Posted by Eric Troy on 05 Apr 2015 00:52
Buying shrimp can be a confusing and somewhat overwhelming process because of all the myriad choices, including multiple sizes, headless, peeled, unpeeled, deveined, etc. The most basic question about grocery store shrimp, however, is, "fresh or frozen?"
Most people buy their shrimp from the seafood section at the grocery store. No matter how much foodies snark at this and tell us to "go to a fish vendor" most people will not. Not everyone even has access to a real seafood market. When it comes to fresh shrimp from the grocery store, most customers are concerned that the shrimp is not really fresh, so frozen may be a better option. Is this true? What is the best choice?
The answer is simple. Most "fresh shrimp" sold at the grocery store, by the pound, in the seafood section, is not fresh. It has been previously frozen because it arrived at the grocery store in a frozen state. In fact, if you were to ask, they would tell you as much. As well, you may even be able to find the words "previously frozen" in small print. Previously frozen is not fresh. I've bought "fresh" shrimp from the grocery store to find that some of it was still frozen. What you are buying is thawed shrimp.
Should You Buy the Thawed Shrimp?
Most of us know what we mean by the word fresh, and we don't mean previously frozen then thawed. We don't buy frozen shrimp and think of it as "fresh." The food industry has lots of terms, such as 'fresh frozen' or 'frozen fresh' to describe frozen seafood and other foods, but none of it means the same as fresh. It is certainly misleading for a grocery store to make you think you are buying fresh shrimp when it has been previously frozen.
But, if you are aware that the shrimp has been frozen and then thawed, but you don't want to have to buy frozen shrimp and wait for it to thaw yourself, what's the harm?
Well, if the shrimp has been frozen once and thawed once, and you take it home and cook it up, it will probably be OK. Shrimp does pretty well with freezing. It is not as good as absolutely fresh shrimp from the coast, but if you don't live on the coast, then you'll get your shrimp the way most of it comes to the market, either individually quick frozen (IQF) or frozen in blocks. Either is fine. Most of the shrimp we buy has been frozen right on the boat, so at least it was frozen as soon as possible. The textural and taste differences are slight, as we can still enjoy our shrimp. Even if you could get live whole shrimp, it would be mighty expensive.
The problem is that the shrimp you buy thawed may have been subject to multiple freeze and thaw cycles. This is what really starts to much up the shrimp's texture and taste. It may have partially thawed and then refroze. If you are not sure, you should ask, "has this shrimp been refrozen?" If you get an 'ummm…," in response, you have your answer. Not only does the freeze-thaw process, when repeated, damage cells and mess up the texture, but each time the temperature is reduce microorganism get a chance to start growing.
In general, it is OK to buy the thawed shrimp at the grocery store, but there is no reason to unless you just want the convenience. Your best best is to just go ahead and buy frozen. If it comes in a block (frozen in ice) then you'll want to thaw all the shrimp and use it. If you get individually quick frozen shrimp, you can remove just the amount you want from the bag and put the rest back in the freezer.
Sure, it is possible that the frozen shrimp has been inadvertently allowed to thaw and then been refrozen due to improper handling and storage, but it is less likely to have been thawed than, well, shrimp that has been thawed.
Can you Refreeze Shrimp?
It is not a good idea to refreeze thawed shrimp, for the reasons above. If you are not sure you will want to cook all of the shrimp, go for the IQF shrimp so that you use only as much as you need. Most of use probably will want to have extra shrimp on hand anyway. You can get a huge back of shrimp frozen for less money that the thawed shrimp from the seafood section, and you'll have it for multiple meals. It is easy to thaw under cold running water, but the best way is to plan in advance and let it thaw in the refrigerator.
When it comes to refreezing, keep in mind that the textural changes, and the safety are two different concerns. Thawing slowly in the refrigerator, so that a certain minimal temperature is maintained (usually 42 F), make shrimp or any other food safer for refreezing, although not fool-proof. Thawing at room temperature and then re-freezing is more risky.
All shrimp must be properly cooked, no matter if it has been frozen..but of course not over-cooked. Even fresh and washed shrimp harbors bacteria. As shrimp is stored, the bacteria grows, and how the shrimp is stored, and even the individual shrimps location in a storage bin can affect how much bacteria is present.
Previously, shrimp was caught and stored for days in huge bins, between alternating layers of ice. This had a lot of disadvantages, not the least of which was that the water from the top ice layer would thaw and this water would trickle down through the layers and spread bacteria with it. The huge weight for upper layers of shrimp would also crush the bottom layers. The amount of bacteria which was able to grow on this shrimp, and the damage that ensued, meant that even "fresh caught" shrimp was not so fresh once it was brought to market. Freezing shrimp on board the boat immediately after catching was a big advance forward, although this advance didn't come without a lot of experimentation and study. Regardless, the quality of shrimp is maintained much better than with the previous ice method.
Concerns About IQF Shrimp
Some people have complained that when they buy IQF shrimp and thaw it it becomes "slimy." These people say that they prefer block frozen shrimp. This slime problem probably occurs from attempts to thaw the shrimp too quickly. If you try to thaw IQF under warm or semi-warm water, you may notice a certain slimy feel to the shrimp. While thawing too fast is not the best idea, this slimy quality does not really extend into the cooking or affect the taste. Thawing your portion of shrimp in the refrigerator, starting the day before to give it plenty of time, will yield the best results.
Another concern is the freezing process itself. Often fish and shrimp are coated with a solution of
tripolyphosphates or hexametaphosphates, by dipping them in a liquid or spraying them. These solutions are thought to help maintain the quality and extend the shelf-life, while helping to retain moisture and flavor. Although many claim that this is a problem, they don't explain what the problem is. The form in which you buy shrimp is a personal choice. In the fishing industry, there are many concerns that go past simple scientific considerations as to storage-life and quality. The ability of large companies to freeze huge amounts of shrimp on board and stay out for extremely long periods, can make it difficult for local fisherman to compete and survive. Although this is a legitimate concern, passionate advocates for local fisheries often conflate these economic concerns with quality concerns, real or imagined.
Avoid Imported Shrimp
Whether you buy fresh shrimp right off the boat, thawed shrimp, block-frozen shrimp, or IQF shrimp, if you want the finest quality, just make sure it is USA shrimp, especially wild-caught Gulf shrimp. Avoid shrimp imported from China, Thailand, Vietnam, and Indonesia, most of which is raised by huge 'aquaculture' businesses, aka "farm-raised," in industries that are not nearly as well regulated and much of the fish and shrimp reaches our shores tainted. India is actually the largest exporter of shrimp to the U.S. and you'll want to avoid this as well, as many of the same problems are present. Some of this seafood is treated with drugs and antibiotics unapproved for use in the U.S., such as malachite green, nitrofurans, fluoroquinolones, and gentian violet. Read more here.
Many other concerns have been raised, such as shrimp and tilapia farms in China and Thailand using untreated animal manure and human waste as feed. Be aware that at least 60% of the seafood we consume is imported from other countries, but only a small portion of it is inspected.
Try to look for wild caught gulf shrimp or Alaskan shrimp. Some people are worried about the remaining effects of oil spills in the Gulf. If you are concerned about this then shrimp from the Northeast coastal waters or Alaska may be a better bet for you. Be aware that most store brands (generic) frozen shrimp will be imported from Thailand or another country, including "organic" store brands. If you can't find a good choice at your supermarket, and you have no other place to but your shrimp, it is possible to have high quality gulf caught shrimp shipped to you.
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