The biogenic amines and bacterial changes of farmed rainbow trout ( Oncorhynchus mykiss) stored in ice

Abstract

The biogenic amine content and related bacterial changes ( Pseudomonas spp., psychrotrophic and mesophilic counts) in whole farmed rainbow trout ( Oncorhynchus mykiss) were monitored during ice storage for 18 days (at 0, 3, 6, 9, 12, 15 and 18 days). Levels of putrescine, cadaverine and histamine, and bacterial loads, increased ( P < 0.05) during storage, but tyramine was not detected in any of the tested samples. Concentration of putrescine ranged from 0.4 initially to 8.97 μg/g, and psychrotrophic microorganisms were dominant. The best linear regressions (correlations) were for putrescine and Pseudomonas spp. and psychrotrophs ( r = 0.98), and for cadaverine with Pseudomonas spp. ( r = 0.82). Putrescine content was a good quality marker. Histamine was detected only at later stages of storage and was therefore less suitable than the other biogenic amines as freshness indicator.