Deterpenation of mandarin (Citrus reticulata) peel oils by means of countercurrent multistage extraction and adsorption/desorption with supercritical CO2

The mandarin (Citrus reticulata) peel oil consists of more than 98 wt.% terpenes and a small fraction of oxygenated components responsible for its distinct smell. The terpene fraction is composed mostly of limonene and the oxygenated aroma fractions are composed mainly of linalool and decanal. The removal of terpenes must be performed in order to increase the storage time of citrus oils. In this work, the deterpenation of two different cold-pressed mandarin peel oils employing countercurrent extraction and ad-/desorption with supercritical CO2 and a combination of these processes were investigated. Countercurrent experiments were carried out at pressures ranging from 8.5 to 10.0 MPa and at 50 and 60 °C. At 10.0 MPa and 60 °C, a maximum selectivity of 12.8 between terpenes and aromas could be obtained at a folding ratio of 5.0, showing that the fractionation by means of countercurrent gas extraction could be employed. To investigate the complete removal of terpenes, ad-/desorption experiments were also performed and both the raffinate samples obtained through the countercurrent fractionation and the crude cold-pressed peel oils were used as feed material. The components evaluated were desorbed from silica-gel and the best fractionation results were obtained at 40 °C, 25 wt.% oil loading in two sequential pressure steps. Initially, terpenes were completely desorbed at 8.0 MPa. The second desorption step was carried out at 20.0 MPa and a selective fractionation of important aroma components was observed. Additionally, scale-up experiments were performed.