New functional faba bean ingredients with fermentation

Faba bean flour is an economically sound and sustainable raw material to make baked and extruded products high in protein. The protein content of faba beans is approximately 30%. However, consumption of faba beans is hindered by their poor digestibility and presence of several anti-nutritional factors such as phytate, vicine and convicine, tannins, lectins and trypsin inhibitors. This study aimed to improve nutritional properties and technological functionality of faba bean flour by fermentation with lactic acid bacteria (LAB). Potential autochthonous LAB were isolated and identified for use as starter cultures in faba bean sourdoughs. Fermentations with different LAB including Lactobacillus plantarum and exopolysaccharide (EPS) producing strains such as Leuconostoc lactis and Weissella confusa were carried out in 0.5 kg and in 15 kg scales. The functionality of fermented faba bean flours as ingredients in extruded products was studied. Extruded samples were made with 25, 50 and 100 % fermented faba flour and compared with native faba flour by using APV Baker Perkins twin screw extruder. During extrusion rice flour was used as a starch carrier. This study revealed that faba beans are a natural source of EPS producing LAB. Weissella strains that could be used as starter cultures in faba bean fermentations were identified and applied. LAB fermentation and in situ production of dextran had a positive impact on nutritional and technological properties of faba bean flour. Fermentation released proteins from the cell wall matrix and increased the amount of free amino acids. Furthermore in vitro protein digestibility was modified. Phytic acid may form complexes with proteins thus hindering proteolysis and protein digestibility. Fermentation of faba bean flour had minor effect on the degree of expansion for high protein extrudates but increased instrumental crispiness index and lowered hardness values. Fermented faba bean flours were also promising ingredients in baking applications. LAB fermentation provides a natural bioprocessing tool for modification of nutritional and technological properties of faba bean flours that could be applied in the development of novel plant-protein based products. This study is part of an EU SUSFOOD Era-net project BIOPROT (Novel multifunctional plant protein ingredients with bioprocessing) which aims to develop novel protein enriched bran and faba bean ingredients for various food categories.