Bioactive extracts, obtained by supercritical CO2 extraction, from Citrus processing wastes

Citrus plants belong to the Rutaceae family and include Citrus reticulata (sweet mandarin), Citrus paradisi (grapefruit), and Citrus limon (lemon); all of which are among the most popular fruits in the world. The main use of citrus fruits is to produce citrus juice, however, the processing waste of the citrus industry such as peel, pulp and seeds are also a potential source of valuable by-products. Citrus seeds are also used in the food, cosmetics and pharmaceutical industry. This study investigates the fixed oil obtained by supercritical CO2 extraction (SFE), at 250 bar and 40 °C, and by n-hexane in a Soxhlet apparatus (SE) from seeds of mandarin, lemon and grapefruit waste discarded by a local industry in Sardinia (Italy). High percentages of linoleic, from (35 to 42) %; oleic, (22 to 28) %; palmitic, (21 to 25) %; linolenic, (4 to 10) % and stearic, (4 to 7) % acids were observed in SFE Citrus seed oils. The fatty acid profiles of the three oils were similar; linoleic acid was the major fatty acid. The content of linolenic acid was higher in the lemon oil than in the mandarin and grapefruit seed SFE oils; 10 % with respect to 4 %. Citrus SFE oils were also evaluated for their attractant effect on the Mediterranean fruit fly Ceratitis capitata by behavioral assays. The three oils obtained by solvent extraction were identical to the ones obtained by means of SFE but without the additional benefit of not having unwanted traces of solvent.