Molecular features of proteins and starch in sprouted bean-fortified bread.

Pulses are a worldwide component of human diet and play a crucial role in meeting protein requirements, particularly in developing countries. However, pulses contain antinutritional factors such as phytates and enzyme inhibitors. Currently, sprouting is gaining attention as a low-cost, sustainable, and effective way to increase both the levels of health-promoting components and nutrients' digestibility. This study explores changes in the protein pattern in wheat bread enriched with flour from 72-hours germinated cowpea (Vigna unguiculata), a time shown to be sufficient for almost complete breakdown of antinutritional factors. Bread was prepared by adding 25% of unsprouted or sprouted cowpea flour to wheat flour. Samples were characterized in terms of protein content and profile, and for the content in residual anti-nutritional factors (trypsin inhibitors and phytates), starch (total, slowly/rapidly digestible, resistant), and gut-fermenting oligosaccharides. A slight increase in total protein in bean-fortified breads was related to the incorporation of a legume-derived component with Mr around 45 kDa. A decrease in total, rapidly digestible, and total digestible starch was observed in bread enriched with either sprouted or unsprouted bean flour, whereas the content of resistant starch increased in samples containing flour from sprouted beans. The sprouted bean flour breads also exhibited the lowest levels of trypsin inhibitors and phytates, as expected. Bread samples were subjected to in vitro digestion following the INFOGEST protocol to evaluate protein breakdown at various digestion phases. Large and medium-sized proteins bands were no longer present in SDS-PAGE tracings of the supernatant of digests after the gastric phase. Duodenal digestion produced small-size peptides, not retained in SDS-PAGE gels. The nature of the protein hydrolysis products, their bioaccessibility, and the presence of potential bioactive species are current under study.