Protein-bound and free glycation compounds in human milk: A comparative study with minimally processed infant formula and pasteurized bovine milk

The role of the Maillard reaction and the accumulation of non-enzymatic glycation compounds in human milk have been scarcely considered. In this study, we investigated the proteins most susceptible to glycation, the identity of the corresponding modified residues and the quantitative relationship between protein-bound and free glycation compounds in raw human milk and, for comparison, in minimally processed infant formula and pasteurized bovine milk. In human milk, total protein-bound lysine modifications were up to 10% of the counterparts in infant formula, while Nε-carboxymethyllysine reached up to 27% of the concentration in the other two products. We demonstrated that the concentration of free pyrraline and methylglyoxal-hydroimidazolone were of the same order of magnitude in the three milk types. Our results delineate how the occurrence of some glycation compounds in human milk can be an unavoidable part of the breastfeeding and not an exclusive attribute of infant formulas and pasteurized bovine milk.

his research was funded by: i) EIT FOOD project Minimally-modified AMino Microbiota heALth (MAMMAL) (contract n. 21256); ii) the Italian National Research Council for the project “Nutrizione, Alimentazione ed Invecchiamento Attivo (NUTRAGE)” (FOE 2021-2022); iii) the National Recovery and Resilience Plan, mission 4, component 2, investment 1.3, call n. 341/2022 of Italian Ministry of University and Research funded by the European Union - NextGenerationEU for the project “ON Foods - Research and innovation network on food and nutrition Sustainability, Safety and Security - Working ON Foods”, project PE00000003, concession decree n. 1550/2022, CUP B83C22004790001. MCC and CB acknowledge the support from H2020-ERC Starting Grant 639226, from Spanish Ministry of Science and Innovation (MCIN) research grant (ref. PID2022-139475OB-I00) and Centre of Excellence Accreditation Severo Ochoa to IATA-CSIC (CEX2021-001189-S).

Peer reviewed