專討摘要

The study aimed to investigate how different stages of commercial dairy processing affect whey protein composition and bioactivity, with particular emphasis on the effects of high-temperature, short-time (HTST) pasteurization of milk and whey on protein retention and bioactive protein characteristics. Three distinct batches of raw milk (RM), pasteurized milk (PM), resulting whey (RW), and pasteurized whey (PW) were collected from a commercial-scale cheese manufacturing process. PM and PW were pasteurized at 72°C for 16 s. Protein solubility at pH 4.6 and surface hydrophobicity were evaluated, while SDS-PAGE was used to examine protein profiles. Enzyme-linked immunosorbent assays (ELISA) were performed to determine the retention of lactoferrin (LF), IgG, IgA, and IgM. Xanthine dehydrogenase/oxidase (XDO/XO) activity was also measured. In addition, LC-MS/MS-based proteomics was used to identify and quantify proteins and evaluate changes in protein abundance across the processing stages. Protein solubility decreased significantly from RM to PM and from RW to PW, whereas no significant differences in surface hydrophobicity were observed. The retention of LF, IgA, and IgM decreased after HTST pasteurization of RM and RW, while IgG retention remained relatively stable. XDO/XO activity also decreased following pasteurization. Proteomic analysis revealed a decrease in the performance of LF, milk fat globular membrane proteins, and fatty acid binding protein from RM to PM and RW to PW, whereas the relative distribution of some thermo-stable proteins increased. The results demonstrate that protein composition of milk and whey changes throughout the HTST pasteurization and commercial-scale cheesemaking process. Although major whey proteins such as β-lactoglobulin and α-lactalbumin showed relatively stable profiles, several bioactive proteins and enzyme activities were reduced after processing. These findings indicate that different processing stages, particularly HTST pasteurization, can influence the retention of whey proteins and should therefore be considered when evaluating the quality of whey protein products.