SP was obtained from Phichit Agricultural Research and Development Center. Sodium hydroxide and potassium tartrate were purchased from UNIVAR (Ajax Finechem, Australia). D-glucose was obtained from BiomarkTM Laboratory, India. Yeast extract was purchased from Lab M Limited, UK. PGO Enzyme Preparation, ortho-Dianisidine dihydrochloride, and 3,5 dinitrosalicylic acid were provided by SIGMA-ALDRICH, USA.