A C-13-NMR STUDY OF LIPID ALTERATIONS DURING FISH CANNING - EFFECT OFFILLING MEDIUM

Carbon-13 nuclear magnetic resonance spectroscopy was applied to study the effect of the filling medium on lipid modifications occurring dur ing the industrial canning of tuna (Thunnus alalunga). In the two medi a studied-brine and soybean oil-increases in the free fatty acid level were observed with preferential hydrolysis of polyunsaturated fatty a cids esterified in the sn-2 position of the glycerol moiety. The exten t and mechanism of lipolysis seem to be independent of the filling med ium used. Quantitative results obtained for the main lipid classes sho wed dilution of the natural lipids of muscle by triacylglycerols from the filling medium in oil-filled cans.