Why is fish always fishy? Why does the fish look fishy

Fishy Smell Fish is a nutritious and delicious food, but the fishy smell is annoying. Why does it smell fishy? It turns out that the fishy smell comes from the metabolism and putrefaction of fish proteins, a substance called trimethylamine, which is liquid and easily soluble in water.

The intensity of the fishy smell is related to the concentration of trimethylamine. Usually make fish with an appropriate amount of cooking wine, vinegar and ginger to remove the fishy smell. Fish are fishy because a large part of the total nitrogen in the final products of marine fish metabolism is in the form of trimethylamine oxide, volatile base, betaine, choline, etc.

These nitrogenous substances in fish are generally soluble in water, so the fish can be stewed and boiled to reduce the fishy smell. However, the volatility of water and the penetration of the fish body are not as good as some organic solvents, such as ethanol, acetic acid, ethyl cheese, etc., so when cooking fish, add some vinegar (mainly containing acetic acid), and then put some wine (mainly containing ethanol), the effect of deodorization is excellent. When vinegar is added, some of the substances that cause the fishy smell in the fish oil will also become soluble salts, so that the fishy smell is reduced, and the vinegar and wine have an aroma, and they also have the effect of pressing the fishy with incense.

In addition, adding vinegar when cooking fish can also hydrolyze the rich protein in the fish meat under the action of acid, which not only produces many amino acids with umami characteristics, but also makes the bones and bones of the fish soften and fluff during the cooking process and convert them into calcium acetate. Calcium acetate is easily soluble in water, which is convenient for the human body to absorb and improve the utilization rate of calcium.

It turns out that there is a mucus gland in the fish, and the mucus secreted by this mucus gland contains a fishy smell of trimethylamine. At room temperature, trimethylamine is easy to volatilize from the mucus and disperse in the air.

There is a mucus gland in the body of the fish, which has a fishy smell.

1.Open the abdomen of the fish, you can see that there is a layer of black membrane in the abdomen of the fish, this layer of black membrane is the place where the fishy smell is concentrated, and it should be cleaned up when handling the fish, in addition, the fish blood is also the place where the fishy smell is concentrated, and it should be cleaned with clean water.

2.The processed fish can be put into cooking wine.

Vinegar and ginger marinated.

After a while, wash and dry the fight;

3.You can put the fish in tea for 5 minutes, and then wash it, and the tea can also remove the fishy.

I. .The freshness of the fish itself.

In ordinary life, there will be such an experience, just bought fresh fish does not smell strong, but with a long time or buy some frozen fish that have been dead for a long time and are not fresh, its fishy smell is very strong.

2. Improper storage can also make the fish fishy.

The freshness of the fish has a lot to do with the fishy smell, so after the fish stops life activities, if the next preservation efforts are done well, then the fishy smell will be relatively light, and if the preservation measures are not done well, the fish will increase the fishy smell in the process of spoilage.

Fish have a fishy smell, but freshwater fish and marine fish have a different fishy smell. The fishy smell of freshwater fish is due to the presence of humus in the living environment, so actinomycetes can enter the bloodstream through the gills of the fish, causing them to contain a fishy smell. The fishy smell of marine fish is due to the fact that it contains trimethylamine oxide, which will become trimethylamine after being decomposed by microorganisms after the fish dies, so it will emit a fishy smell.

1. Why does it smell fishy?

Fish have a fishy smell, but the fishy smell of freshwater fish is not the same as that of marine fish. Since marine fish live in seawater, their own osmotic pressure is lower than that of seawater, so they will constantly lose water, and in order to prevent water loss too quickly, some amino acids as well as amines are needed to fill the cells, which contain trimethylamine oxide. The substance itself has no taste, but when it is broken down by microorganisms, it turns into trimethylamine, giving off a fishy smell.

The fishy smell of freshwater fish mainly comes from the environment, because they live in ponds, lakes and rivers that contain humus, which contain a large number of microorganisms, among which actinomycetes can enter their bloodstream through the gills, causing them to have an earthy smell.

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There is a white line on each side of the fish's body, called "fishy gland", and the mucus secreted by this mucus gland contains a fishy smell of trimethylamine. At room temperature, trimethylamine is easy to volatilize from the mucus and disperse in the air. Since the fish scalp contains the most components such as trimethylamine, the head of the fish is the fishiest part of the fish.

Trimethylamine is not present in fresh fish! There is a large amount of trimethylamine oxide in the body of fish, and trimethylamine is formed under the action of microorganisms and enzymes. The main components of stinky fish are hydrogen sulfide, ammonia, methyl mercaptan, carcassion, cadaverine, indole, tetrahydropyrrole, hexahydropyridine, etc.

Therefore, when the fishy smell on the fish is strong, it is possible that the fish has spoiled. Trimethylamine and others are easily soluble in ethanol. Therefore, adding some wine when cooking fish can make trimethylamine dissolve in ethanol and volatilize after heating.

