Chemical characterization of pomegranate and alfalfa seed oils obtained by a two-step sequential extraction procedure of expeller and supercritical CO2 technologies

A combination of two green extraction technologies, i.e., expeller and supercritical CO2, have been applied in a sequential two-step methodology for the extraction of pomegranate and alfalfa seed oils, considering material valorization and environmental sustainability. High yields of oil extraction have been obtained for pomegranate (77.2%) and alfalfa (94.6%) seeds, and press cakes and defatted flours have been produced. The procedures do not require refining and the properties of the oils are found to be superior in terms of valuable minor compounds. A thorough chemical characterization of the extracted oils has also been carried out to demonstrate the high quality of the extracted seed oils. Unexpected positional distributions of some fatty acids have been found in pomegranate seed oil, such as sn-1,3 position in punicic acid. New chemical findings have been described for alfalfa oil for the first time, such as considerable levels of squalene (1.03 g/100 g) and the sn-1,3 positional distribution in alpha-linolenic acid. Moreover, phosphatidylinositol is the main phospholipid found and the oxidative values are shown to be within the standard limits.