Peracetic Acid and Hydrogen Peroxide Post-Dip Decay Kinetics on Red Meat and Poultry
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PEER-REVIEWED ARTICLE Richard J. Walsh,1* Bruce White,1 Food Protection Trends, Vol 38, No. 2, p. 96–103 1 1 Copyright© 2018, International Association for Food Protection Lauren Hunker, Oriana Leishman, 6200 Aurora Ave., Suite 200W, Des Moines, IA 50322-2864 John Hilgren1 and Deborah Klein1 1Ecolab, 655 Lone Oak Drive, Eagan, MN 55121, USA Peracetic Acid and Hydrogen Peroxide Post-dip Decay Kinetics on Red Meat and Poultry ABSTRACT chicken, with a 95% confidence interval of (26.2,30.0), Antimicrobial processing aids are used to mitigate the and 3.5 minutes for beef, with a 95% confidence interval food safety risk from pathogens that may be present of (3.1,4,0). Hydrogen peroxide levels reached < LOD at on poultry and beef products. Although efficacy is well 29.1 minutes for chicken, with a 95% confidence interval documented, post-application decay of the antimicrobial of (27.4,31.0), and 12.3 minutes for beef, with a 95% peracetic acid (and the equilibrium by-product hydrogen confidence interval of (10.7,14.5). These results support peroxide) has not been documented. This was the purpose the use of up to 2000 ppm peracetic acid antimicrobial of the study. Chicken and beef samples were dipped in interventions as processing aids in meat and poultry solutions of > 2000 parts per million (ppm) peracetic operations, with no long-term residues. acid for 30 seconds and then set on a drying rack for set time periods. After times ranging from 0.5 to 30 INTRODUCTION minutes, samples were assayed for residual peracetic Current methods for processing of freshly slaughtered acid and hydrogen peroxide content. The assay consisted poultry or beef rely on use of water in the process for of immersing the sample in water and shaking for 30 various functions, including cleaning of the inside and seconds to recover the residue. The rinse water was then outside of the carcass as well as chilling of the carcass to titrated to measure residuals. Exponential decay kinetics preserve meat quality and retard microbial growth. Recent were used to predict the time at which < LOD was reached data for water consumption rates limited to processing for peracetic acid and peroxide on both chicken and beef operations (not including facility cleaning) is not widely samples. Because ln(0) is undefined, < LOD was defined available; however, studies for broiler processors have as 0.1 to fit the model. Based on the fitted models, reported a use range of 21–30 l/bird (all sizes) (7), and peracetic acid levels reached < LOD at 27.9 minutes for a more recent study for beef processors conducted at a *Author for correspondence: Telephone: +1 651.795.6615; E-mail: [email protected] 96 Food Protection Trends March/April beef processing facility measured 470 l/1000 kg Live of degradation, which is the focus of the present study, has Body Weight for intervention processes (14), which is a not been published/studied. The study design was to treat refinement and reduction from prior reports of 570–1700 chicken and beef samples at a level of peracetic acid slightly l water/animal (2). Although the mechanical action of above the current allowable maximum level of 2000 ppm, water can provide some removal of surface microbial drain treated samples for incremental periods of time, and contamination that may naturally be present on the carcass, then recover and measure the residual levels of peracetic the use of water alone introduces a food safety risk, as a acid and hydrogen peroxide from the samples, allowing for single carcass may cross-contaminate pathogenic bacteria to calculation of decay kinetics of both chemical species. In uncontaminated carcasses being processed at the same time addition to demonstrating the degradation of both species or later (6). on either meat type, this study provides a time estimate This use of water relates directly to the importance of the zero-point residue levels for each chemical species of critical control points in use at processing facilities (peracetic acid or hydrogen peroxide) for each type of meat for organisms of public health significance. To control tested. Such data are frequently used in the evaluation of both pathogenic and spoilage microorganisms naturally finished food product safety and meeting certain regulatory present on the meat surface and decrease the presence of authority requirements of negligible residue remaining on microorganisms due to cross-contamination, the use of product for processing aid qualification. an antimicrobial agent(s) in process water is common. This method can achieve a reduction in microbial levels MATERIALS AND METHODS by several orders of magnitude. Options available for Fresh, non-frozen chicken drums (with skin and bone) use in processing include oxidative chemicals, such as and round steak samples were acquired at a local grocery hypochlorite, acidified sodium chlorite, bromine, or