Enzymatic hydrolysis of the protein from an edible insect species, the cotton leafworm Spodoptera littoralis (Lepidoptera) leads to the release of angiotensin I converting enzyme (ACE) inhibitory peptides. The subsequent hydrolysis with pepsin, trypsin and a-chymotrypsin was designed to simulate the human gastrointestinal digestion process. After fractionation of this hydrolysate using consecutive chromatographic techniques, including size exclusion chromatography and reverse-phase high-performance liquid chromatography, a new ACE inhibitory tripeptide was identified. The amino acid sequence of the tripeptide was determined as Ala-Val-Phe and the in vitro ACE inhibitory activity assay revealed an IC50 value of 2123 mu M. (C) 2008 Elsevier Ltd. All rights reserved.