Sprouted bean flour as a new potential nutritious and functional ingredient in bakery product

Many food manufacturers today are looking to replace wheat flour by alternative flours to be included in novel formulations with high nutritive value and bioactive properties. Legumes are a good source of dietary fiber, protein, low glycemic index carbohydrates and low in fat. However, anti-nutrient activities due to the presence of trypsin inhibitors and metal-sequestering phytates are commonly found in legumes and could interfere with protein digestibility and nutrients bioavailability. Nowadays, the use of sprouted legumes as means to innovate and obtain foods with improved nutritional quality and improved content of bioactive compounds. The potential of sprouting as an effective, low-cost and sustainable practice to enhance the levels of functional compounds and healthy properties, but also the digestibility and bioavailability of micronutrients, including metals of biological relevance and non-metal micronutrients. In this study we investigated the effect of sprouting on cowpea (Vigna unguiculata) seeds by assessing the residual levels of phytates and of trypsin inhibitors, along with the extent of protein hydrolysis in germinated seeds. Sprouting was carried out on seeds, previously soaked in water (weight ratio 1:2, 8 hours). Samples of germinated seeds were collected after keeping the soaked seeds at room temperature and 90% of relative humidity for 24, 48 and 72 hours. After drying and grounding, phytates content and trypsin inhibitors in aqueous extracts from individual meals were determined by a commercial kit and according to the EN ISO 14902 standard, respectively. Protein hydrolysis was evaluated by SDS-PAGE and by the OPA assay for free amino groups. The results indicate that sprouting decreased the trypsin inhibitors activity and the phytates content, with a concomitant increase in protein hydrolyses in a time dependent manner. The maximum effect was already reached at 48h of germination. Although further studies are needed to better define the effect of germination at the protein level - particularly in terms of the interactions between proteins and vitamin-derived cofactors - these first results underline the significance of this bioprocess as for increasing the nutritional value of legumes to be used in the formulation of bakery products with a higher health impact.