Valorization of brewer's spent grain by consecutive supercritical carbon dioxide extraction and enzymatic hydrolysis

The double effect of supercritical carbon dioxide, sc-CO₂, in a biorefinery concept applied to brewer's spent grain (BSG) was assessed in this work. Extraction conditions to remove and valorize the lipophilic fraction were studied (20-40 MPa and 40-80 °C) obtaining a maximum yield of 5.70 ± 0.07 g/100 g_BSG at 80 °C and 40 MPa. High pressures and temperatures resulted in higher content of total phenolic and flavonoid compounds, as well as higher antioxidant capacity. It was observed an improvement of the enzymatic hydrolysis yield by cellulase in the sc-CO₂ treated BSG compared to the non-treated. This improvement could be partially attributed to the removal of the lipid fraction and to morphological changes of BSG after sc-CO₂. Based on this double benefit, sc-CO₂ can play an important role on biomass valorization.