Key Laboratory of Dairy Science (Northeast Agricultural University), Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin 150030, PR China.
National Enterprise Technology Center, Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, PR China.
Food Res Int. 2024 Sep;192:114764. doi: 10.1016/j.foodres.2024.114764. Epub 2024 Jul 14.
Protein emulsion gels, as potential novel application ingredients in the food industry, are very unstable in their formation. However, the incorporation of sour substances (phosphoric acid, lactic acid, acetic acid, malic acid, glutamic acid, tartaric acid and citric acid) would potentially contribute to the stable formation of whey protein isolate (WPI) emulsion as well as its gel. Thus, in this work, physical stability of seven acid-treated WPI emulsions, and microstructures, rheological properties, water distribution of its emulsion gels were characterized and compared. Initially, the absolute zeta-potential, interfacial protein adsorption, and emulsifying characteristics of acid-induced WPI emulsions were higher in contrast to acid-untreated WPI emulsions. Moreover, acid-induced WPI emulsions were thermally induced (95 ℃, 30 min) to form its emulsion gel networks via disulfide bonds as the main force (acid-untreated WPI emulsions were unable to form gels). High-resolution microscopic observation revealed that acid-induced WPI in emulsion gel network showed the morphology of aggregates. Dynamic oscillatory rheology results indicated that acid-induced emulsion gel exhibited highly elastic behavior and its viscoelasticity was associated with the generation of protein gel networks and aggregates. In addition, PCA and heatmap results further illustrated that malic acid-induced WPI emulsion gels had the best water holding capacity and gel characteristics. Therefore, this study could provide an effective way for the foodstuffs industry to open up new texture and healthy emulsion gels as fat replaces and loading systems of bioactive substances.
蛋白质乳液凝胶作为食品工业中具有潜在新颖应用的成分，其形成非常不稳定。然而，酸性物质（磷酸、乳酸、醋酸、苹果酸、谷氨酸、酒石酸和柠檬酸）的加入可能有助于稳定乳清分离蛋白（WPI）乳液及其凝胶的形成。因此，在这项工作中，我们对七种酸处理的 WPI 乳液的物理稳定性、微观结构、流变特性和乳液凝胶的水分分布进行了表征和比较。首先，与未经酸处理的 WPI 乳液相比，酸处理的 WPI 乳液的绝对zeta 电位、界面蛋白吸附和乳化特性更高。此外，酸处理的 WPI 乳液通过二硫键（未经酸处理的 WPI 乳液无法形成凝胶）作为主要作用力被热诱导（95℃，30 min）形成其乳液凝胶网络。高分辨率显微镜观察表明，酸处理的 WPI 在乳液凝胶网络中呈现聚集物的形态。动态振荡流变学结果表明，酸处理的乳液凝胶表现出高度弹性行为，其粘弹性与蛋白质凝胶网络和聚集物的产生有关。此外，PCA 和热图结果进一步表明，苹果酸诱导的 WPI 乳液凝胶具有最佳的持水能力和凝胶特性。因此，本研究为食品工业提供了一种有效的方法，可以开发新的质地和健康的乳液凝胶，作为脂肪替代品和生物活性物质的负载系统。
