School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
J Dairy Res. 2013 Nov;80(4):418-28. doi: 10.1017/S0022029913000502. Epub 2013 Oct 15.
The total calcium content of cheese, along with changes in the equilibrium between soluble and casein (CN)-bound calcium during ripening can have a major impact on its rheological, functional and textural properties; however, little is known about the effect of other alkaline earth metals. NaCl was partially substituted with MgCl2 or SrCl2 (8·7 and 11·4 g/kg curd, respectively) at the salting stage of cheesemaking to study their effects on cheese. Three cheeses were produced: Mg supplemented (+Mg), Sr supplemented (+Sr) and a control Cheddar cheese. Ca, Mg and Sr contents of cheese and expressible serum obtained therefrom were determined by atomic absorption spectroscopy. Addition of Mg2+ or Sr2+ had no effect on % moisture, protein, fat and extent of proteolysis. A proportion of the added Mg2+ and Sr2+ became CN-bound. The level of CN-bound Mg was higher in the +Mg cheese than the control throughout ripening. The level of CN-bound Ca and Mg decreased during ripening in all cheeses, as did % CN-bound Sr in the +Sr cheese. The presence of Sr2+ increased % CN-bound Ca and Mg at a number of ripening times. Adding Mg2+ had no effect on % CN-bound Ca. The +Sr cheese exhibited a higher G' at 70 °C and a lower LTmax than the control and +Mg cheeses throughout ripening. The +Sr cheese had significantly lower meltability compared with the control and +Mg cheeses after 2 months of ripening. Hardness values of the +Sr cheese were higher at week 2 than the +Mg and control cheeses. Addition of Mg2+ did not influence the physical properties of cheese. Supplementing cheese with Sr appeared to have effects analogous to those previously reported for increasing Ca content. Sr2+ may form and/or modify nanocluster crosslinks causing an increase in the strength of the para-casein matrix.
奶酪的总钙含量以及在成熟过程中可溶性钙和酪蛋白（CN）结合钙之间平衡的变化会对其流变学、功能性和质地特性产生重大影响；然而，对于其他碱土金属的影响知之甚少。在奶酪制作的加盐阶段，用 MgCl2 或 SrCl2 部分替代 NaCl（分别为凝乳 8.7 和 11.4 g/kg），研究它们对奶酪的影响。生产了三种奶酪：添加 Mg 的（+Mg）、添加 Sr 的（+Sr）和对照切达奶酪。通过原子吸收光谱法测定奶酪及其可提取血清中的 Ca、Mg 和 Sr 含量。添加 Mg2+或 Sr2+对水分、蛋白质、脂肪和蛋白水解度没有影响。一部分添加的 Mg2+和 Sr2+成为 CN 结合。在整个成熟过程中，+Mg 奶酪中的 CN 结合 Mg 水平高于对照奶酪。在所有奶酪中，CN 结合 Ca 和 Mg 的水平在成熟过程中降低，而 +Sr 奶酪中的 CN 结合 Sr 水平在成熟过程中降低。Sr2+的存在增加了许多成熟时间点的 CN 结合 Ca 和 Mg 的百分比。添加 Mg2+对 CN 结合 Ca 的百分比没有影响。与对照和+Mg 奶酪相比，+Sr 奶酪在整个成熟过程中在 70°C 时具有更高的 G'，并且 LTmax 更低。与对照和+Mg 奶酪相比，在成熟 2 个月后，+Sr 奶酪的熔融性显著降低。在第 2 周，+Sr 奶酪的硬度值高于+Mg 和对照奶酪。添加 Mg2+对奶酪的物理性质没有影响。用 Sr 补充奶酪似乎会产生类似于以前报道的增加 Ca 含量的效果。Sr2+可能形成和/或修饰纳米簇交联，从而增加副酪蛋白基质的强度。
