ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

Inhibition oftrypsin obtained with the screening procedures ranged from 16.5 to 20.6 mg
gol. The TIA content was found to be lowest in the raw tubers of the Esikhawini purple
variety (16.5 mg pure trypsin :inlnbitedlg DM) and highest (20.6/g DM) in Mtubatuba
white. All three domestic processing methods completely inactivated the initial trypsin
enzyme inhibitor level in the Amadumbe tubers.
The :inlnbitory effect of the crude extract on other proteases was also investigated and
results are expressed in Table A3-5 Apart from the activity of papain, which was not
inhibited, all other proteases were inlnbited by crude Amadurnbe extract. It is noted that
the inlnbitory activity on fungal proteases was minimal.
Table A3-5: Inhibitory effect ofcrude extract on other proteases
white purple white purple
Protease (Bacillus Lkheniformif) 0.55 0.42 0.5 Undetected
Type xiii Fungal 1.5 0.15 0.25 0.15
Type xiv Bacterial 11.1 10.4 9.65 12.2
Type xviii Fungal: Rhizopus 0.45 0.5 Undetected 2.5
Papain Undetected Undetected Undetected Undetected
a-ehymotrypsin 0.5 0.45 Undetected 0.55
Both varieties of Amadurnbe contained lectins that stimulated platelet agglutinization by
about 300-6000/0, as showed in Table A3-4a.
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