Steering protein and carbohydrate digestibility by food design to address elderly needs: The case of pea protein enriched bread

A “source of protein” and a “high protein” bread intended for the elderly were obtained by replacing wheat flour in bread dough with 50 and 165 g/kg pea protein concentrate. Carbohydrate and protein digestibility was evaluated in vitro by mimicking adult and elderly digestive conditions. Protein digestibility was measured by the OPA assay. Carbohydrate digestibility was assessed by determining the incremental area under the glucose curve during the intestinal phase to estimate the glycaemic index (GIe). Pea proteins negatively affected some key features accounting for elderly acceptability of bread, mainly the textural ones, with firmness increasing from 1.2 to 3.3 N. Proteolysis was not affected by physiological conditions but by reformulation, with “high protein” bread presenting the highest proteolysis, followed by “source of protein” and soft wheat bread (around 110, 80 and 70 mmol free NH2/gdw, respectively). Conversely, carbohydrate digestibility was restrained in elderly settings compared to adult ones, with glucose concentration during digestion reaching maximum values of 0.5 and 0.8 respectively, with no differences between enriched bread. Results may contribute to a better understanding of food digestibility under different gastrointestinal conditions and of its dependence on technological factors and would help to design age-tailored foods.