Variation of antinutrients in faba bean cultivars during seed development

Several chemical compounds of seven faba bean cultivars—Sampo, Louhi, Talia, Tiffany, Julia, Gloria, and Vroma—grown in Finland were determined. The effect of seed maturity on the levels of vicine/convicine (vc), trypsin inhibitors, condensed tannins, phytic acid, lectins, and oligosaccharides was analyzed. The overall vc ratio remained similar in all the samples, and the largest amounts of vc were found in the early stage of the bean and decreased during maturation. Talia and Gloria had lower trypsin inhibition than the other cultivars. The smallest amounts of condensed tannins were found in the Talia and Gloria cultivars, and the largest in the Tiffany and Julia cultivars. Overall, it seems that maturation decreased the amount of condensed tannins. The fully mature faba bean contained an average of 10.3 to 13.4 g/kg (DW) phytic acid, and there was no difference between the seven cultivars. The highest lectin activity was found in the Sampo, Julia, and Tiffany cultivars, and the lowest activity was in Vroma and the mature seeds of Talia and Louhi. The simple sugars (rhamnose, galactose, glucose, sucrose, and fructose) were dominant in the early developmental stage, whereas the amount of long chain oligosaccharides (stachyose and verbascose) increased during maturation of beans, and the level of raffinose was similar in all developmental stages. In conclusion, the content of chemical compounds depended on the maturation stage and the faba bean cultivar. The low content of stachyose, verbascose, and raffinose in young Tiffany and Julia beans is beneficial when consumed as green bean.