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How Safe is Home-Smoked Salmon?

As safe as you make it, say the pros

For many salmon anglers, part of the joy of landing the fish is taking it home and smoking it to share with friends. But with recent news about Listeria bacteria, a potentially deadly foodborne pathogen, detected on some smoked salmon made by well-known fish producers, the question arises: How safe is home-smoked fish?

Fortunately, there’s no mysterious hocus-pocus involved in smoking your own fish. The name of the game comes down to preventing foodborne illnesses by following basic, straightforward guidelines: keeping things clean, using the right ingredients, and keeping the fish at the right temperatures, before, during and after smoking.

A surprise to many people is that the biggest problem with contamination comes after the smoking is done, said Barbara Rasco, professor at Washington State University and food-safety attorney, in an interview with Food Safety News.

She ticked off some examples of how that can happen, among them handling the finished product with unwashed hands or letting it come into contact with dirty water, brine, sauce or coatings. And, as with all foods, cross-contamination can occur if the fish comes into contact with a utensil or surface that has been contaminated with pathogens such as Listeria, Salmonella or the dangerous form of E. coli — or even from a knife used to cut up the fish before it was smoked. Then there’s always what Rasco refers to as “the dirty rag or sponge from hell.”

Her advice about “keeping things clean” mirrors information — based on federal guidelines — from the National Center for Home Preservation. According to those guidelines, all equipment, work surfaces and utensils should be cleaned and sanitized before and after use. An example of a sanitizing solution for home use is one tablespoon of chlorine bleach in a gallon of warm water. The guidelines also point out that “cross-contamination between raw and/or dirty surfaces with clean or cooked food products should be of prime concern.”

Most consumers making smoked salmon in the Northwest are making hot-smoked salmon. Rasco said in cases like that, contamination is almost always caused by handling problems after the fish has been smoked.

Referring to the smoked salmon that has been the subject of recent recalls, Rasco said that Listeria present in the marine environment can “come in” with the fish, and since there is no “kill step,” it would remain in the final product. She also pointed out that, during the recent recalls, no one actually became infected with Listeria. It was just that it was detected on the fish.

Among the smoked-salmon processors caught up in the recent recalls were Ocean Beauty, Marine Harvest and Pacific Seafood Group. Some of the big retailers hit by the recalls were Whole Foods Market, Walmart, Ralph’s, King Sooper’s and Sam’s Club.

With that in mind, Rasco said that if the large commercial smokers have been having problems with Listeria in smoked fish, “God knows what the home-smokers are doing.”

“The reason I’m worried about this is that, by following food-safety guidelines, you can kill Listeria and other pathogens,” she said. “But if Listeria gets on the fish after it has been smoked, it can keep growing on it in the refrigerator. Freezing doesn’t kill it; it just keeps it from growing.”

Commercial cold-smoking

The smoking process used in the recalled commercial fish is referred to as “cold-smoking,” which is considered a riskier method than “hot-smoking.” According to a Pacific Northwest Extension publication about smoking fish at home, cold-smoked fish is cured and smoked at temperatures below a range of 80-90 degrees F during the smoking process. That means it is unpasteurized and, for that reason, must be handled carefully to avoid illness from harmful bacteria.

While some home-smokers cold-smoke their salmon, most hot-smoke it. However, home smokers can use both of these methods safely as long as they follow instructions and abide by basic food-safety guidelines.

According to a Colorado State University Extension’s SafeFood Rapid Response Network newsletter, cold-smoked salmon is considered safe for healthy, non-immune-compromised persons. However, as with other raw or semi-raw meat products, it is risky for pregnant women, the frail elderly and others with compromised immune systems due to disease or medical therapy. Many countries, including the U.S., recommend that these groups avoid cold-smoked fish.

The shelf life of cold-smoked salmon is very short, one to two weeks in the refrigerator and about one month in the freezer. Storage time is another critical factor in the proliferation of Listeria bacteria since it can grow at low temperatures. Rasco recommends that individuals who are particularly susceptible to Listeria, such as pregnant women, consider lightly heating smoked salmon prior to eating it to reduce the risk.

It’s important to know that, no matter which method you use, smoke by itself is not an effective food preservative without proper cooking. The danger zone for microbial growth is between 40 to 140 degrees F. That’s why it’s important to store, age, cure and smoke the fish at the right temperatures.

The ABCs of hot-smoking

The good news about home-smoked salmon, according to the same Pacific Northwest Extension publication about smoking fish at home, is that you can smoke any fish without worrying about foodborne illnesses if you follow some basic practices in preparing, salting, smoking, cooking and storing it.

Salt, smoke and heat are the three common factors in hot-smoking salmon. Fish smoked without proper salting and cooking can not only make people sick, it can also be lethal. That’s because many dangerous bacteria can, and will, grow under the conditions normally found in the preparation and storage of smoked fish.

Of those bacteria, Clostridium botulinum, which causes botulism, is of special concern in smoked salmon stored in vacuum packing in the refrigerator for long periods. According to the Centers for Disease Control and Prevention, all forms of botulism can be fatal and are considered medical emergencies. Foodborne botulism is a public-health emergency because many people can be poisoned by eating a contaminated food.

In addition to botulism and Listeria, other harmful foodborne illnesses such as Salmonella and the pathogenic form of E. coli can infect people who eat smoked fish that hasn’t been correctly prepared or has been mishandled after it has been smoked.

