2.2 Screw pressing of Qingjinju seeds
Qingjinju seeds were pre-roasted in a DAIHAN SOF-155 oven at 170 °C for 8 min with frequent agitation. Approximately 1000 g of the pre-roasted seeds were immediately pressed using a laboratory mechanical screw press (Bestday ZYJ9018, Jiangmen BestdayBear Electric Co., Ltd., Jiangmen, China). The seed oils were centrifuged (Heal Force Neofuge 15R, Shanghai Lishen Scientific Equipment Co., Ltd., Shanghai, China) at 4000 rev/min for 10 min and transferred to brown reagent bottles. This process was repeated three times. The oil samples were stored at 3 °C in a refrigerator.