Sorghum - Bioenergy Crop Plants - page 488

provide fodder for livestock. The juice from sweet sorghums can be used to produce syrups and sugar
or be fermented into alcohol. An estimated 40% of grain sorghum production worldwide is used
for human consumption (Rooney and Waniska 2000). High-yielding white grain, tan-plant grain
sorghum hybrids have developed an export market to Japan and other Asian countries for production
of snack foods and beer because of their bland tastes, lack of gluten proteins, and genetically
modified organism (GMO) traits. Gluten, the protein found in wheat ( Triticum aestivum L.), barley
( Hordeum vulgare L.), and rye ( Secale cereale subsp. Cereale), is indigestible by people with celiac
disease (Fasano and Catassi 2001). Sorghum grain can be milled into fractions of bran, germ, meal,
flour, and grits of different sizes. The general methods of dry milling have been summarized by
Hahn (Rooney et al. 1980) and Munck (1995). Sorghum flour can be used as a blend with wheat flour
in baked products and has gained consumer acceptability (Munck 1995; Ragaee and Abdel-Aal
2006). In India and Africa, sorghum is used to make thin or stiff porridges and fermented beverages
(Lochte-Watson et al. 2000) whereas in Central America and southern Mexico it is a total or partial
replacement for maize in tortilla production (Almeida-Dominguez et al. 1991). A brewer using
white food-grade sorghums and waxy sorghum grits can achieve reduced color, shorter conversion
and runoff times, and improved yields for brewing (Figueroa et al. 1995).
Sorghum is being evaluated for use in health food supplements because of the presence
of antioxidants, phytosterols, and policosanols in the germ and pericarp. Concentrated in the
byproducts of milling and alcohol fermentation, these products might be in high enough quantities
for commercial use. Sorghum oils have high levels of phytosterols (Singh et al. 2003) which reduce
cholesterol absorption (Weller 2006), whereas sorghum wax contains policosanols, which reduce
cholesterol production (Rooney and Awika 2004; Weller 2006). In the United States, sorghum is
the second most important feed grain behind maize. The feeding value of grain sorghum for feed-lot
cattle is 85-100% of maize (Kriegshauser et al. 2006) and 90-95% of maize for swine and poultry
(Hulan and Proudfoot 1982). White-grain, tan-plant cultivars are ideal for feeding broilers because
the absence of colored glumes reduces the amount of dark specks found on carcasses (Rooney and
Waniska 2000). Hicks et al. (2002) reported that hybrids with heavy kernel weights had increased
crude protein and fat content with reduced starch, which improved broiler chicken performance to
be equal to or better than maize (Kriegshauser et al. 2006). Sorghum provides a source of starch for
ethanol production in Nebraska and Kansas, and the byproducts have become important dairy and
beef cattle feeds. In all countries except the United States, sorghum is used extensively as a cereal food.
The grain is an excellent food source when ground into flour and used to make pancakes, porridge,
and flatbreads. Sorghum grain produces edible oil, starch, dextrose, paste, and alcoholic beverages.
Sorghum can be puffed, popped, shredded, and flaked to produce ready-to-eat breakfast cereals.
Economically, the use of sorghum grits and commercial enzymes is also practical. In the United
States, sorghum is used primarily as a corn substitute for livestock feed because their nutritional
values are very similar. Some hybrids commonly grown for feed have been developed to deter birds
therefore contain a high concentration of tannins and phenolic compounds, which causes the need
for additional processing to allow the grain to be digested by cattle. In arid regions in less-developed
regions of the world, sorghum is an important food crop especially for subsistence farmers.
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Researchers and ethanol producers have shown that grain sorghum is a good feedstock for ethanol
that is comparable to that from corn grain and could make a larger contribution to the nation's fuel
ethanol requirements. However, in the past, factors affecting ethanol yield were less well studied
for sorghum than for corn. Little research has been conducted on performance of sorghum varieties
in ethanol fermentation. Several researchers have investigated the digestibility of sorghum starch
and sorghum protein (Duodu et al. 2003; Selle et al. 2010; Wong et al. 2009) as related to its use in
feed or food. Others have investigated the isolation of sorghum starch and its properties (Park et al.
2006; Sang et al. 2008). The economic viability of an ethanol production facility depends on several