The primary enzyme that speeds up the breakdown of protein in food is pepsin.

Here's why:

* Pepsin is a protease, which means it's an enzyme specifically designed to break down proteins. It's produced in the stomach and works best in the acidic environment there.

* Other enzymes also play a role in protein digestion, including:

* Trypsin and chymotrypsin: These are proteases produced in the pancreas and released into the small intestine.

* Carboxypeptidases: Also produced in the pancreas, these enzymes break down the end of protein chains.

While all these enzymes contribute to protein breakdown, pepsin is the key player in the initial stages of digestion within the stomach.