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Alternative Intervention Methods For Pathogen Control In Foods And On Food Contact Surfaces

Harrison, Mark
University of Georgia
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Overall Goals Research will determine the bactericidal activity of commonly used antimicrobial formulations against foodborne pathogens (e.g., Salmonella, Campylobacter, L. monocytogenes) on poultry used for ground chicken. Treatments will determine optimal intervention methods to decontaminate chicken skin and meat prior to grinding. Research will also determine the efficacy of antimicrobial potential in preventing cross-contamination by examining the post-chill water.Research will determine if a chlorine stabilizer will enhance the stability and activity of surface sanitizers against foodborne pathogens (e.g., Salmonella, Campylobacter, L. monocytogenes, E. coli O157:7).Research will determine if selected, naturally occurring compounds or formulations exhibit antimicrobial activities that could be used against foodborne pathogens (e.g., Salmonella, L. monocytogenes, E. coli O157:H7) and spoilage organisms.

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Specific Objective: The objective is to determine if different antimicrobial treatments (chlorine and peracetic acid with or without a sanitizer stabilizer) applied in the pre-chill step used in poultry processing influences whether water retained in the pre-chill tank is a likely cause of increased microbial counts on cut-up chicken parts and ground chicken or if the contamination source can be attributed to other sources such as poor sanitation in processing facilities or cross-contamination by workers during cut-up.

Approach: Ground poultry products are frequently contaminated with significantly higher levels of Salmonella and other bacteria than the whole parts used for the ground product. Some theorize this increase might be due to release of entrapped bacteria from feather follicles or other pores in the tissues during grinding. While entrapped, the bacteria may not be exposed to antimicrobials used on whole carcasses. In a preliminary study, Salmonella levels in ground poultry appeared to be lower if the pH of a peracetic acid (PAA) intervention step was adjusted to 9.0-9.5 rather than the typical 4.3-5.0 pH and if this wash was included in the pre-chill step (ambient water temperature). It is possible the follicles and pores may be opened more during pre-chilling at this temperature and pH resulting in deeper tissue penetration of the antimicrobial and thus greater inactivation of entrapped Salmonella. The objective is to determine if addition of sodium hydroxide to PAA in the pre-chill step during poultry processing will increase uptake of the resulting antimicrobial into the tissues of broiler carcasses, further reducing the likelihood of cross-contamination. Poultry carcasses will be pre-chilled in water at ambient temperature containing 20 ppm PAA at either pH 4.3-5.0 or 9.0-9.5 and subsequently chilled. Carcasses will be analyzed before treatment, after pre-chill, after chill and after grinding to determine microbial levels. Significantly lower contamination levels on alkaline treated samples would provide supporting evidence for the possibility that entrapped bacteria are inactivated to a greater degree due to enhanced penetration of the antimicrobial.Results of a previous study involving the application of pathogen interventions in the pre-chill stage of poultry processing indicate that the use of the chlorine stabilizer T-128 (SmartWash, may also enhance the activity of peracetic acid (Steininger, current Thesis project). Additional evaluations are needed to establish this is the case.

Pre-chill treatments to evaluate include: 50 ppm chlorine, 50 ppm chlorine + 0.5% T-128, 20 ppm peracetic acid, 20 ppm peracetic acid + 0.5% T-128, 0.5% T-128, and water.For both of these specific objectives, methods used by Steininger (current Thesis project) will be applied. This includes methods to isolate, enumerate and identify Salmonella and the methods used to simulate the steps used in poultry processing. Post-evisceration broiler carcasses will be followed through sequential poultry processing steps (in a pilot-scale process) and sampled for total aerobic microorganisms, selected pathogens (Campylobacter spp., Salmonella spp., Listeria) and E. coli/coliforms at various stages of the process (e.g., before processing, after pre-chill, after chilling, and following cut-up into parts). Data will be analyzed statistically (e.g., GLM, Tukey's) to determine the effectiveness of the intervention procedures.

Specific Objective: The objective is to determine if a chlorine stabilizer will enhance the stability and activity of surface sanitizers.

Approach: Chlorine sanitizers with or without the chlorine stabilizer T-128 will be evaluated to determine if the stabilizer enhances the antimicrobial action when the sanitizer is used on food contact surfaces. Materials commonly used for food contact surfaces (high density polyethylene, stainless steel (type 304, 4B finish), polyvinyl chloride sheet) will be spot inoculated with different bacteria (e.g., Salmonella, L. monocytogenes, E. coli O157:H7, Pseudomonas aeruginosa ATCC 15442). In other trials, biofilms of the same bacteria will be allowed to form on the contact surfaces. Sodium hypochlorite solutions (50-200 ppm) prepared with or without T-128 will be prepared and held for up to 5 days. At daily intervals, the chlorine and free chlorine concentrations in the solutions will be measured, and the sanitizers will be applied to surfaces with a hand sprayer in a uniform manner (e.g., uniform amounts, uniform distance, etc.). Variable sanitizer contact times (10-60 sec) will be used before samples are collected and analyzed. D/E neutralizing broth will be used to neutralize the sanitizer at the time of sampling. The number of surviving bacteria on the surfaces after treatments have been applied will be compared to initial numbers on the surfaces. Surface inoculation and sampling will be based on the methods used by Piansay (3) and Rodriguez (4).

Specific Objective: The objective is to determine if selected, naturally occurring compounds or formulations exhibit antimicrobial activities towards foodborne pathogens and spoilage organisms.

Approach: The approach to this objective will be multipronged. One will investigate a newly recognized naturally-occurring, volatile mixture isolated from Muscodor crispans that has exhibited antimicrobial activity towards a variety of bacteria (2). In addition, the substance is GRAS and has some potential as a natural flavoring. We will evaluate the use of this antimicrobial to inactivate foodborne pathogens (e.g., Salmonella, L. monocytogenes, E. coli O157:H7) and spoilage bacteria on food surfaces and food contact surfaces. Food surfaces (e.g., fresh produce, fresh meat or poultry) and food contact surfaces will be inoculated with known numbers of selected foodborne pathogens (e.g., Salmonella, L. monocytogenes, E. coli O157:H7) and treated with the antimicrobial by either direct contact or by exposing the inoculated items to the volatiles in an enclosed package. The effectiveness of the treatments will be determined based on the reductions observed in the microbial numbers. The other approach will involve investigations using plant extracts. Carella (1) who recently completed her thesis in my lab investigated the use of oregano essential oil alone and in combination with acetic acid as a produce wash that could be used by individuals of small food preparation or processing operations. With the growing interest in local, organic, and small food operations, additional efforts to evaluate naturally occurring plant extracts that show some antimicrobial potential will be investigated. Methods will be similar to those used by Carella (1).

References cited:1. Carella, Lee. 2014. Use of oregano essential oil and acetic acid to reduce salmonella contamination on romaine lettuce. M.S. Thesis, University of Georgia. 67 pgs.2. Mitchell, A.M., G.A. Strobel, E. Moore, R. Robison and J. Sears. 2010. Volatile antimicrobials from Muscodor crispans, a novel endophytic fungus. Microbiol. 156:270-277.3. Piansay, Christabelle. 2011. Salmonella transfer and survival on tomatoes and contact surfaces under various transportation and storage conditions. M.S. Thesis, University of Georgia. 55 pgs.4. Rodriguez, Ana. 2009. Effect of organic acids and quaternary ammonium compounds on survival of Salmonella serovars with SGI1- mediated multi-antibiotic resistance. M.S. Thesis, University of Georgia. 75 pgs.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
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Project number
Accession number
Escherichia coli
Bacterial Pathogens
Meat, Poultry, Game