Crude bromelain extract preparation
followed the method of Pardo et al. (2000). Crude
bromelain extract was obtained by mixing
pineapple juice with cold 0.1 M sodium phosphate
buffer (pH 8.0) containing 5 mM EDTA and 25
mM cysteine. This was then centrifuged for 30
min at 16,000 g. The supernatant (“crude
bromelain extract”) was then collected. All
operations were carried out at 0-4°C.