Efficacy of Chitosan-Turmeric Bioactive Nanoparticles for Antimicrobial protection and Postharvest Loss Mitigation in Tomatoes

The synthesis of chitosan nanoparticles and chitosan-turmeric nanoparticles out of fresh water mussel shells along with the turmeric bioactive extract was through ionic gelation which provided nanoparticles with desirable characteristics. Chitosan nanoparticles (CNPs), chitosan-turmeric nanoparticles (CTNPs), and turmeric bioactive extract (TUE) were prepared and characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Powder X-ray Diffraction (PXRD), Dynamic Light Scattering (DLS) and UV-visible Spectroscopy. Their potential on different parameters of fruit quality, postharvest shelf life, and antimicrobial efficacy was examined. The shells were subjected to a chemical process that involved four stages: demineralization, deproteinization, decolorization, and deacetylation, which resulted in chitosan yield of 21.08% and a degree of deacetylation (DD) of 87.97%. Deacetylation was confirmed by FT-IR spectra as well as the successful incorporation of turmeric, whereas PXRD depicted semi-crystalline features with the main peaks moving after loading the turmeric which showed the changes in the structure. SEM images indicated that chitosan nanoparticles possessed a porous and irregular shape, while after the addition of turmeric they became denser. The DLS results show CTNPs and CNPs have a size of 206.1 nm and 227.6 nm, respectively, with PDI of 0.276 and 0.232. UV-Vis spectra exhibited typical broad absorption peaks which supported both nanoparticle development and turmeric entrapment. It is worth mentioning here that, among the treatment, TUE showed the best results by extending the average shelf life of tomatoes to 69 days and with a preservation efficiency of 62.5%, thus surpassing CNPs and CTNPs markedly in performance. The results of antimicrobial tests confirm the significant antimicrobial activities of turmeric and chitosan formulations against bacteria and fungi, which is consistent with their potential as natural preservatives. In general, the combination of turmeric bioactive with locally derived chitosan from mussel shells not only provides a promising and environmentally friendly method for reducing losses in postharvest tomatoes but also promotes food security.