Alginate/κ-Carrageenan-Based Edible Films Incorporated with Clove Essential Oil: Physico-Chemical Characterization and Antioxidant-Antimicrobial Activity

Abstract

This study aimed to enhance the properties of CaCl2 crosslinked sodium alginate/k-carrageenan (SA/KC) incorporated with clove essential oil (CEO). An evaluation of the modification effects on physicochemical, morphological, antioxidant, and antibacterial properties was performed. The properties were observed at various SA/KC ratios (10/0 to 1.5/1), CEO (1.5% to 3%), and CaCl2 (0% to 2%). The surface morphology was improved by addition of KC and CaCl2. The Fourier transform infrared (FTIR) result showed insignificant alteration of film chemical structure. The X-ray diffraction (XRD) result confirmed the increased crystallinity index of the film by CaCl2 addition. On physicochemical properties, a higher proportion of SA/KC showed the declined tensile strength, meanwhile both elongation at break and water solubility were increased. The incorporated CEO film reduced both tensile strength and water solubility; however, the elongation at break was significantly increased. The presence of Ca2+ ions remarkably increased the tensile strength despite decreased water solubility. Overall, the addition of KC and CaCl2 helped in repairing the mechanical properties and flexibility. CEO incorporation showed the effectiveness of profiling the antioxidant and antimicrobial activity indicated by high 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity up to 90.32% and inhibition zone of E. coli growth up to 113.14 mm2.

Keywords

• alginate
• antimicrobial activity
• antioxidant
• carrageenan
• clove essential oil
• edible films