Modeling effects of African Yam Bean (Stenostylis stenocarpa (Hochst. ex A. Rich.) Harms) extract on the digestibility of African Yam Bean flour by an extracted barley malt alpha-amylase

RESUME

In this study, the African Yam Bean flour inhibitors of alpha-amylase were extracted using 5 solvents, namely: acetone / water mixture (70/30; V/V), acetone / water mixture (50/50; V/V), distilled water, water / acetic acid mixture (90/10; V/V), distilled water/acetic acid mixture (80/20; V/V). The digestibility of resulted flours was shown to be significantly affected by the extraction procedure. The acetone/water mixture (70/30; V/V) extraction presented the highest starch digestibility by barley malt alpha-amylase. The acetone/water mixture (70/30; V/V) extract was also responsible of reducing the hydrolysis rate of corn starch. The kinetic parameters of inhibition were determined by studying the effect of increasing corn starch concentration (2, 3 and 4 g/l) used as a substrate on the initial velocity of the reducing sugars release (V0) in the presence of the various concentrations of acetone / water mixture (70/30; V/V) extract. The results obtained show that the inhibition of alpha-amylase by the African Yam Bean acetone/water mixture (70/30; V/V) extract on the digestibility of Corn starch (66 % amylose) is of competitive type.

Key-words: African Yam Bean, modeling, alpha-amylase, inhibition, digestibility.

Arthur Amisi Kapepa, Willy Kasembe, Patrick Baguma Kalimba, Jean-Claude Bwanganga Tawaba