Vacuum impregnation as a sustainable technology to obtain iron-fortified broad bean (Vicia faba) flours

Abstract

Iron-fortified broad bean flours were obtained by vacuum impregnation during soaking. The impact of vacuum impregnation and iron fortification on the hydration kinetics of broad beans, as well as the processing (soaking, autoclaving, and dehulling) on the iron-absorption inhibitors (phytic acid and tannins), iron content, iron bioaccessibility, and physicochemical and techno-functional properties of flours was investigated. Results showed that the use of vacuum impregnation during soaking reduced the broad beans’ soaking time by 77%, and using iron solution instead of water did not affect the hydration kinetics. After soaking, iron-fortified broad bean flours increased twice (without hull) or more (with hull) the iron and bioaccessible iron content regarding non-fortified flours. Cooking broad beans by autoclaving modified the tannin content, the iron content and its bioaccessible fraction, and the physicochemical and techno-functional properties of the flours. Autoclaving increased the water holding capacity and absorption rate, swelling capacity, bulk density, and particle size, while decreased the solubility index, whiteness index, emulsifying capacity, emulsion stability, and gelling capacity. Finally, dehulling did not practically affect the physicochemical and techno-functional properties of flours, but showed a decrease in iron content, although increased iron bioaccessibility was observed, occurred mainly due to the reduction in tannin concentrations. The results obtained in this study demonstrated that vacuum impregnation is a useful technology for obtaining iron-fortified broad bean flours with different physicochemical and techno-functional properties depending on the production process used.