal stability of VE.The results showed thatβ-LG combined with VE to form a complex through hydrogen bonds and hydrophobic interaction,and that binding toβ-LG reduced the aggregation of VE in aqueous solution and increased its solubility.Bio-layer interferometry corroborated the binding betweenβ-LG and VE,and the binding constant was 7.493×10^(-2) mol/L.The loss rate of VE in complex fortified milk was significantly lower than that in common fortified milk,(4.01±0.18)%versus(10.90±0.17)%(P<0.05).The above results showed thatβ-LG/VE could effectively improve the thermal stability of VE,which provides a theoretical basis for the development of vitamin fortified dairy products.