Relevance of dietary fibres on the gastrointestinal digestion of food proteins: in vivo vs. in vitro digestions

The global food system is currently facing great challenges, motivated by environmental
and health-related concerns. The existing food resources are not efficiently exploited, and the
unhealthy dietary habits of modern societies are leading to a dramatic increase in the incidence of diet-related chronic diseases. In this context, the food industry is actively working to develop ‘novel’ food products with added health benefits and good nutritional quality. Regarding the nutritional quality of proteins, not only the amino acid profile is relevant, but also the digestibility and the bioavailability of essential amino acids (AAs) are key factors. Although traditionally in vivo methods, involving human studies or animal experiments, have been used to estimate the digestibility of proteins, with the emergence of numerous new protein-based products, this would be impractical and against the ethical guidelines. Thus, the use of in vitro methods to measure digestibility has emerged as a rapid and affordable alternative and it is expected to provide sufficient sensitivity for regulatory needs in the future. Accordingly, in this proposal we would like to characterize the nanostructure of the digestion products from blends of proteins and dietary fibres, obtained through in vitro and in vivo digestions. This will allow us to ascertain the validity of the in vitro protocol and, if needed, propose adjustments to make it more representative of the physiological conditions. The chosen dietary fibres are abundant in alternative food sources such as seaweeds, and, therefore, with the results from these experiments (in combination with complementary microscopy, rheology and peptidomics), we also aim to understand the effect of these components on the digestion mechanism of alternative proteins. Finally, we will also perform in operando digestions on selected substrates to obtain information on the kinetics of the digestion process.