Plant protein hydrogel as a delivery system of curcumin: Characterization and in vitro release Kinetics

Abstract

In recent years, non-animal protein sources have led many consumers to eat plant-based alternatives. The Green gram protein is more biocompatible, highly sustainable and safer than animal proteins. Nutraceuticals have drawbacks such as poor water solubility, chemical instability at neutral and alkaline pH, auto-oxidation and poor absorption. Hydrogels are used to enhance the efficiency of these bioactive compounds. In this study, Green gram protein hydrogel enriched with curcumin was prepared. Protein was extracted from Green gram seeds using alkaline extraction and acid precipitation. Curcumin was extracted from turmeric using a Soxhlet Apparatus. A hydrogel was prepared using a sodium hydroxide concentration of 0.5 M to efficiently encapsulate curcumin and was characterized. The physicochemical properties of green gram protein hydrogels were evaluated by entrapment efficiency, swelling degree, FTIR, XRD, DSC, SEM, in vitro release and free radical scavenging assessment method. The encapsulation efficiency was 89.02 ± 0.56% respectively. The successful incorporation of curcumin in the hydrogel was confirmed by FTIR analysis. The surface properties of hydrogels were investigated using the SEM technique. The synthesized hydrogels are highly porous in nature and form cross linked structures. Moreover, hydrogels have a high swelling capacity. The swelling behaviour was due to the presence of hydrogen bonding interaction with the aqueous media. The hydrogel possesses a hydrophilic character when investigated by the contact angle. The contact angle of curcumin-loaded green gram hydrogel was increased by 9 °. The inhibition zone of 30 ± 03 mm was effective against E. coli. bacteria. The antioxidant property of the hydrogel gets increased by 50.46% after the addition of curcumin. Slow release of curcumin from hydrogel was studied using UV–vis Spectroscopy and it was inferred that it follows Korsmeyer-Peppas Kinetics model. The hydrogel was applied to tomato and apple as a coating. Generally, the results emphasised the potential use of Green gram protein hydrogel as a coating on fruits and vegetables.