The SDS–PAGE analysis (Fig. 4D) revealed the efficiency of the
protocol used to purify bromelain from pineapple wastes by ethanol
precipitation. Two polypeptide bands of 27.1 and 14.9 kDa
were shown, although some authors have reported that up to six
enzyme forms can be obtained from the fractionation of stem bromelain
[35]. Similar results were reported by Hebbar et al. [34],
Takahashi et al. [36] and Wharton [37], which revealed a molecular
weight of 26 kDa, 28 kDa and 28.4 kDa for polypeptide bands of
bromelain, respectively.