Nutrient release and oxidative stability during in vitro digestion of linseed oil emulsions produced from cow milk, soy drink, and green tea extract

Abstract

The fortification with ω-3 fatty acids is of great interest, but their vulnerability to oxidation can adversely affect the nutritional quality of food. The objective of this study was to emulsify linseed oil in cow milk or soy drink, with or without adding green tea extract, and compare the nutrient release and lipid oxidation during in vitro gastrointestinal digestion. A protein-free emulsion, prepared with Tween 20, was also studied. The soy-based emulsions showed the highest fatty acid release, but exhibited lower proteolysis in comparison with the cow milk emulsions. Emulsions produced with Tween 20 were the most sensitive to oxidation during digestion, while the emulsions prepared in soy drink were more stable than the emulsions prepared in cow milk. The aggregation pattern of oil droplets under gastric conditions was shown to contribute to the emulsion oxidative stability. Green tea extract reduced the oxidative degradation and acted synergistically with cow milk and soy drink to reduce the formation of lipid oxidation products during digestion. This study shows the potential of cow milk and soy drink constituents, combined to green tea, to enhance the oxidative stability during digestion of emulsions rich in ω-3 fatty acids.