Separation of Citrus Essential Oil and Hesperidin from Citrus Peel Through Combined Mixed-Solvent and Multi-Phase Salting Out Extraction

Abstract

Large amounts of citrus peel are discarded as solid waste owing to the lack of recycling methods. In this study, mixed solvent extraction combined with multi-phase salting-out extraction was performed to explore the extraction process of essential oil and hesperidin. Optimal conditions were used for mixed solvent extraction (citrus peel 6%; ratio of ethanol to n-hexane 1:5; duration, stirring speed, and temperature were 150 min, 120 r/min, and 45°C, respectively) and multi-phase salting-out extraction (citrus peel residue 10%; ratio of salt to ethanol 19:24; mass fraction of n-hexane 25%; extraction duration 120 min). Under two-step extraction conditions, 63.74±2.40% essential oil and 27.13±1.36% hesperidin were recovered, with total extraction efficiencies of 5.19±0.09 and 1.91±0.25%, respectively. The amplification effect was not significant, and the organic solvents could be reused three times while maintaining 80% recovery in both steps to balance the commercial cost and extraction efficiency.