TY - JOUR
T1 - Insight into protein crosslinking and casein polymerization in pre- and posthydrolyzed lactose-free ultra-high-temperature milk during long-term storage
AU - Knudsen, Lotte J.
AU - Rauh, Valentin
AU - Pedersen, Jannik N.
AU - Dekker, Peter
AU - Otzen, Daniel E.
AU - Larsen, Lotte B.
AU - Nielsen, Søren D.H.
N1 - Publisher Copyright:
© 2024 American Dairy Science Association
PY - 2024/12
Y1 - 2024/12
N2 - 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.
AB - 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.
KW - aggregation
KW - dehydroalanine pathway
KW - field-flow fractionation
KW - Maillard reaction
KW - multiple reaction monitoring
UR - http://www.scopus.com/inward/record.url?scp=85210141325&partnerID=8YFLogxK
U2 - 10.3168/jds.2024-25103
DO - 10.3168/jds.2024-25103
M3 - Journal article
C2 - 39265836
SN - 0022-0302
VL - 107
SP - 10497
EP - 10511
JO - Journal of Dairy Science
JF - Journal of Dairy Science
IS - 12
ER -