Oxidative quality and color variation during refrigeration (4 degrees C) of rainbow trout fillets marinated with different natural antioxidants from oregano, quillaia and rosemary

The study aimed at determining the antioxidant effect of natural extracts on the oxidative quality and color variation of rainbow trout fillets during storage at 4 degrees C. The fillets were marinated and samples from the belly flap area and Norwegian quality cuts were used for lipid oxidation determination while the dorsal region was used for color measurements. The fillets were marinated with the different treatments: 470 mg l(-1) of oregano extract, 6.84 ml l(-1) of quillaia extract, 7.2 ml l(-1) of rosemary extract and 2 ml l(-1) of a synthetic antioxidant. Maximum TBARS (Thiobarbituric acid reactive substances) values of belly flap and Norwegian quality cuts occurred at five and six days of storage, respectively. The susceptibility of treatments to lipid oxidation in decreasing order was: control>quillaia >oregano>rosemary>synthetic antioxidant. An increase in lightness (L*) and redness (a*) were observed for rosemary and quillaia extracts when compared to control samples. Marinates with natural antioxidants may be an alternative for extending shelf-life of trout fillets at least during the first six days of storage at 4 degrees C.