A techno-economic comparison of subcritical water, supercritical CO2 and organic solvent extraction of bioactives from grape marc

Subcritical water extraction (SWE) is a modern extraction technique that posits a number of advantages to traditional solvent extraction. This is especially so in the extraction of medically and commercially important phenolic compounds from food and food by-products. SWE uses water at elevated pressures and temperatures to extract compounds of different polarities, adjusting the water polarity by changing the system temperature. A techno-economic analysis of the extraction of bioactive phenolic compounds from New Zealand grape marc showed that the cost of manufacture (COM) by SWE (NZ$89.60/kg product) approached that of current solvent extraction techniques (NZ$87.0/kg) although was less profitable overall. These were both far below the COM of supercritical CO2 extraction (NZ$123.40/kg). High energy consumption also meant that SWE had higher Potential Environmental Impacts (PEI) than solvent extraction, and higher greenhouse emissions, but outperformed supercritical CO2 extraction in these domains as well. (C) 2017 Elsevier Ltd. All rights reserved.