クロルテトラサイクリン (CTC) 処理底引漁獲物の鮮度およびCTC残存量に対する魚の種類,大きさ,処理方法等の影響

In case of cutlass fish which is flat and long shaped, keeping quality by a direct CTC-icing was superior to that resulted from placing parchment paper on fish which is now in common use by most fishermen. It is to be noticed that the preservative effect of CTC-ice could be only noted in upper part of the container, but not in lower part. The increase in CTC concentration of dip solution resulted in better quality but the effect was not so marked probably due to a rapid rate of spoilage in cutlass fish having flat shape and soft flesh. The sprinkling of CTC solution yielded a better quality in upper part of the container whereas no effect in the lower part. A twice sprinkling gave little better results. The similar results were also obtained in case of croaker. As to the effect on keeping quality of the position of the container in fish hold and of fish position in the container, it was found that cutlass fish held in lower part of the fish hold and of the container gave inferior quality and that not appreciable difference in quality was noted between fish container held in upper and middle part of the fish hold. The CTC residue in unskinned flesh of cutlass fish was smaller than 0.08ppm in the direct CTC-icing and 0.05ppm in the indirect icing. Once sprinkling of sea water solution of CTC up to 150ppm resulted in the residue smaller than 0.1ppm. The once sprinkled fish lot showed a marked difference in CTC residue between upper and lower part of the contai-ner, while a twice sprinkled lot contained rather uniform CTC residue between upper, middle and lower part. The dip treatment yielded CTC residue of 0.75ppm at 100ppm CTC level and of 0.2ppm at 25ppm level. In case of croaker, once sprinkling of 100ppm CTC solution yielded residue smaller than 0.1ppm in flesh where as dip treatment in 25 and 50ppm CTC solution resulted in 0.09ppm and 0.2ppm CTC, respectively. The decrease in CTC residue of croaker with depth of flesh was comparable with that observed in salmon13), mackerel11) and others3), 12).