Ultrasonic-assisted foam fractionation for recovering bovine serum albumin from aqueous solution: Structure and function evaluation

Abstract

In this work, a technology of ultrasonic-assisted foam fractionation had been used to recover bovine serum albumin (BSA) from its aqueous solution. First, the operation parameters (e.g., height ratio of liquid phase and foam phase, aperture size of gas distributor and gas flow rate) of foam fractionation were optimized. Subsequently, ultrasonic treatment was assembled into foam fractionation operation. Experimental results indicated that the surface excess of BSA molecules first increased and then decreased with increasing ultrasonic intensity from 0 W/cm2 to 75 W/cm2. Considering enrichment ratio and recovery percentage of BSA, the suitable intensity of ultrasonic treatment was 45 W/cm2. Fourier transform infrared (FTIR) spectroscopy and SDS-PAGE analysis suggested that ultrasonic-assisted foam fractionation could not only destroy the intramolecular covalent bonds within BSA, but also prevent the oxidation of free sulfhydryl groups. The circular dichroism spectroscopy showed that the secondary structure of BSA had become loose and well-ordered after suffering foam fractionation with assistance of ultrasonic treatment. Ultrasound wave contributed to inhibiting the formation of BSA aggregates in foam fractionation. Furthermore, the surface hydrophobicity, emulsibility, and foaming property of BSA could be effectively maintained by assembling ultrasonic treatment into foam fractionation.