Comparative Efficacy of Bulk Chitosan and Chitosan Nanoparticles in Reducing Microbial Contamination of Fresh-Cut Apples (Malus domestica)

Background: Broad spoilage of apples by either bacterial pathogens or fungal pathogens after harvest can be devastating, resulting in considerable economic loss. Chitosan is a biodegradable, non-toxic antimicrobial but the antimicrobial activity of chitosan nanoparticles (CSNPs) is increased with their larger surface area to volume ratio and better interaction with the microbial membrane. Method: Chitosan and CSNPs (bulk 0.5–2.0%, CSNP 0.25–1.0%) were prepared for determination of their antimicrobial activity vitro & IN VIVO against six spoilage microorganisms for a period of 7 days to mimic realistic storage conditions. Results Significant dose-dependent antimicrobial effect observed across treatments. In vitro and in vivo log reductions obtained against P. fluorescens were as high as 2.84 to 3.17 and 4.00, respectively, for 1.0% CSNPs. This was confirmed by the statistically equivalent efficacy of 0.5% CSNP treatment to that of 2.0% bulk chitosan, which implies a 75% decrease in active material. Conclusion: These results demonstrate the potential of CSNPs as a higher efficient and green alternative candidate to replace the conventional post-harvest restoration methods for apple fruits.