Ahmadi Elaheh, Vasiljevic Todor, Huppertz Thom
Advanced Food Systems Research Unit, Institute for Sustainable Industries and Liveable Cities, College of Health and Biomedicine, Victoria University, Melbourne 8001, Australia.
FrieslandCampina, 3818LE Amersfoort, The Netherlands.
Foods. 2024 May 31;13(11):1724. doi: 10.3390/foods13111724.
Micellar calcium phosphate (MCP) plays an important role in maintaining the structure and stability of the casein micelle and its properties during processing. The objective of this study was to investigate how heating (10 min at 80 or 90 °C) at different pH levels (6.3, 6.6, 6.9, or 7.2) impacted the acid-induced gelation of MCP-adjusted milk, containing 67 (MCP), 100 (MCP), or 113 (MCP) % of the original MCP content. The unheated sample MCP at pH 6.6 was considered the control. pH acidification to pH 4.5 at 30 °C was achieved with glucono delta-lactone while monitoring viscoelastic behaviour by small-amplitude oscillatory rheology. The partitioning of calcium and proteins between colloidal and soluble phases was also examined. In MCP-depleted skim milk samples, the concentrations of non-sedimentable caseins and whey proteins were higher compared to the control and MCP-enriched skim milk samples. The influence of MCP adjustment on gelation was dependent on pH. Acid gels from sample MCP exhibited the highest storage modulus (G'). At other pH levels, MCP resulted in the greatest G'. The pH of MCP-adjusted skim milk also impacted the gel properties after heating. Overall, this study highlights the substantial impact of MCP content on the acid gelation of milk, with a pronounced dependency of the MCP adjustment effect on pH variations.
胶束磷酸钙（MCP）在维持酪蛋白胶束的结构和稳定性及其加工过程中的特性方面起着重要作用。本研究的目的是调查在不同pH值（6.3、6.6、6.9或7.2）下加热（80或90°C加热10分钟）如何影响含有原始MCP含量67%（MCP）、100%（MCP）或113%（MCP）的MCP调节牛奶的酸诱导凝胶化。pH值为6.6的未加热样品MCP被视为对照。使用葡萄糖酸δ内酯在30°C下将pH值酸化至4.5，同时通过小振幅振荡流变学监测粘弹性行为。还研究了钙和蛋白质在胶体相和可溶相之间的分配。在MCP耗尽的脱脂牛奶样品中，与对照和MCP富集的脱脂牛奶样品相比，不可沉淀酪蛋白和乳清蛋白的浓度更高。MCP调节对凝胶化的影响取决于pH值。来自样品MCP的酸性凝胶表现出最高的储能模量（G'）。在其他pH值水平下，MCP导致最大的G'。MCP调节的脱脂牛奶的pH值在加热后也会影响凝胶特性。总体而言，本研究突出了MCP含量对牛奶酸凝胶化的重大影响，MCP调节效果对pH值变化有明显依赖性。
