Effect of extrusion technology on hempseed (Cannabis sativa L.) oil cake: Polyphenol profile and biological activities.

Effects of extrusion with varying barrel temperature, moisture content, and screw speed on hempseed oil cake were studied for the first time. Extrusion at lower moisture (30%) and higher screw speed (300 rpm) significantly increased the proportion of free polyphenols, flavonoids, and phenylpropionamide content, and α -glucosidase and acetylcholinesterase inhibition activities. Full factorial design confirmed the three-way interactions among all extrusion parameters for all chemical assays with the bound phenolic fraction, total flavonoid content, and DPPH inhibition activity of the free phenolic fraction. HPLC-DAD-ESI-QTOF-MS/MS analysis tentatively identified 26 phenylpropionamides, and the contents of N-trans-caffeoyltyramine (66.26 µg/g) and total phenylpropionamides (85.77 µg/g) were significantly increased after extrusion at the lower moisture and higher screw speed extrusion conditions. The higher α -glucosidase inhibition activity at higher screw speed could be due to the N-trans-caffeoyltyramine (r = 0.99, p < 0.01), while the AChE inhibition activity appeared to be influenced more by the cannabisins A-C, M (r > 0.8, p < 0.01). PRACTICAL APPLICATION: Hempseed oil cake is a byproduct of oil extraction, with high protein and high fiber contents. The results of this research could be used directly in food industry to improve the nutritional and commercial value of hempseed oil cake by extrusion technology.