Effects of rosemary and green tea extracts on frozen surimi gels fortified with omega-3 fatty acids

Two different sources of omega-3 fatty acids (fish oil concentrate and menhaden oil) with or without the addition of natural antioxidants (rosemary and green tea) were incorporated into surimi gels at equivalent levels and examined for changes in sensory and physical properties and resistance to oxidation during 9 months of frozen storage. Gels with menhaden oil showed higher acceptance than gels with fish oil concentrate, which displayed a fishy taste that was partially masked by natural antioxidants. Formation of volatile compounds was similar in all samples. Upon heating to form the gel, there was a ca 20-25% decrease in the relative polyene index of the control containing no rosemary or green tea extract. Formulations with menhaden oil containing green tea and rosemary were more stable immediately after cooking; however, a slight pro-oxidant effect occurred during storage. Omega-3 fortified gels were whiter than gels with no added oil. Rosemary and green tea extracts increased yellowness (b*) and redness (a*), respectively. Strength increased in all formulations during frozen storage.