Rhamnolipid assisted recovery of lycopene from the tomato-based processing wastewater using foam fractionation

• The recovery of lycopene from the tomato-based processing wastewater was studied.
• Rhamnolipid was used as the foam stabilizer for achieving co-adsorption effect.
• Lycopene were greatly enriched through foam fractionation by adding rhamnolipid.
• Rhamnolipid in the supernatant of the foamate could be reused to recover lycopene.

The feasibility of foam fractionation for recovering lycopene from the tomato-based processing wastewater was investigated by using tomato proteins as the collectors. Rhamnolipid would be used as the foam stabilizer to improve the interfacial adsorption of protein–lycopene complex. Under the optimal conditions of rhamnolipid concentration 1.5 g/L, temperature 50 °C, pH 7.0, volumetric gas flow rate 150 mL/min and loading liquid volume 500 mL, the enrichment ratio and the recovery percentage of lycopene were 4.42 and 83.43%, respectively. Meanwhile, the recovery percentage of rhamnolipid reached 94.52% in the foamate. Moreover, rhamnolipid in the supernatant of the foamate could be reused to recover lycopene from tomato-based processing wastewater for three times with a constant recovery percentage of lycopene. This work has provided a new insight into the recovery of a non-surface-active material from its aqueous solution and is expected to facilitate the research on the resourceful treatment of food wastewaters.