In this work, the thermodynamic equilibrium and applying of PEG4000/Phosphate ATPS on the purification of
bromelain extracted from pineapple was studied. A rigorous study of the equilibrium curves and tie-line length from
PEG4000/phosphate ATPS were done for the pH 6-11 at 25°C. Results showed that there was augment in the PEG
and salt contents with the high pH value from PEG4000/Phosphate ATPS and two-phase formation needed only
increasing the PEG content. Two tie-line length at pH 11 from PEG4000/Phosphate ATPS were optimal condition
for bromelain purification, one on composition of 14% PEG and 13% salt and other at 12.6% PEG and 12.2% salt,
while a 25-62 folds of enzyme was found. SDS-PAGE electrophoreses had one band only, which showed that
bromelain was purified. Optimum conditions of bromelain use were found at pH 7 and between 30-40°C.
