Oxidative stability of tuna fat spreads (O/W/O emulsions) using conventional lipid oxidation methods, SPME-GC/MS and sensory analysis

Oxidative analysis of omega-3-enriched fat spreads (oil-in-water-in-oil, O/W/O emulsions) was carried out using conventional lipid oxidation methods (lipid hydroperoxide and p-Anisidine values) and compared with volatile compound analysis using SPME-GC/MS and sensory evaluation. Fat spreads were produced using novel double-emulsion technology. More volatile compounds were detected in tuna oil-enriched spreads (Ross and Smith in Compr Rev Food Sci Food Saf 5:18-25, 2006) than control (no tuna oil) (Lund and Hølmer in Eur Food Res Technol 212:636-642, 2001). As storage time of spreads increased, volatile concentration increased. Conventional lipid oxidation results correlated well with the GC/MS results, as the tuna spread had consistently higher values than the control spread. Lipid hydroperoxides and GC/MS volatile compounds increased with storage time, whereas p-Anisidine values remained level. The control spread achieved the highest score from the sensory panel for odour and flavour acceptability. Flavour of all tuna spreads became unacceptable after 8 weeks. To the authors' knowledge, this is the first study-detecting volatiles using SPME-GC/MS, in omega-3-enriched double-emulsion fat spreads.