Disclosed is a method where corn stover and/or corn cobs have been irradiated by electron beam radiation and then saccharifyied to produce a sugar. The sugar is fermented to butyric acid with anaerobic microorganism comprising Clostridium in the presence of iron. Also disclosed are methods for processing biomass, such as cellulose, lignocellulose, hemicellulose, plant material, waste material and the like, by processes such as fermentation to form a product. The products can be sugars, alcohols, combustible fuels and further downstream products. The biomass may be pre-treated with radiation, sonication, oxidation or pyrolysis.
