Expert: Sherman D. Date: 12/31/2004 Subject: Sashimi
Question Can freezing kill the bacteria? Can pollutants be cleaned off by salt water?
Grateful for your time and explanation.
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Followup To
Question -
What does it mean by sashimi grade salmon or sashimi grade raw seafood? How was the raw seafood processed to make it sashimi grade?
If I fish a salmon out of an Alaskan river, will it be the best choice for sashimi if I consume it shortly after?
Thanks
Answer -
This site will tell you what Sashimi Grade means.
As for how it is processed, i believe what the do is check to see if there are any kind of pollutants or bacteria that might be in the fish.
As for the last question, just because the fish was caught fresh does not mean that the fish is fresh. The fish you caught hasn't been tested/checked for bacteria content or contaminants. In short, you might be able to consume the fish, but it will be at your own risk, because there is no telling what microscopic organisms could be swimming around in the Alaskan River.
In comparison, Sashimi Grade is like eating the non-poisonous part of a Puff Fish, which is a small percentang. And non-Sashimi Grade is like eating the poisonous part of a Puff Fish, which is a large percentange. In otherwords, the non-poisonous part can be eaten, and the poisonous part can't be eaten. And just like a Sashimi Grade fish which has been checked, if the Puff Fish is cut precisely, then it can be eaten.
Sorry if i am not of better help.
Answer This site may be of some help.
www.biokill.com.hk/PRODUCTS/citrox.htm
www.griffin.peachnet.edu/cfs/hottopics/EOWater.html
1.) This is more of a preservation technique, but it doesn't get rid of all bacteria in food, thats why you most foods have to be cooked or heated, because heat kills bacteria. However, you shouldn't over cook food, because that can cause bacteria that probably wasn't there to form. Thank of it like this, just because you take food out of a freezer doesn't mean its ok to eat it raw. The food would have to be cooked. However i can't say the same thing about food that is of sushi/sashimi grade, since its ok to eat raw to begin with, and freezing it would just be keeping it fresh as the day you bought it. Just watch out for freezer burn, because if something gets freezer burn, then it isn't ok to eat. In short, if you were to freeze food that has bacteria swimming around inside of it, freezing would only kill the bacteria that can't live at that kind of cold temperature, however there are still other bacteria that can survive at temperatures that low, and thats why you have to cook the food, so that the bacteria that is still there will be killed.
2.) Salt is just another form of preservation. If salt water was a good source of killing pollutants, then you could eat salt water fish right after you catch, which you can't do if the fish is polluted. I guess it will depend on what kind of pollutants exist, then you would be able to find a way to clean the pollutants out of them.
Fish that is bought in stores is just good to eat cooked, boiled, steamed, grilled, etc... any kind of heat method cooking. Canned fish should be ok to eat raw after all, its served with some kind of sauce when it is canned.
As for everything else, i'm more of a shellfish person myself.
Freezing does not destroy spoilage organisms but it stops their growth as long as the food is kept at -180C. Any bacteria present will become active as the food thaws so it is safest to thaw the food in the refrigerator.
Any remaining food would then be kept in the refrigerator to slow the growth of organisms.
Refrigeration will slow down the growth of bacteria and fungi but doesn't stop it completely as freezing does. Hence refrigeration only keeps food for days rather than the months that freezing does.
Salting
Salting, especially of meat, is an ancient preservation technique. The salt draws out moisture and creates an environment inhospitable to bacteria. If salted in cold weather or under cold conditions, to prevent the meat spoiling before the salt has time to take effect, salted meat can last for years. The meat is cut into small salting blocks, and course salt is patted over the meat. It is then laid piece by piece into the container where it is going to be stored, careful that no two pieces touch each other. The slabs are laid like bricks, and salt is applied in the spaces.
Today, salting is still used to create salt-cured "country ham" and corned beef and pastrami, which are made by soaking beef in a 10-percent salt water brine for several weeks.
