Ultrasound-assisted extraction of oil from hempseed (Cannabis sativa L.): Part 1

BACKGROUND Ultrasound-assisted extraction of the intermediate product from the mechanical expression of hemp (Cannabis sativa L.) seed oil was investigated to improve the overall expression yield without compromising oil quality. Complementary ultrasound technology was used as an out-of-line treatment carried out at 20 kHz frequency and optimized with respect to amplitude (80 and 152 mu m), sonication time (2, 10, 20 min) and to the hemp paste properties, in particular its particle size and hydration, which drive the compressibility of the press cake. RESULTS Under the conditions evaluated, the optimal ultrasound treatment was found to be the one applied on the hydrated press cake for 2 min at 152 mu m, which resulted in an oil yield of 13.4%, with an increase in extraction efficiency equal to 73% with respect to the control (untreated press cake). Sonication had a positive effect on the press cake texture and on the extracted oil antioxidant activity. Soaked samples treated for 2 min at 152 mu m yielded the lowest hardness. Oil recovered from soaked samples treated at 80 mu m and 152 mu m ultrasound for 2 min had the highest antioxidant capacity. CONCLUSIONS The technological results gathered in the present investigation are preliminary to the design and engineering of scaled-up equipment that combines the mechanical screw expression and the in-line ultrasound unit. (c) 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Automated summary

Ultrasound-assisted extraction of intermediate product from mechanical expression of hemp seed oil was investigated to improve expression yield without compromising quality. The optimal ultrasound treatment was found to be 2 minutes at 152 mu m, resulting in a 13.4% oil yield and 73% increase in extraction efficiency compared to the control. Sonication had positive effects on press cake texture and extracted oil antioxidant activity.