60
ssf for foods and beverages
3.1.4 Aeration
In the SSF fermentation process with aerobic micro organ isms, micro-
bial growth and biomass are often limited by oxygen transfer. Oxygen
transfer both in the solid medium and among the particles of mass are
the main transfer processes.
In SSF fermentation, the most important oxygen transfer process
among the mass particles is the oxygen transfer from the void volume
of the medium to micro organ isms. e size of void volume is deter-
mined by the property, size, and the water ratio of particles. Chaff
is added to the medium to increase the void volume. e water ratio is
related to the transfer of oxygen to the void, because the water in the
medium prevents air from flowing. To a certain size of vo