Production and identification of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from discarded cowhide collagen

•Double enzymatic hydrolysis combined with IL-US improved DPP-IV inhibitory activity.•IL-US pretreatment induced the exposure of active sites and hydrophobic amino acids.•IL-US pretreatment enhanced the gastrointestinal stability of collagen peptides.•Five new antidiabetic peptides were identified via LC-MS/MS and molecular docking.•The identified GPVGPPG sequence might be the most effective DPP-IV inhibitor.