A method for making comestible protein meal includes: producing an alcohol based fuel (such as ethanol) from a starch-based plant feedstock (such as duckweed)； then separating stillage that remains afterwards into solids and a thin stillage； drying the solids to a comestible protein meal (minimum 40% protein)； and recycling the thin stillage as plant fertilizer. Another method includes: determining a desired amino acid profile； while producing ethanol from a plant feedstock in a process that comprises a fermentation stage, adding a reagent prior to the fermentation stage to adjust an amount of an amino acid output from the fermentation stage to match an amount of the amino acid in the desired amino acid profile； separating stillage remaining after producing the ethanol into solids and a thin stillage； and drying the solids to a comestible protein meal comprising the amount of the amino acid.