After cooking in this way, the fish no longer has a fishy smell. In addition, ginger, green onions, garlic, etc., are rich in volatile organic compounds, which have the same effect as wine. Therefore, ginger, green onions, garlic, and wine are commonly used when cooking fish.

The earthy smell of fish is related to the environment in which they live. Chen Shunsheng, director and professor of the Department of Aquatic Product Processing and Storage Engineering of the School of Food Science and Technology of Shanghai Ocean University, said that freshwater fish such as carp, grass carp and silver carp generally have an earthy smell, which is closely related to their growth environment. Freshwater fish generally grow in ponds, rivers, and lakes, where there is more humus and are suitable for microbial reproduction.

Bacteria with an earthy smell attach to plankton such as diatoms and cyanobacteria, as well as some aquatic plants, and freshwater fish ingest these substances through the food chain, which then enter muscles, blood, and tissue cells; However, there is obviously less humus and plankton in large water bodies such as large rivers, large rivers, and reservoirs, and the earthy smell of fish living in them is also relatively weak.

Regarding the impact of fishy smell on the human body, Chen Shunsheng said that the composition of fishy smell is very complex, but it is harmless to humans, and there is no evidence to support that the earthy smell of fish is related to drugs.

There are many ways to get rid of the fishy smell, the simple ones are: wash the river fish, put it in cold water, and then pour a small amount of vinegar and pepper to remove the fishy smell; Or add half a tael of salt to a basin of about five liters of water, soak the live fish in the salt water for an hour, the salt water will soak into the blood through the two gills, and the earthy smell will disappear; Even if it is a dead fish, soaking it in salt water for two hours can remove the earthy smell; A fish of 500 1000 grams, mix a cup of strong tea into weak tea, soak the fish for 5 10 minutes, and the fishy smell will disappear.

In addition, freshwater fish such as crucian carp, carp, and silver carp have a heavier fishy smell than marine fish, and these fish have a watershed line on both sides of the fish, which is also called a fishy line. When handling fish, remember to pull out these two lines to reduce the fishy smell of the fish. Here's how:

If you make a cut about a finger's width behind the gills of the fish, you will see a white thread in the flesh, which is called a fishy thread. Cut a knife at the finger width of the fish tail, you can also see this fishy line, you can grab the head of the fish from the head of the fish, slowly pull it outward with your hand, and pat the fish body with the back of the knife while pulling, and soon the fishy line can be taken out, and the fishy line on the other side of the fish body is also pulled out according to this method.

The fishy smell of freshwater fish is a different story. Freshwater fish do not need trimethylamine oxide to balance osmotic pressure, but there are many external forces that cause them to smell fishy in the environment in which freshwater fish live.

Freshwater fish mostly live in ponds, rivers or lakes that contain a lot of humus, and these environments are also a habitat for microorganisms and algae.

Fishy smell refers to the fishy smell of newly purchased fish. The fishy smell is mainly the smell of trimethylamine in the fish body, and there is also the fishy smell in fish oil. Dead fish can also produce a fishy odor when their body fat is oxidized and rancid.

Fish meat contains a lot of umami trimethylamine oxide, this compound is easily reduced to trimethylamine after the fish dies, and trimethylamine is completely different from trimethylamine oxide, which not only makes the fish lose its umami, but presents a fishy smell. The body fat of the fish contains whole acids, which has a special fish oil smell and also presents a fishy smell.

Fish is a nutritious and delicious food, but the fishy smell is annoying. Why does it smell fishy? It turns out that the fishy smell comes from the metabolism and putrefaction of fish proteins, which are substances called trimethylamine and piperidine, which are gases and are easily soluble in water.

Piperidine is a liquid with ammonia odor, and the intensity of fishy smell is closely related to the concentration of trimethylamine.

Sugar deodorization.

Add an appropriate amount of sugar when cooking fish to remove the fishy smell.

Orange peel deodorization.

When grilling fish, add a little orange peel to remove the fishy smell.

Liquor deodorization method.

After the fish is washed, it is applied to the whole body with white wine, and after 1 minute, it is washed off with water to remove the fishy smell.

Red wine deflavoring.

First, the fish is disemboweled, marinated in red wine, and the tannic acid and aroma in the wine can eliminate the fishy smell.

The fishy smell of freshwater fish is due to the presence of humus in the living environment, so actinomycetes will enter the bloodstream through the gills, resulting in a fishy smell in freshwater fish. The sea laughing sedan chair is because there is a white gland on both sides of the body, called the mucus gland, the mucus gland can secrete a large amount of mucus, and this mucus contains a fishy smell of trimethylamine, at room temperature, trimethylamine is easy to volatilize from the mucus, so the sea fish also have a fishy smell. <

The fishy smell of freshwater fish is due to the presence of humus in the living environment, so actinomycetes will enter the bloodstream through the gills, resulting in a fishy smell in freshwater fish. Marine fish are because there is a white gland on both sides of the body, called the mucus gland, the mucus gland can secrete a large amount of mucus, and this mucus contains a fishy smell of trimethylamine, at room temperature, trimethylamine is easy to volatilize from the mucus, so the sea fish also have a fishy smell.