What are the parts of crayfish that you cannot eat? The shrimp thread, the shrimp roe, or...

In summer, crayfish becomes the "king of midnight snacks". At night, call a few friends and start the nightlife. Spicy crayfish, thirteen-spice crayfish, garlic crayfish, steamed crayfish, braised crayfish... There are all kinds of crayfish, each of which is delicious.

However, although crayfish are delicious, there have been constant controversies surrounding them. Some people say that crayfish have no roe, which is all shit, and eating the roe is like eating shit; others say that the shrimp thread is all shit and must be removed...

Just a few days ago, someone left a message asking me to talk about whether the roe of the shrimp should be eaten. Today, let's talk about what part of crayfish should not be eaten.

01. Shrimp threads are dirty and cannot be eaten?

The shrimp thread is the black or green line you see when you peel the shrimp skin and break open the shrimp back.

When eating crayfish, the thing that most people dislike is probably the shrimp thread. People always say that it is full of shrimp feces and cannot be eaten. In our family, every time we buy crayfish, my wife will take great pains to remove the shrimp thread.

In fact, the shrimp thread belongs to the shrimp's digestive tract, and the black stuff inside is naturally the excrement that the crayfish has not yet excreted from the body. Yes, it is what you are talking about (you know what I mean).

Theoretically, it is not clean, and many people feel uncomfortable with it, so they will remove it when handling shrimp. However, if you are really busy, or find it troublesome to handle, or eat it accidentally... it's okay. Because the crayfish is cooked, the bacteria in the shrimp thread will be killed by high temperature, and it is safe. Even if you eat it, it will be further digested and metabolized by our digestive tract. It's just that it may taste worse.

In fact, animal excrement is not as scary as everyone imagines. For example, the world-famous Kopi Luwak is a coffee made from the feces of civet cats that eat coffee beans. Because the coffee made from coffee beans fermented in the stomach of civet cats has a unique flavor, Kopi Luwak has become a hot commodity in the international market, with a price of several hundred dollars per pound.

In addition, ambergris is a precious seafood that contains ambergris and is often used to make perfume. It is the intestinal secretion of sperm whales. Some sperm whales will spit it out, while others will excrete it from the intestines.

Of course, if you are really worried, you can remove the shrimp thread, or keep the crayfish in clean water for a few hours after buying them home, so that the crayfish can excrete their waste.

02. Shrimp roe is shit and cannot be eaten?
There has always been a "controversial" saying about crayfish, saying that there is no "yellow" in the crayfish head, and the yellow stuff in the shrimp head is "shit", not shrimp roe at all, and cannot be eaten. So, does crayfish have shrimp roe? What is the yellow stuff in it, and can it be eaten?

Although crayfish are small, they have all the organs. The shrimp body and shrimp balls we usually eat are just its tail. The crayfish's brain, heart, gonads, digestive glands, stomach, antennae and other miscellaneous organs are all concentrated in the head.

The "yellow" in the shrimp head is neither shrimp eggs nor shrimp feces, but the crayfish's digestive gland, that is, the hepatopancreas, which mainly includes the shrimp's liver and pancreas. Its main function is to help crayfish digest food.

Some studies have analyzed the nutrition of shrimp roe and found that it is rich in protein and unsaturated fatty acids, among which fatty acids are its main feature, such as DHA, EPA, etc., which are good for our health. As for the heavy metals that many people worry about, in fact, regular crayfish are within the safe range. Therefore, shrimp roe can be eaten with confidence.

However, the problem with crayfish is that they are not big in size, and most of the time the crayfish we eat do not contain much roe, and they are not particularly convenient to eat. If you don’t choose them well, you will also eat other not-so-good internal organs, such as gills. Crayfish rely on gills to filter impurities in the water, which can easily accumulate toxins.

Therefore, if you like eating shrimp roe, don’t mind the trouble, and are good at eating it, then it is worth eating shrimp roe. However, if you really find it troublesome, you don’t have to feel bad if you don’t eat it. If you don’t like eating it, you don’t have to force yourself.

03. Shrimp heads are prone to accumulating heavy metals, so they cannot be eaten?

Regarding the delicious crayfish, there is also a saying: shrimp heads are easily enriched with heavy metals and cannot be eaten?

