A team of Clemson University researchers worked on “ Preventative sanitation measures for the elimination of Listeria monocytogenes biofilm in critical postharvest sites” (https://www.centerforproducesafety.org/researchproject/429/awards/Preventive_sanitation_measures_for_the_elimination_of_Listeria_monocytogenes_biofilms_in_critical_postharvest_sites.html) .
They looks at difficult-to-sanitize micro-environments within a packinghouse where bacteria may inhabit that could serve as reservoirs. The study investigated biofilm impact on organism survival. The effect of material used in packaging line such as porous surface on biofilm formation is being investigated. Co-Principal Investigator – Claudia Ionita said “We’re discovering that certain materials actually favor biofilm attachment more than others,… “That could be very helpful for the brush industry or the peach packers.” The plan is to inoculate the surfaces m with Listeria and allow biofilms to form. The researchers will then treat the biofilm with various concentrations of commercial packinghouse sanitizers using different contact times and temperatures to gauge Listeria die-off. @ https://www.centerforproducesafety.org/article/151/Research_examines_antilisterial_fruit_coatings.html
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Listeria monocytogenes is an important foodborne pathogen commonly found in the environment. Recent Listeria foodborne outbreaks have been linked to fresh produce including stone fruits. Contamination of stone fruits is problematic since these products are usually consumed without heating. In addition, some surfaces associated with packing operations are inherently difficult to sanitize. In the proposed research, these surfaces will be characterized and inoculated with Listeria monocytogenes in fluid chambers for biofilm formation. Biofilms will be treated with sanitizers commonly used in the stone fruit packing industry. Results from this study will provide improved pathogen control in addition to the basic good agricultural practices, thereby helping fruit industry to produce safer produce for human consumption.
Technical Abstract
The number of human outbreaks associated with foodborne pathogens contaminating fresh produce has increased in the past decade. Stone fruits such as peaches and nectarines are usually consumed raw but these fruits were considered ‘safe ‘since they had not been implicated in major human outbreaks. In 2014, a stone fruit packing company issued the first recall of certain stone fruits because of concern about contamination with Listeria monocytogenes. Although limited with only 2 illnesses, this outbreak highlighted the potential of L. monocytogenes to cause outbreaks via foods that had been considered unlikely vehicles for this pathogen. The packing house is an open environment, where raw materials, products, and workers are introduced continuously in the packing season. In addition, because of the specific operations, surfaces and equipment may present topographical features, increased roughness, or difficult-to-clean areas which can lead to colonization by background microflora and foodborne pathogens. We hypothesize that these critical areas can have an important role in microbial retention, and promote formation of biofilms. In this project, we propose to investigate critical microenvironments where bacteria can reside and serve as reservoirs. These critical areas will be identified directly in the packing house in collaboration with plant management (California), through topographical measurements, and microbiological swabbing. These critical areas will be recreated as fabricated surfaces for laboratory testing regarding potential for biofilm formation (Objective 1). Engineered surfaces will be inoculated L. monocytogenes and allowed to form biofilms in flow-through enclosures (Objective 2). These biofilms will be treated with sanitizers commonly used in the packing house such as chlorine, QUAT and an organic sanitizer. Temperature, concentration, and contact time will be optimized for biofilm inactivation. In Objective 2, we will also test if sanitizers selected for this study meet or exceed EPA requirements for hard surfaces other than stainless steel that can be found in the packing house. We will use in our experiments hard non stainless-steel surfaces fabricated in collaboration with the packing houses, such as wood. In addition to identifying problematic areas, biofilms will be inactivated with commonly used sanitizers and optimal conditions will be determined regarding sanitizer concentration and contact time. This project addresses CPS Part 1.1.3. Listeria monocytogenes preventive controls -cleaning & sanitation/ interventions.
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A team of Clemson University researchers are working on a project entitled, “Preservation of stone fruits by spray application of edible coatings with antimicrobial properties,”( https://www.centerforproducesafety.org/researchproject/413/awards/Preservation_of_stone_fruits_by_spray_application_of_edible_coatings_with_antimicrobial_properties.html) that examines food grade coatings of stone fruits that could reduce Listeria monocytogenes populations without affecting storability, appearance, or taste. Coatings based on gelatin- and pectin was selected as carriers for the antimicrobials. The coating was applied by the immersion of the fruits. The fruits were inoculated with Listeria monocytogenes, then applied the antimicrobial coating and put the fruit into simulated packinghouse cold storage. After storage, the coating was washed and the level of L. monocytogenes survival was determined. “We want to make sure the coating we’ve applied doesn’t affect the firmness compared to the current industry coating,” Kay Cooksey the lead investigator, said. “The idea is to not negatively impact (the fruit) but still have a positive impact as an anti-listeria treatment.”
Listeria monocytogenes is an important foodborne pathogen commonly found in the environment. Recent Listeria foodborne outbreaks have been linked to fresh produce including stone fruits. Contamination of stone fruits is problematic since these products are usually consumed without heating. In addition, some surfaces associated with packing operations (brushes, peach rollers) are inherently difficult to sanitize. In the packing house, these fruits are covered (brushed) with a wax-‐based coating, containing antifungal agents to prevent moisture loss and fungal infection. We propose to develop and compare alternative coatings based on edible components that have antilisterial properties in addition to their physical barrier and antifungal role. The coatings will be formulated to contain safe antimicrobial agents such as nisin, Listex P100, organic acids and or their combinations and could be applied as a spray reducing the risk of cross-‐contamination in the packing house. Experiments will be performed in laboratory settings and validated in challenge studies with inoculated stone fruits. The coating will prevent Listeria contamination on fruits and bacterial persistence on packing equipment. Results from this study will provide improved pathogen control in addition to the basic good agricultural practices, thereby helping fruit industry to produce safer produce for human consumption.
