ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

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harvest, packaging, storage conditions and melhod utilized for processing (Morris et al.,
2004).
The primary purpose ofprocessing is to render food palatable and develop its aroma, but
it has inevitable consequences on lhe nutritional value of foods. Washing and peeling
result in lhe loss ofmany water-soluble vitamins, since lhese are more concentrated in lhe
peel and outer layers. Wilh careful control of the processes, nutrient losses can be
minimized wilhout affecting palatability.
The term "food processing" covers an enormous field, from simple boiling to lhe use of
irradiation. The types of cooking melhods differ in countries around lhe world and also
vary wilh lhe elhnic background of lhe family. Processing (cooking) can be bolh
beneficial and detrimental to nutrient composition of foods. It is known that processing
techniques may decrease the food value of some nutrients (Nestares et al., 1996): for
example, lhere is some inevitable leaching of nutrients into lhe cooking water during
processing. The cooking water may or may not be discarded, depending upon cultural
and personal preference.
On lhe olher hand, processing may enhance the nutritional quality offood by reducing or
destroying the anti-nutrients present in it, as well as increasing the digestibility of
proteius and starches. Elimination or inactivation of anti-nutritional compounds is
absolutely necessary to improve lhe nutritional quality and effectively utilize human
foods to lheir full potential. Processing generally inactivates heat-seusitive factors such as
enzyme inlnbitors, lectius and volatile compounds such as HCN. A typical example is lhe
protein in legumes, which is made more digestIble by heating because ofthe inactivation
ofanti-nutrients such as trypsin inlnbitors (Siddhuraju and Becker, 1992).
The use of some processing methods, such as boiling, baking, microwave- and pressure
cooking are known to achieve reduction or elimination ofanti-nutritional factors (Udensi
et aI., 2005; Bhandari and Kawabata, 2006; Habiba, 2002; Khokhar and Chauhan, 1986).
Radiation processing and extrusion have also been used as a means to inactivate anti-
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