Abstract
Aims:  To determine the efficacy of X-ray processes in inactivating L. monocytogenes levels in smoked catfish during storage at 5°C and to determine the effects of X-ray doses on controlling the growth of spoilage bacteria on smoked catfish during storage at 5°C for up to 5 weeks.

Methods and Results:  Smoked catfish fillets inoculated with L. monocytogenes were treated with 0·0–2·0 kGy X-ray and stored at 5°C for 5 weeks. The negative controls (uninoculated/untreated) and uninoculated samples treated with the lowest (0·1 kGy) and highest (2·0 kGy) doses were stored at 5°C and tested for psychrotrophs count during the 5 weeks of storage. The initial L. monocytogenes population on smoked catfish was significantly (P < 0·05) reduced to undetectable level by a treatment of 1·0 kGy or higher. The initial psychrotrophs count on smoked catfish was significantly reduced from 4·7 CFU g−1 to below the detectable level by a treatment with 2·0 kGy.

Conclusions:  Smoked catfish treated with 2·0 kGy X-ray had no detectable L. monocytogenes throughout 35 days of storage at 5°C. A treatment with 2·0 kGy X-ray also kept the levels of psychrotrophs in the smoked catfish within the acceptable level until 35 days.

Significance and Impact of the Study:  The results of this investigation indicate that X-ray at 2·0 kGy can eliminate L. monocytogenes and extend the shelf life of smoked catfish stored at refrigeration temperature.

http://onlinelibrary.wiley.com/doi/10.1111/j.1472-765X.2012.03242.x/abstract