Microbiological quality and shelf-life of vacuum-packaged 'gravad' rainbowtrout stored at 3 and 8 degrees C

Microbiological and sensory changes of vacuum-packaged 'gravad' rainbow tro ut slices were studied during storage at 3 and 8 degreesC. At the time of s poilage, after 27 and 20 days of storage at 3 and 8 degreesC, respectively, both mesophilic viable counts (MVC) and psychrotrophic viable counts (PVC) reached 10(6)-10(7)cfu/g at 3 degreesC and 10(7)-10(8) cfu/g at 8 degreesC . H2S-producing bacteria constituted a high proportion of the PVCs and lact ic acid bacteria (LAB) counts were lower than the other determined bacteria l counts. Sensory scores decreased with increasing MVC and PVC. The judges considered samples unfit for human consumption at MVC and PVC levels exceed ing 10(6) and 10(7) cfu/g for samples stored at 3 and 8 degreesC, respectiv ely. At respective levels of 10(7) and 10(8) cfu/g, most of the samples wer e deemed unfit. The main reasons for sensory rejection at both storage temp eratures were the lack of the typical product odour or an ammonia off-odour and colour change to dark violet. The shelf-lives of the rainbow trout sli ces based on microbiological and sensory analyses were 20 days and 18 days at 3 and 8 degreesC, respectively. (C) 2001 Elsevier Science B.V. All right s reserved.