The effect of natural antioxidant (Thymus vulgaris Linnaeus) on flesh quality of tuna (Thunnus thynnus (Linnaeus)) during chilled storage

Tuna Thunnus thynnus flesh was treated with dried thyme Thymus vulgaris, vacuum-packed and then stored at 0 °C for 18 days. Proximate composition, thiobarbituric acid reactive substance (TBARS), total volatiles bases, trimethylamine, pH and fatty acids composition were determined throughout the period of storage. No significant differences (p > 0.05) between moisture, ash, protein and lipid were found between lots. The antioxidant effect of thyme was shown by the lower TBARS levels and the unaffected fatty acids composition found in thyme-treaded lot. Significant differences (p < 0.05) were observed in fatty acid profiles of control lot before and after storage, whereas no significant differences were recorded for treated lot in any class of fatty acids after 15 days of storage. In control samples, saturated and monounsaturated fatty acids percents increased from 30.66 to 34.16 and from 20.33 to 21.32 respectively, whereas the polyenes percent decreased from 41.32 to 38.64%.