Sustainability-driven fractionation of hemp seed hulls into novel ingredients by the integrated high-pressure, ultrasound, and enzyme-assisted extractions

Supercritical CO 2 (SFE-CO 2 ), pressurised liquid (PLE), ultrasound (UAE), and enzyme-assisted (EAE) extractions were applied for hemp seed hulls. Conventional and UAE with hexane and SFE-CO 2 recovered non-polar constituents. Consecutive PLE with acetone, ethanol, and water efficiently isolated higher polarity fractions. The antioxidant amounts after SFE-CO 2 and PLE were up to 16.5 mg GAE/g DW, 35.9 mg TE/g DW, and 77.4 mg TE/g DW for the TPC, ABTS, and ORAC assays, respectively. UAE with acetone before PLE increased the antioxidant potential of extracts. EAE at optimized parameters yielded 4.3-21.0 g/100 g DW of water-soluble substances, containing 17.3-50.1 mg GLU/g DW of reducing sugars. Enzymatic treatment increased the recovery of soluble constituents, the yield of sugars, and the antioxidant characteristics of supernatants and solid residues. The results on bioactivity indicate that all fractions can serve as sources of antioxidants and other nutrients, with potential applications in foods and nutraceuticals.