Multi-functional polysaccharides composite film containing cashew and jik leaf carbon dots: Properties and bioactivities
Gokulprasanth Murugan, Ajahar Khan, Krisana Nilsuwan, Jun Tae Kim, Soottawat Benjakul, Jong‐Whan Rhim
Abstract
• Carbon dots (CDs) from cashew (C) and jik (J) leaves or 1:1 mixture were prepared • CDs (3 %, w/w ) was added into chitosan/starch (CS) film as active packaging • Presence of various CDs affected properties of the resulting CS film differently • CDs from cashew leaf (C-CDs) improved elasticity and UV barrier property of film • C-CDs added films achieved higher antioxidant activity amongst all films • Films containing CJ-CDs showed strong antimicrobial activity against some bacteria Carbon dots (CDs) from the leaf powders of cashew (C-CDs), jik (J-CDs) and the mixed cashew/jik (1:1) (CJ-CDs) using hydrothermal method were synthesized and characterized. All three CDs were incorporated into chitosan/starch composite (CS) film at the level of 3 % ( w/w ). Microstructure images revealed that all films had slight differences in surface and internal structure. Thickness of the CS film increased with the inclusion of fillers (CDs). Inclusion of CDs slightly reduced the tensile and water vapor barrier properties of the CS film. CS film containing C-CDs exhibited the improved elasticity, UV barrier and antioxidant activity among all the films tested. Color and opaqueness of the resulting films were governed by the yellowish CDs. Distinctive peaks of resulting CS film were detected in FTIR spectra, while all CDs had no marked effect on the spectra. The release of CDs from films was more pronounced in water than in alcoholic solutions (10–95 % ethanol). Strongest antibacterial activities against Listeria monocytogenes and Escherichia coli were recorded for CDs added film, in which the highest activities were found for CS/CJ-CDs film. Thermal stability was also enhanced in CS/CJ-CDs film. Thus, the CS film loaded with CDs, especially from the mixture of cashew and jik leaf powders could serve as promising active packaging for inactivation of some pathogens in food products.