The impact of alternative dietary lipids on the in vitro bioaccessibility of sole fillets for human consumption

Abstract

The fatty acid profile of farmed Senegalese sole (Solea senegalensis) fed three different diets (control with fish oil - CTL; 50% replacement by vegetable oil – D50; 100% vegetable oil replacement – D100) was determined and the bioaccessibility of fatty acids (FA) in these fish was determined using a human in vitro digestibility model. The effect of the different diets on the FA profile of sole as well as on the bioaccessibility of each FA in human—taking into account the digestive action upon different lipid classes, such as triacylglycerols (TAG) — was studied. The relative FA profile varied as a function of fish diet ingredients with a progressive decline of the ω3/ω6 ratio with growing replacement of fish oil by vegetable oil. Regarding FA bioaccessibility in human, differences between total ω3 polyunsaturated fatty acids (ω3 PUFA) (58–70%) and total ω6 PUFA (34–55%) were statistically significant in CTL and D50 sole groups. But, for D100 sole, the bioaccessibility of ω3 PUFA was not higher than that of ω6 PUFA. The bioaccessibility of each ω3-PUFA varied widely between 36 and 74%, depending on the particular FA and the diet fed to the farmed sole. Strong evidence supporting a predominantly regioselective action of lipase during in vitro digestion was observed and the FA hydrolysis of docosahexaenoic, myristic, and palmitic acids was found less complete, which correlates with their higher binding frequency at the 2-position (sn-2) of TAGs in fish. It was shown that full, but not partial, dietary replacement of fish oil by vegetable oil was detrimental not only to ω3/ω6 ratio in the Senegalese sole muscle, but also to the FA bioaccessibility (after digestion) of saturated fatty acids (including palmitic acid), oleic, eicosapentaenoic, and docosapentaenoic acids. But a partial (50%) replacement of fish oil by vegetable oils may ensure Senegalese sole fillet nutritional quality for human consumption. © 2017