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Partially "cooked" Fish ---- Safe? [moved from General Topics board]

It seems like every other menu and every cook book contains a form of "seared" tuna. You know, cooked half an inch or so around the outside and raw in the middle. This has always puzzled me as I was lead to believe that you should either eat something

2)cooked but cold;

but that halfway is the worst breeding ground for bacteria. If this is true, WHY do so many people endorse this method of preparing tuna and is it in fact safe?


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  1. One might ask the same question about a rare steak. Absence any widespread anecdotal evidence that people are constantly getting sick because of this, I wouldn't worry about it.

    In terms of the tuna, I like it totally raw, or seared, if it is cooked too much (i.e. all the way through) the taste and texture change to cardboard, in my opinion.

    1. the bacteria aren't going to be on the inside -- they are on the outside of the fish. If it is seared, or keep cold (raw), no problems should arise. (This is why some say that chopped meat/hamburgers shouldn't be rare, as they were all external, exposed, etc.)

      1. The main risk isn't bacteria but parasites, most of which are killed by freezing. Also, saltwater fish are less likely than freshwater fish to host parasites dangerous to humans. All in all, you're probably safe buying sushi-grade tuna from a reputable fishmonger.

        That said, I once heard a parasitologist claim that even thinking about sushi made him nauseous. Of course, he also told the interviewer he would eat lettuce only if it had been cleaned with a flamethrower.

        1 Reply
        1. re: carswell

          Is it just me, or does that just sound like the kind of profession that would turn one's life into an unending parade of misery?

          1. re: Robert Lauriston

            No offense, Robert, but these are hardly authoritative sources and pretty much rely upon anecdotal evidence.

            A few years ago, a bunch of folks did get parasites from eating fish in California. But none had eaten sushi. Turned out they got the infections from undercooked rockfish (Pacific snapper). At that time, some health official said that he knew of no case of anyone in California getting parasites from eating sushi because the types of parasites that infect most fish (a cold blooded ocean temperature critter) are not the ones that infect people (different types of flesh at different temperatures). One of the exceptions was the particular parasite that affected the rockfish consumers because it is primarily a seal/sea lion parasite that finds a temporary home in the rockfish waiting for them to be eaten by the seal or sea lion. Salmon may pose a similar risk because of its time in rivers.

            I have eaten raw fish now for over 20 years and have never been sick. Almost every time I get food from a Burger King (maybe 10 times in the last 10 years), I get a mild case of food poisoning. A number of years ago, Consumer Reports did a study on choloform levels in fast food and found alarming choloform levels at most restaurants mostly caused by parking cooked food under heat lamps or in other warm moist locations which are perfect bacteria breeding grounds.


            1. re: Phoo D

              I hail you, brother.

              People give me a hard time about my tendency to eat raw or less cooked things, but the reality is every time I eat fast food I feel pretty damned awful afterwards.

              A night of sushi offers no such ill effects.

              1. re: Phoo D

                I got wary about raw fish after talking with a well-trained, very experienced Japanese sushi chef about why he wouldn't serve certain fish unless they'd been frozen.

            2. Given the ridiculous lengths to which American health departments go to keep us safe from ourselves, if it were the least bit dangerous, they'd not allow it at all... but every fancy restaurant in the country serves some kind of seared tunny.

              I love it. I hate it when people cook it all the way through.

              2 Replies
              1. re: Das Ubergeek

                You are giving the government way too much credit. Americans are sold products containing all kinds of potentially unhealthful ingredients (for example, Olestra, the fake fat in Wow chips that can cause severe gastrointestinal distress) because the FDA is entirely politically and bows to powerful lobbys. And U.S. meat inspection - ouch! Makes me glad I gave up red meat.

                1. re: lvecch

                  Yes, the federal government are a bunch of buffoons -- but I'm talking about the local public health authorities, who tend to be MUCH more vigilant, and have much broader purview to ban potentially (in their theories) unsafe practises.

              2. Let's stop being scared of things.

                It's really amazing what you can get away with eating.

                Fear of being sick from food is no different from flying or rollercoasters. It's best just to eat what you want.

                I love all manner of things as close to raw as possible.

