Bioprocessing of protein-rich raw material towards improved functionality

Faba bean flour is economically sound and sustainable way to make high protein baked and extruded products. However, the use of plant proteins is complicated due to anti-nutritional factors, taste issues and poor technological functionality. This study aimed to improve nutritional properties and functionality of faba bean flour by bioprocessing with lactic acid bacteria (LAB) and enzymes. Fermentations with different LAB including Lactobacillus plantarum and exopolysaccharide (EPS) producing species such as Leuconostoc lactis and Weissella confusa were carried out in 0.5 kg and in 15 kg scale. Several new potential EPS producing lactic acid bacteria were isolated from faba beans. Furthermore, different treatments with food-grade phytase were performed in order to decrease phytic acid content and increase protein solubility. The functionality of bioprocessed faba bean flours was studied in baked and extruded products. Fermentation and in situ production of dextran had positive impact on nutritional and technological properties of faba bean flour. Microbial exopolysaccharides have the potential to replace hydrocolloids thus improving textural properties in fermented food products. LAB fermentation released proteins from the cell wall matrix and increased the amount of free amino acids. Protein release could be also enhanced by reduction of phytic acid which may form complexes with proteins and thus hindering proteolysis. This study showed that over 80% of the phytic acid could be degraded already after 1-2 hours treatment with food-grade phytase enzyme. Lactic acid bacteria and food-grade enzymes offer a natural tool to upgrade of plant-protein ingredients.