The Effect of Steaming Process on Fat Soluble Vitamins Content and Fatty Acid Profile in Bluefish and Rainbow Trout Fillets

Abstract

Fatty acid composition and all-trans-retinol, alpha-tocopherol, and cholecalciferol content was determined and compared in raw and steamed Bluefish and Rainbow trout. Total lipids were extracted by Bligh and Dyer method followed by GC-MS. All-trans-retinol, cholecalciferol and alpha-tocopherol were analyzed simultaneously using HPLC. In comparison with raw fish fillets, analyzed fat soluble vitamin’s content in steamed fish filletsfor the Trout and Bluefish decreased significantly to about 54.2% and 49.8% for retinol and 32.6% and 43.5% for alpha-tocopherol, respectively. After steaming, the cholecalciferol amounts in processed fillets decreased significantly only in Rainbow trout (23.5%), whereas in Bluefish the losses were non-significant. After cooking, the polyunsaturated fatty acid content changed significantly in the Rainbow trout (45.8%), whereas the variations in the Bluefish were minor. The major PUFA in all samples were linoleic acid (LA) and docosahexaenoic acid (DHA). PUFA/SFA ratios were between 1.01 and 1.68 for both species. Steaming increases PUFA/SFA ratio by 8.33% in Rainbow trout, but does not affect this ratio in Bluefish.