Effect of electrochemistry modification on the macromolecular, structural, and rheological characteristics of citrus peel pectin

Abstract

Electrochemical techniques including electrophoresis, electrolysis, and electrophoretic deposition have been widely used in the construction and modification of biomacromolecules such as proteins and chitosan. In this study, the negatively charged citrus peel pectin (CPP) was used to explore its modification by electrochemistry. The electrochemically modified CPPs were successfully fabricated by an H-type cell in anodic and cathodic regions at 25V for 1, 2, 4 and 8h. After 8h, the pH of anodic region was reduced from 3.62 to 1.76, whereas the cathode region was elevated to 11.61. Oxidation reduction potential (ORP) of anodic region was increased from 316 to 463 mV, whereas the cathode region was decreased to −273 mV. Molecular weight distribution (Mw), neutral sugar (NS), degree of methylation (DM) and acetylation (DA), Fourier transform-infrared spectra (FT-IR), and thermogravimetric analysis (TGA) were examined to investigate the structure changes of CPPs. The results showed the Mw, NS, DM and DA of modified CPPs decreased, while the content of galacturonic acid (GalA) increased. The hydrogels modified by cathodic region displayed superior gel characteristics, while hydrogels modified by anodic region demonstrated effective antibacterial properties. The correlation analysis demonstrated storage (G′) and loss modulus (G″) values of hydrogels were negatively correlated with DM and Mw. Our results provide valuable insight into modification of pectins by electrochemistry, which may be applied in food and pharmaceutical applications.