Antioxidant capacity of egg, milk and soy protein hydrolysates and biopeptides produced by Bromelia pinguin and Bromelia karatas-derived proteases

Given the lack of knowledge in the generation and biological activity of biopeptides (BP) produced by Bromelia pinguin and Bromelia karatas-derived proteases, the objective of this work was to evaluate the antioxidant capacity (AOX) of protein hydrolysates and peptide fractions from hydrolysis of egg, milk and soy proteins with enzymes extracted from Bromelia pinguin and Bromelia karatas fruits. The degree of hydrolysis (DH) of the mentioned proteins was measured. The hydrolysates were sequentially fractionated by ultrafiltration using different membrane pore sizes (≤30, ≤10, ≤5 and ≤1 kDa) to obtain biopeptide fractions (BPF). The antioxidant capacity (AOX) of protein hydrolysates and BPF were evaluated. AOX was performed using 2,2´-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. after the enzymatic action of B. pinguin and B. karatas proteases, the highest DH values for egg, milk and soy protein hydrolysates ranged from 50-61%, 55-68% and 73-81%, respectively. The AOX was higher for soy hydrolysates than for egg and milk hydrolysates. Additionally, the highest AOX from ABTS and FRAP assays was observed for BPF ≤30 kDa, PF ≤5 kDa and ≤1 kDa, respectively. These results highlight the potential of B. pinguin and B. karatas proteases to hydrolyze food proteins and release bioactive peptides. Moreover, it has been shown that the hydrolysis products are a mixture of BP of different molecular weights, which could present AOX through different mechanisms.

Comparison of Digestibility and Quality of Intact Proteins with Their Respective Hydrolysates

Quality of proteins depends on their composition in essential amino acids and on the availability of amino acids. Great interest has been shown in the role played by hydrolysates of proteins in clinical diets for pathologies with reduced absorptive capacity and food allergies caused by intact protein epitopes. Milk proteins are the most important protein source used in the development of protein hydrolysates designed for nutritional support of patients. Several studies have shown that casein and whey hydrolysates have a composition in amino acids equivalent to that in native milk proteins and that digestibility is similar or better. Among plant proteins, soy is the major source of hydrolysates. Soy hydrolysates are also used in infant formulas. Plant hydrolysates have good functional properties and a nutritional quality similar to that of starting material. Some technical improvements in production of hydrolysates, particularly for plants, are nevertheless necessary to improve product palatability.