Sequential subcritical water process applied to orange peel for the recovery flavanones and sugars

Abstract

The economically viable orange peel biorefinery can be based on a single process capable of extraction and hydrolysis. One of the major barriers in the OP biorefinery concept is the lack of an efficient separation technology for the complete removal of valuable components from the biomass. To address this issue, a new two-step hydrothermal process for sequential removal flavanones and sugars was evaluated. In the first stage, flavanones are extracted by subcritical water at 150 °C. The second stage consists of hydrolyzing the residual biomass at temperatures greater than 200 °C. The maximum flavanones yield (24.4 mg/g OP) was observed at a flow rate of 10 mL min–1. In the hydrolysis step, the main products were glucose, xylose, arabinose, and fructose, with small amounts of HMF and furfural. Spectroscopic and thermal analysis provided information on the bulk composition of the residual biomass and pectin extracted during hydrolysis temperatures above 200 °C.