Recovery of valuable compounds from orange processing wastes using supercritical carbon dioxide extraction

Abstract

Citrus processing industries produce high volumes of wastewater containing significant polluting loads for the environment, many of which are functional bioactive compounds. In this study, it was aimed to recover valuable bioactive components by supercritical CO2 extraction from orange processing wastes. For this purpose, an optimization study was carried out using the response surface methodology (RSM) in terms of pressure and temperature. The optimum experimental conditions were found to be 28.7 MPa and 60 °C for maximum extract yield, total phenolics content, total flavonoids content and antioxidant activity values. It was determined that some valuable phenolic compounds such as hesperetin, quercetin, apigenin, cyanidin, p-coumaric acid, ferulic acid, sinapic acid, isorhamnetin and their derivatives have been increased between 2 and 260 times in the extracts by supercritical CO2 extraction. Another important finding of this study was that short and medium chain saturated fatty acids were detected in the wastewater extracts while longer chain fatty acids were detected in the orange peel extracts. This may be due to the fact that more soluble short-chain fatty acids are transferred from the fruit to the juice during fruit processing.