Antioxidant and metal-chelating activities of mixed hydrocolloid systems formed by hard-to-cook Phaseolus vulgaris protein hydrolysates and flamboyant (Delonix regia) modified gum

Abstract

Introduction. Proteins and polysaccharides are frequently used simultaneously in the food industry. The interactions between both biopolymers play an important role in the structure and stability of many processed foods since they can result in a system with different bioactive properties as in the case of functional ones. Objective. Evaluate the changes in the antioxidant capacity of mixed hydrocolloid system formed by a hard to cook bean (P. vulgaris) protein enzymatic hydrolyzate and modified flamboyant gum (Delonix regia) (SHM). Materials and methods. The study was conducted from February to October 2014 in Merida, Mexico. For this, the protein concentrate of P. vulgaris was treated with Pepsin-Pancreatin® and the gum extracted from the flamboyant were modified enzymatically by carboxymethylation, preparing 1% dispersions of each of the biopolymers, determining the intrinsic Trp fluorescence (FIT) as an indicator of the interaction between both biopolymers and the antioxidant and chelating activity of the resulting system. Results. The main results indicated that an extensive protein hydrolyzate with 28.8% degree of hydrolysis and a flamboyant gum with a substitution degree of 0.91 were obtained. The greatest interaction between both biopolymers was obtained using a 5:1 ratio of SHM to pH 4 according to the FIT value. Conclusions. The mixed hydrocolloid systems prepared with extensive hydrolyzate of the hard to cook P. vulgaris and modified flamboyant gum proteins showed an increase in antioxidant activity, compared to the hydrolyzate depending on the oxidation mechanism, as well as the pH conditions used and interaction between both components.