Abstract: Streblus asper (Kesinai) leaf contains a protease, which can be used to coagulate milk. This extract however, has a undesirable, very dark brown colour due to enzymatic browning. Several browning inhibitors were used in this study with the objective of preventing browning during extraction of the protease. Ascorbic acid at 10 mM concentration reduced browning and polyphenol oxidase (PPO) activity by 41 percent and 10 percent. The protease specific activity and coagulation activity were 88 percent and 143 percent. Citric acid at 10 mM concentration reduced browning and PPO activity by 64 percent and 72 percent. However, it has reduced protease and milk coagulation activity by 76 percent and 65 percent, respectively. L-cysteine inhibited browning and the minimum threshold was found to be 5 mM. It improved protease activity and milk coagulation activity, but did not inhibit PPO activity. Sodium metabisulphite was found to be more effective inhibitor of Streblus asper browning and the minimum threshold for inhibition was 2 mM. Metabisulphate treated extract has higher protease activity, milk coagulation activity and lower PPO activity compared to extracts prepared using other chemicals and to the control.