4. CONCLUTION
It may be concluded that the different extraction methods modify the
physicochemical properties, nutrient substances, and volatile compounds
of Qingjinju seed oils. The oil yield obtained by solvent extraction
(35.07%) was higher than that of
screw press (31.04%) and supercritical CO2 (27.69%)
extraction. Specific gravity, refractive indices, acid values, peroxide
value, and unsaponifiable matters of SO were lower than that of SPO and
SCO, suggesting that SO possessed superior physicochemical properties.
The Qingjinju seed oils consisted of major fatty acids
including oleic acid
(34.08-35.49%), linoleic acid (29.79-30.79%), palmitic acid
(17.17-17.76%), stearic acid (8.02-8.94%), and linolenic acid
(6.50-6.81%), making the oil a good source of unsaturated fatty acids.
SPO and SCO contained limonin (3544.63 mg/kg, 3052.96 mg/kg) and nomilin
(534.90 mg/kg, 673.13 mg/kg), which were underrepresented in SO (722.49
mg/kg, 65.02 mg/kg). Supercritical CO2 and screw press
extraction were therefore more beneficial for retaining the limonoid
content in Qingjinju seed oils. The volatile compounds of SPO and SCO
were primarily aldehydes, while hydrocarbons were the major volatile
class in SO. The seven main volatile compounds were identified across
the extraction methods. Qingjinju seed oils could provide valuable stock
oil for food or chemical industries and different extraction methods can
be selected according to their intended use.