There are four reasons for the blackening of the yolk of the female crab:

1, mother crab

The yolk of the mother crab is actually the ovary and digestive glands of the mother crab, the fertilized egg of the crab develops for a period of time in the body of the mother crab, and when it is about to be discharged, the whole yolk of the crab will appear to be discoloured, usually in black or grey, and it is mostly the melanin, anthocyanin and other ingredients, which can be eaten.

2, crab stomach swelling crab stomach in the top of the crab back shell, is a triangular capsule, which contains a lot of sediment dirt, is not edible part.

If a crab eats a lot of things before it is born, its stomach will swell up. After steaming, it will look like a big piece of black substance. In fact, if you remove the crab's stomach, you can eat it normally.

3. The color of the membrane inside the shell.

There may be a layer of black film in the shell of female crabs, which covers the crab yolk and makes the yolk look black, in this case it is harmless to eat it directly.

4, dead crabs

Eat hairy crabs, must eat live crabs. If the crab is cooked after it is dead, it is not edible. The toxins and parasites in the body of hairy crabs spread rapidly after death. When this kind of crab is steamed again, the crab yolk will be bruised and black, which is not suitable for consumption.

Extended information:

Selection of female crabs

1, look at the abdomen

Bazaar crab sellers summarized a sentence: male crabs wearing thongs, female crabs wrapped in diapers, which describes the male and female crabs is very spot on! The first thing you need to do is to turn the crab over and look at the abdomen to understand that the shells on the abdomen of the male crab are pointed, and the female crab is rounded.

2, look at the bottom

Judging the crab male and female there is a way to look at the bottom, this place is the crab's genitals, the female crab's genitals are round, while the male crab's genitals are pointy, the feeling of the female crab and round can not be separated, the male crab and pointy can not be separated, huh?

3, look at the umbilicus

This method is also very good to distinguish, the discernment part of the crab abdomen that cover the following, if the more pointed more narrow is the male crab, if the more wide more round is the female crab.

4, look at the content

This method is to open the crab's shell, if there is a yellow flow, that is the crab yolk, is definitely a female crab, if the flow is white liquid, that is the crab paste, must be a male crab.

5, selection method

Buy crab to buy back green and shiny, the same size, the heavier the better, because of this crab meat, like to eat female crab in the selection should pay attention to look at the tail, to pick the tail is thicker, because the tail is thicker, which means that the female crab crab yolk is more.

6, eat the season

Eat crab season every year is generally in the lunar calendar August to September, earlier than this period, the crab has not grown mature, relatively small, meat is not much, so you can choose to eat the female crab in August every year, this period of crab yolk is more, and in the lunar calendar in September, when the crab paste is more, to eat the male crabs is better.