High-efficiency foam fractionation of anthocyanin from perilla leaves using surfactant-free active Al2O3 nanoparticle as collector and frother: Performance and mechanism

Anthocyanin (ACN) is a natural pigment with significant industrial applications. However, foam fractionation of ACN from perilla leaves extract presents theoretical challenges due to its limited surface activity and foaming capacity. This work developed a surfactant-free active Al2O3 nanoparticle (ANP) as a collector and frother, which was modified with adipic acid (AA). The ANP-AA efficiently collected ACN through the electrostatic interaction, condensation reaction, and hydrogen bonding, with a Langmuir maximum capacity of 129.62 mg/g. Moreover, ANP-AA could form a stable foam layer by irreversibly adsorbing on the gas-liquid interface, reducing surface tension, and alleviating liquid drainage. Under the appropriate conditions of ANP-AA 400 mg/L and pH 5.0, we achieved a high ACN recovery of 95.68% with an enrichment ratio of 29.87 after ultrasound-assisted extraction of ACN from perilla leaves. Additionally, the recovered ACN displayed promising antioxidant properties. These findings hold significant importance in the food, colorant, and pharmaceutical industries.

Automated summary

This study developed a surfactant-free active Al2O3 nanoparticle (ANP) modified with adipic acid (AA) as a collector and frother for efficient recovery of anthocyanin (ACN) from perilla leaves. The ANP-AA had a high collection capacity for ACN and formed a stable foam layer at the gas-liquid interface. Under appropriate conditions, ACN recovery of 95.68% with an enrichment ratio of 29.87 was achieved. The recovered ACN also exhibited promising antioxidant properties, highlighting the significance of these findings in the food, colorant, and pharmaceutical industries.