Influence of seasonal variation and processing on protein glycation and oxidation in regular and hay milk

• Published in: Food chemistry Vol. 337; p. 127690
• Main Authors: Wölk, Michele, Milkovska-Stamenova, Sanja, Schröter, Theres, Hoffmann, Ralf
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2021
• Subjects: advanced glycation end products; climate; food chemistry; glycation; hay; Hay milk; Maillard reaction; milk; Oxidation; pasteurization; peptides; proteome; Seasonal variation; Thermal processing; UHT treatment; Maillard reaction; Hay milk; Oxidation; Thermal processing; Seasonal variation
• ISSN: 0308-8146; 1873-7072; 1873-7072
• DOI: 10.1016/j.foodchem.2020.127690

•Diverse glycations, AGEs, and oxidations were targeted in regular and hay milk.•Protein modification degrees were similar in regular and hay milk over one year.•Pasteurization and UHT affected both milk types at similar degrees.•Lactosylation increased after processing in particular for UHT treatment.•AGEs and oxidations were not significantly affected by thermal processing. Climate and feeding influence the composition of bovine milk, which is further affected by thermal treatment inducing oxidation and Maillard reactions. This study aimed to evaluate season- and processing-related changes in the modified proteome of milk from two different feeding systems. Therefore, tryptic digests of regular and hay milk were analyzed by targeting 26 non-enzymatic modifications using LC-MS. Forty-five glycated, 48 advanced glycation endproduct (AGE-) modified, and 20 oxidized/carbonylated peptides representing 44 proteins were identified with lactosylation, formyllysine, and carboxymethyllysine being most common. The numbers and quantities of glycation- and oxidation-related modifications were similar between regular and hay milk and among seasons. The effects of pasteurization and ultra-high temperature (UHT) treatment were comparable for both milk types. In particular UHT treatment increased the numbers of identified modifications and the relative quantities of lactosylated peptides. The number of identified AGE-modified and oxidized residues increased slightly after UHT-treatment, but the contents were stable.