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.