Safety tips

Because it’s hard for the home-smoker to know the exact salt content of the finished product, the Pacific Northwest Extension publication advises that the following conditions be met so salmon will not support the growth of harmful bacteria:

  • Salt preserves smoked fish by reducing the moisture content, but because home-smokers don’t usually have a way to accurately analyze the salt content of the finished product, it’s important that the fish be properly cooked and refrigerated.
  • Cut the pieces of fish into uniform size and thickness to reduce the chance that some pieces will be either under- or over-salted. Doing this will help prevent foodborne pathogens from contaminating the fish.
  • Salt or brine fish long enough to ensure that enough salt is present throughout the entire piece of smoked fish.
  • Salt the fish before smoking it in a strong salt solution — one part table salt and seven parts water by volume for one hour for most fish. (One cup salt with seven cups of water will salt about two to three pounds of fish.)

The National Center for Home Food Preservation Guide warns that only food-grade salt without additives, such as iodine, should be used. Rasco suggests using food-grade rock salt dissolved in water.

“Don’t use salts with anti-caking agents because that can lead to quality problems with the fish,” she said.

  • If you plan on storing the smoked fish, keep it under refrigeration at 38 degrees F or less.
  • Do not let fish sit longer than two hours at room temperature after cleaning and before smoking. Rasco also said that it’s important when using frozen fish to make sure it’s thoroughly thawed out since the salt can’t penetrate into the tissue when it’s frozen. This, in turn, could lead to food-safety problems.
  • Once the fish has been brined, rinse the surface of the fish and allow it to air-dry, meat side up, for at least an hour on a greased rack in a cool place until a pellicle forms. A pellicle is a shiny, slightly tacky skin that will form on the meat surface of the fish. The pellicle will give the smoke a chance to deposit evenly during smoking and also help prevent the surface from spoiling during smoking.
  • You can add ingredients such as brown sugar and soy sauce, but don’t add any oil.
  • Smoke the fish for up to two hours at about 90 degrees F in a smoker and then increase the heat until the fish reaches at least 150 degrees F (preferably 160 degrees F) and then cook it for at least another 30 minutes. Use a thermometer to make sure the thickest section of the fish is at a high-enough temperature.
  • Since it’s difficult to reach high-enough temperatures for proper cooking when using the small metal smokers available in most hardware or sporting-goods stores, follow up the smoking process by putting the fish in a home oven to bring it up to a core temperature of 150-160 degrees F.

Rasco said that one of the small metal smokers could be used for up to two hours to complete the first part of the smoking process. After that, put the fish in a home oven to finish it up.

If, after the fish has been smoked, the right outdoor cooling conditions (cool, dry air) aren’t present, Rasco said you can put the fish in a smoker with low heat (80 to 90 degrees F), no smoke, and with the doors open so the pellicle can form. She advises to cool the fish down to 110 degrees F or lower before packaging it.

When packaging the fish, it has to be cool enough, Rasco said. When fish that hasn’t been cooled down enough is put into a ziplock bag or vacuum-sealed in a plastic package, the difference in temperature between the fish and the refrigerator can cause condensation.

  • If you don’t plan to immediately eat the smoked fish you’ve vacuum-packed, put it in the refrigerator (preferably at 38 degrees F or less) or into the freezer. And, if you don’t vacuum-pack your fish, keep it refrigerated to ensure quality and safety.
  • If you’re storing the fish for longer than two weeks, tightly wrap and freeze it. Properly frozen smoked fish can hold for up to one year.

Susan Westmoreland, food director for Good Housekeeping, offers this advice about storing smoked salmon: Put it on the bottom shelf of your refrigerator, where it’s coldest. Unopened, it will keep for two weeks; after opening, one week. Store opened salmon in the original package; over-wrap it in plastic wrap or place it in a self-sealing plastic bag to prevent dryness. (If the edges dry out, just snip them away with a pair of scissors.)

  • Use only hardwood for smoking. Maple, oak, alder, hickory, birch and fruit woods are good choices. Woods from conifers such as fir, spruce, pine or cedar will leave an unpleasant taste on the fish.

What ifs

What if a friend proudly offers you some salmon he or she has smoked? You can’t very well grill the person about how the fish was smoked. Rasco suggests that you graciously accept it. Then, later, heat it up to 150 to 160 degrees F and eat as is or use it to make sauces or sandwiches.

When asked about statistics pertaining to food poisoning caused by home-smoked salmon, Rasco said that information like that isn’t available, in large part because there aren’t many illnesses of this sort.

“Most people who consume smoked salmon are healthy,” she said. “The elderly and the very young don’t usually want it because of its strong taste and high salt content.”

She also believes that, in general, there’s more paranoia about smoked salmon than is warranted.

“People don’t eat a lot of it, and they usually eat only one or two ounces at a time,” she noted.

When asked about the safety of fish and other meats “back in the old days,” Rasco said that the way it was done then, before refrigeration, called for a lot of salt. As a result, smoked fish (or other meats) were very salty and very dry.

“But we like products that are less salty now,” she said, adding that using the right amount of salt is important when it comes to preventing Listeria and other foodborne pathogens.

For more information and details about safely hot-smoking salmon, refer to the Pacific Northwest Extension’s publication on this topic.

© Food Safety News
  • Richard

    A really interesting article, although the advice to store the smoked salmon at the bottom of the fridge is likely to result in cross-contamination. In the UK we always recommend storing raw food at the bottom of the fridge and cooked food on the higher shelves.
    The difference in shelf life for frozen hot and cold smoked salmon (One year to one month) is surprising
    Richard Sprenger

  • sgkritzik

    If someone offers you a piece of fish that is contaminated with botulinum toxin, heating it in the oven to 160 isn’t going to help.

    • MrOmykiss

      Botulinum toxin is easily killed with heat, it’s the spore that’s difficult to kill.