store and used within 48 hours of purchase. Samples were peroxyacids; organic acids, such as lactic acid; and the stored at refrigerated temperatures until used. Chicken quaternary ammonium antiseptic cetylpyridinium chloride drums were used as purchased, beef samples were cut (11). Information on the use of each type of antimicrobial approximately in half, such that each chicken or beef sample is lacking; however, the use of oxidative chlorinated tested was in the range of 50–100 g. Commercial peracetic interventions has declined for various reasons. Restrictions acid (herein referred to as “commercial peracid”) was used on meat or poultry processed with hypochlorite have for each of the studies, with nominal equilibration levels been in effect since 2010 for Russia, and a ban on the use of 15.2% peracetic acid and 11.2% hydrogen peroxide of pathogen reduction treatments other than water or (Ecolab Inc. St. Paul, MN). All dip water used in this study lactic acid has been in effect for the EU since 1997(8) . was controlled at 5 grains per gallon hardness. Water was at Import/Export restrictions are continually revised and room temperature (20–22°C) at time of use. subject to change, with the most recent list of approved or disapproved agents permitted for United States exported Antimicrobial solution preparation meat and poultry product use listed in the U.S. Department Peracetic acid (PAA) dip solution was prepared by of Agriculture Food Safety and Inspection Service (USDA adding 10 kg of water to a clean, 20 l plastic pail, into which FSIS) Export Library (13). the commercial peracid was added and thoroughly mixed. Of the aforementioned options for microbial intervention, The mixed solution was then analyzed using the suppressed peracetic acid has almost certainly increased in usage over peroxide iodometric method (10) for peracid and peroxide the past decade. Adoption and acceptance of its use is levels with 0.1 N thiosulfate titrant. The peracetic acid and attributable to several factors, including broad allowance by hydrogen peroxide levels of the dip/immersion solution beef and poultry importing countries, a large operating range was verified before and after all testing to verify that the with efficacy at low levels, a high tolerance for organic load, concentration of peracetic acid was between 2000 and 2300 and the unique property, by comparison with the others, ppm. For each test of meat immersion, ~600 ml of a large of a breakdown path resulting in innocuous acetic acid (the stock of immersion solution was added to a 1 l beaker, and acid component of vinegar), water, and oxygen. The use of more was added if needed to fully submerge the chicken or peracetic acid thus falls in the category of a processing aid by red meat sample. Immersion solutions were used once and regulatory definition(12) , exhibiting no ongoing technical or discarded, so that the nominal peracetic acid solution used functional effect in finished food products. throughout the study was kept constant. Along with the expanded use throughout the industry, recent regulatory updates have approved the use of per- Meat preparation and antimicrobial application acetic acid at levels ten times higher than that specified Samples were manually placed into the peracetic acid in the original approval (e.g., FDA FCN 1495). Although dip solutions and agitated for 30 s, after which time they regulatory authorities agree that peracetic acid and hydro- were aseptically removed with a plastic utensil and set on gen peroxide do not persist on meat and poultry, their rate a rubber-coated metal rack for the set drain times. Whirl- March/April Food Protection Trends 97 Pak bags were pre-filled with 205 g of de-ionized water to in the solution color from white or colorless and back to facilitate sufficient coating of the sample piece during the dark blue indicated the presence of hydrogen peroxide. recovery process, and so that each rinse solution titration The solution was further titrated using the same 0.01 N sample weighed at least 100 g. Individual meat samples thiosulfate standard, previously described, delivered in were placed into the bags after set drain times had elapsed. 200 µl or 20 µl increments. The bags were sealed and manually shaken for 30–40 s, in such a way that the rinse solution completely covered Limits of detection (LOD) and quantitation (LOQ) the sample. The bags were then opened, the meat samples LODs and LOQs were determined for this titration were removed and discarded, and the rinse solutions were method via visual observation of the colored indicator analyzed for peracetic acid and peroxide levels. and changes imparted by titrant addition. LODs and LOQs were calculated based on potential observable Sampling and analysis color change, combined with the smallest titrant volume, Both types of meat samples were tested in duplicate a defined minimum sample weight, and the concentration at each time point, and measurements were repeated on of the titrant addition.