Pilot-plant scale extraction of phenolic compounds from mango leaves using different green techniques: Kinetic and scale up study

Mango leaves contain high levels of phenolic compounds, such as mangiferin which have multiple antioxidant and pharmaceutical properties and great potential in nutraceutical, cosmetic and food applications. In the study reported here, mango leaf extracts were obtained using supercritical fluid extraction (SFE), pressurized liquid extraction (PLE) and enhanced solvent extraction (ESE). ESE and PLE gave higher global extraction yields (up to 37%) than SFE using CO2 + 20% ethanol (around 8%). The addition of high concentrations of ethanol (50-100%) to the CO2 enhanced the solubility of mango polyphenols and thus increased the global and mangiferin yields at relatively low flow rates (20-30 g/min). The scale-up of high pressure processes was studied from the laboratory scale (0.1 L) to the pilot-plant scale (5.0 L) by applying the mathematical model of Sovova and different similarity criteria. The results indicate that Sovova's model can satisfactorily predict the kinetic curves and the best similarity criterion was to keep a constant solvent mass flow-to-feed mass ratio Qm.d/M, which includes the extractor diameter (d). Kinetic and model analyses showed that the SFE of mango leaves is mainly limited by diffusion whereas the PLE and ESE processes are controlled by both convection and diffusional mechanisms. (C) 2016 Elsevier B.V. All rights reserved.