Maodu is also called tripe, commonly known as tripe, which is actually the flap stomach of cattle. Cattle is a ruminant, which is different from other domestic animals. The biggest feature is that it has four stomachs, namely rumen, reticular stomach (honeycomb stomach), flap stomach (louver stomach, commonly known as bovine louver) and abomasum. The first three stomachs have no gastric glands and do not secrete gastric juice, which are collectively called forestomachs. The fourth stomach has gastric glands, which can secrete digestive juice, similar to the stomachs of pigs and people, so it is also called true stomach. There are also two kinds of beef in venetian blinds. Those who grow up eating feed are black, and those who grow up eating food crops are yellow. Tripe is not a plant, but a fresh tripe with black surface. White cowhide is bleached and frozen food.

Pay attention when buying hairy belly, especially white hairy belly, which will turn white after soaking in hydrogen peroxide and formaldehyde for three or four days. When making water-based products, some unscrupulous traders first soak in industrial caustic soda to increase the volume and weight, and then add formaldehyde and hydrogen peroxide in proportion to stabilize the volume and weight and keep the surface fresh and bright. The hairy belly brewed with industrial caustic soda is full and watery. The use of formaldehyde can make the hairy belly more crisp and taste good. Hydrogen peroxide can corrode human gastrointestinal tract and lead to gastric ulcer. Long-term consumption of hairy tripe soaked in these toxic substances will lead to diseases such as gastric ulcer, and in severe cases, it can cause cancer.

If the hairy belly is white, more than it should be, and the amount is large, you should avoid buying it. The hairy belly soaked in formaldehyde will lose its original characteristics. Hands are easy to break when pinched, and will shrink quickly after heating, so avoid it.

You can also add a little hairy belly to a small glass, soak it in water, then take out the hairy belly, tilt the glass, carefully add a little concentrated sulfuric acid along the glass wall, and divide the liquid into two layers to avoid mixing. If a purple ring appears at the junction of the liquid surface, it proves that formaldehyde is mixed in the hairy belly.

It is for this reason that the black one is more expensive than the white one!