There are a number of different assays to determine how well an enzyme will hydrolyze protein to peptides and amino acids. They will vary based on the pH of the reaction or the substrate.

The HUT assay method is often used for fungal proteases with acid pH optimums.

The PC assay is often used to determine the activity of bacterial proteases that have a neutral pH optimum.
Assay – Protease PC

Other protease assay methods are found in the section on Papain and Bromelain.