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216 Refining Biomass Residues for Sustainable Energy and Bioproducts

in the tune of 500 million metric tons (MMT) is available in India per year with a
possible generation of 18,000 MW energy. Alternative and efficient ways of
unlocking the energy potential in biomass, which has not been exploited
completely, is the main focus and is the need of the hour for researchers. On the
other hand, huge quantities of agricultural wastes have been burnt in fields and
municipal solid wastes decaying in landfills in an uncontrolled manner, which pro-
duces hazardous and noxious gases to the atmosphere creating environmental pollu-
tion (Aro, 2016; Devarajan et al., 2017; Ramadhas, 2016; Sukumaran et al., 2010).
The well-controlled deployment of renewable biomasses would yield in the
improvement of rural economy, and decrease in greenhouse gases (GHGs) and pol-
lution to air, water, and land. Recently, biorefineries are being developed to
enhance or extract the energy from biomasses as much as possible, fuels, and
value-added chemicals with less ecological foot prints (Hombach et al., 2016; Miret
et al., 2016).

10.2 Sweet sorghum

Sweet sorghum genus Sorghum Moench, which was originally proposed by Clayton
in 1961 as Sorghum bicolor (L.) Moench for cultivated sorghum, which is at present
widely the accepted one, belongs to the grass family Poaceae, tribe
Andropogoneae, and subtribe Sorghinae (Clayton and Renvoize, 1986; Linnaeus,
1799). Sorghum is an adaptable and multipurpose crop from African source because
of its numerous applications to use the grains as food, leaves for feed, bagasse for
fiber, and sugary juice for fuel. It is cultivated all over the world in tropical, semi-
tropical, and semiarid tropical regions. There is a huge variation in the genus of
Sorghum, which is divided into 22 species and 5 sections. Throughout the world, it
is a known commodity and popularly known as jowar, cholam, and jonna in India.
Rice, wheat, and sorghum are the three most important crops in order of cultivation
in India and sorghum alone contributes around 16% of the world’s production. It is
usually cultivated during and after monsoon seasons (Aruna et al., 2018;
Ratnavathi, 2019).

10.2.1 Distribution
“Sorghum” is classified into five sections—Eusorghum, Chaetosorghum,
Heterosorghum, Parasorghum, and Stiposorghum. In these sections, 22 species of
sorghum have been identified; however, only 1 species (Sorghum bicolor bicolor)
is grown throughout the world. Other natural varieties of sorghum are usually
unique to the cultivators as they are resilient species and resistant to pests and
pathogens (Venkateswaran et al., 2019).
S. b. bicolor is a very unpredictable one and includes 28 different species culti-
vated excluding Sorghum aterrimum, Sorghum drummondii, and Sorghum nitens.
Spikelet morphology and grain characteristics are used and presented clearly to