ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

A.2.3.6.8
A.2.3.6.9
A.2.3.6.10
A.2.3.6.11
Phytate
Double acid extraction (HCl and H2S04) was perfonned on sample materials for three
hours. Samples were filtered under vacuum through Wbatrnan no 1 filter paper. Colour
was developed by adding ammonium molybdate, ascorbic acid and potassium
antimonytartrase and absorbance was measured at 820 run. A standard curve was
prepared, expressing the results as potassium-hydrogen-phosphate equivalent. The
concentration ofphytate was calculated from its phosphorus content.
Alkaloid
Amadumbe alkaloids were detected by the method utilized by Harbome (1973).
Amadumbe samples were soaked in a 10 per cent solution ofacetic acid in ethanol for four
hours. This was filtered and the extract was concentrated on a water bath. Precipitation was
executed by adding concentrated ammonium hydroxide. The precipitate thus obtained was
washed with diluted ammonium hydroxide, dried and weighed The percentage yield ofthe
alkaloid was calculated.
Oxalate
Oxalate was detennined employing the method used by Munro and Bassir (1969). The
oxalate was extracted with 0.15 per cent citric acid and treated with tungstophosphoric
acid Precipitated oxalate was solubilized with hot diluted H2S04 and titrated against
KMn04. Oxalate content was expressed as calcium oxalate equivalent.
Saponin
Saponin content was detennined utilizing the method employed by Fenwick and
Oakenfull (1981). Saponin was extracted for 24 hours in a reflux condenser containing
pure acetone. Re-extraction with methanol in the Soxhlet apparatus was carried out for
another 24 hours. Colour development was achieved by using vanillin in ethanol and
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