Identification of the coagulation properties of Chinese Holstein bovine milk : Effects of milk compositions, milk protein polymorphism, and phosphorylation levels on milk coagulation ability

Milk coagulation ability plays critical roles in cheese production. To assess the effects of milk composition, protein polymorphisms, and phosphorylation levels on milk coagulation properties, milk samples were collected from 3625 Chinese Holstein cows and milk was pooled based on their coagulation properties. The results showed that good coagulating milk had shorter rennet coagulation time and higher gel firmness with tighter connections within the formed gel. Multiple factors were observed to differ among milk with different coagulation ability. For example, lower milk pH, higher amounts of proteins and casein, were related to good coagulation properties. The salt distributions also influenced milk coagulation ability. Especially the calcium content has a large influence on milk coagulation. This may be due to its influence on the aggregation of paracasein micelles in the secondary phase of rennet coagulation. Protein polymorphisms and phosphorylation degrees were found being higher in non-coagulating milk. The proteomics results showed that lower amounts of αS1-casein may result in non-coagulation. Differences of milk fat globule membrane proteins were also observed among milk samples with different coagulation ability, possibly being related to milk protein and fat synthesis, in turn influencing the coagulation process. In addition, Ser76 of αS2-CN was found being highly phosphorylated in non-coagulating milk which may be related to its binding with other caseins during the second phase of rennet coagulation. Of these factors, salt distribution, mainly calcium and magnesium, may be the most important factor affecting casein structures and thereby milk coagulation. Importantly, these factors can affect each other while forming the cheese matrix, resulting in a complex relation with milk coagulation.

Bibliographic Details

Main Authors:	Zhang, Wenyuan, Zheng, Sifan, Gao, Peng, Ren, Qing, Zhang, Yumeng, Chen, Baorong, Hettinga, Kasper, Pang, Xiaoyang, Lv, Jiaping, Zhang, Shuwen
Format:	Article/Letter to editor biblioteca
Language:	English
Subjects:	Bovine milk, Coagulation properties, Phosphorylation, Polymorphism, Proteomics,
Online Access:	https://research.wur.nl/en/publications/identification-of-the-coagulation-properties-of-chinese-holstein-
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