How do astronauts eat in space?
swallowing of food or water from mouth to stomach is done with the help of peristalsis action of esophagus

Then rhythmic, unidirectional waves of contractions will work to rapidly force the food into the stomach. This process works in one direction only and its sole purpose is to move food from the mouth into the stomach.

In earth it also happens but it is assisted with gravity but in space Peristalsis action is the only process by which food or water is taken to stomach .