Biopolymer-based sanitizers for fresh produce, traditional application vs dry engineered water nanostructures approach

Authors: COHEN, YAEL - Agricultural Research Organization Of Israel; MWANGI, ESTHER - Hebrew University Of Jerusalem; TISH, NIMROD - Bar-Ilan University; XU, JIE - Harvard University; VAZE, NACHIKET - Harvard University; FALIK, ELAZAR - Agricultural Research Organization, Volcani Center; Luo, Yaguang - Sunny; DEMOKRITOU, PHILIP - Harvard University; RODOV, VICTOR - Agricultural Research Organization Of Israel; POVERENOV, ELENA - Agricultural Research Organization Of Israel

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2022
Publication Date: 1/6/2022
Citation: Cohen, Y., Mwangi, E., Tish, N., Xu, J., Vaze, N., Falik, E., Luo, Y., Demokritou, P., Rodov, V., Poverenov, E. 2022. Biopolymer-based sanitizers for fresh produce, traditional application vs dry engineered water nanostructures approach. Food Chemistry. 378:132056. https://doi.org/10.1016/j.foodchem.2022.132056.
DOI: https://doi.org/10.1016/j.foodchem.2022.132056

Interpretive Summary: Food safety continues to be a major issue facing produce consumers in the US and around the world; current technologies are difficult to control and can result in byproducts harmful to workers and the environment. In this study, we modified the natural biopolymer chitosan to synthesize and test a range of novel sustainable and environment friendly sanitizers designed to be applied in extremely small doses directly to produce surfaces, which maintains sanitization effectiveness while eliminating buildup or release of harmful byproducts. We then further tested the most promising candidate and found it can quite effectively inactivate human pathogen surrogates and spoilage microbes on spinach leaves, both in a more traditional “wet” application, as well as in a novel “dry” application. This work will benefit produce industry stakeholders and consumers by improving food safety and sustainability.

Technical Abstract: A series of spontaneously self-assembling quaternary dimethyl-(alkyl)-ammonium chitosan (QACs) nanoaggregates was synthesized and evaluated. The antimicrobial activity of QACs was examined in vitro on the Gram-negative Escherichia coli and Gram-positive Listeria innocua bacteria as well as the phytopathogenic fungus Botrytis cinerea. The highest antimicrobial potency was manifested by a six-carbon alkyl chain-substituted QAC-6 demonstrating 2.0- and 4.5-log CFU mL-1 reduction of E. coli and L. innocua, respectively and reduced the germination of B. cinerea by 52%. The QAC-6 was tested for antimicrobial activity on spinach, using a traditional ‘wet’ application (spray) and ‘dry’ engineered water nanostructure (EWNS) approach. In both approaches, significant reduction of microbial count on the treated spinach was observed. The wet approach showed strong antimicrobial efficacy, while the EWNS approach required miniscule doses of active ingredients for fast sanitizing activity with the treated product remaining visibly dry.