Dead crabs cannot be eaten, so why do supermarkets still sell frozen crabs?

It's crab season again

The crabs in autumn are tender and have rich roe.

It is the "favorite" of many friends.

But the "accident" caused by crabs

Not a few

When it comes to crabs, we often hear that "crabs cannot be eaten after they die". Why is that? But we see some frozen, thawed, or even disassembled crabs in supermarkets. Why is that?

Today we will study:

Why can’t dead crabs be eaten?

What's up with the frozen crabs in supermarkets?

What are the precautions when eating crabs?

Dead Crab

Song Jinlong, an associate researcher at the Chinese Academy of Fishery Sciences, said that there are two main factors to determine whether crabs are risky to eat after they die:

The first point is to see whether the total number of colonies increases rapidly and whether it contains pathogenic bacteria . The second point is to see whether harmful biogenic amines such as histamine, cadaverine, and putrescine are produced in the body after the crab dies .

The researchers purchased two experimental samples, hairy crabs and swimming crabs, in the market. They took samples from the two types of crabs when they were fresh and at different time periods within 24 hours after death, and determined the total colony count and harmful biological amines contained in them.

The results showed that the total colony count of the hairy crab increased dramatically from the time it was just dead to two hours after death. The total colony count increased by 22% in two hours and 55% in 24 hours. The hairy crab had a noticeable stench one day after death .

Experimental data showed that the total bacterial count in swimming crabs began to surge 24 hours after death, while harmful bioamines appeared in hairy crabs 5 hours after death.

Experts say that biogenic amines are normal active ingredients in organisms, and are classified into: putrescine, cadaverine, spermine, histamine, tryptamine, etc. Take histamine as an example. Trace amounts of histamine have important physiological functions in biological cells, but when the human body ingests excessive amounts of histamine, it can cause food poisoning, and in severe cases, it can be life-threatening .

Histamine is an allergic poison, which can also be said to be allergic food poisoning. Don't think that it's okay to eat only a little dead crab meat. People who are allergic to histamine can cause a reaction even if they eat a bite. For example, some people will have symptoms 10 minutes to 3 hours after eating dead crabs, such as flushing of the cheeks, flushing of the chest and skin all over the body, conjunctival congestion, as well as headache, dizziness, chest tightness, general fatigue and irritability .

Fresh frozen crabs in supermarket

We often see fresh frozen crabs in the market. Since they are also dead crabs, are there any safety risks in eating fresh frozen crabs?

Some of the sea crabs caught in deeper waters with nets or crab cages, such as the swimming crab, the swimming crab, the Japanese crab, the rusty crab, etc., will be transported alive to the market and the dining table; others will be frozen on board or at the port when conditions are not suitable for live transportation, and will be quickly frozen before the crab dies to ensure that no bacteria will grow after death, thus avoiding corruption and deterioration . This is why we see fresh sea crabs sold in supermarkets.

In this case, once the frozen dead sea crabs are thawed, they must be eaten as soon as possible, otherwise there is still a risk of spoilage .

Dead crabs in supermarkets and markets are usually either dead after being transported to the market alive and then frozen or chilled for emergency treatment, or frozen crabs are thawed and sold. However, although frozen crabs can be eaten, the taste and flavor will become worse as the freezing time increases. Therefore, relatively speaking, fresh crabs are more suitable for consumption than frozen ones.

Another type of dead crabs is "cooked frozen". After the crabs are caught, they are quickly cooked while they are still alive, and then frozen at low temperatures. The crabs treated in this way are already cooked, so they can be eaten directly after thawing. This method is more common in imported shrimps and crabs, such as snow crabs, king crabs, brown crabs (common zodiac crabs), Arctic shrimps (northern long-browed shrimps), etc. Similarly, they cannot be kept for a long time after thawing and must be eaten as soon as possible.

Precautions

1. Steam the crabs for 20 minutes after the water boils.

Boiling crabs in water will cause the deliciousness and nutrients in the crabs to diffuse into the water, thus destroying the delicious flavor and nutritional value of the crabs. Therefore, steaming is generally used for cooking, and the temperature of steaming is higher than that of boiling, which not only cooks the crabs faster, but also kills the microorganisms and parasites on the crabs . Steaming crabs can also keep the crab body intact, making its color ruddy and bright, and at the same time, it reduces the contamination of the crab meat by the contents of the crab's gastrointestinal tract.

However, it is important to note that the crabs must be cleaned before steaming. Hold the two sides of the large cover at the base of the two rows of crab legs with your hands (to prevent pinching your hands), and then use a toothbrush to scrub all the places you can reach. When steaming crabs, be sure to steam them for at least 20 minutes after the water boils, so that the bacteria can be killed only when they are cooked thoroughly .

2. Eat crabs with some stomach-warming food

Xu Huichao, from the Nutrition Department of the Affiliated Hospital of Shandong Jining Medical College, pointed out that crabs need to be eaten with stomach-warming foods, such as minced ginger, vinegar, and rice wine. This is related to the traditional Chinese medical belief that crabs are cold in nature.

In China, rice wine and crabs have been considered a perfect match since ancient times. Although crabs are delicious, they are cold in nature and eating too much can easily hurt the stomach. Rice wine has the effect of promoting blood circulation and warming the stomach, and is mild in nature. Therefore, it has always been considered the best choice to remove the cold when eating crabs.

3. Crabs are delicious, but don’t eat too much

The cholesterol content of crabs is high, especially the crab roe, so crabs should be eaten in moderation and not too much, otherwise it will easily lead to high cholesterol. In addition, crabs are cold foods, so people with weak spleen and stomach should not eat too much.