Li Quanyang, Zhao Zhengtao
College of Light Industry and Food Engineering, Guangxi University Nanning 530004 China
RSC Adv. 2020 Mar 25;10(20):11883-11891. doi: 10.1039/d0ra00677g. eCollection 2020 Mar 19.
This research investigated the influence of processing history on physicochemical properties of dairy protein-stabilized emulsions. Emulsions were heated (UHT) either before or after a single homogenization (UHTSH, SHUHT) or homogenized both before and after heating (double homogenization, DHUHT). The results demonstrated that UHT treatment increased the protein load at the oil/water interface while homogenization prior to UHT (SHUHT) inhibited displacement of protein by surfactant molecules, and this emulsion exhibited higher interfacial protein coverage and wider size distribution compared to the emulsion produced by UHTSH. The use of the double homogenization with UHT resulted in emulsion droplets with the smallest average size and lowest concentration of unabsorbed protein. However, no difference in the protein load in a specific area was noticed between emulsions produced by DHUHT and SHUHT. When changes of surface tension at the air/water interface were measured using a drop tensiometer, SHUHT emulsion showed the fastest decrease of surface tension due to the occurrence of a lower level of surfactant displacement where more surfactant was available for fast adsorption. Emulsions prepared with DHUHT or UHTSH decreased the surface tension in a slower speed than SHUHT. During storage, partial coalescence of emulsion droplets was observed for emulsions produced with single homogenization, regardless of whether this was carried out before or after heating. Double homogenization formed more stable emulsions than single homogenization. This work clearly showed that it is possible to tailor physico-chemical functionalities of dairy protein-based emulsions by controlling the interactions between proteins or with surfactants during processing.
本研究调查了加工历史对乳蛋白稳定乳液物理化学性质的影响。乳液在单次均质化之前或之后进行加热（超高温瞬时灭菌，UHTSH、SHUHT），或者在加热之前和之后均进行均质化（双重均质化，DHUHT）。结果表明，超高温瞬时灭菌处理增加了油/水界面处的蛋白质负载量，而在超高温瞬时灭菌之前进行均质化（SHUHT）可抑制表面活性剂分子对蛋白质的置换，与UHTHTSHUHTSH所制得的乳液相比，该乳液表现出更高的界面蛋白质覆盖率和更宽的粒径分布。超高温瞬时灭菌与双重均质化相结合的方法可得到平均粒径最小且未吸收蛋白质浓度最低的乳液滴。然而，DHUHT和SHUHT所制得的乳液在特定区域的蛋白质负载量并无差异。使用滴形张力仪测量空气/水界面处的表面张力变化时，SHUHT乳液的表面张力下降最快，这是因为表面活性剂置换水平较低，有更多表面活性剂可用于快速吸附。用DHUHT或UHTSH制备的乳液表面张力下降速度比SHUHT慢。在储存期间，对于单次均质化所制得的乳液，无论均质化是在加热之前还是之后进行，均观察到乳液滴的部分聚并现象。双重均质化形成的乳液比单次均质化形成的乳液更稳定。这项工作清楚地表明，通过在加工过程中控制蛋白质之间或蛋白质与表面活性剂之间的相互作用，可以调整基于乳蛋白的乳液的物理化学功能。
