Extract Orange Oil

When we usually eat oranges, the peeled layer is the exocarp of the orange, which consists of two parts: the yellow exocarp (flavedo) and the white exocarp (albedo). The yellow exocarp is the thin yellow layer on the outside of the orange, while the white exocarp is the thick white layer on the inside. The yellow exocarp contains many oil sacs, which are rich in essential oils, the source of orange oil. When we peel an orange, some of the oil sacs will be accidentally destroyed, and the oil inside will flow out, which is why a layer of oil sticks to our hands after peeling the orange.

Supercritical fluid extraction is a new method to extract and separate effective components in liquid or solid by utilizing the characteristics of high permeability, high diffusion coefficient, low viscosity and strong solvency of supercritical fluid. CO₂ is the supercritical fluid commonly used in the extraction of citrus peel essential oil. Using microwave and supercritical CO₂ extraction technology to extract orange peel essential oil, the extraction time, extraction pressure, extraction temperature and CO₂ flow have a great influence on the yield of essential oil. The optimized process is as follows: the average yield of essential oil is 2.08% when the extraction time is 20 min, the extraction pressure is 910MPa, the extraction temperature is 40C, and the CO₂ flow rate is 20 L/h. This technology has the characteristics of short extraction time, high yield and good quality of essential oil. GC-MS was used to analyze the components of orange peel essential oil, and 22 compounds were identified. Among them, limonene had the largest content of 55.65%, followed by D limonene and B terpinene with 6112% and 5.48% respectively. Using absolute ethanol as entrainer, the essential oil of citrus peel was extracted by supercritical CO₂ extraction technology. Under the conditions of extraction pressure of 15MPa, extraction temperature of 35C, extraction time of 150min, and CO₂ flow rate of 23 L, the extraction rate of essential oil of citrus peel was 10.164 %. Using supercritical CO₂ to extract citrus essential oil, the yield of essential oil is significantly higher than other methods, and the extraction time is short, which can better retain the aroma components of citrus essential oil without solvent residue. However, the supercritical CO₂ method has high technical content, expensive equipment and high economic cost.