Key Laboratory of Meat Processing and Quality Control, Ministry of Education China, College of Food Science and Technology , Nanjing Agricultural University , Nanjing 210095 , China.
Department of Food Science and Technology , University of Nebraska-Lincoln , 1901 21st Street , Lincoln , Nebraska 68588 , United States.
Langmuir. 2018 Jul 31;34(30):8848-8856. doi: 10.1021/acs.langmuir.8b01279. Epub 2018 Jul 19.
Protein conformational rearrangement triggered by adsorption to the hydrophobic interface of oil droplets has long been considered as a key factor in emulsification. In this study, an alkaline pH-shifting-driven conformational adaptation enhanced interfacial proteins was used to improve their stability against heat-induced flocculation of myosin emulsions. We used the unfolded myosin at pH 12 to emulsify soy oil and then readjusted the pH of the emulsion to neutral. The corresponding myosin emulsion (0.5% w/v protein, 10% v/v soy oil, and 0.6 M NaCl) almost not flocculated when heated at 75 °C for 30 min. Moreover, after thermal treatment, the particle size of the emulsion was not significantly increased ( P > 0.05) and the emulsion did not exhibit a creaming phenomenon after a week. Based on the circular dichroism and Fourier transform infrared analysis, we speculated the superiority of the emulsion is closely related to the alkaline pH-shifting-driven conformational adaptation enhanced interfacial protein. Additionally, the resulting steric stabilization in overcoming the attractive hydrophobic forces between denatured protein molecules coated droplets might be the main factor for the inhibition of heat-induced flocculation of the emulsion. Our research may have important implications for the formulation of protein-stabilized oil-in-water emulsions.
蛋白质构象重排触发吸附到油滴的疏水界面长期以来一直被认为是乳化的关键因素。在这项研究中，利用碱性 pH 转换驱动构象适应增强界面蛋白来提高其对肌球蛋白乳液热诱导聚沉的稳定性。我们使用在 pH 12 下展开的肌球蛋白来乳化大豆油，然后将乳液的 pH 调整回中性。相应的肌球蛋白乳液（0.5% w/v 蛋白质，10% v/v 大豆油和 0.6 M NaCl）在 75°C 加热 30 分钟时几乎不聚沉。此外，经过热处理后，乳液的粒径没有明显增加（P＞0.05），并且乳液在一周后没有出现分层现象。基于圆二色性和傅里叶变换红外分析，我们推测乳液的优越性与碱性 pH 转换驱动构象适应增强界面蛋白密切相关。此外，克服变性蛋白质分子涂覆的液滴之间的吸引力疏水力的所得空间稳定化可能是抑制乳液热诱导聚沉的主要因素。我们的研究可能对蛋白质稳定的水包油乳液的配方具有重要意义。
