Optimizing the properties of Zodo gum and examining its potential for amino acid binding by periodate oxidation

Abstract

In this study, the Zodo gum exudated by Amygdalus scoparia spach underwent the periodate oxidation process for chemical modification and the formation of dialdehyde groups. Modification of the Zodo gum properties was done using the periodate oxidation method, response surface methodology (RSM) and central composite design (CCD), with 4 factors of sodium periodate volume (6.4–19.2 mL), temperature (35–55 °C), pH (3–5) and time (2–4 h). Dialdehyde Zodo gum (DZG) was produced by controlling test variables and measuring some responses including dialdehyde content and efficacy, in addition to evaluating the rheological parameters. Quadratic, linear polynomial equations were then fitted with the insignificant Lack of fit and high R2 to address the relationship between the mentioned variables and responses. Optimal test conditions, including pH = 3.9, T = 43 °C and Time = 3.5 h, were also determined for the production of DZG10, DZG20 and DZG30 samples. The results of 1H-13C NMR, FTIR and determination of the aldehyde content indicated the formation of dialdehyde groups in equilibrium with the dominant hemiacetal form. The AFM study of the DZG30 sample also showed over-oxidation and depolymerization, which could be associated with increased hydrophobic properties and the reduced viscosity. Although the DZG30 sample had the highest amount of the dialdehyde factor group with the tendency to combine with the amino group of proteins, DZG10 and DZG20 samples could be recommended for industrial applications due to the nonoccurrence of overoxidation.