Fermentation saccharification

Fermentation can be combined with other operations. For example, feedback inhibition of enzymatic hydrolysis of cellulose can be relieved by removal of the product glucose by fermentation as it forms. This is teni ed. simultaneou.s-saccharification-fermentation (SSF). 

The use of wood for energy, fuels, and chemicals can be conveniently divided into four major categories direct combustion, saccharification-fermentation (SF), thermal decomposition, and thermochemical liquefaction. These methods are discussed in more detail in the following sections.5... 

The saccharification-fermentation (SF) method for the derivation of fuels and chemicals from wood is based on the breakdown or hydrolysis of the polysaccharides in wood to the constituent monomeric sugars. The six carbon or hexose sugars (glucose, galactose, and mannose) then are fermentable to ethyl alcohol... 

Fig. 33.13. Simultaneous saccharification fermentation (SSF) and simultaneous saccharification and co-fermentation (SSCF) concepts.

Adaptive Control of the Simultaneous Saccharification - Fermentation Process from Starch to Ethanol... 

S. Ochoa, A. Yoo, J-U. Repke, G. Wozny and D.R. Yang. 2007, Modeling and Parameter Identification of the Simultaneous Saccharification-Fermentation Process for Ethanol Production, Biotechnol. Prog., 23, 1454-1462. 

The cellulose-to-ethanol process has five basic steps as shown in Figure I. They are feedstock handling and pretreatment, enzyme production, yeast production, simultaneous saccharification/fermentation (SSF) and ethanol recovery. Cellulose is the most abundant organic material on the earth. It is annually renewable, and not directly useful as a foodstuff. It is a polymer of glucose linked /8-1,4 as compared with the a-1,4 linked polymer starch which by contrast is easily digestible by man. There are three basic classes of potential cellulose feedstocks. These are agricultural by-products, industrial and municipal wastes, and special crops. The availability of these materials in the U.S. is shown in Table I. For economic reasons, we are concentrating our efforts on those materials that are collected for some other reason. 

The fermentation of starchy or sugar crops to bioethanol is performed using a series of different processes which are dependent on the raw material used. A general hioethanol process includes milling, liquefaction, saccharification, fermentation, distillation and dehydration, as shown in Figure 6.1. 

Starch Milling- liquefaction- saccharification- fermentation- distiUation Maize Wheat Cassava Caspar et al. (2007), Persson et al. (2009) Nigam (2001) Amutha and Gunasekaran (2001), Kosugi et al. (2009)... 

Figure 2 An illustration of the various research activities underway to develop the next generation bioethanol plant. The 3 key areas of R D are in pretreatments, enzyme hydrolysis andfermentations. Significant efforts focus on process engineering cmd plant designs with the following at the core SHF -separate hydrolysis and fermentation, SSF - a simultaneous saccharification-fermentation, or SSCF - a simultaneous saccharification-cofermentation.

In the wet mill process (Fig. 24.6), com is cleaned, steeped, degermed to obtain germ from which com oil is extracted, defibered to obtain fiber, and subjected to the separation of gluten and starch. This is followed by the same steps as fliose of the com grind process, including saccharification, fermentation, distillation and dehydration of ethanol, etc. (Singh and Eckhoff, 1997). 

Simultaneous liquefaction, saccharification, fermentation, and in situ ethanol removal... 

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