Graduate Student North Dakota State University, North Dakota, United States
Abstract: Hemp (Cannabis sativa) seed oil is valued as a promising healthy oil. Crude hemp seed oil is highly pigmented due to the presence of chlorophylls, carotenes and other antioxidants, which may negatively affect downstream yield. However, its fatty acid profile makes it a promising edible oil and bio-product feedstock upon refining, bleaching and deodorizing (RBD). The study focused on identifying the optimal refining conditions for mechanical and solvent extracted oil, and to compare the quality parameters of the refined oils. Cold pressed crude oil was extracted using a twin-screw press, and the solvent (hexane) extracted oil was extracted from cracked whole hempseeds using a 12-liter Soxhlet extraction unit. The oils were water degummed and then acid degummed at three different acid concentrations (500 ppm, 2500 ppm, 5000 ppm) with two acids (citric and phosphoric) before NaOH neutralization process. The efficacy of these process conditions was determined by measuring the residual phospholipid content using AOCS method Ca 12-55 and free fatty acid content using AOCS method Cd 3d-63. The type of acid used did not significantly affect the amount of phospholipid removed, but the concentrations of each acid did. The mechanical and solvent extracted oils had significantly different initial oil quality parameters; hence, the process conditions were optimized based on the extraction technique used. Water degumming alone removed 30% of the initial phospholipids in mechanical extracted oil meanwhile it was less than 10% in the solvent extracted oil. Therefore, the most effective acid concentration was at 2500 ppm and 5000 ppm for mechanical and solvent extracted oil, respectively. The fatty acid profile and free fatty acid (FFA) contents were not influenced by the extracted type. The initial FFA was less than 2% where citric acid degummed oil required less NaOH base solution to remove all FFA.
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