Impact of HTST pasteurization of human milk on the kinetic of digestion of macronutrients after in vitro dynamic digestion

Donor human milk (DHM) represents the best alternative when mother’s own milk is not available,a common occurrence in Neonatal Intensive Care Units. Heat treatment of DHM is mandatory forsafety reasons. Holder pasteurization (HoP, 62.5°C-30’) is recommended by all human milk bankguidelines. Recent studies have demonstrated that HoP affects the digestion profile and behavior ofseveral human milk components. High Temperature-Short Time pasteurization (HTST, 71°C-15’’)is currently under evaluation as a promising alternative technology to limit the denaturation of somebiological compounds of raw human milk.ObjectiveThe aim of the present work was to assess whether the different types of pasteurization (HoP,HTST) impacted the digestive kinetics of human milk during in vitro dynamic digestion.MethodologyPooled raw HM (RHM) was collected and processed by using the two pasteurization techniques.The pasteurized samples and RHM were digested in vitro using preterm gastrointestinal conditions.Samples were collected at different digestion times. Undigested and digested milks samples werecharacterized for their particle size distribution (PSD), triglyceride content, protein and amino acid(AA) profiles.Main findingsDuring gastric digestion, both pasteurization methods modified PSD, as compared to RHM. Caseinswere rapidly hydrolyzed in the gastric phase unlike that for the whey proteins. Lactoferrin was hydrolyzedfaster in the pasteurized samples in comparison to RHM, in which lactoferrin was resistantto gastro-intestinal digestion. Heat-treatments, consequently, affected the intestinal release of someAA, and a higher bioaccessibility of AA was found for HTST, as compared to HoP. Concerning lipolysis,at any time of the intestinal digestion phase, the lipolysis of HoP samples was significantlylower (p < 0.05) than in both RHM and HTST samples.ConclusionThis work provides the first evidences about the differential impact of HoP and HTST pasteurizationtechniques on bioaccessibility of DHM nutrients and biological compounds, for preterm newborns.