Drapala Kamil P, Auty Mark A E, Mulvihill Daniel M, O'Mahony James A
School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
Food Chemistry and Technology Department, Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
Food Res Int. 2016 Oct;88(Pt A):42-51. doi: 10.1016/j.foodres.2016.01.028. Epub 2016 Feb 1.
Whey protein hydrolysate (WPH) ingredients are commonly used in the manufacture of partially-hydrolysed infant formulae. The heat stability of these emulsion-based formulae is often poor, compared with those made using intact whey protein. The objective of this study was to improve the heat stability of WPH-based emulsions by conjugation of WPH with maltodextrin (MD) through wet heating. Emulsions stabilised by different protein ingredients, whey protein isolate (WPI), whey protein hydrolysate (WPH), heated WPH (WPH-H), and WPH conjugated with MD (WPH-C) were prepared and heat treated at 75°C, 95°C or 100°C for 15min. Changes in viscosity, fat globule size distribution (FGSD) and microstructure, evaluated using confocal laser scanning microscopy (CLSM), were used to monitor the effects of hydrolysis, pre-heating and conjugation on the heat stability of the emulsions. Heat stability increased in the order WPH<WPI<<WPH-H<<<WPH-C; emulsions WPH, WPI and WPH-H destabilised on heating at 75°C, 95°C or 100°C, respectively. Flocculation and coalescence of oil droplets were mediated by protein aggregation (as evidenced by CLSM) on heat treatment of WPH-H emulsion at 100°C, while no changes in FGSD or microstructure were observed in WPH-C emulsion on heat treatment at 100°C, demonstrating the excellent thermal stability of emulsions prepared with the conjugated WPH ingredient, due principally to increased steric stabilisation as a result of conjugation.
乳清蛋白水解物（WPH）成分常用于生产部分水解婴儿配方奶粉。与使用完整乳清蛋白制成的配方奶粉相比，这些基于乳液的配方奶粉的热稳定性通常较差。本研究的目的是通过湿加热使WPH与麦芽糊精（MD）共轭，以提高基于WPH的乳液的热稳定性。制备了由不同蛋白质成分稳定的乳液，即乳清蛋白分离物（WPI）、乳清蛋白水解物（WPH）、加热的WPH（WPH-H）和与MD共轭的WPH（WPH-C），并在75°C、95°C或100°C下热处理15分钟。使用共聚焦激光扫描显微镜（CLSM）评估粘度、脂肪球大小分布（FGSD）和微观结构的变化，以监测水解、预热和共轭对乳液热稳定性的影响。热稳定性按WPH<WPI<<WPH-H<<<WPH-C的顺序增加；乳液WPH、WPI和WPH-H分别在75°C、95°C或100°C加热时不稳定。在100°C对WPH-H乳液进行热处理时，油滴的絮凝和聚结是由蛋白质聚集介导的（CLSM证明），而在100°C对WPH-C乳液进行热处理时，未观察到FGSD或微观结构的变化，这表明用共轭WPH成分制备的乳液具有优异的热稳定性，这主要是由于共轭导致空间位阻稳定增加。
