热处理对罗非鱼分离蛋白乳液稳定性的影响

Improving the Stability of Tilapia Protein Isolate Emulsion by Heat Treatment

【目的】提高鱼蛋白乳液的稳定性,拓宽其乳化应用领域。【方法】以罗非鱼分离蛋白(tilapia protein isolate,TPI)作为乳化剂,高压均质制备O/W型TPI乳液,考察热处理(60、70、80、90℃,30 min)对乳液电位、黏度、粒径、乳析指数和微观结构的影响,探讨热处理对乳液稳定性的改善及机理。【结果】未经热处理的TPI乳液稳定性较差,4℃条件下贮藏5 d出现分层。经热处理后乳液的平均粒径显著减小(9.16~136.15 nm)(P<0.05),电位绝对值显著增大(4.28~8.60 mV)(P<0.05),4℃贮藏28 d无明显的分层和絮凝现象。不同温度热处理结果比较发现,70℃加热30 min后乳液粒径减小至(507.21±7.98)nm,表面净电荷和黏度最大,液滴形状规则且分布均匀,贮藏28 d未分层。【结论】热处理导致乳液液滴的表面净电荷和体系黏度增大,界面蛋白空间位阻增大不易发生聚集,液滴粒径小且分布均匀,乳液稳定性增加。其中TPI乳液经70℃加热30 min效果最佳,稳定性最佳。

【Objective】To improve the stability of fish protein emulsion and broaden its emulsifying application field.【Methods】The oil-in-water emulsion stabilized by tilapia protein isolate(TPI)was prepared by high pressure homogenization,and the effects of heat treatment(60,70,80,90℃,30 min)on the emulsion potential,viscosity,particle size,creaming index and microstructure were investigated to explore the improvement of emulsion stability and its mechanism.【Results】The TPI emulsion without heat treatment had poor stability and appeared delamination when stored at 4℃for 5 days.After heat treatment,the average particle size of the emulsion was significantly decreased by(9.16-136.15 nm)(P<0.05),and the absolute potential of the emulsion was significantly increased by(4.28-8.60 mV)(P<0.05).There was no obvious delamination and flocculation in the emulsion after 28 days of storage at 4℃.In comparison,after heating at 70℃for 30 min,the particle size of emulsion decreased to(507.21±7.98)nm,the surface net charge and viscosity of emulsion reached the maximum,the droplets were small and evenly distributed,and the emulsion had the best stability.【Conclusion】As a result of heat treatment,the surface net charge and viscosity of the emulsion droplets increased,the steric resistance of the interfacial proteins increased,and it was difficult to aggregate.The particle size of the droplets was small and evenly distributed,and the stability of the emulsion increased.The TPI emulsion heated at 70℃for 30 min had the best stability.