Personal view of FDA document on Pathogens associated with Cold Smoking Fish as it relates to home curers/smokers ie occasional producers..
Document lists 4 pathogenic issues: listeria monocytogenes, clostridium botulinum, biogenic amines and parasites.
Occasional sporadic outbreaks in smoked mussels and cold smoked trout, no reported cases in salmon.
Capable of growing in normal salt/temperature combinations but in ï¿½naturallyï¿½ contaminated products growth is slow. Therefore good hygiene in processing is the major hurdle.
Widespread prevalence but incidence is low. Anaerobic. No reported outbreaks of botulism arising from cold smoked fish.
Inhibited by low temperature, therefore try and keep storage temperatures as low as possible.
Because the bacteria is anaerobic, vac packing could be an issue.
Not generally seen as an issue for salmon.
Pre frozen fish is suggested, not sure if domestic freezers get down to the required temperature level. ï¿½Smokeï¿½ will kill surface parasites but not any inside the flesh. Interestingly, Farmed salmon fed on pellet food should have no parasites as the parasites are passed up the food chain.
Try to obtain good quality fish.
Keep well chilled
Process the fish under good hygiene conditions.
Try to achieve 3.5% salt content in finished fish*
Donï¿½t smoke for more 24 hours.
Keep the finished product chilled if to be eaten in days (as opposed to weeks), freeze for longer keeping periods.
* Difficult to establish why 3.5% is the ï¿½magicï¿½ figure. In general the higher the salt content the less pathogenic problems but poor eating quality. The 3.5 % level seems to be a compromise figure but very difficult to see any specific scientific basis, and may not be an issue for home curers/smokers who either eat their fish within days or freeze for future use. Testing for final salt content would seem to be impractical for home producers, more useful would be some sort of input calculation.
These is my personal precis of the FDA document, I am not a microbiologist or biochemist, however, the key issues are ones I will be trying to follow for any future fish that I cure/smoke. If you have any concerns you must refer to the original document.
I would welcome any comments/discussion.