                1. I'm not afraid of raw fish, just informed about parasites and bacteria. I trust trained sushi chefs. I'm skeptical that the other chefs on the raw-fish fad have a clue.

                  Reporter: ... is it true you can infect yourself by eating raw sushi and ceviche?

                  Dr. Scott Smith: Yes, but I have never seen anyone in this country with a tapeworm they got from eating sushi. There are public-health laws that require flash freezing of sushi fish to kill parasites, and sushi chefs also know how to "read the meat," looking for the larvae of the parasites. ...


                  1. Interesting feedback. I'd always wondered about this . . . and the whole rare steak thing. I agree that tuna is better not cooked all the way thru, but I just wanted to know more about the health angle.


                    1. A lot of the bacteria that wind up in your food come not from the inside but from the outside.... dirty chef, dirty chef fingers, dirty chef knif, dirty cutting board, you get the idea. Poor handling (or mis-handling) of raw foods and "cross-contamination" are much more likely to get you sick than something partially cooked.

                      In fact, the searing of the outside of the flesh (while the inside flesh has not been exposed to the air or to contamination) would probably actually help ELIMINATE much of the bacteria on the outside of the meat.

                      Steaks, especially aged steaks, are another good example. The flesh inside, even served blood-rare, is less "contaminated" than the outside aged steaks - guess what - "aged" steaks are "rotten" on the outside... that tasty aged flavor is actually DECAY (read: bacteria) but the nice searing on the outside helps get rid of the worst of it.

                      Also, someone mentioned the FDA and Americans. I often wonder how its possible that more Americans don't drop dead every day from the food we all eat. (I'm not talking about long-term like heart attacks, strokes) but the quality, care, handling, and preparation of the food in most sub-par establishments is REALLY GROSS. Its sort of like the old adage about "don't drink the water in Mexico" - Americans digestive systems are used to certain "nasties" in common foods, and our stomachs can handle these (to some extent) without making us sick.

                      1. As far as seared tuna being in the "unsafe" temperature range, I think the key point is that it shouldn't be at that temperature long enough for bacteria to breed. Fridge to stove to plate in a matter of minutes hopefully.

                        A related question I sometimes ponder is how long does it take cooked foods to actually reach the "safe" temparature zone in the fridge. They say you shouldn't put hot food straight into the fridge. It can take an hour or more to let a big pot of soup or stew cool down adequately before putting it in the fridge. Then, who knows how long it lingers in the "unsafe zone" before it actually cools to under 39 degrees? I've never had a problem with this, so I'm not too worried really. I supsect the whole "never leave food at room temperature for more than two hours" rule errs heavily on the side of caution.

                        4 Replies
                        1. re: Low Country Jon

                          I always allow hot foods to cool somewhat before putting them in the fridge. However, I read recently that this bit of wisdom is from a time when refrigerators were not able to handle adequately the cool down process and that with today's appliances this is no longer the case.

                          1. re: lvecch

                            I take those freezer packs (you know, the ones they ship cold-storage food with, the ones they sell for coolers) and freeze them solid. Put the pot in the sink (on something so it doesn't crack the sink), run cool water halfway up the side, and then put the freezer packs in.

                            It's cool enough to put in the fridge in 10 minutes.

                            1. re: Das Ubergeek

                              Good idea, I may have to try that - I don't think my apartment's fridge is particularly modern!

                              1. re: Das Ubergeek

                                I do this too, always. I stir the stock/soup/stew periodically, to speed things along.

                          2. OK....I had to reply to this one since there are a number of "misconceptions" that were stated in some of the previous posts.
                            1. When it comes to eating "seared" or raw (as in sashimi, sushi, "poke", "oka") preparations that use fresh tuna (bluefin, yellow tail, albacore) or certain other free swiming fish (Hamachi or "Ono" i.e. Wahoo) based on my reasearch it is OK to do so (and I do so reguraly). Here is why: these fish do not have issues with intra-muscular parasites hence freezing them will not make them any safer from a parasite/nematode point of view. Freezing will/can affect (lower) certain bacteria that might be present on the surface but it will not eliminate the bacterial risk. Hence my advice is to buy the freshes fish possible from a reputable vendor.

