A method for producing a solid transformation product of a substrate, wherein the solid transformation product is a product of the transformation of proteinaceous matter and/or carbohydrates originating from a biomass, comprising the following steps: • preparing a substrate of biomass comprising carbohydrates and proteinaceous matter that originate from soya bean seed, seed of rape seed, or mixtures thereof, wherein at least 20 % by weight of said biomass comprises carbohydrates and proteinaceous matter originating from soya bean seeds, seed of rape seed, or mixtures thereof, optionally in further mixture with carbohydrates and proteinaceous matter originating from seeds of fava beans, seed of peas, seed of sunflower, seed of lupine, and/or seed of cereals; • mixing said substrate with a live microorganism or a combination of live microorganisms, which live microorganism or combination of live microorganisms is not, or does not comprise, live yeast, and adding water in an amount which provides an initial incubation mixture having a water content from 30 % to 70 % by weight, and a ratio of wet bulk density to dry bulk density from 0.60 to 1.45, wherein the dry bulk density is the measured bulk density (weight/volume) of the biomass without the added water, and the wet bulk density is the measured bulk density (weight/volume) of the biomass with the added amount of water; • incubating said initial incubation mixture for 1-240 hours at a temperature of 15-70 °C, and recovering solid transformation product from the incubated mixture; further comprising that the incubating step is performed as a uniform, continuous plug-flow process in a vertical, non-agitated incubation tank with inlet means for said mixture and additives and outlet means for said solid transformation product, wherein transport of the biomass within the vertical, non-agitated incubation tank is mediated by gravitational force. • preparing a substrate of biomass comprising carbohydrates and proteinaceous matter that originate from soya bean seed, seed of rape seed, or mixtures thereof, wherein at least 20 % by weight of said biomass comprises carbohydrates and proteinaceous matter originating from soya bean seeds, seed of rape seed, or mixtures thereof, optionally in further mixture with carbohydrates and proteinaceous matter originating from seeds of fava beans, seed of peas, seed of sunflower, seed of lupine, and/or seed of cereals; • mixing said substrate with a live microorganism or a combination of live microorganisms, which live microorganism or combination of live microorganisms is not, or does not comprise, live yeast, and adding water in an amount which provides an initial incubation mixture having a water content from 30 % to 70 % by weight, and a ratio of wet bulk density to dry bulk density from 0.60 to 1.45, wherein the dry bulk density is the measured bulk density (weight/volume) of the biomass without the added water, and the wet bulk density is the measured bulk density (weight/volume) of the biomass with the added amount of water; • incubating said initial incubation mixture for 1-240 hours at a temperature of 15-70 °C, and recovering solid transformation product from the incubated mixture;