Models for solid-state cultivation of Rhizopus oligosporus

Physical and mathematical models for solid state fermentation were developed, using cultivation of Rhizopus oligosporus on soy beans as an example. A simple mathematical model was developed which predicts the dynamic behaviour of an adiabatic homogeneous packed-bed reactor accurately during the first 40 hours. Biomass measurements and experimental verification of the substrate composition are required to improve model validation. After 40 hours, the simple kinetic model gives very poor predictions. Axial gradients and bed shrinkage make the packed bed with soy beans an unsatisfactory physical model. Based on the problems encountered, the experimental set-up has been modified: agar beads with an oleic acid emulsion are a suitable model substrate; a scraped-drum reactor offers better perspectives than the packed bed for studies of solid-state fermentation.