Ke Lijing, Xu Yang, Gao Guanzhen, Wang Huiqin, Yu Zhaoshuo, Zhou Jianwu, Rao Pingfan, Wang Qiang, Yu Ji
Food Nutrition Science Centre, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China.
Food Nutrition Science Centre, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China.
Food Res Int. 2020 Jul;133:109169. doi: 10.1016/j.foodres.2020.109169. Epub 2020 Mar 18.
The physicochemical and oxidative stability of oil emulsion has been one of the major challenges in food industry. Factors influencing the emulsion stability have seemingly been exhaustedly elucidated, such as temperature, pH, salts, proteins, polysaccharides and digestive enzymes. Here we report the previously unrecognized influence of catalase on emulsion stability. Submicron oil-in-water fish oil emulsion was prepared by high speed homogenization in the presence of polysorbate 80. Influence of catalase on the emulsion's stability was investigated in comparison with its deactivated version and bovine serum albumin (BSA) by visual examination, turbidity and DLS measurement and TEM observation. Catalase demulsified the emulsion instantly in a concentration-responsive manner at concentrations higher than 0.8 μmol/L, resulting a decreased turbidity, oil flocculation and precipitation of the enzyme itself. Neither BSA nor the thermally inactivated CAT caused demulsification at the same speed, indicating that CAT's demulsification effect was attributed to its enzymatic activity rather than its general protein properties. The enlargement of oil-polysorbate droplets and precipitation of CAT were confirmed by both TEM and DLS. Furthermore, CAT's demulsification effect was found irrelevant of the lipid oxidation. This insight into catalase's influences on emulsion not only sheds lights on food processing and shelf-life, nutritional value and potential biological effects, but also presents an exciting challenge to elucidate the mechanism behind.
油乳液的物理化学稳定性和氧化稳定性一直是食品工业面临的主要挑战之一。影响乳液稳定性的因素似乎已被详尽阐明，如温度、pH值、盐、蛋白质、多糖和消化酶等。在此，我们报告过氧化氢酶对乳液稳定性此前未被认识到的影响。在聚山梨醇酯80存在的情况下，通过高速均质制备亚微米水包油型鱼油乳液。通过目视检查、浊度和动态光散射测量以及透射电子显微镜观察，将过氧化氢酶与其失活形式和牛血清白蛋白（BSA）进行比较，研究过氧化氢酶对乳液稳定性的影响。当浓度高于0.8 μmol/L时，过氧化氢酶以浓度响应方式使乳液立即破乳，导致浊度降低、油絮凝以及酶本身沉淀。BSA和热失活的过氧化氢酶均未以相同速度引起破乳，这表明过氧化氢酶的破乳作用归因于其酶活性而非其一般蛋白质特性。透射电子显微镜和动态光散射均证实了油 - 聚山梨醇酯液滴的增大和过氧化氢酶的沉淀。此外，发现过氧化氢酶的破乳作用与脂质氧化无关。这种对过氧化氢酶对乳液影响的认识不仅为食品加工、保质期、营养价值和潜在生物学效应提供了启示，也为阐明其背后的机制提出了一个令人兴奋的挑战。
