Sprouting improves the flavour quality of faba bean flours

Abstract

Flours were made from the sprouted seeds of the low- and high-tannin faba bean cultivars Fabelle, FB9-4, Snowbird, and Snowdrop. Headspace measurements on sprouted flours found the most favourable aroma profiles following 48 h sprouting and 24 h drying at 60 °C. Lipoxygenase activity, and the tannin, protein, and moisture contents were determined for unsprouted and sprouted faba bean flours. Lipoxygenase activity was higher in sprouted seeds before drying. Protein content increased after sprouting, whereas the tannin content decreased, especially for high-tannin varieties. Key volatile flavour compounds of faba bean flours included pentanal, hexanal, heptanal, octanal, nonanal, decanal, 1-hexanol, 1-octen-3-ol, 3-methylbutanal, phenyl acetaldehyde, 3-methylbutyric acid, d-limonene, β-linalool, menthol, and estragole; these include oxidative degradation products of oleic, linoleic, and some amino acids. An overall flavour improvement was achieved after germination, as indicated by a decrease in bitter compounds (tannins) and beany flavours (hexanal, nonanal, 2-heptanone, and 2-pentylfuran).

Keywords: Faba bean flour; Headspace volatiles; Lipoxygenase activity; Sprouting; Tannin content; Vicia faba.