Protein enabled foam fractionation of anthocyanins from purple perilla leaves: Mechanisms, performance, and optimization

Anthocyanins (ACNs) are the primary bioactive compounds of purple perilla leaves with a variety of biological activities. The scale separation of perilla ACNs is crucial for their practical application. This study presents the development of a green and highly efficient foam fractionation technology employing a protein-based frother and collector. The protein utilized, namely perilla seed meal protein (PSMP), is derived from perilla seed meal (PSM), which is normally discarded as an industrial waste during seed oil extraction. PSMP demonstrated notable foamability and foam stability. The interaction or collection mechanism between PSMP and ACNs was comprehensively investigated by SEM-EDS, FTIR, and fluorescence spectroscopy, revealing a hydrophobic interaction between PSMP and ACNs. Furthermore, the impacts of PSMP concentration, pH, and gas velocity on the foam fractionation of ACNs were thoroughly examined. Response surface methodology (RSM) was used to optimize the operating conditions for ACNs separation. Remarkable results were achieved under the optimum conditions, including a high recovery percentage of 95.13% and an impressive enrichment ratio of 27.56. The composition and antioxidation of isolated ACNs product were characterized, revealing its excellent antioxidant activities. This highlights its potential applications in drugs, food, and cosmetics. This work not only highlights an efficient foam fractionation technology for ACNs separation, but also offers valuable insights into the separation of other active plant components.