Incorporation and Interaction of Grape Seed Extract in Membranes and Relation with Efficacy in Muscle Foods

The interaction and location of phenolic antioxidants in model membranes has been related with their effectiveness for inhibiting lipid oxidation of fish mince with the aim to identify mechanisms involved in the antioxidant effectiveness in muscle foods. For such scope, the effect of grape seed extract and its main components, catechin, epicatechin and procyanidin B-2 to be located and induce changes in phospholipid model membranes was studied by different biophysical techniques and related to their antioxidant efficiency. Grape seed extract showed the highest inhibition of oxidation in chilled minced fish muscle. Antioxidant in- vitro capacities were also studied but they did not show a clear relationship with the antioxidant efficiency found in fish muscle. The phospholipid/water partition coefficients and fluorescence quenching studies showed that procyanidin B2 was located in a more internal location than monomeric catechin and epicatechin within the phospholipid palisade. Grape seed extract showed strongest effect compared to its main components in the increase of the lipid order at the DMPC fluid phase by fluorescence anisotropy measurements. Grape seed extract also promoted a dehydration effect in DMPC membranes at the phospholipid/water interface and resistance to solubilization by nonionic detergents in DMPC membranes. The presence of molecular linkages, probably by hydrogen bonding, is proposed between procyanidins (or some galloylated catechins) and the polar head groups of the phospholipids to account for the dehydration effect at the phospholipid/water interface and membrane-stabilizing effects. These effects may be directly related to the higher efficacy of grape seed extract to inhibit lipid oxidation in fish muscle, probably by hindering radical propagation.