The kiwifruit enzyme actinidin enhances the hydrolysis of gluten proteins during simulated gastrointestinal digestion

•Actinidin hydrolysed peptide bonds adjacent to proline residues.•Gastric hydrolysis rate of gluten was higher with actinidin than with pepsin alone.•pH and actinidin activity affected the gluten gastric hydrolysis by actinidin.•Actinidin had a greater efficacy in hydrolysing gliadin than papain and bromelain. This study investigated the effect of actinidin, a cysteine protease in kiwifruit, on the hydrolysis of gluten proteins and digestion-resistant gluten peptides (synthetic 33-mer peptide and pentapeptide epitopes) under static simulated gastrointestinal conditions. Actinidin efficacy in hydrolysing gliadin was compared with that of other gluten-degrading enzymes. Actinidin hydrolysed usually resistant peptide bonds adjacent to proline residues in the 33-mer peptide. The gastric degree of hydrolysis of gluten proteins was influenced by an interaction between pH and actinidin concentration (P