Chandrapala Jayani, Bui Don, Kentish Sandra, Ashokkumar Muthupandian
Advanced Food Systems Research Unit, College of Health and Biomedicine, Victoria University, VIC 3030, Australia.
School of Chemistry/Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
J Dairy Res. 2014 May;81(2):238-44. doi: 10.1017/S0022029914000132. Epub 2014 Apr 3.
The aggregation of proteins after heating of calcium-fortified milks has been an ongoing problem in the dairy industry. This undesirable effect restricts the manufacture of calcium rich dairy products. To overcome this problem, a completely new approach in controlling the heat stability of dairy protein solutions, developed in our lab, has been employed. In this approach, high intensity, low frequency ultrasound is applied for a very short duration after a pre-heating step at ⩾70 °C. The ultrasound breaks apart whey/whey and whey/casein aggregates through the process of acoustic cavitation. Protein aggregates do not reform on subsequent post-heating, thereby making the systems heat stable. In this paper, the acid gelation properties of ultrasonicated calcium-enriched skim milks have also been investigated. It is shown that ultrasonication alone does not change the gelation properties significantly whereas a sequence of preheating (72 °C/1 min) followed by ultrasonication leads to decreased gelation times, decreased gel syneresis and increased skim milk viscosity in comparison to heating alone. Overall, ultrasonication has the potential to provide calcium-fortified dairy products with increased heat stability. However, enhanced gelation properties can only be achieved when ultrasonication is completed in conjunction with heating.
在乳制品行业，钙强化牛奶加热后蛋白质聚集一直是个长期存在的问题。这种不良影响限制了富含钙的乳制品的生产。为克服这一问题，我们实验室开发了一种全新的控制乳制品蛋白溶液热稳定性的方法。在该方法中，在⩾70°C的预热步骤之后，以非常短的持续时间施加高强度、低频超声。超声通过声空化过程使乳清/乳清以及乳清/酪蛋白聚集体分解。蛋白质聚集体在随后的后加热过程中不会重新形成，从而使体系具有热稳定性。在本文中，还研究了超声处理的富钙脱脂牛奶的酸凝胶化特性。结果表明，单独超声处理不会显著改变凝胶化特性，而与单独加热相比，先预热（72°C/1分钟）再超声处理会导致凝胶化时间缩短、凝胶收缩减少以及脱脂牛奶粘度增加。总体而言，超声处理有潜力为钙强化乳制品提供更高的热稳定性。然而，只有在超声处理与加热结合完成时才能实现增强的凝胶化特性。
