Biorefinery approach in the processing of orange peel

Primjena biorafinerijskog pristupa u iskorištavanju biomase, kao obnovljivog izvora energije, predstavlja potencijalno rješenje za smanjenje potrebe za fosilnim gorivima te ublažavanje klimatskih promjena. Kako bi se koncept biorafinerije u potpunosti temeljio na ekološki prihvatljivim načelima, prilikom valorizacije biomase, poželjno je korištenje zelenih otapala kao što su eutektička otapala. U ovom radu je ispitana mogućnost primjene eutektičkog otapala kolin-klorid:etilen-glikol sa 30 %, 50 % i 80 % vode (w/w) u biorafineriji otpadne narančine kore. Ispitano eutektičko otapalo se pokazalo kao dobra zamjena za zakiseljeni etanol pri ekstrakciji polifenola iz kore naranče, dok je pokazalo vrlo slab ekstrakcijski učinak pri ekstrakciji proteina. Također je ispitana aktivnost enzima pektin-esteraze ekstrahiranog iz otpadne narančine kore, pri čemu je pektin-esteraza pokazala značajno veću aktivnost u eutektičkom otapalu u odnosu na pufer. Osim toga, otapalo kolin-klorid:etilen-glikol se pokazalo boljim otapalom za enantioselektivnu hidrolizu (R,S)-1-feniletil acetata primjenom hidrolitičkih enzima iz narančine kore u odnosu na pufer.Application of biorefinery approach in the utilization of biomass, as a renewable energy source, represents the potential solution for reducing the need for fossil fuels and mitigating the climate change. In order to make the biorefinery concept fully based on environmentally acceptable principles, during biomass valorization, green solvents such as deep eutectic solvents (DESs) are desirable. In this paper, the possibility of using choline chloride:ethylene glycol with 30%, 50% and 80% of water (w/w) in the biorefinery of waste orange peel has been investigated. Investigated DES was found to be a good substitute for acidified ethanol in extraction of polyphenols from orange peel, while it showed low protein extraction efficiency. The activity of pectin-esterase, which was extracted from waste orange peel, was also examined and it was observed that pectin-esterase exhibit significantly higher activity in DES in comparison to buffer. In addition, choline chloride:ethylene glycol was shown to be a better solvent for the enantioselective hydrolysis of (R,S)-1-phenylethyl acetate using hydrolytic enzymes from orange peel in comparison to buffer