Solid state fermentation requirements

Mass is balanced at the beginning and the end of process. The evaporated water in solid-state fermentation may not be required for energy balance. 

In countries where a strong environmental regulation for industrial wastewater exists, purification of waste streams from potato factories regarding both the fruit water and the pulp is required. Several attempts have been made to dehydrate the by-products and to utilize them for different purposes. Its high moisture content (80%) requires an expensive drying due to the problem of spoilage, if left untreated. The starch industry tries to sell as much pulp as possible as wet or partially dried cattle feed. However, the need for potato pulp by farmers is limited. Potato pulp is being used as cattle feed as well as a solid-state fermentation media for the production of different biomolecules. Conventional applications of potato pulp are listed in Table 16.2. 

It is a commonly held view that cellulase is an inducible enzyme, and that cellulose is the best inducer. In solid-state fermentation for cellulase production, cellulosic materials act as either the carbon source or the inducer. Some of the raw materials for solid-state fermentation and their composition are listed in Table 1. From Table 1 it is very clear that the raw materials for cellulase production using solid-state fermentation are abundant and cheap. Proper pretreatment of raw materials is generally required. The nitrogen source for solid-state fermentation includes inorganic compounds, such as urea and (NH4)2SO4, or natural products, such as bran. 

A bioreactor is a vessel in which biochemical transformation of reactants occurs by the action of biological agents such as organisms or in vitro cellular components such as enzymes. This type of reactor is widely used in food and fermentation industries, in waste treatment, and in many biomedical facilities. There are two broad categories of bioreactors fermentation and enzyme (cell-free) reactors. Depending on the process requirements (aerobic, anaerobic, solid state, immobilized), numerous subdivisions of this classification are possible (Moo-Young, 1986). 

There is no stirrer in most types of solid-state fermentor and the requirements for water and aeration are less than that in submerged fermentation. Therefore, the energy consumption is low and there is no wastewater produced in the process. 

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