EFFECT OF PACKING MEDIA ON THE OXIDATION OF CANNED TUNA LIPIDS - ANTIOXIDANT EFFECTIVENESS OF EXTRA VIRGIN OLIVE OIL

The effectiveness of packing media differing in the content of natural antioxidants has been tested on Lipid oxidation occurring during tuna canning. Extra virgin olive oil, having a high content in natural pol yphenols, and other filling media lacking phenols (refined olive oil, refined soybean oil, and brine) were selected. The three oils also sho wed different quantities of tocopherols, the highest amount being dete cted in refined soybean ail. Different rates of oxidation were observe d among the four media after thermal processing and storage of tuna ca ns; extra virgin olive oil showed a potential antioxidant activity on fish lipids. The verified antioxidant ability may be attributed to the solubilization of hydrophilic phenols into the water-muscle interface . The phenolic composition from extra virgin olive oil studied by reve rsed-phase HPLC showed a marked change after fish processing, thus sug gesting phenol decompositions and strong interactions between oil phen ols and fish muscle components. The aqueous environment built by brine made fish lipids more prone to oxidation, presumably due to the accum ulation of unsaturated fatty acids at the ail-water interface.