Improving α-amylase inhibitory activity of simulated gastrointestinal digested pea protein by pH shifting assisted proteolysis

To mitigate postprandial hyperglycemia, α-amylase inhibitory peptides have been casually prepared by various pretreatments and proteolysis without exploring their impacting mechanisms and digestive stabilities. In this study, pea protein treated by pH 2 shifting followed by flavourzyme hydrolysis (PS₂-PF) expressed excellent protein recovery rate (40.06 %) and α-amylase inhibitory activity (IC₅₀ of 6.75 mg/mL) after simulated gastrointestinal digestion. A moderate decrease of α-helix structure (by 10.80 %) but increases of β conformations (by ∼17.75 %) and small molecules (< 5 kDa, 94.73 %) on the pea protein were beneficial to enhance α-amylase inhibition of the digested PS₂-PF. 13 of potential α-amylase inhibitory peptides were identified from the digested PS₂-PF to inactivate α-amylase via hydrogen bonding, Pi-Alkyl, Pi-Pi and attractive interactions of phenylalanine, proline, leucine, arginine, glutamic acid and lysine. Overall, pH 2 shifting assisted flavourzyme hydrolysis could be a valuable strategy to enhance α-amylase inhibition of in vitro digested pea protein for diabetes mellitus.