Antifungal films for strawberry packaging using carbon quantum dots derived from lemon and onion juice via green hydrothermal method

Abstract

Fungi are the prime concern since they cause post-harvest decay in fruits such as strawberries; the fungi motivate the need for new antifungal agents. Among all these nanoparticles, the carbon quantum dots (CQDs) show the most promising results for their use in food packaging applications. Lemon carbon quantum dots (LCQD), which is derived from lemon juice, and onion carbon quantum dots (OCQD), which is derived from onion juice, were synthesized using the one-step hydrothermal method. The synthesized materials were then characterized using a transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and ultraviolet-visible (UV-Vis) spectroscopy. LCQD and OCQD solutions were applied to fresh strawberries for the purpose of conducting studies on weight loss, decay, and shelf-life extension. The antifungal activity of both CQDs was assessed against Rhizopus sp., Penicillium sp., Candida albicans, Aspergillus sp., and Botrytis cinerea using the agar-well diffusion technique. The obtained average size was 4.33±1.67 nm for LCQDs and 3.34±1.72 nm for OCQDs. Strawberries packaged with OCQDs and LCQDs showed weight loss of 5.21%±1.03% and 8.14%±1.09% on the fourth day of observation, respectively, against 18.71%±2.2% by control. On the same day, the decay rate for OCQDs was 11%, 40% for LCQDs, and 96.65% for control. Both exhibited antifungal activity, with inhibition zones ranging from 12.6-44.5 mm for various fungi. OCQD exhibits higher activity packaging compared to LCQD due to their smaller size and superior antifungal activity against a variety of fungi.