Colloidal Calcium Phosphate-cross-linkage in Casein Micelles.

人们认识到，胶体磷酸钙（CCP）在牛奶加工（例如加热、冷却和冷冻）中参与了酪蛋白胶束的特性。然而，中国共产党的地位和作用尚未得到充分阐明。本文研究了加热对CCP交联的影响以及CCP交联与冷却时血清酪蛋白释放的关系，证实了在60-90 ℃加热10 min或135-140 ℃加热15-75 sec时，CCP含量增加。在135-140 ℃下加热75秒时，由CCP交联的酪蛋白聚集体的含量在CMD中从51.9%下降到46.1%，在浓缩CMD中从52.5%下降到43.6%，表明CCP交联的断裂。CCP交联的酪蛋白聚集体含量从49.3%提高到68.3%。从酪蛋白胶束中释放的血清酪蛋白的量随着CCP含量的增加而减少。当CCP含量增加到很大程度时，冷却时释放的β-酪蛋白从总酪蛋白的31.8%下降到2.1%，而由CCP交联的β-酪蛋白和未交联且冷却时不释放的β-酪蛋白分别从总β-酪蛋白的46.2%增加到69.9%和从22.0%增加到28.0%。CCP交联的β-酪蛋白的增加以及β-酪蛋白与其他酪蛋白组分之间相互作用的加强被认为是冷却时β-酪蛋白释放减少的原因。

It is recognized that colloidal calcium phosphate (CCP) participates in characteristics of casein micelles in milk processing such as heating, cooling and freezing. However, the state and role of CCP has not yet been elucidated sufficiently. In the present study, the effects of heating on CCP-cross-linkage and the relation between CCP-cross-linkage and the release of serum casein on cooling were examined.It was confirmed that CCP content was increased on heating casein micelle dispersion (CMD) and concentrated CMD at 60-90 ﾟC for 10 min or 135-140ﾟC for 15-75 sec. The content of casein aggregates cross-linked by CCP was decreased from 51.9 to 46.1% in CMD and 52.5 to 43.6% in concentrated CMD on heating at 135-140 C for 75 sec, indicating the cleavage of the CCP-cross-linkage.CCP-increased CMD was prepared by addition of calcium and phosphate. The content of casein aggregates cross-linked by CCP was increased from 49.3 to 68.3%. The amount of serum casein released from casein micelles was decreased with increasing CCP content. When the CCP content was increased to a large extent, beta-casein released on cooling was decreased from 31.8 to 2.1% of the total casein while beta-casein cross-linked by CCP and beta-casein which is not cross-linked and not released on cooling were increased from 46.2 to 69.9% and from 22.0 to 28.0% of the total beta-casein, respectively. The increase in beta-casein cross-linked by CCP and strengthening of interaction between beta-casein and other casein constituents were considered to be reasons for the decrease of beta-casein release on cooling.