ABSTRACT
Solid-state fermentation (SSF) is a microbial process where a solid material is used as the substrate or the inert support over which microorgan isms are immobilized.
e SSF system has gas, liquid, and solid phases, in which microbial growth and heat/ oxygen transfer result in temperature gradients, where transfer of heat and mass are obstacles. erefore, the control of process parameters of the SSF is critical. ese parameters include temperature, pH value, aeration, water activity, and moisture. e physical-chemical properties of a medium are influenced by water activity and moisture, and provide a humid environment for the growth of micro organ isms. Water activity and moisture will also pose an effect on the utilization of oxygen and heat transfer.
