Supercritical fluid-assisted extraction of hop cone residue from craft breweries

This study aimed to use supercritical fluid-assisted extraction in hop cone residue from craft breweries and define the best extraction parameters. Yield, compounds extracted, in vitro chemical and cell-based antioxidant ac-tivities, and antimicrobial and cytotoxic potentials were evaluated. The variables studied were temperature (40-60 degrees C), pressure (10-20 MPa), and ethanol percentage as co-solvent (5-10%) using a Taguchi experimental design (11 runs). The extracts showed inhibitory action towards Gram-positive and Gram-negative bacteria, mainly Proteus mirabilis and Enterococcus faecalis (MICs = 5-10 mg/mL). Furthermore, up to the maximum tested concentration (400 & mu;g/mL), the extracts showed no hepatotoxicity on a healthy porcine liver cell line (PLP2), indicating safety for food and pharmacological applications. Lower temperatures (40 degrees C), pressures (10 MPa), and ethanol percentages (5%) resulted in higher concentrations of some compounds (alpha-copaene, & gamma;-elemene, & gamma;-muurolene, & alpha;-muurolene, caryophyllene oxide) and higher antioxidant activity in cell-based assays, but lower yields. At the same time, lower temperatures (40 degrees C) and pressures (10 MPa) but higher ethanol percentages (10%) resulted in higher concentrations of other compounds (nerolidyl acetate, linalyl isobutyrate, & alpha;-acorenol, and geranyl isovalerate) and increased antioxidant activity in chemical systems. Our results support that the hop cone residue can be used to obtain supercritical fluid-assisted extracts with biological potentialities that might virtually be upcycled into multifunctional ingredients for the food and pharmacological industries. Using 40 degrees C, 10 MPa, and 5 or 10% ethanol percentage as process parameters is advisable.The authors extend gratitude to the Brazilian National Council for Scientific and Technological Development – CNPq (Process no. 308505/ 2019-2) and the Foundation for Science and Technology (FCT, Portugal) for financially supporting CIMO (UIDB/00690/2020 and UIDP/00690/ 2020) and SusTEC (LA/P/0007/2021). Additionally, they acknowledge the Coordination for the Improvement of Higher Education Personnel (CAPES) and research contributions from Cesumar Institute of Science, Technology, and Innovation (ICETI), Cesumar University (Unicesumar), Instituto Polit´ecnico de Bragança (IPB), and State University of Maringa (UEM). Lastly, they appreciate national funding by FCT, P.I., for institutional scientific employment program contracts for L. Barros, C. Pereira, and R. Calhelha, and the individual scientific employment program contract for S.A. Heleno (CEECIND/03040/2017).