                            2. Other fish that is commonlly eaten "raw" is salmon and all species of salmon suffer from intra-muscular parasite issues some of which can result in human transmission and health problems. Because of this samon intended for "raw" consumption should be frozen for a specified period of time. I do not remember the exact times but it is in the order of 7-10 days at minus 20 deg. C. Freezing overnight will not do it (i.e. parasites will survive). Other preparations of "raw" salmon such as cold smoked salmon or "gravlax" relay on the presenc of salt in the tissues that can affect the parasite problem but again freezing is recomended to ensure complete elimination. Hot smoking of salmon (>145 deg. F) will destroy all parasites.

                            3. Another fish that is also eaten "raw" (sushi/sashimi) and very often used in "ceviche" preparations is halibut. As with salmon the parasite problem is an issue and should be addressed by freezing. This hold true for almost all "bottom" living fishes (flouders, etc.) and most of the "rock" fish species which for some reason are parasite carriers. One thing to keep in mind is that many of these type of "white" flesh fishes are very often used in variety of "ceviche" preparations and here lies the problem / possible risk area. In this case using "fresh" fish will not make the "ceviche" safer....only freezing would. It is true that a prolonged exposure (not sure how long but probably in the order of hours)of parasites to acids (lemon / lime juices) used in "ceviche" preparations will kill these parasites but to my knowledge / experience most "ceviches" are prepared rather quickly with the fish exposed to the acid for a relatively short time (30-60 minutes).

                            By the way....from what I have seen in the meat industry I will take my chances with "raw" tuna ANY DAY but I will never order/eat any type or form of undercooked/rare hamburger (bacterial contamination issues). However, "steak tatare" if prepared as it should be from fresh beef tenderloin is OK (internal portions of entire muscles are "free" from microbial contaminants).

                            2 Replies
                            1. re: Pollo

                              That's interesting info about gravlax/cold smoked salmon. Do most places that smoke or cure salmon freeze it first?

                              1. re: Pollo

                                Here's an article about this very issue in the salmon context.



                              2. a couple times I saw worms in cod. Once in wild sockeye salmon, so it is important to keep a close watch. And believe or not, one time in a chicken. ok, I am grossing myself out too much.

                                1. "SoCal diners got lung infection from eating raw crabs"


                                  1. I just recently read an article where they tested raw fish, looking for parasites. They took samples of several kinds of fish-- different samples from different establishments. The only one that came up "clean" consistently was the raw tuna. This suits me fine, since tht is the only kind of sushi or sashimi I have been daring enough to try. I work with a doctor who got parasites in his liver, and he claimed it was from eating sushi. However, he eats everything offered to him, so who knows exactly what it was.

                                    1. Worms...... monkfish.... hold it up to a lightbox.....

                                      Its on my very short list of "Things I Will Never Eat".

                                      1. I'm finding all this very interesting. In Portugal, a country with very high consumption of fresh fish, people take deworming medicine once or twice a year as a preventative measure. It's readily available without a prescription. My friends there are amazed that we don't do the same here in America!

                                        This is not (just) a cleanliness issue; it has to do with the fact that we can't always control how well cooked our fish will be in a restaurant, and we might even not be vigilant enough at home. I'm especially leery of freshwater fish in that regard. Re: people who say they've "never gotten sick" from raw fish, a recent article in the NYT pointed out that you can host intestinal parasites like tapeworms for a very, very long time without knowing they're there.

                                        Don't get me wrong, I'm an avid sushi eater, and I'm not going to stop eating fish in all its yummy forms anytime soon, especially not after having had my fish horizons broadened considerably by living in Portugal. But I'm actually considering asking my doctor about the advisability of picking up some deworming pills the next time I go to Lisbon!

                                        1 Reply
                                        1. re: Kitchen Imp

                                          If that doesn't work, apparently a regular diet of hot peppers (or an occasional cigarette chewed and swallowed) will take care of them.

                                          http://en.wikipedia.org/wiki/Anthelmi... (note: unpleasant reading)

                                        2. For what its worth, I once cold-smoked un-cured grouper with the intention of finishing the cooking in the oven. I just wanted the smokey flavor. After about 25 minutes in the smoker I removed the fish only to find a three inch white parasite worming out of the flesh. It think we ate buttered noodles that night.
                                          I still eat grouper (my wife will not), but it is hard to get that image out of my mind.