In vitro gastrointestinal digestion of pea protein isolate as a function of pH, food matrices, autoclaving, high-pressure and re-heat treatments

- Pea protein digestibility was studied as a function of processing, pH and matrix.
- HPP followed by re-heating showed highest rate of in vitro gastric digestion.
- The initial pH affected the rate and degree of in vitro gastrointestinal digestion.
- Pea protein in apple puree was less digestible owing to procyanidin-protein binding.
- Autoclave or HPP treatments can overshadow such food matrix effects.

This study investigated the influence of pH and processing conditions (autoclave at 93 °C/13 min or high pressure processing (HPP) at 600 MPa/5 min without/with follow-up reheating at 80 °C/30 min) on the digestibility of pea protein isolate. Both aqueous solutions and real food matrices (apple and carrot purees) containing pea protein was examined at 37 °C. In vitro gastrointestinal digestion was followed using sodium dodecyl sulphate polyacrylamide gel electrophoresis, titrimetric techniques and theoretical calculations. Pea protein with HPP followed by re-heating showed the highest rate of proteolysis in gastric conditions. In case of sequential intestinal digestion of the gastric chyme, pea protein at pH 6.2 demonstrated higher degree and rate of digestibility as compared to that at pH 3.6, the latter being close to the isoelectric point of pea protein. However, autoclave treatments overshadowed such pH effects. Processing-induced enhancement in digestibility might be attributed to the unfolding of the globular pea protein subunits. Pea protein in the carrot puree was more digestible than in the apple puree, due to apple procyanidins binding to pea protein. These new findings might have important implications in designing the process parameters and selection of appropriate food matrices for delivering pea protein.