Solid substrate fermentation should be used to define only those processes in which the substrate itself acts as carbon/energy source, occurring in the absence or near-absence of free water:
Solid state fermentation should define any fermentation process occurring in the absence or near-ab sence of free water, employing a natural substrate as above, or an inert substrate used as solid support [1].
During 1991–1992, two reviews were published on SSF describing the general features of SSF and aspects of fermenter design in SSF [2,3].