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Sweet sorghum: a potential resource for bioenergy production      221






























           Figure 10.3 Composition of sorghum biomass. Comparison of various sorghum biomass
           in terms of constituents (lignin, cellulose, hemicellulose, ash, and extractives) and
           carbohydrates (structural and nonstructural). Structural carbohydrates include cellulose and
           hemicellulose, while nonstructural carbohydrates include glucose, sucrose, fructose, and
           starch (Ratnavathi et al., 2016; Staggenborg, 2016). PS, Photoperiod sensitive.

           10.2.3.3 Hemicellulose
           Hemicellulose containing pentose and hexose sugars is a low molecular weight het-
           eropolysaccharide (Gollakota et al., 2018), and in sweet sorghum, it contains major
           amount of glucose (17% 50%), xylose (15% 29%), and galactose (11% 40%) and
           minor amount of arabinose (5% 14%), mannose (0% 14%), rhamnose (2% 10%),
           and uronic acids (1% 2%) (Ray et al., 2019). Fig. 10.4 depicts the hemicellulose
           composition in the sweet sorghum. In hemicellulose the ratio of arabinose and xylose
           determines the degree of branching. Higher degree of polymerization and shorter
           polymer chain are due to the lower ratio and vice versa. Covalently bonding is
           observed between hemicellulose and lignin; however, hydrogen bonding is observed
           between cellulose and hemicellulose, which amalgamate easily with one another cre-
           ating strength and elasticity (Chen et al., 2012; Hunsigi et al., 2010; Rao et al., 2009).

           10.2.3.4 Other components
           It mainly includes the minerals, amino acids (protein), fat constituents, dietary
           fibers, and extracted vitamins. Sweet sorghum is used as food and fuel and also
           finds usage as animal feed. Fig. 10.5 shows the composition of minerals, amino
           acids (protein), fat constituents, dietary fibers, and extracted vitamins obtained from
           sweet sorghum (Rao et al., 2009). Sorghum bagasse contains a high amount of soluble
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