A method for preparing a fermentation product including lactic acid, the method including: a) treating lignocellulosic material with caustic magnesium salt in the presence of water to provide treated aqueous lignocellulosic material; b) saccharifying the treated aqueous lignocellulosic material in the presence of a hydrolytic enzyme to provide a saccharified aqueous lignocellulosic material comprising fermentable carbohydrate and a solid lignocellulosic fraction; c) simultaneously with step b), fermenting the saccharified aqueous lignocellulosic material in the presence of both a lactic acid forming microorganism and caustic magnesium salt to provide an aqueous fermentation broth comprising magnesium lactate and a solid lignocellulosic fraction; d) recovering magnesium lactate from the broth, wherein the saccharification and the fermentation are carried out simultaneously.