Evaluation of Chitosan/Curcumin loaded Nanobubbles with and without Photoactivated light for Food Preservation

The global demand for fruits and vegetables is projected to be about US$ 2.0 trillion in 2050. Major challenges in the supply chain of fruits and vegetables are to extend storage time and to prevent the contamination by pathogenic microorganisms. Microbial contamination can occur during production, harvest, processing, storage, and distribution due to exposure of fruits and vegetables to the environment. Fresh fruits and vegetables, for example, get spoiled within a few days due to high perishability, if not treated properly, and resulting in huge industrial losses (almost 45% loss in grown produce globally). The most efficient approach to reduce the risks of disease outbreaks and postharvest spoilage is to prevent contamination from primary sources by appropriate sanitation and decontamination methods. Chitosan-shelled Nanobubbles (NBs) based on a natural biocompatible and biodegradable polymers (i.e. curcumin), are known to exert antimicrobial effect as curcumin & chitosan having the property of antibacterial and antifungal activity. So, the present work aimed at investigating NBs antimicrobial properties against food bacteria i.e. Escherichia coli, Staphylococcus aureus or Enterococcus faecalis. NBs was loaded with curcumin either within their core or by conjugation to the shell to enhanced antimicrobial nature against food born bacteria. The effectiveness of Curcumin/Chitosan NBs against different strains of bacteria was further enhanced by irradiating the internalized NB’s with photodynamic (blue) light (optimal wavelength of 425nm, which is the proper one emitted by curcumin). Depending on the formulations (NBs) antibacterial properties were measured through microbiological and biochemical assays such as to find out minimum inhibitory concentration (MIC) and minimum bactericidal concentration. We ascertained that curcumin (alone) with blue light have a robust effect against the mentioned bacterial strains i.e. we find out MIC at a very low concentration of curcumin 0.125mg/ml, < 0.06mg/ml and < 0.015mg/ml against E. coli, S. aureus and E. faecalis respectively. Curcumin/Chitosan NBs have shown interesting effectiveness. Keeping under control bacterial proliferation may prolong the time in which food quality is acceptable for marketing therefore enhancing its economic value and preserving public health. Thus, it is interesting to speculate on a potential role of Curcumin NBs with photodynamic light, as to enhance antimicrobial activity and to preserve food. Our preliminary data show that Curcumin alone and NB could be useful for reducing the levels of bacterial contamination on the surface of foods, and thus be promising for applications in the field of microbiological food safety.