| Summary: | The possibilities of the direct determination of the thiobarbituric acid (TBA) value in trichloracetic acid (TCA) extracts instead of distillates were evaluated. Tests carried out on herring ( Clupea harengus L.), redfish ( Sebastes marinus L.), cod ( Gadus morhua L.), plaice ( Pleuronectes platessa L.) and spurdog ( Squalus acanthias L.) of varying degree of oxidation gave 95.3% recovery in the teleost species but only 75.2% in the elasmobranch spurdog, due to the urea present. With the distillation technique, recoveries were lower and averaged 66.1% for teleosts and 43.0% for spurdog. Addition of 0.1% of both propyl gallate and EDTA to the TCA solution lowered TBA values by 25 to 59%. When fish samples were submitted to a 4 hours forced oxidation period, TBA values increased to a greater extent with the direct extraction procedure than with the distillation method
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