ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

Carbohydrates supply the most energy in a diet and for this reason make up a greater
percentage than fats or proteins. The presence of starch contnbutes to the textural
properties of many foods. Starch has many industrial functions, including gelling agent,
colloidal stabilizer and thickener (Lii et aI, 1996). Potato, rice, wheat and corn are the
most important sources of starch, but differ noteably in structure and morphology (Singh
et al., 2007).
The starch and soluble sugar levels of the different Amadumbe corms indicated that
Amadumbe tubers store a high level of starch, ranging between 15 and 28 per cent. For
this reason, they can be considered carbohydrate foods (Swinkels, 1985). These starch
levels are similar to those ofbetween 19.2 and 26.1 per cent, recorded for taro by Huang
et al,. (2000; 2007). Differences in starch content were observed among investigated
Amadumbe corms from different locations. This finding corroborates the observations of
Jane et at. (1992) that the carbohydrate content of taro cultivated in different locations
showed variation.
Lee (1999) estimated the digestibility of taro starch to be 98.8 per cent and the size ofthe
taro starch grain as one tenth the size of that of the potato. The good levels of starch in
taro and cocoyams mean that these tubers can be used in the preparation of foods which
prevent allergic diseases, in the manufacture ofiufant meals and for patients with chronic
liver problems, peptic ulcers and inflammatory bowel disease (Sefa-Dedeh and Agyir­
Sackey, 2004; Emmanuel-Ikpeme et al., 2007).
The soluble sugar levels of Amadumbe tubers (1.1 - 4.0 per cent) were generally higher
than those reported for taro corms (Huang et al., 2007) and other roots, including yam,
cassava, and potato (Bradbury and Holloway, 1988; Wanasundera and Ravindran, 1994).
However, levels were similar to those reported for sweet potato (Zhang et al., 2004). The
higher soluble sugar content of Amadumbe tubers highlights their superior taste as a
staple food (Huang et al., 2007). Levels of soluble carbohydrates IIlay indicate a degree
ofdormancy; however, Amadumbe samples were freshly collected.
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