Insight into protein crosslinking and casein polymerization in pre- and posthydrolyzed lactose-free ultra-high-temperature milk during long-term storage
ABSTRACT: During processing and storage of both conventional and lactose-hydrolyzed UHT milk (LHM), aggregation of milk proteins occurs. Protein aggregation can inter alia occur via nonreducible covalent cross-links derived from either Maillard or dehydroalanine (DHA) pathways. To study this further...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2024-12-01
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| Series: | Journal of Dairy Science |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022030224011251 |
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| Summary: | ABSTRACT: During processing and storage of both conventional and lactose-hydrolyzed UHT milk (LHM), aggregation of milk proteins occurs. Protein aggregation can inter alia occur via nonreducible covalent cross-links derived from either Maillard or dehydroalanine (DHA) pathways. To study this further in relation to processing method and lactase enzyme purity, LHM was produced using 3 different lactase preparations, with lactase enzymes added in a dairy setting either before (prehydrolysis) or after (posthydrolysis) UHT treatment. The prepared LHM types were subsequently stored at either 25°C or 35°C for up to one year. Mass spectrometry was used to absolutely quantify the level of furosine, N-ε-(carboxymethyl)lysine, N-ε-(carboxyethyl)lysine, lanthionine, and lysinoalanine in these products using a newly developed method on triple quadrupole for these processing-induced markers. The results showed higher levels of Maillard-related processing markers in prehydrolyzed LHM compared with posthydrolyzed LHM and conventional UHT milk, which, on the other hand, contained higher concentrations of DHA-derived cross-links. Proteomics of collected particles from asymmetrical flow field-flow fractionation in combination with gel electrophoresis indicated the presence of intramicellar cross-links during storage, especially for larger particles involving αS1- and αS2-caseins. |
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| ISSN: | 0022-0302 |