Highlights
•This is the first study which reports biohydrogen production from waste pastry.
•Effects of HRT on hydrogen production in the CSTR and CMISR were compared.
•One gram pastry could be converted to 0.345 g glucose in the pastry hydrolysate.
•One gram waste pastry could produce 83.29 mL hydrogen in the CSTR.
•This study provides a novel way for biohydrogen production from organic solid wastes.