An antibacterial hydrogel prepared from a licorice residue extract

Abstract

A licorice residue extract was used as a precursor to prepare hydrogels in this study. The hydrogels were successfully prepared by dissolving the licorice residue extract in an NaOH/urea aqueous solution system and crosslinking it with epichlorohydrin (ECH). A scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) were used to analyse the morphology and structure of the hydrogels. The water retention capacity of the hydrogels was also studied. After being characterized, the hydrogels were applied to fruit preservation. Blueberries were selected for the application, and sensory evaluation, weight loss ratio, decay ratio and vitamin C content were taken as indicators to evaluate the effect of hydrogels on fruit preservation. The hydrogels which were brown had good water retention and antibacterial effect on Escherichia coli and Staphylococcus aureus. They can retain the sensory properties of blueberries, significantly reduce the weight loss ratio and rotting ratio, delay the decrease of vitamin C content, and have a good fresh-keeping effect. In summary, this hydrogel could be used as a water-retaining, antibacterial and fresh-keeping material, and provides a more efficient and potential choice for substituting plastic in various branches.