In the previous popular variety show "A Longing for Life", Qi Wei and He Jiong were peeling crayfish together. She saw Teacher He throw away the shrimp heads, so she asked: "Do you really not eat (shrimp) heads?"

It has been said that crayfish live in dirty water, have dirty heads, and are prone to accumulating heavy metals. Is this true? In fact, you may have misunderstood crayfish.

Crayfish are indeed very adaptable to the environment and can survive in heavily polluted waters. However, they are also afraid of dirt. If the water quality is too poor, crayfish will not only not grow well, but may also die. Moreover, most of the heavy metals they ingest are transferred to their shells. As they continue to grow and shed their shells, these heavy metal toxins are removed from the body. Therefore, the heavy metals in normal crayfish do not exceed the standard.

As for the head of crayfish, most of the heavy metals in the body of crayfish are concentrated in the gills and internal organs, and the gills and internal organs are mainly concentrated in the head, so the head of crayfish is indeed more likely to be enriched with some heavy metals. But this does not mean that the head of crayfish cannot be eaten.

In fact, as long as the shrimps are farmed in a formal manner, they can be eaten with confidence.

Heavy metals in shrimps mainly come from water and feed. Generally speaking, the content in the viscera (shrimp head) and shrimp shells is higher. However, if the water quality and feed are too poor, the shrimps cannot survive. Therefore, the heavy metals in regular farmed crayfish are generally within the safe range. According to the current survey data on aquatic products such as crayfish in my country, the risk of heavy metals in eating crayfish is still very small.

Moreover, consumers mainly eat crayfish in the summer. The consumption in a short period of time may be relatively large, but the average intake throughout the year is still relatively small. As long as you don't eat it every day, every meal, or all year round, there is no need to panic. Moreover, the heavy metal enrichment of farmed shrimps and crabs is generally mild, and it is generally not a concern for adults. If you really have doubts, then concentrate on eating the shrimp meat. Anyway, there is less meat on the head and it is not very delicious.

Of course, heavy metals have a greater impact on children, pregnant women and the elderly, so it is a better choice not to eat shrimp heads.

04. How to eat crayfish in a healthy way?

So, how to cook and eat crayfish safely in the hot summer? Although crayfish are delicious, they may also be contaminated by pathogenic bacteria and parasites. It is recommended that you:

1. If you buy crayfish yourself, it is recommended that you try to go to a regular market to choose fresh crayfish.

If you find dead crayfish, try not to buy them, because dead crayfish are more likely to be contaminated by bacteria. When eating, it is best to soak them in clean water for half an hour, then remove the intestinal thread, clean the shrimp tail, and then cook them thoroughly.

2. If you are outside, try to go to a regular restaurant to eat crayfish, and try not to go to roadside vendors.

It is particularly important to fully heat and cook crayfish before eating, so as to kill any bacteria and parasites that may be present. If you can't finish eating the crayfish, you can refrigerate it and seal it, but remember to fully heat it when you take it out to eat the next day.

3. Eat in moderation, don’t eat too much.

Crayfish is really delicious. I can't get enough of it every time I eat a big bowl of it. I will buy several kilograms of it myself. It is recommended to eat it slowly, because many crayfish now have a stronger taste to make them delicious, such as spicy crayfish, which has a lot of oil and salt. Eating too much is not healthy.

References:

[1] Peng Qian. Heavy metal pollution in crayfish and human health risk assessment[D]. Jiangsu: Nanjing University, 2015.

[2] Yan Zhi. Risk monitoring of aquatic product quality and safety and heavy metal risk assessment of crayfish in Yangzhou[D]. Jiangsu: Yangzhou University, 2018.

[3] Wang Hui, Mao Weifeng, Jiang Dingguo, et al. Assessment of exposure to four common heavy metals in aquatic products of Chinese residents[J]. Chinese Journal of Food Hygiene, 2019, 31(5): 470-475.

[4] Chen Shengjun, Li Laihao, Yang Xianqing, et al. Research progress on the sources and risk assessment of aquatic product safety in my country[J]. Food Science, 2015, 36(17): 300-304.