Environmental Engineering Reference
In-Depth Information
13
Cassava
Satya S. Narina
Virginia State University
Damaris Odeny
Agricultural Research Council
contents
13.1 Introduction ........................................................................................................................ 303
13.2 Botanical Description and Cultural Practices .................................................................... 304
13.3 Starch Yield and Ethanol Production from Cassava........................................................... 305
13.4 Cassava Breeding for Improved Bioenergy Production ..................................................... 306
13.5 Commercialization of Cassava as a Bioenergy Crop ......................................................... 307
13.6 Problems and Concerns of Current Biofuel Production ..................................................... 308
13.7 Future Prospects ................................................................................................................. 309
References ...................................................................................................................................... 310
13.1 IntroductIon
Cassava (
Manihot esculenta
Crantz), also known as
yuca
,
manihoc
,
and
mandioca
in Spanish,
French, and Portuguese, respectively, belongs to the family Euphorbiaceae. The Euphorbiaceae
family contains many flowering plants with 300 genera and approximately 7500 species. The
other important members of this family include castor oil plant (
Ricinus communis
), barbados nut
(
Jatropha curcas
), para rubber tree (
Hevea brasiliensis
), and many ornamental plants.
Cassava ranks sixth among crops in global production, with Africa being the largest center of
production (Table 13.1). The enlarged starch-filled roots contain nearly the maximum theoretical
concentration of starch on a dry-weight basis among food crops (Cock 1985). Cassava is considered
a staple root crop for approximately 900 million people living in the developing tropical countries
(Nassar 2006). It is the third largest source of carbohydrates for human food in the world (Phillips
1983) and the primary source of carbohydrates in sub-Saharan Africa (Okogbenin et al. 2007). The
leaves and tender shoots are eaten in many parts of Africa as a source of vitamins, minerals, and
proteins (Cock 1982; Balagopalan 2002; Nweke et al. 2002) and also as animal feed.
Apart from its conventional role as a food crop, cassava has gained high importance as a fuel com-
modity. It is one of the few non cereal sources of commercial starch (Ceballos et al. 2007) important
for ethanol production. Although fossil fuels are considered as the major sources of energy available
for world consumption, bioethanol has been recognized as environmental friendly because of less
greenhouse gas emissions (Nguyen and Gheewala 2008). Recent assessments of the potential of
alternative crops as sources of bioethanol production reported that sweet potato [
Ipomoea batatas
(L.) Lam] and cassava (
Manihot esculentum
) have greater potential as ethanol sources than the
existing sources, including maize (
Zea mays
L.) (Ziska et al. 2009; Sriroth et al. 2010).
In general, the plants of the Euphorbiaceae family have been reported to have great potential as
renewable sources of energy. The
J. curcas
L. is valued for its rich oil obtained from seeds known in the
trade as curcas oil. This oil can be used in place of kerosene and diesel and as a substitute for fuel wood
(Augustus et al. 2002). Castor oil plant (
R. communis
), another Euphorbiaceae member, is the source
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