Effect of indigestible residue from foodstuffs on trypsin and pancreatic α‐amylase activity in vitro

Abstract

AbstractIndigestible residues from black beans (B; Phaseolus vulgaris L cv Tacarigua), green beans (G; Phaseolus vulgaris L), carrots (C; Daucus carota L) and rice bran (R; from Oryza saliva L) were prepared by the pepsin/pancreatin method of Hellendoorn et al and their effect on trypsin and pancreatic α‐amylase was evaluated comparing two experimental procedures. When the remaining caseinolytic enzyme activity was assayed in the soluble fraction of the fibre/trypsin mixtures, a statistically significant decrease was observed with C, R and G residues. However, assessment of trypsin activity in the presence of residues showed that C has a stronger inhibitory effect, followed in intensity by G and B. With the exception of carrot residue, the highest inhibitory effect was observed if a synthetic substrate of trypsin (BAPNA) is employed. Although all of the residues assayed inhibited α‐amylase activity on soluble starch, the effect of black bean fibre seems to be due to its tannin content. As observed for trypsin, the magnitude of α‐amylase inhibition by indigestible residue proved to be dependent on the experimental system employed. These results indicate that both experimental procedure and type of substrate have an influence on the enzyme inhibitory effect of fibre. C, R and B indigestible residues produced a slight but statistically significant decrease of in‐vitro casein digestibility index.