The impact of heating-induced lactosylation on the digestibility of lactotransferrin

Lactosylation of lysines occurs during the heating of dairy products, yet how lactosylation impact the lysine release during digestion remains largely unknown. This study examines the effect of lactosylation on the digestibility of lactotransferrin using chemical analysis, proteomics, and peptidomics. Under the applied heating conditions, lactotransferrin primarily undergoes early-stage Maillard reactions, producing lactulose-lysine. Furosine content increases with heating time and temperature, with time being more influential. And 23 out of 54 lysines in lactotransferrin were lactosylated. Following in-vitro infant digestion, free lysine levels in samples heated at 130 °C for 30s decreased by 25 % compared to unheated ones, likely due to lactosylation hindering protease cleavage. Intriguingly, lactosylated lysine was absent in peptides ranging from 5 to 17 amino acids but remained in larger peptides. The formation of large lactosylated peptides from heating impeded free lysine release. Further investigation is needed to determine if the human body can utilize these lactosylated peptides. •Time plays more important role than temperature inducing lactosylation of LTF•23 of 54 lysines in LTF were prone to be lactosylated during heating•Lactosylation blocked the release of lysine during in vitro infant digestion of LTF•Lactosylation blocked lysine into peptides larger than 17 amino acids after digestion