Summary
Post‐harvest preventive control is a critical research topic for the produce industry because post‐harvest handling is an essential stage in supply chain regarding food safety. A practical preventive control will not only make a great impact on public health but also on produce industry’s long term profitability. Despite previous interest in fouling of mainstream FDA-approved food contact substances (FCS), there has not been a comprehensive evaluation of non‐fouling properties of any FCS, or the practicality of industrial sanitization procedures for the produce industry. We propose to fill this gap and develop an applicable post‐harvest preventive control approach to enhance the non‐fouling properties of FDA‐approved FCS against Listeria monocytogenes (Lm) biofilm. We will: 1) evaluate non‐fouling properties of existing FDA‐approved FCS; 2) enhance FCS performance by simple and cost‐effective physical/topographical modification without altering the chemical composition; 3) evaluate whether the top‐performing FCS are compliant with sanitary designs for the fresh produce industry; and 4) validate the findings at a fresh‐cut processing pilot plant. Project outcomes will provide scientific information that will support sanitary design of packing, holding, and processing equipment/devices, coatings and coating modifications to simplify cleaning/sanitization, and to prevent pathogen attachment and biofilms on FCS for new and retrofitted equipment.
Technical Abstract
Sanitary design and sanitization are critical steps to help ensure food safety and prevent pathogen cross‐contamination mediated by Food Contact Substances (FCS). In response to CPS RFP priority 1.1.3 (Lm preventive controls) and 1.3.1 (Preventive controls for packing and holding operations), this project will develop an applicable intervention strategy to further enhance the non‐fouling properties of FDA-approved FCS against Lm biofilm. Specifically, we will 1) evaluate 304/316 stainless steel, plastic, and wood substrates and a series of FDA‐approved FCS for their non‐fouling properties against Lm and other normal flora biofilm formers unique to the fresh produce industry; 2) enhance FCS performance through simple and cost‐effective physical modification of surface microscale topography. Original and enhanced FCS will be further screened to identify top‐performing FCS that prevent Lm biofilm under simulated industrial processing condition; and 3) determine which of the top‐performing FCS are consistent with industrial use, including material properties and integrity, and sanitization efficiency. Project outcomes will provide scientific information to the industry in selecting materials to support sanitary design of packing, holding, and processing equipment and apparatus, coatings and coating modifications to simplify cleaning and sanitization, and to prevent pathogen attachment and biofilm formation on FCS for both new and retrofitted equipment.
Research Objectives
1. Evaluate the baseline non-fouling properties of FDA-approved food contact substances (FCS) using fresh produce processing conditions.
2. Enhance the non-fouling properties of FDA-approved FCS by topographical modification without altering the chemical composition, and identify top-performing FCS that are not fouled by Listeria monocytogenes biofilm.
3. Determine the compliance of top-performing FCS with current industrial sanitary design, which includes material properties and integrity, and sanitization efficiency.
4. Evaluate the performance of top-performing FCS in a USDA pilot plant.
Findings & Recommendations
The key take-home messages from this study are as follows:
• Surface chemistry (coating) has a significant impact on Listeria monocytogenes (Lm) biofouling and biofilm development.
• Surface topography has impacts on Lm biofouling, and the impact is limited at the pattern scale of ~50 micron tested in this study.
• Surface wettability is not a good indicator of FCS non-fouling properties against Lm biofilm, as both hydrophilic and hydrophobic coating showed antifouling property.
• Dursan coating appears to have the best non-fouling properties against Lm monoculture biofilm among the FCS coatings tested.
• Normal microflora from produce and processing environment have significant impact on Lm biofouling and biofilm development and FCS non-fouling properties, including Dursan coating.
• Lm risk could be commodity-specific (different microflora) and processing line-specific (different surface properties).
• The presence of normal microflora appears to protect Lm in the cocktail biofilm against sanitizer and reduce sanitation efficiency.
• More studies are needed to develop universally effective risk mitigation technologies against Lm biofilm with the presence of complex microflora.