Sprouting favourably impacts on antinutritional factors, protein profile and hydrolysis in Cowpea (Vigna unguiculata) seeds

Legumes are a good source of dietary fiber, proteins, and low glycemic index carbohydrates. However, low protein digestibility and anti-nutrient activity due to the presence of trypsin inhibitors and phytate are commonly found in legumes and could interfere with nutrients bioaccessibility and bioavailability. Nowadays, the potential of sprouting as gained cost, and sustainable practice to enhance the levels of functional compounds and healthy properties, but also the nutrient digestibility and bioavailability. In this study we investigated the effect of different sprouting time on cowpea (Vigna unguiculata) seeds on protein profiles and hydrolysis and anti-nutritional factors as trypsin inhibitors activity and phytate content. Sprouting was carried out on cowpea seeds, previously soaked in water, for 24, 48 and 72 hours. After drying and grounding, phytate content and trypsin inhibitors were assessed by a commercial kit and according to the EN ISO 14902 standard, correspondingly. Moreover, proteins profiles and hydrolysis in beans flours water extract were evaluated by SDS-PAGE and OPA assay, respectively. The results indicated as sprouting favourably reduced in a similar manner trypsin inhibitors activity and phytates content. Moreover, sprouting determined a reduction of globulin fraction, which represents the major protein classes founded in Cowpea flour: in particular, the two fraction of globulin, legumin (~ 96KDa) and vicilin (~ 60KDa) are reduced in a time dependent manner, with the maximum effect already reached at 48 hours, which was associated an increase of protein hydrolysis. Although further studies are needed to better understand the effect of sprouting at the protein level; these first results underline the importance of this bioprocess to increase the nutritional value of legumes to be used in the formulation of foods with a higher health impact.