水産食品油脂のチオバルビツル酸（ＴＢＡ）測定法の検討 Ｉ 水蒸気蒸留法

Abstract

The TBA test is a chemical method for the estimation of oxidative rancidity which is particularly useful for fish oils rich in highly unsaturated fatty acids. However, high erroneous TBA values were often observed in various fish samples containing iron compounds in higher level. The authors found that the experimental condition by CASTELL et al. was not sufficient for preventing such spurious TBA values. In the present experiments hemoglobin or myoglobin and Fe2+ were used as iron compounds. TBA value of the mixture (fish oil 0.5g, sodium carboxymethyl cellulose 1.0g, distilled water 50g) with or without suitable amounts of antioxidant and/or EDTA was determined by CASTELL's procedure. The results obtained were as follows: 1) The TBA values increased with the amounts of hemo-protein or Fe2+ in the test mixture. On the basis of Fe content in the mixture, the effect of hemo-protein was larger than that of Fe2+. 2) EDTA added to the mixture prevented completely the effect of Fe2+ on TBA values. Among antioxidants tested, BHA was the most effective to prevent the spurious TBA values induced with hemoglobin. 3) The TBA value found in the test mixture containing 500μg of Fe2+ was reduced by the addition of 150mg of EDTA to the same level as in the mixture excluding Fe2+. On the other hand, the TBA value found in the mixture containing 15mg of hemoglobin was reduced by the addition of 150mg of BHA to the same level as in the mixture without hemoglobin.