Solid-state fermentation (SSF) is a process whereby an
insoluble substrate is fermented with sufficient moisture but
without free water. (The abbreviation SSF is also used for
"simultaneous saccharification and fermentation." But SSF
is retained here for "solid-state fermentation" because it is
also commonly used [4, 8, 29], and it is an antonym to
another state of fermentation, i.e., "liquid-state fermentation"
[LSF].) In liquid-state fermentation (LSF), on the
other hand, the substrate is solubilized or suspended as fine
particles in a large volume of water. In most LSF, substrate
concentrations ranging from 0.5 to 6% are used depending
upon the density of the substrate. SSF requires no complex
controls and has many advantages over LSF (8); however, it
has its own inherent problems (4)