Extraction of phenolic compounds and production of biomethane from strawberry and raspberry extrudates

Abstract

This study proposes a biorefinery approach system to treat two berry extrudates generated by the berry-tasted products industry. The berry extrudates studied were strawberry extrudate (SE1 and SE2) and raspberry extrudate (RE), both of them processed in the same industrial plant. The proposed biorefinery approach consists in the extraction of bioactive compounds after hydrothermal pre-treatment followed by anaerobic digestion of the remaining biomass after extraction. A high concentration of valuable phenolic compounds was extracted from each extrudate through the absorption-desorption processes, i.e. 876, 392 and 2402 mg of gallic acid equivalents/kg extrudate in SE1, SE2 and RE, respectively. Anaerobic digestion of the remaining biomass after extraction led to high methane production, between 371 and 503 mL CH4/g VS. The economical evaluation showed that the proposed biorefinery approach would offer higher benefits than just anaerobic digestion of the untreated extrudate, although this last option would be economically feasible as well.