under the condition of fresh-keeping and cold storage, some water gurgling will produce formaldehyde, and its formaldehyde content will gradually increase when its freshness gradually decreases, but under the condition of natural decay, the formaldehyde content of water gurgling will drop sharply with the high degree of corruption of the body. The formaldehyde produced by Shuichan itself is the same as that artificially added, but there is no good way to remove it because the formaldehyde content is gradually produced. However, according to the previous experiments of some experts, it is not completely proved that the formaldehyde content will be reduced after boiling the water for several minutes, and some of them can even reach more than 4%, and there has never been an example of death or pathological changes caused by eating water. As long as you don't eat much, there is basically no problem. When buying water gurgling, try to buy fresh water gurgling. Try not to eat it if its freshness drops or it is kept for too long.