Cooling-assisted cold-pressing: a sustainable approach to high-quality hemp seed oil extraction

Hemp seed oil (HSO) is valued for its rich nutritional profile and bioactive compounds, including polyunsaturated fatty acids, tocopherols, and phytosterols. As demand for sustainable, high-quality functional foods grows, optimizing extraction methods is essential to preserving these compounds while ensuring environmental responsibility. Mechanical cold pressing is a preferred method because it avoids the use of chemical solvents; however, excessive mechanical friction can increase temperatures, leading to oxidation and nutrient degradation. This study evaluates the effect of an integrated cooling system (CO) versus a non-cooled system (NCO) in HSO extraction. A screw press with a copper coil cooling mechanism and food-grade propylene glycol coolant was designed to regulate temperatures, monitored via thermal imaging and resistance temperature detectors. Key oil quality parameters, including peroxide value, free acidity, fatty acid profile, tocopherol, phenolic content, and phytosterol composition, were analyzed. Results show that the CO system reduced extraction temperatures (by 11 % in the compression chamber and 15 % in the extracted oil), enhancing oxidative stability and bioactive retention, particularly phenolics, while maintaining oil yield and efficiency. Integrating cooling technologies into industrial cold pressing offers a sustainable solution to enhance nutritional stability, extend shelf life, and reduce oxidative waste, aligning with the shift toward eco-friendly food processing.