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Figure 10.4 Hemicellulose composition in sweet sorghum. Components of hemicellulose
(GlcA, GalA, Xyl, Gal, Glc, Ara, and Rha) in sorghum bran, bagasse, and biomass (Qiu
et al., 2017; Ratnavathi et al., 2016). Ara, Arabinose; Gal, galactose; GalA, galactose acid;
Glc, glucose; GlcA, glucuronic acid; Rha, rhamnose; Xyl, xylose.

and insoluble dietary fibers as compared to bran and biomass. The energy value
obtained from sweet sorghum is higher as compared to the other biomasses such as
rice and wheat. Sweet sorghum is wealthy in minerals and nutrients such as K, P, Mg,
and Ca and niacin, thiamin, riboflavin, and B6, respectively (Doggett, 1970; Rooney,
2014; Smith and Frederiksen, 2000). In the case of fat constituents, polyunsaturated fat
is in higher amount as compared to the saturated and unsaturated fat in sweet sorghum.

10.3 Pretreatment

Lignocellulosic biomass is complex and recalcitrant in nature, so pretreatment of bio-
mass is essential before conversion for biofuel production. Various pretreatments have
been conducted to degrade or partially remove one or more components of biomass.
The pretreatments available for lignocellulose removal may be categorized as physical,
chemical, biological, thermal, or combined approaches. Pretreatment of lignocellulose
biomass should be fast, efficient, cheap, eco-friendly, and readily utilized at an industrial
scale. However, majority of above pretreatments do not fall in that criteria so emerging
and combinational pretreatment approaches become essential (Hassan et al., 2018).

10.3.1 Physical

Crystallinity of lignocellulose, reduction in size, and lowering the degree of poly-
merization are effectively obtained in physical pretreatment as compared to other