The effect of temperature on in vitro digestibility, fat globular size and free fatty acid bio-availability in milk fat.

BACKGROUND The rate at which a particular fat is digested has an effect on its bioavailability and on the lipid profile of the blood. Milk fat is a very complex mixture of triacylglycerols, resulting in a very wide melting range (from –40 to +40°C). Because temperature has a pronounced effect on the physicochemical state of milk fat (i.e. crystallisation of different fat fractions), this study analysed the bioavailability of milk fat at different temperatures. METHODS A simplified model simulating digestion in the intestine at various temperatures was used. The released fatty acids and the changes in the emulsion of milk fat under the effect of lipase were compared. RESULTS The amount and profiles of the released fatty acids varied depending on the incubation temperature of the studied sample. At lower temperatures, the fractions which were hydrolysed to a greater degree were those which contained more unsaturated oleic acid, but contained less C14, C16 and C18 saturated acids. Changes in the emulsion system also differed depending on temperature. CONCLUSIONS The obtained results indicate that, depending on the temperature, not only different amounts, but also different fractions of milk fat were hydrolysed by lipase, which indicates the role of the physico- chemical state of milk fat during its digestion.