Journal of Nanomedicine & Nanotechnology

First attempts to control microbial contamination of strawberries by ZnO nanoparticles

Nanotechnology Congress & Expo

August 11-13, 2015 Frankfurt, Germany

Z Luksiene and K Aponiene

Poster-Accepted Abstracts: J Nanomed Nanotechnol

Abstract:

Introduction: It is well documented that most of the harmful and pathogenic microorganisms are able to develop high resistance to many conventional chemical fungicides and disinfectants. During the past decade the emphasis in food protection has shifted from using chemicals to various alternative techniques. Recently antimicrobial nanotechnologies have the potential to play a critical role in crop protection, water disinfection and food safety. Objective: Evaluation of antimicrobial properties and mechanism of action of nano-sized light-activated ZnO particles with aim to apply them for preservation of strawberries. Methodology: The antibacterial activity of photoactivated ZnO nanoparticles (ZnO NPs) (?=400 nm) against Escherichia coli O157:H7, Listeria monocytogenes ATCL3C 7644 and Botrytis cinerea was investigated in vitro. Strawberries were sprayed ZnO nanoparticles (4x10-5M and illuminated with visible light (?=400 nm, 76 J/cm2). Results & Discussion: Data indicate that photoactivated ZnO NPs (200 nm) have strong bactericidal activity against Gram (+) and Gram (-) bacteria, achieving more than 7 log reductions in bacterial counts. Scanning electron microscopy (SEM) images of treated bacteria indicated cell wall disintegration and cell lysis. Results obtained on examinations of antifungal activity of ZnO NPs reveal remarkable photoinactivation (58%) of B. cinerea growth at concentration 1�10-3 ? 5�10-3 mol l-1 and incubation time 24h. SEM data analysis confirmed substantial morphological changes in microfungus. Photoactivated ZnO NPs, sprayed on the surface of strawberries can reduce the microbial contamination by 95%. No impact on strawberry antioxidant activity, amount of total phenols, anthocianins, ascorbic acid have been found. Moreover, no harmful effects were observed on strawberry visual quality and color. Just fruit firmness reduced by10%. Conclusion: Such ZnO NPs properties obviously could be used for the development of effective fungicides in agriculture or innovative non-thermal antibacterial technique, so important in food microbial control.