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United States Department of Agriculture

Agricultural Research Service

Title: Vapor-Phase Decontamination of Apples Containing Escherichia Coli

Authors
item Sapers, Gerald
item Walker, Paul - PENNSYLVANIA STATE UNIV
item Sites, Joseph
item Annous, Bassam
item Eblen, Denise - FSIS

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 6, 2002
Publication Date: March 15, 2003
Citation: SAPERS, G.M., WALKER, P.N., SITES, J.E., ANNOUS, B.A., EBLEN, D.R. VAPOR-PHASE DECONTAMINATION OF APPLES CONTAINING ESCHERICHIA COLI. JOURNAL OF FOOD SCIENCE. 2003. V. 68 (3). P. 1003-1007.

Interpretive Summary: Apples and other fruits and vegetables may become contaminated with human pathogens during production or processing, resulting in elevated risk to consumers of food poisoning. Conventional washing and sanitizing treatments used for fresh produce are capable of removing or killing 90-99% of attached bacteria but cannot achieve greater reductions in the bacterial population, required to assure safety, because of the inaccessibility of some bacteria attached in pores, crevices or other protected sites. To obtain such reductions, improved methods of decontaminating commodities that permit better contact between sanitizers and inaccessible human pathogens are required. In this investigation, application of gaseous antimicrobial agents to apples, artificially contaminated with a non-pathogenic surrogate for the human pathogen E. coli O157:H7, was investigated. Experiments were carried out with an apparatus that transfers vapor from hot sanitizer solutions to a treatment vessel containing the contaminated apples. Vapor from highly concentrated acetic acid at 140 ºF provided reductions in the bacterial population exceeding 99.9% but induced discoloration. Vapor from heated hydrogen peroxide and chlorine dioxide solutions gave population reductions less than 99%. However, chlorine dioxide gas, applied at 68 ºF in an airtight container, achieved a population reduction better than 99.99%, with minimal quality loss. Reductions in bacterial population achieved with this treatment greatly exceed those obtained by other decontamination methods for raw commodities. Use of this technology, if efficacy and practicality are confirmed in continuing studies, could greatly improve the microbiological quality of fresh fruits and vegetables and reduce the risk of produce-related illness.

Technical Abstract: Improved methods of decontaminating apples containing human pathogens are required. In this investigation, application of gaseous antimicrobial agents was investigated. An apparatus, which transfers vapor from hot antimicrobial solutions to a treatment vessel, was evaluated with Golden Delicious apples inoculated with E. coli. Vapor from glacial acetic acid at 60 deg C provided population reductions exceeding 3.5 log10CFU/g but induced discoloration. Vapor from heated hydrogen peroxide and chlorine dioxide solutions gave reductions 2 logs. However, chlorine dioxide gas, applied at 20 deg C in an airtight container, achieved a 4.5 log reduction, with minimal quality loss. Reductions achieved with this treatment greatly exceed those obtained by other decontamination methods for raw commodities.

Last Modified: 11/27/2014
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