Bacteriological spoilage, organoleptical quality and amino acid composition of fresh trout were studied during storage at +4– +6° C. Experiments were carried out with living fish (control), with fish 4 hours after killing and during storage. The fish were kept in air, in ice and packed in polyethylene and vacuum bags. It was observed that the type of packing considerably influences both the bacteriological and organoleptical quality. These changes were not, however, directly correlated with each other. In connection with vacuum packing, the amounts of anaerobic sulphide producing bacteria were so high that this aspect needs a detailed investigation before vacuum packing can be recommended for fresh trout. The amino acid composition of iced trout changed only slightly during storage. Current experiments concerning changes in volatile amino acid contents will provide additional information in this respect.

Changes in the amounts of free amino acids in rainbow trout during refrigerated storage in ice at + 4 . . + 6°C and in frozen storage at –18°C were investigated. The control sample was prepared directly from the killed, bleeded, and gutted fish. The results indicated that the total amounts of free aimino acids decreased in the refrigerated and in the frozen fish. These decreases depended mostly upon the steady decrease of the three quantitatively largest components, namely histidine, tryptophane, and glycine. Histidine formed 36.1 per cent, tryptophane 25.0 per cent, and glycine 15.1 per cent of the total amount of free amino acids in the control sample. In connection with many other amino acids a decrease in their amounts was noted during storage. Changes appearing in refrigerated fish were more distinct than in frozen fish.