Hazelnut peptide fractions preserve their bioactivities beyond industrial manufacture and simulated digestion of hazelnut cocoa cream

Abstract

Cold press hazelnut cakes represent a concentrated source of proteins that can be industrially exploited. Previously, bioactive attributes of hazelnut protein hydrolysates including antihypertensive and antidiabetic activities were documented. Here, we made an attempt to utilize bioactive hazelnut protein hydrolysates (1 % w/w) in the manufacture of industrial hazelnut cocoa cream and investigate their stability through processing and simulated gastrointestinal digestion. The inclusion of bioactive peptide fractions was a safe practice in the microbiological sense. Proteolysis lowered the potential allergenicity of hazelnut proteins in the cocoa cream products up to about 20 %. In silico trypsinolysis predicted partial degradation for 51.8 % of the peptide sequences (i.e., 43/83) that were present in the hydrolysates. However, partial degradation and mixing of degraded vs non-degraded peptides preserved and/or further elevated bioactive attributes in the digested cocoa cream products in terms of Angiotensin converting enzyme (ACE)-inhibitory (up to about 92 %) and antidiabetic activities (between 7.5 and 44.4 %). In most cases, however, antioxidative activity was < 10 %. While simulated in vitro digestion potentially influenced the bioactive attributes of protein hydrolysates, the influence of cocoa cream processing and food matrix were relatively limited for hydrolysate fractions and more pronounced for protein isolates. Hazelnut press cakes represent a significant resource for the generation and industrial utilization of bioactive peptides, which could preserve their bioactivity beyond industrial manufacture and digestion and lead to slightly reduced allergenicity.