Summary of Awards to Date

Establishment of operating standards for produce wash systems through the identification of specific metrics and test methods

Date

Jan. 1, 2017 - Dec. 31, 2018

Award Number

2017-107F

Funding Agency

Center for Produce Safety

Amount Awarded

$225,724.50

Investigator

Ana Allende, Ph.D.
CEBAS-CSIC Campus de Espinardo, Spain

Co-Investigator(s)

Maria I. Gil, Ph.D.

Summary

The main objective of this proposal is helping producers to maintain the quality of the process water in commercial washing systems through control of water quality variables and the selection of adequate test methods for monitoring the process. Water disinfection is one of the most critical processing steps in fruit and vegetable production aimed at preventing cross-contamination. In the packinghouses and processing facilities, it is difficult to treat and maintain properly the quality of the process water because of the variability in the demand of disinfectant, the lack of operational limits and test methods to monitor the process and the different commercial operations. This project will investigate the most common disinfection agents used in packinghouses and processing facilities. Four scenarios have been selected based on different water characteristics including fresh-cut onions (excessive cell exudates, very high organic matter and turbidity), chopped lettuce (high organic matter and low turbidity), baby leaves (low organic matter and low turbidity) and peppers and tomatoes (low organic matter and high turbidity). Operational limits will be established commercial facilities and lab-scale experiments using inoculated foodborne pathogens. Results obtained should inform producers about the realistic expectations for controlling selected water quality variables in produce washing systems.

Technical Abstract

The establishment of scientifically-based critical operating standards for specific washing systems can be successfully performed when based on a sound experimental design, which usually require carrying out testing in the producer's facilities. Critical factors suitable to establish monitoring standards need to be identified and controlled for each specific washing system under current industrial conditions. Additionally, a greater understanding of in-practice dose measurement in relation to water quality and commodity-specific parameters are needed to select the most adequate test methods for operational monitoring standards. Therefore, collaboration with industrial partners aware of the need of evidence-based standards for produce wash systems is mandatory to successfully identify critical factors. This proposal is based on this type of collaboration with up to seven industry cooperators.

The main objective of this proposal is the establishment of critical monitoring standards for different produce wash systems and the adequate test methods of the selected metrics. Disinfection agents commonly used in packinghouses and processing facilities including sodium hypochlorite, calcium hypochlorite, T-128 (2nd generation process aid), stabilized pure chlorine dioxide and peroxyacetic acid (PAA) will be evaluated in four different produce wash waters with very different water characteristics including fresh-cut onions (excessive cell exudates conferring very high organic matter and turbidity), chopped lettuce (high organic matter and low turbidity), baby leaves (low organic matter and low turbidity) and whole peppers and tomatoes (low organic matter and high turbidity). Each case scenario of produce wash system, which includes a combination of disinfection agent/fresh commodity, will allow us to understand the relevance of different water quality variables for the identification of specific metrics and test methods. Selection of water quality variables (e.g. sanitizer residual, oxidation reduction potential (ORP), chemical oxygen demand (COD), UV Absorbance, turbidity, pH, conductivity) able to monitor the efficiency of the disinfection system are still needed for these produce wash systems that represent a whole range of different situations. Selected water quality variables will be proposed as critical parameters to control disinfection of produce wash under commercial industrial practices. Validation of critical limits for specific produce wash water will be performed under lab scale conditions to demonstrate that the proposed variables are able to control cross-contamination mimicking industrial conditions. Different fed rate of product in relation to the absolute volume of water in the stage as well as the rate of make-up water will be determining considering the wash system as a reactor to be modeled. Within this project, a greater understanding of on-line measurements of commercially available sensors in relation to water quality characteristics and commodity-specific parameters will be also determined.

The proposed objective will be performed in collaboration with six Industry Cooperators. A close collaboration between fresh produce producers and producers of wash systems has been scheduled in order to evaluate specific case studies. The main beneficiaries of the project will be the growers who will be guided using evidenced-based standards for washing of specific commodities.