The use of enzymes for improved production and enhanced quality of industrial products in particular fermented foods, received considerable attention of both academic studies as well as industries. This in turn, triggered interest in re-evaluating alternative new or existing technologies in the field of enzyme production. Solid State Fermentation (SSF) is briefly defined as the fermentation with far less (to almost no) free water when compared to the submerged fermentation. The sufficient amount of the moisture is needed to maintain cellular growth. SSF exhibits interesting features, e.g. considerably less water use, therefore more environmentally friendly, easier to downstream, decreased overall process cost, improved product stability, larger portfolio of enzymes or locally very specific productivity rates owing to the heterogeneity of the substrate of generation of sub-populations.
This review lists and discusses the merits of the recent studies on the production of some of the well-studied enzymes in various industries, namely amylase, proteinase and pectinase via solid-state fermentation, vis-à-vis to various factors affecting the process e.g. moisture content, aeration rate, substrate particle size, temperature, and inoculum size. A separate focus is dedicated on the differences between submerged and solid state fermentation, not only from a fermentation unit operation but also from overall process design point-of-view. Lastly, we discuss the challenges in scale-up of SSF process and various reactor types.