Solid state fermentation

Solid state fermentation grows microorganisms on a low-moisture solid support, typically under non-septic conditions where full sterility is not maintained. It uses little energy yet can deliver high product concentrations, and downstream processing is facilitated because there is no large volume of broth to handle. Agricultural residues including wheat straw, rice hulls, and corn cobs serve as supports for producing enzymes and secondary metabolites. Traditional foods like tempeh and koji are classic examples, though heat build-up and contamination control remain the engineering challenges at scale.