Rules and recommendations for internal temperature of hot-smoked fish

[pmmpete]

I've done some reading up on the internal temperature required to produce safe hot-smoked fish, and am writing to report what I found, and the conclusions I've reached from what I found.

The USDA recommends that you bring fish to an internal temperature of 145 degrees when cooking it. http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/safe-food-handling/safe-minimum-internal-temperature-chart/ct_index.  However, the federal regulations relating to smoked fish, 21 CFR Chapter 1, Part 123, basically just say that commercial producers of smoked fish must have a plan for producing safe smoked fish.  Specifically, a Hazard Analysis and Critical Control Point (HACCP) plan.  See 21 CFR Chapter 1, Section 123.6.  These regulations don't provide those of us who are brewing up smoked fish in our kitchens and garages with any concrete guidance.

Regulations in several states require that hot-smoked fish be held at 145 degrees for at least 30 minutes.  These include Alaska's smoked fish regulations, 18 Alaska Administrative Code Section 34.310(h); Wisconsin's smoked fish regulations, Wis. Admin. Code ATCP (Agriculture, Trade & Consumer Protection) Section 70, Appendix A; and New York's regulations for vacuum packaged smoked fish, 1 NY CRR (Codes, Rules, and Regulations) Section 262.5(f).  The Association of Food and Drug Officials guidelines recommend the same temperature and time.

With respect to ground meat products such as sausage, the USDA and the Food Safety Inspection Service have published schedules of the temperatures and times required to kill the microbes which can cause food poisoning.  For example, these schedules show that bringing sausages to 145 degrees for 4 minutes will kill microbes just as effectively as bringing them to 155 degrees for 23 seconds.  These schedules are available at http://www.fsis.usda.gov/oa/fr/95033f-a.htm and http://www.fsis.usda.gov/wps/portal/frame-redirect?url=http://www.fsis.usda.gov/OPPDE/rdad/FRPubs/95-033F/95-033F_Appendix_A.htm .  I suspect that the same general principles apply to killing microbes in smoked fish.  However, I haven't been able to find similar temperature and time tables for fish.

Some food preservation experts recommend that you bring all smoked fish to an internal temperature of 160 degrees for half an hour in order to kill the bacteria which can cause food poisoning. See, Smoking Fish at Home - Safely, by K.S. Hilderbrand, Pacific Northwest Extension Publication #238, which is available at http://cru.cahe.wsu.edu/cepublications/pnw238/pnw238.pdf , and Smoking Fish at Home, by Chuck Crapo, University of Alaska Fairbanks Cooperative Extension Service FNH-00325, which is available at http://www.uaf.edu/files/ces/publications-db/catalog/hec/FNH-00325.pdf . These food preservation experts say that producing safe smoked fish requires three things: (a) salting or brining the fish long enough to ensure that adequate salt is present in the smoked fish, (b) heating the fish to a 160 degree internal temperature for at least 30 minutes, and (c) refrigerating and/or freezing the fish after it has been smoked.

I asked Chuck Crapo why he recommended 160 degrees for 30 minutes, which is considerably higher than the 145 degrees for 30 minutes required by the state regulations listed above.  He replied in an e-mail as follows:  "The publication that I co-wrote with the Cooperative Extension Service in Alaska was a case of being over cautious since one of the concerns for home smokers was the wide variation that they saw in their smokers.  I guess you could call this a 'safety factor'; since finding the coldest spot in one of the Little Chief, Bradley or home built smokers is often not done.  Some of the testing we did on these smaller smokers showed a 10-15 degree variation between top and bottom when finishing off the cook.  Hence that 160 recommendation.  Same with Ken's publication.  The 1/2 hour recommendation comes from the commercial regulations.  For commercial fish smokers their process requirement is 145 F IT for 30 minutes.  This is often a regulation in many states. . . .  If you can accurately find the cold spot in your smoker and the exact center of the thickest fillet in the smoker, then you can use those times and temperatures [from the USDA/FSIS charts].  If there is some uncertainty, then adding some fudge factor is desirable.  I have not seen any similar chart for fish.  I would guess one of the reasons is the wide variation in raw material (ie varying fat contents and moisture contents), brining times and processes.  Sausages are fairly homogeneous mixtures."

