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

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.