Method for testing pH and catalase in liver: I am looking for materials and method for a

Method for testing pH and catalase in liver: I am looking for materials and method for a
This online resource looks at the digestive system.
Year 12 Biology (Rennet). Dear Sir or Madam, I am just wanting to source Rennet for Yr 12 Bio experiments. We have previously used 'Simply Junket' powder, which is now very expensive.
Enzyme preparation for experiments: Could you provide guidance in the correct preparation of enzymes such as trypsin, pepsin and amylase for enzyme digestion practical activities?