Effect of essential oils treatment on the frozen storage stability of chub mackerel fillets

The effect of bay leaf (BLO), thyme (TO), rosemary (RO), black seed (BSO), sage (SO), grape seed (GSO), flaxseed (FSO) and lemon (LO) essential oil from vegetable extracted on lipid oxidation and some other quality parameter of frozen chub mackerel during frozen storage at −20°C were examined over a period of 11 months. Taste, odour, texture and overall acceptability of control samples were given ‘unacceptable’ scores by the sixth month. Based primarily on sensory data, the shelf-lives of frozen chub mackerel were found 6 month for samples treated with oil of TO, RO, BSO, SO and LO and 7 month for samples treated with BLO, GSO and FSO. During the 11-months storing process of chub mackerel, the values of pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) both in control group samples and samples treated with oils did not reach to deterioration levels. Thiobarbitüric acid (TBA) and free fatty acid (FFA) values for all treatments remained lower than TBA and FFA values of control samples throughout the 11 month storage period. Particularly, thyme oil treatment is effective in delaying lipid oxidation. Bay leaf, rosemary, sage, lemon, flaxseed and grape seed oils were fallowed.     

Amino Acid and Vitamin Composition of Raw and Cooked Horse Mackerel

Amino acid, vitamin (A, E, B₁, B₂, B₃ and B₆), and proximate composition were determined in raw and cooked horse mackerel. The changes in amino acid, vitamin, and proximate content were found to be significant for all cooking methods (frying, grilling, and steaming). Cooking did in general significantly increase the contents of essential, semi-essential, and other amino acids compared to raw fish species. Amino acid contents of grilled mackerel were significantly higher (p < 0.05) than those found in fried and steamed mackerel. The A, E, B₂, and B₆ vitamin content of fried horse mackerel was found to be significantly (p < 0.05) higher than the grilled and steamed samples. The B₁ content of steamed and B₃ content of grilled were found higher than the other cooked samples. Moisture, protein, fat, ash, and carbohydrate contents of cooked fish ranged between 56.52% to 61.34%, 20.79% and 23.93%, 13.44% and 19.61%, 1.70% and 2.47%, and 1.02% and 4.36 %, respectively. Fried fish had intermediate fat values, while grilled and steamed fishes had a comparatively low value.     

Impacts of natural antioxidants on the fatty acid profiles of vacuum-packaged tuna-like muscles

The impacts of natural preservatives such as olive leaf (Olea europaea L.) and sweet marjoram (Origanum majorana L.) extracts (OLE and SME) and cold storage on the fatty acid profiles of vacuum-packaged tuna-like muscles were evaluated. At the end of the storage time, the lowest content of the total saturated fatty acids (SFA) was observed in both ordinary and dark muscles of the treated samples (OLE and SME) whereas the highest content was found in their counterparts from the untreated samples (control). The total polyunsaturated fatty acid (PUFA) and total monounsaturated fatty acid (MUFA) contents decreased markedly in both ordinary and dark muscles of the control samples. In contrast, treated samples remained relatively stable throughout the storage time since the employment of plant extracts had protective effects against lipid oxidation and help maintain MUFA and PUFA levels in frigate tuna muscles. In addition, the PUFA/SFA ratio and polyene index which are considered important dietetic parameters showed that the used plant extracts (OLE and SME) did not result in a reduction in the PUFA/SFA ratio and prevented PUFA damage in both frigate tuna muscles during storage. Thus, the use of plant extracts such as OLE and SME can be recommended as natural preservatives for the fish processing industry.