Ultrasound-assisted extraction as a first step in a biorefinery strategy for valorisation of extracted olive pomace

Martínez Patiño, José CarlosGómez Cruz, IreneRomero, InmaculadaGullón Estévez, BeatrizRuiz, EncarnaciónBrnčić, MladenCastro, Eulogio2020-05-112020-05-112019Martínez-Patiño, J.C., Gómez-Cruz, I., Romero, I., Gullón, B., Ruiz, E., Brnčić, M., Castro, E. (2019). Ultrasound-assisted extraction as a first step in a biorefinery strategy for valorisation of extracted olive pomace. Energies 12(14), 2679. doi: 10.3390/en12142679http://hdl.handle.net/10347/22195Currently, interest in finding new feedstock as sources of natural food antioxidants is growing. The extracted olive pomace (EOP), which is an agro-industrial residue from the olive pomace extracting industries, is generated yearly in big amounts, mainly in the Mediterranean countries. EOP was subjected to an ultrasound assisted extraction with ethanol-water mixtures. The effect of main parameters, such as ethanol concentration (30–70% v/v), ultrasound amplitude (20–80%), and extraction time (5–15 min), on the extraction of antioxidant compounds was evaluated according to a Box–Behnken experimental design. The antioxidant capacity of the resulting extracts was determined by measuring their content in total phenolic compounds (TPC) and flavonoids (TFC), as well as their antioxidant activity by DPPH, ferric reducing antioxidant power (FRAP), and ABTS assays. Considering the simultaneous maximization of these five responses, the optimal conditions were found to be 43.2% ethanol concentration, 70% amplitude, and 15 min. The ultrasound assisted extraction of EOP under these optimized conditions yielded an extract with a phenolic and flavonoid content (per gram of EOP) of 57.5 mg gallic acid equivalent (GAE) and 126.9 mg rutin equivalent (RE), respectively. Likewise, the values for DPPH, ABTS, and FRAP assay (per gram of EOP) of 56.7, 139.1, and 64.9 mg Trolox equivalent, respectively were determined in the optimized extracteng© 2019 by the authors. Open Access. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)https://creativecommons.org/licenses/by/4.0/Extracted olive pomaceResponse surface methodologyPhenolic compoundsFlavonoidsAntioxidant activityUltrasound-assisted extraction as a first step in a biorefinery strategy for valorisation of extracted olive pomacejournal article10.3390/en121426791996-1073open access