Recently, there has been an upsurge of "testing the formaldehyde content of edible fungi with indoor formaldehyde detection kit" on the Internet. Many We Media bloggers have "ended" the evaluation and released the detection results in the form of video. In these videos, many bloggers claim that formaldehyde has been detected on such edible fungi as shiitake mushroom, white jade mushroom and golden needle mushroom. After seeing this, many viewers are shocked and have a fear of edible fungi. They are afraid that eating these edible fungi containing formaldehyde will cause cancer, and they have threatened not to eat edible fungi any more. So, is it scientific to use indoor formaldehyde detection kit for food detection? Does the edible fungus sold on the market contain formaldehyde? What should we pay attention to when buying and eating food? Today we will talk about these things. Formaldehyde is a colorless organic compound with strong pungent smell. Formaldehyde can be divided into exogenous formaldehyde and endogenous formaldehyde according to the production route. Exogenous formaldehyde refers to formaldehyde added to commodities by illegal means. In order to maximize the economic benefits, some unhealthy businesses used formaldehyde as a preservative and bleach to prolong the storage time of edible fungi and prevent them from rotting. These illegal acts really have a negative impact on the food safety of the people. However, as the concept of health and environmental protection has become increasingly popular and relevant national laws and regulations have been gradually improved, this phenomenon has basically disappeared. According to the current Food Safety Law of the People's Republic of China, the Law of the People's Republic of China on the Quality and Safety of Agricultural Products, the Standards for the Use of Food Additives and other relevant provisions, formaldehyde shall not be used as food processing aids for production and operation, and it is illegal to add formaldehyde in food in any way. At the same time, various supervision departments in China attach great importance to food safety issues, and relevant staff will detect edible fungi sold on the market and severely crack down on illegal formaldehyde addition. In addition, formaldehyde, as a compound with a special pungent smell, is not very secret and is easy to be found by ordinary consumers. Nowadays, few businesses are willing to take risks to try the law, and the possibility of adding formaldehyde illegally is very small. Therefore, in the above video, the formaldehyde detected from edible fungi can be basically determined not to be exogenous formaldehyde. Since the trace formaldehyde produced during biological metabolism is not exogenous formaldehyde, the formaldehyde in edible fungi in the video can only be endogenous formaldehyde. Endogenous formaldehyde is produced in the process of biological metabolism. At present, many scientists have found that the edible fungus itself will produce trace formaldehyde according to the changes in the natural environment. For example, Japanese scholars have studied the formaldehyde content and its formation mechanism in shiitake mushroom as early as the 1970s. Therefore, it is normal for many bloggers to detect trace formaldehyde in edible fungi recently. Since endogenous formaldehyde is produced by organisms during metabolism and naturally exists in many foods, will they be harmful to human body? The answer is no. Because under normal circumstances, the formaldehyde produced by edible fungus is very little, and people will wash it before eating, and the formaldehyde contained in it is very soluble in water, which is easy to be washed away