Impact of pasteurisation on the digestion of human milk as simulated in an in vitro dynamic system

Human milk is the ideal food for infant nutrition and optimal growth. This is especially truefor preterm neonates that are preferentially fed donor milk when their own mother milk is notavailable. For sanitary reasons, donor milk is pasteurized. This may have structural andbiochemical consequences on the maternal milk emulsion and affect kinetics of digestion anddisintegration of the emulsion in the digestive tract of the newborns. This has been rarelyinvestigated, thus that was the aim of our study.An in vitro dynamic system was used to simulate the gastric digestion phase of a 1-month oldnewborn [1,2]. A pool of mature human milk (n = 5 donors) was digested as raw orpasteurised (holder pasteurisation: 62.5°C, 30 min), triplicate digestions. Structural changes ofdigested samples were evaluated by confocal microscopy and laser light scattering. Lipolysisand proteolysis were monitored over 120 min. Hydrolysis kinetics were followed by SDSPage,thin-layer and gas chromatography methods, followed by densitometry for semiquantitativeestimations.Pasteurization impacted the emulsion structure by increasing the protein susceptibility to acidaggregation especially on the milk fat globule membrane. Structure of fat globule wasmaintained during gastric digestion mainly in pasteurised human milk. Lipids were digestedfaster in raw than in pasteurised milk. In the end of the gastric phase, less triglycerids andmore free fatty acids were observed for raw milk (p