Assessing the Refinement Conditions for Mechanical and Solvent Extracted Hempseed Oil

Highlights The phospholipid and chlorophyll amounts were significantly different in the mechanical and solvent extracted oils. Water degumming was sufficient in removing phospholipid in the mechanically extracted oil. The type of acid used did not influence the amount of phospholipid removed in solvent extracted oil. The same amount of sodium hydroxide was needed during neutralization since the free fatty acid values were not significantly different after extraction. Abstract. Crude hemp (Cannabis sativa) seed oil is highly pigmented due to the presence of chlorophylls, carotenes, and other antioxidants, which can potentially hinder downstream processes, rendering it undesirable for food and bioproduct applications. The composition and quantity of impurities in hempseed oil are likely influenced by the oil extraction method. Therefore, this study aimed to identify the optimal chemical refining conditions for mechanical and solvent extracted oils and compare the quality of the refined oil. Crude oils were obtained through two extraction methods: cold pressing using a Komet twin-screw for mechanical extraction and solvent extracted oil using hexane in a 12 L Soxhlet extraction unit. Subsequently, the crude oils underwent degumming with citric and phosphoric acids at three acid concentrations, followed by neutralization at varying sodium hydroxide concentrations. The efficacy of the refining conditions was assessed by measuring the phospholipid and free fatty acid contents. The results revealed that the phospholipid content of the crude solvent extracted oil was ten times higher than that of the mechanically extracted oil. Consequently, the solvent extracted oil required approximately three times the amount of acid to reach the target of <15 ppm residual phospholipids. Interestingly, the type of acid used did not influence the refining process of hempseed oil. These findings suggest that the oil extraction method significantly influences the refinement process required to meet the industrial threshold of vegetable oil containing =15 ppm phospholipids. Keywords: Free fatty acid, Hempseed oil, Phospholipids, Refined vegetable oil, Vegetable oil extraction.