β-cyclodextrin assisted two-stage foam fractionation of bromelain from the crude extract of pineapple peels

For reducing the costs of separating bromelain from its crude extract, a two-stage foam fractionation technology with β -cyclodextrin as an activity protector was developed using the foam fractionation column with vertical sieve trays (VSTs). By studying the effects of VSTs, volumetric air flowrate, β -cyclodextrin concentration, aeration time and temperature, the two-stage foam fractionation technology were optimized. The results show that VSTs effectively improved the activity recovery by enhancing the adsorption of bromelain at the gas-liquid interface while β -cyclodextrin significantly reduced the activity loss induced by the gas-liquid interface. At β -cyclodextrin concentration 0.60   mg/mL, a high specific activity of 165.6   U/mg, 7.4 folds of that in the crude extract, was obtained with an activity recovery of 45.2% by using the optimized two-stage foam fractionation technology. Compared to those without β -cyclodextrin, activity recovery and specific activity obtained satisfactory relative increases of 34.1% and 110.7%, respectively.