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

Samira de Oliveira (1) , Claire Bourlieu-Lacanal (1) , Olivia Ménard (1) , Amandine Bellanger (1, 2) , Florence Rousseau (1) , V. Le Bail (3) , P. Pladys (2) , F. Carrière (4) , Didier Dupont (1) , Amélie Deglaire (1)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 Service de Pédiatrie
3 Lactarium, Unité de Nutrition et Diététique Infantile
4 EIPL - Enzymologie interfaciale et de physiologie de la lipolyse

Human milk is the ideal food for infant nutrition and optimal growth. This is especially true for preterm neonates that are preferentially fed donor milk when their own mother milk is not available. For sanitary reasons, donor milk is pasteurized. This may have structural and biochemical consequences on the maternal milk emulsion and affect kinetics of digestion and disintegration of the emulsion in the digestive tract of the newborns. This has been rarely investigated, 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 old newborn [1,2]. A pool of mature human milk (n = 5 donors) was digested as raw or pasteurised (holder pasteurisation: 62.5°C, 30 min), triplicate digestions. Structural changes of digested samples were evaluated by confocal microscopy and laser light scattering. Lipolysis and proteolysis were monitored over 120 min. Hydrolysis kinetics were followed by SDSPage, thin-layer and gas chromatography methods, followed by densitometry for semiquantitative estimations. Pasteurization impacted the emulsion structure by increasing the protein susceptibility to acid aggregation especially on the milk fat globule membrane. Structure of fat globule was maintained during gastric digestion mainly in pasteurised human milk. Lipids were digested faster in raw than in pasteurised milk. In the end of the gastric phase, less triglycerids and more free fatty acids were observed for raw milk (p<0.001). At 120 min of digestion, similar levels of global proteins were observed. However, we observed a faster hydrolysis of casein-β in raw milk and of lactoferrin in pasteurized milk. These results demonstrate that holder pasteurisation of human milk modifies its digestive kinetics in the gastric phase, as simulated in an in vitro dynamic system. The physiologic and metabolic impacts remain unknown, especially in newborns exclusively fed pasteurized milk.

Mots clés: proéine du lait; caséine; phase gastrique; lait humain; traitement thermique; pasteurisation; digestion in vitro; santé

Domaines: Ingénierie des aliments; Alimentation et Nutrition

Samira de Oliveira, Claire Bourlieu-Lacanal, Olivia Ménard, Amandine Bellanger, Florence Rousseau, et al.. Impact of pasteurisation on the digestion of human milk as simulated in an in vitro dynamic system. 12. Eurofed Lipid Congress, Sep 2014, Montpellier, France. 2014. ⟨hal-01209729⟩