Comparative Evaluation of the Nutrients, Phytochemicals, and Antioxidant Activity of Two Hempseed Oils and Their Byproducts after Cold Pressing

Recently, there has been a growing interest in the recovery of agri-food waste within the circular economy perspective. In this study, the nutritional, phytochemical, and biological features of the cold-pressed hempseed oil (HSO) and hempseed meal (HSM) of two industrial hemp varieties (USO 31 and Futura 75, THC <= 0.2%) were evaluated. The HSOs showed a high total phenols and flavonoid content, which were confirmed by LC-DAD-ESI-MS analysis, with rutin as the most abundant compound (56.93-77.89 mu g/100 FW). They also proved to be a rich source of tocopherols (81.69-101.45 mg/100 g FW) and of a well-balanced omega-6 to omega-3 fatty acid ratio (3:1) with USO 31, which showed the best phytochemical profile and consequently the best antioxidant activity (about two times higher than Futura 75). The HSMs still retained part of the phytochemicals identified in the HSOs (polyphenols, tocopherols, and the preserved omega-6/omega-3 fatty acids ratio) and a modest antioxidant activity. Furthermore, they showed a very interesting nutritional profile, which was very rich in proteins (29.88-31.44 g/100 g FW), crude fibers (18.39-19.67 g/100 g), and essential and non-essential amino acids. Finally, only a restrained amount of anti-nutritional factors (trypsin inhibitors, phytic acid, and condensed tannins) was found, suggesting a promising re-use of these byproducts in the nutraceutical field.

Automated summary

This study evaluated the nutritional and phytochemical characteristics of cold-pressed hempseed oil and hempseed meal from two industrial hemp varieties. The oil exhibited high levels of phenolic compounds, vitamin E, and a well-balanced ratio of fatty acids, with strong antioxidant activity. The hempseed meal was rich in protein, fiber, and amino acids, with low levels of anti-nutritional factors, suggesting potential use in nutraceutical products.