The initial characteristics of marine oil emulsions and the composition of the media inflect lipid oxidation during in vitro gastrointestinal digestion.

This work aimed at evaluating the effect of simulated digestive fluids, interface and lipid droplet sizes on the oxidation of oil-in-water emulsions containing long chain n-3 fatty acyls. Emulsions stabilised by a protein or by phosphatidyl-choline/Tween 80 were submitted to gastro-intestinal in vitro conditions in presence of metmyoglobin. The gastric phase was characterised by a decrease of tocopherol amounts and moderate O2 uptake and aldehyde formation. Oxidation developed further during the intestinal phase, with tocopherols tending to zero, oxygen uptake and production of aldehydes at potentially toxic concentrations. The simulated digestive fluids reduced oxygen uptake and MDA formation only during the intestinal step of the phospholipid-stabilised emulsion. Quantitative losses of PUFA (e.g. EPA, DHA) were less than 10% even significant at the end of the digestion.