Do different techniques of human milk pasteurization impact the kinetics of peptide release during in vitro dynamic digestion?

IntroductionIn order to minimize the denaturation of bioactive compounds, which is known to affect donor humanmilk (HM) after the mandatory heat treatment (Holder pasteurization at 62.5°C, 30min – HoP), anumber of alternative processing techniques are currently being investigated. Recently, High Temperature-Short Time pasteurization (HTST, 72°C-15s) was found to limit the denaturation of somebioactive components of human milk.ObjectiveThe aim of the study was to investigate whether different types of pasteurization (HoP and HTST)may differently affect peptide release from human milk during preterm infant gastrointestinal digestion,by using a dynamic in vitro systemMethodologyPooled raw HM (RHM) from 5 donors was collected and processed in triplicate according to HoP andHTST. The pasteurized milks and RHM were digested in triplicate using a dynamic in vitro digestionsystem, mimicking the preterm physiology conditions. Samples were collected at different digestiontimes. Peptides from undigested and digested samples were analysed using a Q-Exactive massspectrometer and peptide abundance was subjected to multivariate statistics to unravel specificprofile trends.Main findingsPre-proteolysis occurred mostly on β-casein, from which originated more than 82% of the peptidesfound in undigested milk. During digestion, a differential behaviour between gastric and intestinalpeptide release was found by multivariate statistics. In particular, whereas in the gastric phase thepeptide pattern was more similar for HTST and RHM with respect to HoP, the opposite was found atthe beginning of the intestinal phase, while at the end of digestion no difference was found. Thesedifferences were mostly due to peptides released from β-casein, especially in the gastric phase.Some bioactive peptides from bile salt-stimulated lipase, caseins and lactoferrin presented significantlydifferent abundances between the different samples during intestinal digestion.ConclusionThe results indicate possible consequences of the different pasteurizations on the biological activityof donor’s human milk.