Supercritical CO2 pretreatment of date fruit biomass for enhanced recovery of fruit sugars

Abstract

This study explores the use of supercritical CO2 (Sc-CO2) as an innovative and green approach for pretreating date fruits to enhance the total sugar yield by water-based extraction. The pretreatment step was investigated based on Box-Behnken factorial design to evaluate the influence of critical variables on the total sugar yield. Sc-CO2 conditioning of the date pulp was investigated by varying the pressure (10–20 MPa), temperature (25–50 °C), and contact time (30–120 min) in a batch setup. Temperature and pressure variables were identified as the significant parameters for the Sc-CO2 treatment. Optimization analysis showed a maximum total sugar yield of 74.1 g/100 g for Sc-CO2pretreated date pulp at 10 MPa and 46 °C for 59 min. Besides, the pretreatment mechanism involved major effects such as swelling, disruption, and explosion that favored the enhanced recovery of total sugars from the date fruit matrix during the extraction. SEM and XRD studies confirmed changes in the microstructure of the date pulp biomatrix before and after pretreatment. Therefore, the consecutive approach of Sc-CO2 conditioning followed by aqueous extraction appears to be an efficient and promising technique for the enhanced recovery of fruit sugars at relatively low temperatures and without the use of any toxic solvents.