Why does seafood go bad faster than meat?

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Why does seafood go bad faster than meat?

In: Biology

Fish live in the cold. Things like cod, salmon, haddock, tuna, and swordfish live in water that is just above the freezing point of water (32F 0C). The “stuff” or enzymes in the meat that make it go bad can still “work” in the refrigerator. “Land meat” does not spend most of its life in the cold so when “land meat” is put into the fridge the “stuff” in the meat slows way down so it takes way longer for the meat to spoil.

Edit: I see a little confusion in the comments so I will simplify a little further.

Fish are cold blooded and their internal temperature is usually around that the temperature of the water is. Cows, pigs, chickens, ect are warm blooded. A cows normal internal temperature is about 101F (38.3C). Most fish live with an internal temperature much closer to a normal refrigerator’s temperature.

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Also, Seafood often contains a different composition of fat.

They often have a higher percentage of Omega-3 fatty acids, which is “healthy” fat but also a much less stable molecule than fatty acids in other meat.

There are several reasons why seafood spoils faster than meat from animals that live on the dry part of the earth.

* Fish has a higher content of water than meat, so it’s easier for bacteria to find a home here, as most bacteria prefer a wetter environment to thrive in.

* Fish doesn’t have a lot of collagen, so bacteria find it easier to penetrate the flesh.

* Fish contains a lot of poly-unsaturated fats (like the well-known omega-3 fatty acids) which makes it healthy, but these fats also spoil faster (they have several double bonds which makes them oxidise easier).

* Lots of fish live in cold water, so the enzymes that break down fish meat are used to the cold. Storing fish at regular fridge temperatures doesn’t slow down rotting as well as storing meat in the fridge does. Storing fish on ice is better, but still not as effective as storing meat in the fridge (2-7 degrees Celcius).

* All animals store energy as glycogen in their muscles. In general, land animals don’t fight a lot before being killed, but fish do. So, fish deplete their glycogen supplies and turn it into readily available energy in the form of glucose in the bloodstream. Turns out bacteria love to feast on glucose.

* EDIT: u/th3cr1t1c pointed out one more important reason! One other thing to watch out for is that fish in the Scombridae family (includes mackerel, tuna, bonito/skipjack) release histamine into the flesh even after death. Thorough cooking does not mitigate this since it’s not a bacteria you’re trying to kill off… It’s when raw scombroid fish are handled at temperatures above 40ยบF at any point in the process from stream to table that it can be dangerous to consume.

Source: studying to become a Registered Dietitian Nutritionist. Most of this information is from The Science of Nutrition by Thompson, Manore & Vaughan.

EDIT: Changed RDN to Registered Dietitian Nutritionist, as indeed it’s not a generally known abbreviation. Also, figured out how to turn * into bullet points ๐Ÿ™‚

EDIT2: Wow, this blew up ๐Ÿ™‚ Thanks for all the replies and the awards, very much appreciated! I tried to answer to everyone to the best of my knowledge. Please let me know if I didn’t reply to you yet, my inbox suddenly was, well, fuller than it had ever been. Thanks to u/GLEN25801 for asking a question that I happened to know an answer to!

Not necessarily, if stored correctly fish dont go bad fast. Japanese sushi chefs take extreme care to prepare and store fish, gutting and removing moisture and blood from the fish stops it from going bad. Fresh fish gutted, cleaned the day its caught and wrapped in kitchen paper and refridgerated can be eaten raw for up to 1 week (can tell by smell if not suitable for eating raw or not). Some fish can last even longer, tuna is a good example where it can be aged for a long period. Almost all good sushi fish is gutted the day its caught.

But if not treated well, bacteria grows really fast in fish guts, and the blood/ and high moisture is perfect conditions for the fish to rot. Meat on the other hand has less moisture inside, usually cut so theres less blood inside. Some fishermen dont keep the fish cold enough after it is caught.

Another possible reason (purely speculation) is more people buy meat than fish, on average your supermarket will have fresher meat than fish.

Source: making sushi and watching sushi chefs on youtube

Tldr; fish has alot of water (duh), moisture/blood is good breeding ground for bacteria. Also fish guts have bacteria.

