Lignin-first biomass fractionation using a hybrid organosolv – Steam explosion pretreatment technology improves the saccharification and fermentability of spruce biomass

•Hybrid organosolv – steam explosion pretreatment was efficiently used for spruce.•Pretreated solids with as high as 72% w/w cellulose are obtained.•High-purity lignin is produced.•Pretreated solids offer excellent enzymatic saccharification yields (up to 61% w/w).•High ethanol titers (61.7 g/L) are achieved in high-gravity SSF.