Food can be fermented in the stomach, so some patients with pyloric obstruction can burp with a putrid odor after the obstruction. Food is fermented in the stomach, and when there is overeating, indigestion, gastrointestinal insufficiency, or pyloric obstruction, the food accumulates in the stomach, and a putrid odor can be smelled after hiccups, which is mostly due to the phenomenon of food fermentation. In addition, the food that is discharged into the intestinal lumen through gastrointestinal peristalsis can also ferment and continue to absorb certain nutrients in the intestinal lumen, after which the fecal residue is discharged from the anus through gastrointestinal peristalsis. The gastrointestinal tract is a cavernous organ, which has the function of accumulating food, as well as fermenting it and digesting it.