Cold Pressing and Supercritical CO2 Extraction of Hemp (Cannabis sativa) Seed Oil

Hemp (Cannabis sativa L.) is an annual plant that has been bred for centuries and its main products are hemp seeds and fibers. Fibers from the stalk are still used in production of durable fabrics and specialty papers, such as paper money, tea bags, canvas, linen, cigarette paper, and other strong, thin papers used to make thick books, like the Holy Bible1. Hemp production was prohibited due to its chemical drug component THC (δ-9-tetrahydrocannabinol)2. Since 1996, hemp varieties containing less than 0.3 % THC can be grown. According to EU legislation, hemp with less than 0.2 % THC can be grown3. Hemp seed has been used as a food and feed. The oil has been used for manufacturing printer’s ink, for wood preservation, and production of soaps and detergents. The seed contains 25–35 % lipids, 20–25 % protein and 20–30 % carbohydrate, 10–15 % insoluble fibers, and an array of minerals4. Hemp oil contains polyunsaturated fatty acids ( PUFAs). Among them are several essential fatty acids like linoleic and a-linolenic acid 3. Hemp seed oil has the perfect ratio (3:1) between two essential fatty acids (linoleic and linolenic acid)2. g-Linolenic acid has a positive effect on patients suffering from rheumatoid arthritis, atopic dermatitis and allergies5. Thus, the oil is ideal for human consumption and for preparing different kinds of body oils and creams, due to good absorption through the skin6. Tocopherols, which are present in hemp oil, may reduce the risk of cardiovascular diseases, cancer, and age-related macular degeneration. They have an antioxidant function and prevent oxidation of unsaturated fatty acids3. The objectives of this work were threefold: (i) to investigate the effects of process parameters during cold pressing of hemp seeds on the oil recovery and oil quality using response surface methodology (RSM); (ii) to recover the residual oil from the press cake using supercritical CO2 in the newly designed supercritical fluid extraction system, and (iii) to investigate the influence of different natural antioxidants and their concentration on the oxidative stability of hemp seed oil.