ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

B.A.2.4 Tannin [Van-Burden and Robinson (1981»)
Weigh out 500 mg ofthe sample into a 50 ml plastic bottle. Add 50 ml of distilled water
and shake for 1 hour in a mechanical shaker. Filter this into a 50 ml volumetric flask and
made up to the mark. Pipette 5 ml ofthe filtered out into a test tube. Mix this with 0.008 M
potassium ferrocyanide and 2 ml of 0.1 N HCL Measure the absorbance at 120 nm within
10 minutes.
B.A.2.S Flavonoid [Bohm and Kocipai-Abyazan (1994»)
100 ml 80% aqueous methanol at room temperature was used to extract 10 g of the plant
sample repeatedly. The entire solution was filtered through No 42 (125 mm) whatman filter
paper. After transferring the filtrate into a cruCIble, it was evaporated into dryness over a
waterbath. Itwas weighed to a constant weight.
B.A.2.6 Saponin [Fenwick and OakeDfull (1981»)
20 g of sample material was weighed and placed in the Soxhlet extractor with acetone for
24 hours. Constituent parts, such as lipids and pigments, were thus removed. The solvent
was changed to methanol and extraction was continued for another 24 hours. At this point,
the method used so far (Hai et al., 1976) was modified. Instead ofbringing the sample up to
250 ml as suggested in the original method, it was concentrated. The methanolic extract was
then transferred to a rotary evaporator and evaporated to dryness. Dry extracts were
suspended in approximately 10 ml ofmethanoL The colour was developed with 0.5 ml of 8
per cent vanillin solution in ethanol (freshly prepared for each determination) and 5 ml of
72 per cent (v/v) sulfuric acid was added to 0.5 ml ofthe methanol solution of the sample.
The mixture was blended well, warmed in a water bath at 60° C for 10 minutes and then
cooled in ice-cold water. The methanol blank with the reagents resulted in a strong yellow
colour. Absorbance was recorded at 500 nm. Saponin was used as a standard to draw the
standard curve.
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