So at least part of the answer is how we treat fish on a commercial level. Like other commenters said some fish isn’t bled or cleaned until after it’s been dead for a while which encourages bacterial growth and decomposition. Then as the fish is processed it might get washed multiple times as it gets scaled, skinned, filleted, portioned and every time it gets washed the temperature rises and that warmer moist environment is great for spoilage.

On an entirely different level, some commercial fishing boats might be out at sea for several days at a time before returning with a catch, so add in the time down in a holding tank before certain fish ever make it to be butchered.

Alternatively if you get fish that’s bled and gutted soon after being caught and then butchered by a seafood specific market you tend to avoid these problems and fish can be good for just as long as meat.

Source- work for a seafood market that gets whole fish caught in this way and butchers them in house.

An answer I’m not seeing here is slaughter method. And there’s very easily observable evidence of this.

In America, beef is king. And it is treated as such. There are strict rules and regulations surrounding the slaughter of cows to be as humane and quick as possible. Typically this involves a calming introduction to the killing line (Temple Grandin method), a stunning phase where the animal is rendered senseless immediately (captive bolt gun typically) and then the animal is immediately bled and hung and processed. Almost all four-legged animals are then hung upside down at which point gravity can help break up the rigor mortis process. This conserves a great deal of the ATP in the animal’s cells as it has not struggled in death which slows the build up of lactic acid. The bleeding of the animal helps to flush and prevent bacterial growth and by all accounts this improves every facet of the animal’s meat in eating. This is why you can age a large primal cut of beef in some instances for over a year.

Perciform fish rarely get the same treatment, especially in the Western world. The vast, vast majority of fish are trawled in a massive net or purse seine, or they are gill netted where they struggle against thousands of pounds of other panicked fish or they die a slow, painful death on the line until they are hauled in. After this frenzied struggle they are typically dumped en masse on to a boat deck to suffocate to death and bake in the sun. This poor method of slaughter causes immense stress to the animal and does the exact opposite of what we discussed with beef. All ATP is consumed and converted into lactic acid, fish are rarely bled, they go immediately into rigor and then they form favorable conditions for bacteria to grow.

But in Japan, tuna is king. A quick Google search of ikejime or shinkeijime will show you how fish should be treated. They are hauled in quickly on a line, they are stunned or spiked to cause instant brain death and then their gills are cut while their heart is still beating to pump out all of the blood. Then they immediately go into an ice slurry to bring their body temperature down.

Properly slaughtered fish can then be aged for a great deal of time and they age much like a steak would with complex proteins breaking down into savory glutamic acid via favorable enzyme activity. This is what makes top tier sushi so delicious, it is simply impossible to develop those sorts of flavors in a fish that was killed that morning. Not that fresh fish is bad or tastes bad, but it’s just sort of been a Band-Aid signal of quality that never addressed the root issue of the problem, that being poor handling practices.

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Source: am chef. Love the fishes. American seafood system is fucked. Not surprised.

Two additional reasons sort of covered below:

When we kill a fish residual nervous static basically causes the meat to tense straight into a destructive activity that introduces lactic acid and other byproducts that begin the decomposition of the meat very quickly. This can be bypassed by the tricky but fascinating process of Ikejime which works by trying to kill the fish as quickly as possible and then breaking the neuroligical structures that allow this to happen.

Video here: [https://www.youtube.com/watch?v=TS4AM9mPX-8](https://www.youtube.com/watch?v=TS4AM9mPX-8)

The other reason is how we prepare the fish which;
1) removes all the natural defensive systems a fish has against bacteria (mucous, scales etc).
2) Then we wash it which introduces a rich easy layer for bacteria similar to how washing your hands without drying them just replaces one bacterial layer with another.

This guy has a fish butchery which goes into the ways we mistreat fish meat as we don’t think of it like other meat. He goes through the steps of avoiding all of that which allows you to do wild things like ageing fish meat. It’s spectacular what you can do when you don’t give the rotting process a massive head start.

His method involves using ice and not touching any of the scales, skin, no washing etc until it’s time to prepare for either aging or cooking.

fasctinating stuff where basically the stinky fishy smell is avoided and you can age fish meats for days or longer to make it a better tasting dish.

[https://fishbutchery.com.au/pages/about](https://fishbutchery.com.au/pages/about)%5Bhttps://www.mrniland.com/%5D(https://www.mrniland.com/)

really really good read on the topic if you get a chance to get a hold of the book.