This sounds like a topic for a paper or a study.
If you are asking for a comparison of the time it takes for exposed food to spoil with the time it takes for the stomach to empty the same, unspoiled food when consumed, there are just too many variables for a definitive answer.
For example, we don't know the food involved, the environment it is in, or how spoilage is defined. Pests could immediately descend upon the food making it inedible. Yeast could start fermentation which could be evident in a couple hours. In a few hours, pathogenic bacteria could reach levels to make someone sick but would not be obvious. A fresh whole piece of fruit could be unaffected for days.
Concerning the time food normally stays in the stomach, different foods will take different times to get through the stomach based on the difficulty of digestion and the quantity consumed. Normalcy would also need some basis of definition.
the stomach is a harsh environment because the acid in it can go through a wall in a school
A persons stomach is normally about the size of their fist.
The stomach is an acidic environment. This helps with the process of digestion.
Is food in the stomach in the external or internal environment of the body?
Your stomach has a mucus lining that protects it from the acid. Cells located in your stomach produce this lining.
by using a chicken or pig stomach. put some gastric acid in the stomach and put the contents in that you normally eat.
Pepsin, which digests protein in the stomach, requires an acidic environment in order to work properly. Hydrochloric acid is stored in the stomach so that pepsin has a good environment to work in.
Lipase and amylase require an alkaline environment such as what is found in the duodenum of the small intestine. Pepsin functions in the acidic environment of the stomach.
The structure in humans that the digestive glands are comparable with crayfish are the glands that are found in the mouth and the stomach. These glands will secrete salivary amylase and HCI respectively to aid digestion in humans.
Antacids neutralise the acid made by your stomach. They are normally used where it is helpful to neutralise the acid made by the stomach. I.e, for acid reflux which causes heartburn. They product normally works in the area between the Sphincter at the top of the stomach and the Gut located at the base of the stomach.
"More acid" is pretty vague, because it's not usually the amount of acid that matters, it's the "strength" (first pKa) and concentration that makes a difference. Stomach acid is much more acidic than anything a person would normally drink, though. Stomach acid has a pH roughly comparable to straight lemon juice; black coffee is actually about 1000 times less acidic than either.
Its like any other transplant you hear of, except with a stomach. Doctors surgically remove your stomach and replace with another healthier one.