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Published on: December 16, 2015
Milk serum peptidomics revealed the age gelation of direct UHT milk
Tai Zhang1, Yisuo Liu1, Jiayuan Cao2
1College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong Province, China; Food Laboratory of Zhongyuan, Luohe 462300, Henan, China.
Abstract:
Age gelation is undesirable for direct UHT (dUHT) milk, which is closely related to protein hydrolysis. However, little information is available for the role of serum peptides during the age gelation. In this study, the composition and protein morphology of serum phase were characterized by RP-HPLC, ICP-MS and TEM. The results showed significant increases in soluble proteins, free amino acids, calcium, and phosphorus from casein micelles, indicating protein hydrolysis and peptide release into the serum phase. 23,466 peptides derived from caseins and other proteins were identified in serum phase by peptidomics. The serum peptide profiles of age gelation milk changed dramatically. Peptide fingerprinting revealed that plasmin and cathepsin contributed to the protein hydrolysis during age gelation, with a significant increase in their activity observed. 23 characteristic peptides were ultimately selected as potential indicators for age gelation. These findings provide new insights into the age gelation of UHT milk.
