Question

The human body can reuse some of the enzymes found in raw fruits and vegetables. Why is this not the case for cooked fruits and vegetables

Answer 1

is this for homework or a test or do you just want to know?

Answer 2

Proteins are usually not stable at high temperatures (there are exceptions to this) making them unfold from their native structure, this process sometimes being irreversible. Enzymes are catalytic proteins in their native structure making them catalyze some chemical reaction. A usual graph of this activity rate \(v\) as a function of temperature usually assemble this form:
You can see the rate is increasing with temperature to some point until it makes a dead drop. This is where so much of the protein begins to denature so the rates. We call the process going from a native to unfolded state for denaturing and may be as previously said irreversible.