Here's why:

* Glycerol tristearate is a triglyceride, a type of fat or oil. It's composed of a glycerol molecule (a three-carbon alcohol) with three stearic acid molecules attached.

* Hydrolysis is a chemical reaction where water is added to break down a molecule. In the case of glycerol tristearate, water reacts with the ester bonds linking the stearic acid molecules to the glycerol.

* This reaction breaks the bonds, releasing glycerol and three molecules of stearic acid.

Reaction Equation:

```

Glycerol tristearate + 3H₂O → Glycerol + 3 Stearic acid

```

This reaction is important in the digestion of fats. When you eat fats, they are broken down into glycerol and fatty acids (like stearic acid) in your digestive system.