Technical Abstract: The number of human outbreaks associated with foodborne pathogens contaminating fresh produce has increased in the past decade. Stone fruits such as peaches and nectarines are usually consumed raw but these fruits were considered ‘safe ‘since they had not been implicated in major human outbreaks. In 2014, a stone fruit packing company issued the first recall of certain stone fruits because of concern about contamination with Listeria monocytogenes. Although limited with only 2 illnesses, this outbreak highlighted the potential of L. monocytogenes to cause outbreaks via foods that had been considered unlikely vehicles for this pathogen. Traditional preservation techniques such as heating, packaging or reduced water activity do not apply for these commodities. In the absence of any practices that prevent L. monocytogenes survival on stone fruit, the exposure of the fresh fruit to contaminated water or postharvest contact surfaces will increase the likelihood of contamination and foodborne outbreaks. In this project, we propose to investigate L. monocytogenes biofilm formation and transfer rate from surfaces typical for the packing house (rubber peach holders, stainless steel surfaces and cleaning and waxing brushes) to stone fruits (Objective 1). In addition to identifying problematic areas, biofilms will be inactivated with commonly used sanitizers and optimal conditions will be determined regarding sanitizer concentration and contact time. We also propose to design a novel fruit coating with antilisterial properties and intended for a hygienic application such as a spray or water flume. The coating will be formulated to contain antilisterial agents that can (i) inactivate L. monocytogenes on contact with equipment and, (ii) maintain the safety of the fruits (Objective 2). Furthermore, the coatings will be tested in challenge studies, regarding fruit preservation, antilisterial properties and consumer acceptability (Objective 3). Stone fruits will be coated with the antilisterial coating and with a commercially available wax for comparison purposes. A set of samples will be inoculated with a L. monocytogenes cocktail. Samples will be stored in conditions to mimic packing house and retail environment and survival of the pathogen over time will be determined by plate counts. Coated samples (antilisterial and wax) not inoculated with L. monocytogenes will be evaluated side-‐by-‐side for their consumer acceptability and shelf-‐life. We anticipate that results from research will point out practical preventive intervention strategies for safer fruit supply. This proposal will address the identified research area (Part3) “California Fresh Fruit Association”.
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On November 30, the FDA made the following statement “There is no recommendation for consumers or retailers to avoid using romaine lettuce that is certain to have been harvested from areas outside of the Central Coast growing regions of northern and central California. For example, romaine lettuce harvested from areas that include, but are not limited to the desert growing region near Yuma, the California desert growing region near Imperial County and Riverside County, the state of Florida, and Mexico, does not appear to be related to the current outbreak. Additionally, there is no evidence hydroponically- and greenhouse-grown romaine is related to the current outbreak.” The FDA recommends that “romaine lettuce entering the market will now be labeled with a harvest location and a harvest date, or labeled as being hydroponically- or greenhouse-grown. If it does not have this information, you should not eat or use it.” @ https://www.fda.gov/Food/RecallsOutbreaksEmergencies/Outbreaks/ucm626330.htm?utm_campaign=Outbreak_Romaine_11302018&utm_medium=email&utm_source=Eloqua
The FDA, along with CDC, state and local agencies, is investigating a multistate outbreak of E. coli O157:H7 illnesses likely linked to romaine lettuce grown in California this fall. The Public Health Agency of Canada (PHAC) and Canadian Food Inspection Agency are also coordinating with U.S. agencies as they investigate a similar outbreak in Canada.
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Researchers from USDA’s Agricultural Research Service and China’s Fujian Agriculture and Forestry University published an online article entitled “Improved estimation of thermal resistance of Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes in meat and poultry – The effect of temperature and fat and A global analysis” by Lihan Huang, Cheng-An Hwang, and Ting Fang, published in Food Control Vol 96, Feb 2019.29-38. They report on the development of a more accurate regression analysis was developed for the combined effect of temperature and fat on the thermal resistance of the most common food pathogens (E. coli O157:H7, Salmonella spp., and L. monocytogenes). Investigators focused on the combined effect of temperature and fat on thermal resistance of pathogens. A reduced model (temperature only, or D-z model) and an expanded model (temperature and fat) were developed by linear regression. The expanded models developed improved the accuracy of estimation of log D. For E. coli O157:H7 in beef, > 93 percent of the variations in log D were attributed to the expanded model developed, > 96 percent for E. coli O157:H7 in non-beef meats and L. monocytogenes and Salmonella spp. in poultry meats. For Salmonella spp. in non-poultry meats, the expended model accounted for 90.4 percent of the variations. This is significantly greater than 74 percent in the reduced model. @ https://www.sciencedirect.com/science/article/pii/S095671351830433X#!
Escherichia coli O157: H7, Salmonella spp., and Listeria monocytogenes are three major foodborne pathogens in meats that frequently cause serious huma…