Abstract
Traditionally made from durum wheat semolina (DWS), pasta composition has evolved in recent years, incorporating diverse raw materials such as legumes, wholegrain and/or other nutritious flours. The objective of our study is to go deeper in the development of nutritionally optimized pasta by using climate-smart (CS) crops and assess protein bioacessibility in these new food matrices. It is part of the H2020 Innofood Africa project, bringing together European and African partners to explore CS crops and develop new products for at-risk populations (children and women) suffering from malnutrition or obesity. We have developed optimized pasta made from wholegrain, gluten-free, CS African cereals and legumes. Special attention has been paid on their in vitro protein digestibility and the nature of the released peptides in relation with protein network structure. Four cowpea-based pasta formulations were obtained by linear programming and met the FAO’s nutritional recommendations for one meal for adult women, ensuring adequate levels of protein, fiber, zinc, iron and B9 vitamin. As all optimized formulations combine cowpea with teff and/or amaranth leaf flours, the impact of adding these two flours individually or in combination on the protein network structure, digestibility and peptides released was studied. The comparison with DWS pasta controls, varying in fiber contents from 3.5 to 16 g/100g d.b allowed to highlight the impact of the high fiber content on the protein structure and digestibility.In vitro protein digestibility was assessed using the enzymatic Megazyme kit and the COST Infogest digestion model with control of the degree of proteolysis by monitoring free NH2. At the end of the intestinal phase, the protein digestibility of DWS pasta controls whatever their fiber contents was higher than that of the four cowpea-based pasta with the Megazyme kit, while the results were reversed with the Infogest model. These difference can be explained by distinct gastric and intestinal proteolysis conditions that will be highlighted during the presentation. Despite the lower protein digestibility assessed for cowpea-based pasta, the Megazyme kit revealed PDCAAS two times higher for these matrices compared to DWS controls due to their higher content of essential amino acids. The peptidomic study shows that all cowpea-based pasta have same size of peptides released at the end of intestinal phase (1150 vs 1120 kDa in DWS controls) and highlights that most peptides were derived from cowpea storage proteins such as vicilin (50%) and legumin (15%) differing thus strongly with gliadin and glutenin derived peptides in DWS controls. With the comparison of two reference methods for digestion, this work has pointed out that pasta associating cowpea with amaranth leaf flour provide superior nutritional benefits combined along with high protein digestibility.