Department of Food Science, University of Guelph, Guelph, Ontario N1G2W1, Canada.
Department of Food Science, University of Guelph, Guelph, Ontario N1G2W1, Canada; iFOOD Center for Innovative Food, Department of Food Science Aarhus University, Blichers Alle, 20, Postboks 50, 8830 Tjele, Denmark.
Food Chem. 2020 Jun 30;316:126199. doi: 10.1016/j.foodchem.2020.126199. Epub 2020 Jan 11.
The aggregation of a mixed suspension of native and pre-acidified casein micelles was observed using rheology. Pre-acidified micelles were prepared by addition of glucono-delta-lactone, once pH of 6 or 5.5 was reached, the suspension was concentrated and added to untreated skim milk. Gelation was followed by addition of chymosin, for mixes before or after re-equilibration to the original milk pH. When pre-concentrated micelles were acidified, an earlier gelation point was shown, as well as a higher elastic modulus, compared to control suspensions. When skim milk containing pre-acidified micelles was re-equilibrated to the original pH no gelation was observed after addition of chymosin, in spite of very similar levels of diffusible calcium and phosphate concentration to those of the original milk. It was concluded that it may be possible to fine tune the rheological properties of the final chymosin induced gel network, by pretreating only a portion of the casein micelles, and modifying their colloidal calcium phosphate and the ratio of soluble to micellar casein.
使用流变学观察了天然和预酸化酪蛋白胶束的混合悬浮液的聚集。通过添加葡萄糖酸-δ-内酯，在 pH 达到 6 或 5.5 后，将悬浮液浓缩并添加到未经处理的脱脂乳中。在添加皱胃蛋白酶之前或之后，将混合物重新平衡至原始牛奶 pH 值，以进行胶凝。与对照悬浮液相比，当预浓缩的胶束酸化时，显示出更早的胶凝点和更高的弹性模量。当含有预酸化胶束的脱脂乳重新平衡至原始 pH 值时，尽管可扩散钙和磷酸盐浓度与原始牛奶非常相似，但在添加皱胃蛋白酶后不会发生凝胶化。因此，可以通过仅预处理一部分酪蛋白胶束并改变其胶体磷酸钙和可溶性酪蛋白与胶束酪蛋白的比例，来精细调整最终皱胃蛋白酶诱导的凝胶网络的流变性质。
