Effect of boiling and roasting on some anti-nutrient factors of asparagus bean (Vigna Sesquipedalis) flour

Nzewi Daniel C and Egbuonu Ant

Abstract

Asparagus bean grains, separately processed by boiling and roasting at (100 oC) and (160 oC) respectively for varied period, were milled into flour using attrition mill. Evaluation of the anti-nutritional properties of the flour showed that boiling significantly (p<0.05) reduced phytate from 1.54 ± 0.04 mg/g to 0.18 ± 0.11 mg/g, representing 88 % reduction, tannins from 3.72 ± 0.12 mg/g to 1.88 ± 0.08 mg/g or 49 % reduction and trypsin inhibitor from 5.58 ± 0.89 Tui/g to 0.74 ± 0.04 Tui/g or 87 % reduction. On the other hand, roasting significantly (p<0.05) reduced phytate from 1.54 ± 0.04 mg/g to 0.13 ± 0.03 mg/g or 92 % reduction), tannins from 3.72 ± 0.12 mg/g to 1.82 ± 0.02 mg/g or 51 % reduction and trypsin inhibitor from 5.58 ± 0.89 Tui/g to 0.16 ± 0.06 Tui/g or 96 % reduction. The observed effects occurred in a time dependent manner, suggesting possible enhancement in quality and safety with increasing boiling or roasting time. Roasting further improved the studied anti-nutritional properties of asparagus bean flour, hence may be preferred to boiling for processing asparagus bean.