Extrusion improves the phenolic profile and biological activities of hempseed (Cannabis sativa L.) hull

The impact of extrusion at different barrel temperature and screw speed on the hempseed hull was investigated. The extrusion treatments showed significant (p < 0.05) increase in total phenolic content, proportion of free phenolic compounds, and DPPH and ABTS radical scavenging activities. At low screw speed (150 rpm), significantly (p < 0.05) higher α-glucosidase and acetylcholinesterase inhibition activities were observed in the extruded samples. The full factorial model revealed a significant interaction between extrusion parameters on total phenolic/flavonoid content and antioxidant activities for free fraction, and α-glucosidase and acetylcholinesterase inhibition for whole fraction. A total of 26 phenylpropionamides, including hydroxycinnamic acid amides and lignanamides, were identified by HPLC-ESI-QTOF-MS/MS. HPLC-DAD analysis showed a 25-78% increase in total phenylpropionamide content in hempseed hull after extrusion. Pearson's correlation displayed significant (p < 0.05) positive correlation of N-trans-caffeoyltyramine, the most abundant phenylpropionamide, with all biological activities (r = 0.832-0.940).