Stability Test of Partially Purified Bromelain from Pineapple (Ananas comosus (L.) Merr) Core Extract in Artificial Stomach Fluid

摘要

This study aimed to isolate and purify bromelain from pineapple core (Ananascomosus (L.) Merr) accompanied by a stability test of its enzyme activity in artificial gastric juice. Purification steps start with fractionation by a precipitation method were carried out stepwise using several concentration of ammonium sulfate salt, followed by dialysis prosess and ion exchange chromatography on DEAE-cellulose column. Each step of purification produced an increasing specific activity in enzyme fraction, starting with crude extract, respectively: 0.276 U/mg; 14.591 U/mg; and 16.05 U/mg. Bromelain fraction with the highest level of purity was obtained in 50-80% ammonium sulphate fraction after dialyzed in the amount of 58.15 times compared to the crude extract. Further purification of the enzyme by DEAE-cellulose column produced bromelain which had a purity level 160-fold compared to crude enzyme. The result of bromelain stability test in artificial stomach juice by milk clotting units assay bromelain fraction have proteolytic activity in clotting milk substrate. Exposing bromelain fraction in artificial stomach juice which gave the highest core bromelain proteolytic activity was achieved at estimated volume of 0.4-0.5 mL. Exposure in a period of reaction time to artificial stomach juice that contained pepsin showed relatively stable proteolytic activity in the first 4 hours.