Industrial utilization of bioactive hazelnut peptide fractions in the manufacture of functional hazelnut paste: ACE-Inhibition and allergy suppression

Abstract

PurposePress cakes are the primary by-products of cold press oil manufacture and are characterized with significant con-centrations of proteins. Recently, our group has investigated the bioactive attributes of peptide fractions generated from hazelnut cakes and demonstrated their angiotensin converting enzyme (ACE)-inhibitory activities in vitro. In the current study, bioactive hazelnut peptide fractions were utilized in industrial settings to generate novel food products.MethodsHazelnut protein isolates were generated via alkali extraction-isoelectric precipitation (AE-IP) method. Papain, bromelain and pepsin were used in the proteolysis of protein isolates and the hydrolysates were fractionated via fast protein liquid chromatography. In vitro ACE-inhibitory activities of the fractions were tested and their corresponding lyophilizates were added to industrial hazelnut paste (1%). Microbiological analyses of the enriched products were carried out in accord-ance with the relevant company procedures to ensure safety. Allergenic properties of hazelnut paste products were determined by an indirect ELISA method. Simulated gastrointestinal digestion was carried out and ACE assays were also performed on digested products.ResultsACE inhibitory fractions were characterized with IC50 values of approx. 2–27 μg ml−1, respectively. Some of the fractions demonstrated considerable bioactivity (i.e., > 90% ACE-inhibition) after simulated digestion. Intact and further hydrolyzed peptides were predicted to be present in the digested paste and partial hydrolysis of the peptides potentially enhanced ACE-inhibitory attributes. Furthermore, allergic suppression was partially achieved in final products bearing the bromelain hydrolysate fractions (i.e., BRF 10). The interactions of current peptides with ACE and a major hazelnut allergen were investigated using molecular docking. A database (BioPepDB) search indicated that all of the current peptides were novel.ConclusionHazelnut cakes represent a resource for ACE-inhibitory and potentially allergy suppressing peptides that can be used in the formulation of functional foods and food supplements.