Effect of reconstitution and Na2Co3 on tannin content and in vitro protein digestibility of faba bean cultivars

Two faba bean cultivars (317/99/81 and Giaz/402) obtained from Shambat Research Station in Northern Sudan, were used for this study. Investigation showed that the tannin contents of untreated seeds were 0.077% and 0.067% for cultivars 317/99/81 and Giza/402. In vitro protein digestibility values were 80.68% and 81.48% for the two cultivars, respectively. The extractable tannin content of the faba bean cultivars was markedly reduced by imbibing water or Na₂CO₃ solution into whole seeds and incubating them at 30°C for 1, 3, 6, 12 or 24 hours, or at 100°C for 5, 10 or 20 minutes. The extent of reduction depended on time, temperature, and Na₂CO₃ concentration; the percent tannin extracted and percent in vitro protein digestibility increased with time or Na₂CO₃ concentration, while application of high temperature reduced the time.