Sweet Sorghum: Breeding and Bioproducts - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 22

fermentation [ 122 ]. There are reports on the production of lactic acid monomer
from different varieties of sorghum wherein the whole ground sorghum grain was
liquefied and fermented to lactic acid using Rhizopus oryzae NRRL 395 and the
efficiency of saccharification was dependent on the native glucoamylase
[ 123 ]. Sweet sorghum bagasse residue after alcohol fermentation can also be used
for the preparation of biodegradable PLA with a tensile strength of 49.5 M and a
flexible strength of 65 MPa [ 124 ].
Protein-Based Films and Adhesives
Sorghum grain has an average protein content of 11 % and its proteins are classified
as prolamins (kafirins) and non-prolamin proteins. Kafirins constitute 77-82 % of
the endosperm proteins and are involved in intermolecular cross-linking. Kafirin
was reported to have potential in biofilm-forming applications. Its mechanical,
water-vapor barrier and color properties of free-standing films from laboratory-
extracted kafirin were comparable to those of zein films of commercial importance
[ 125 ]. Sorghum flour as such can be used as protein extender in phenol-
formaldehyde-based plywood adhesive for sprayline coaters or foam extrusion.
The sorghum-based plywood glue had a viscosity of 1,104 cP and adhesion strength
of 1.37 MPa which was comparable with the industry standard glue [ 126 ].
Summary
Sweet sorghum is the only first generation feedstock that provides both food and
fuel besides fodder with relatively high RUE, WUE, and NUE with greater adap-
tation to semiarid regions [ 127 ]. Though it has gained importance as a stable food
and fodder crop, recently it is increasingly viewed as a viable feedstock for the
production of various bioproducts ranging from biofuels, beverages, food, pharma-
ceuticals, antioxidants, antimicrobial, and antidiabetics. Hence, focused research on
its production and processing is required for efficient exploitation of polymeric
carbohydrates, fermentable sugars, and biomass for varied needs of the society.
References
1. Reddy BVS, Ramesh S, Sanjana Reddy P, Ramaiah B, Salimath PM, Rajashekar K. Sweet
sorghum - a potential alternative raw material for bioethanol and bio-energy. Int Sorghum
Millets Newsl. 2005;46:79-86.
2. Srinivasarao P, Rao SS, Seetharama N, Umakanth AV, Sanjana Reddy P, Reddy BVS,
et al. Sweet sorghum for biofuel and strategies for its improvement. Information Bulletin
No 77. Patancheru: International Crops research Institute for the Semi-Arid Tropics,
80 pp, ISBN: 978-92-9066-518-2, Order Code: IBE 077, 2009.