Ken Hilderbrand states in his article Smoking Fish at Home – Safely, "While regulations for commercial fish smokers may permit a minimum temperature lower than 160 degrees F (30 minutes), home smokers don't have the continuous time-temperature recording equipment necessary to ensure proper cooking.  Therefore, I continue to recommend 160 degrees F (30 minutes) as the minimum internal temperature for home smokers."

I think the concerns which Crapo and Hilderbrand have about uneven temperatures in home smokers are valid.  In an effort to smoke my fish as evenly as possible, I leave ample space between pieces of fish for air to circulate, I have added a fan to my smoker, and I periodically rotate the racks in my smoker, both from top to bottom and by spinning the racks 180 degrees in their supports.  I have also tried to locate the coolest spot in my smoker by smoking batches of fish without rotating the trays, and measure the internal temperature of fish being smoked at that location.

Because notwithstanding these steps, I know that the temperatures in my smoker are still uneven, I have decided to treat the 145 degrees for thirty minutes standard set by various state regulations as a minimum.  I try to get the fish a little hotter, or I hold the internal temperature at 145 degrees for a bit longer than 30 minutes.

[Smokeville]

Great post!

Here's another research project for you, pmmpete.  ;D

The possibility of parasites in raw salmon and the need to freeze before consumption if uncooked. There are slight variations between Europe, Canada and the US as to how many days at certain temperatures will kill the parasites.

That's pretty clear, but what about wild versus farmed? There is a document out there somewhere that quoted a Canadian government agency saying freezing of farmed salmon is not necessary because of the minimal risk of parasites.

Thanks for your great information, pmmpete.

Rich

[pikeman_95]

I worked two summers in the Alaskan salmon canneries a long time ago and I can attest that salmon have plenty of paracites in it. A couple very common paracites are tape worms along with their eggs and pin worms. Pin worms are as fine as a hair so they would be very difficult to detect. I would always make sure that I properly cook salmon.

[Waltz]

Interesting articles. Whilst we are on the subject, here is a link to some UK guidelines:
http://www.fao.org/wairdocs/tan/x5953e/x5953e01.htm#The%20hot%20smoking%20process which state a final smoker temperature of 80C, almost 180F. I don't usually go as high as that.

[pmmpete]

The United Kingdom fish smoking guidelines contain a schedule of procedures, times, and temperatures for smoking fish in a "Torrey Mechanical Smoking Kiln."  The 80 degrees C/180 degrees F temperature specified in the guidelines is a smoker temperature, not an internal temperature for the fish.  The people who prepared the guidelines probably had some internal temperature goal in mind when they prepared the schedule of times and temperatures, but the guidelines don't state what that temperature goal is.  The guidelines just state "the total time, and the proportion spent at each stage, will depend on the species, its size and fat content, and the kind of product required."

The commercial Torrey Mechanical Smoking Kiln referred to in the UK guidelines appears to be considerably different from home smokers.  As a result, it may not make sense to try to use the UK guidelines with a home smoker.

[Waltz]

I agree pmmpete. The Torry kiln is a commercial smoking apparatus in which it would be impractical to measure the internal temperature of the fish, but that is the case for some thin fish fillets in the Bradley also. Personally I don't measure internal temperature when smoking fish but rely on smoker temperature and time. I posted the link to add information to the mix. Some of the information is useful and you can take from it what you want.

[pmmpete]

The first couple times I smoke a new kind of fish, I measure the internal temperature to be sure I'm getting the fish hot enough.  But once I figure out a time and temperature procedure which gets the fish to the necessary internal temperature, while producing the balance of dryness and flakyness which I like, I'm comfortable deciding when to end the smoking and drying process based on the appearance and texture of the fish, without monitoring the internal temperature.  However, if anything changes, I measure the internal temperature.  For example, I frequently smoke lake trout fillets, but if I decided to smoke some particuarly thick lake trout fillets, I'd monitor their internal temperature while smoking them.