Biochemical engineering aspects of solid-state fermentation

Abstract

This chapter discusses the biochemical engineering aspects of solid-state fermentation (SSF). Solid-state fermentation involves the growth of microorganisms on moist solid substrate in the absence of free-flowing water. The necessary moisture in SSF exists in an absorbed or complexed form within the solid matrix, which is likely to be more advantageous because of the possible efficient oxygen transfer process. Most applications of fermentation for the manufacture of industrial products use technology based on submerged fermentation; solid-state fermentation techniques are seen to exhibit great potential and for specific cases, competitive SSF systems have already been developed. Some of the important aspects on which research efforts need to be focused in this area are (1) the development of mathematical models accounting for the interactions of transport of heat and mass with bioreaction kinetics in different types of SSF systems; (2) theoretical predictions and experimental determination of transport parameters for SSF; (3) the development of reliable estimation methods, in particular for biomass in the presence of solids; and (4) better design of bioreactors enablingaccurate measurement and control of variables such as temperature, gaseous concentration, and water activity. To develop an effective SSF process, an interdisciplinary effort involving a combination of microbiological and engineering aspects is essential.