Use of heated milk protein–sugar blends as antioxidant in dairy beverages enriched with linseed oil

Antioxidant preparations were obtained by heating aqueous dispersions of milk protein and sugars at 110 °C for 10 min. The milk protein–sugar blends contained 3.5 g/100 g protein and 10 g/100 mL sugar (with various proportions of lactose, sucrose and their monosaccharide mixtures glucose/galactose and glucose/fructose). These preparations were added at low concentration (5 mL/100 mL) to the formulation of sterilized dairy beverages containing ω-3 polyunsaturated fatty acids. Dairy beverages were also formulated with non heated protein–sugar blends. The total color difference and hydroxymethylfurfural content in dairy beverages increased (P < 0.01) with increasing monosaccharide concentration in the antioxidant preparation. These effects were more important when the protein–sugar blends were pre-heated. Non heated protein–sugar blends did not reduce lipid oxidation during sterilization while pre-heated blends containing monosaccharides were the most effective. Hexanal and propanal concentrations after sterilization were respectively reduced by 100 and 78% when the final concentration of monosaccharides in dairy beverages reached 0.4 g/100 mL. Adding a small fraction of milk protein as pre-heated protein–sugar blend in functional dairy beverage formulations is a promising approach to prevent the oxidation of ω-3 polyunsaturated fatty acids during sterilization treatment.