Reduction of Bacteria on Pork Carcasses Associated with Chilling Method

2003 ◽  
Vol 66 (6) ◽  
pp. 1019-1024 ◽  
Author(s):  
V. P. CHANG ◽  
E. W. MILLS ◽  
C. N. CUTTER
Keyword(s):  
Salmonella Typhimurium ◽  
Meat Products ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Campylobacter Coli ◽  
Test Results ◽  
Bacterial Populations ◽  
Layer Method ◽  
Agar Layer ◽  
Low Levels

In addition to reducing the temperature of pork carcasses immediately after slaughter and before fabrication, blast chilling (snap chill) or conventional chilling can reduce bacterial populations associated with fresh meats. However, there is little information on bacteria survival resulting from the freeze or chill injury of meat products. In this study, porcine fecal slurries with and without pathogens (Listeria monocytogenes, Salmonella Typhimurium, and Campylobacter coli) were inoculated onto skin-on and skin-off pork surfaces and subjected to industry-specific blast or conventional chilling conditions. A thin agar layer method was used for the recovery of freeze- or chill-injured cells. Test results indicated that there were no statistically significant (P > 0.05) differences between blast and conventional chilling treatments with respect to the reduction of high and low inoculation levels of mesophilic aerobic bacteria, total coliforms, or Escherichia coli on either skin-on or skin-off surfaces. Chilling treatments did not differ significantly (P > 0.05) with respect to their ability to reduce low (3 log10 CFU/cm2) levels of L. monocytogenes and Salmonella Typhimurium. However, C. coli was reduced to undetectable levels, even after enrichment, on pork surfaces inoculated with low levels (3 log10 CFU/cm2) and subjected to blast chilling. Blast and conventional chilling treatments were more effective against all pathogenic bacterial populations when pork surfaces where inoculated at high levels (5 log10 CFU/cm2). The effects of chilling techniques on microbial populations could provide pork processors with an additional intervention for pork slaughter or information to modify and/or improve the chilling process. The information obtained from this study has the potential to serve as a means of producing a microbiologically safer product.

UV Irradiation of Shell Eggs: Effect on Populations of Aerobes, Molds, and Inoculated Salmonella typhimurium

1997 ◽  
Vol 60 (6) ◽  
pp. 639-643 ◽  
Author(s):  
FUENG-LIN KUO ◽  
JOHN B. CAREY ◽  
STEVEN C. RICKE
Keyword(s):  
Salmonella Typhimurium ◽  
Uv Radiation ◽  
Uv Light ◽  
The Other ◽  
Uv Exposure ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Fluorescent Light ◽  
Uv Treatment ◽  
Shell Eggs

The effects were investigated of 254-nm UV radiation on populations of Salmonella typhimurium, aerobes, and molds on the shells of eggs. In the first experiment, the CFU of attached S. typhimurium cells on unwashed clean shell eggs were determined after 0, 1, 3, 5, and 7 min of UV treatment (620 μW/cm2) on both ends of the egg. All UV treatments significantly reduced S. typhimurium CFU (P < .01). UVtreatment (620 μW/cm2) in 1-min alternating light and dark cycles for 5 min (three light and two dark) was compared to 0, 3, and 5 min of UV treatment. No significant differences in microbial populations were observed among light and dark cycles and the other UV treatments. In a subsequent experiment, the same UV treatments were utilized to evaluate photoreactivation. After UV exposure, eggs were exposed to 1 h of fluorescent light or I h of darkness or cultured immediately. S. typhimurium CFU were significantly (P < .01) reduced by the UV treatments. However, no significant differences between microbial populations exposed to UV treatment and UV radiation plus photoreactivation were detected. For studies of aerobic bacteria and molds, different UV treatment times (0, 15, and 30 min) at the intensity of 620 μW/cm2 and different intensities (620, 1350, and 1720 μW/cm2) for 15 min were evaluated. Mold CFU per egg were either 0 or 1 for all UV treatments and a 99% reduction of CFU of aerobic bacteria per egg were observed for all UV treatments. It appears from these studies that UV light can significantly reduce populations of S. typhimurium, aerobes, and molds on shell eggs.

Investigation of Chemical Rinses Suitable for Very Small Meat Plants To Reduce Pathogens on Beef Surfaces

2012 ◽  
Vol 75 (1) ◽  
pp. 14-21 ◽  
Author(s):  
SALLY F. YODER ◽  
WILLIAM R. HENNING ◽  
EDWARD W. MILLS ◽  
STEPHANIE DOORES ◽  
NANCY OSTIGUY ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Tap Water ◽  
Natural Populations ◽  
Meat Products ◽  
Sodium Chlorite ◽  
Campylobacter Coli ◽  
Peroxyacetic Acid ◽  
Bacterial Populations ◽  
Labor Resources ◽  
Antimicrobial Interventions

Numerous antimicrobial interventions are capable of reducing the prevalence of harmful bacteria on raw meat products. There is a need to identify effective and inexpensive antimicrobial interventions that could, in practice, be used in very small meat plants because of limited financial, space, and labor resources. Eight antimicrobial compounds (acetic acid, citric acid, lactic acid, peroxyacetic acid, acidified sodium chlorite, chlorine dioxide, sodium hypochlorite, and aqueous ozone) were applied at various concentrations with small, hand-held spraying equipment, and bactericidal effectiveness was examined. Beef plate pieces were inoculated with fecal slurry containing a pathogen cocktail (Escherichia coli O157:H7, Salmonella Typhimurium, Campylobacter coli, and Campylobacter jejuni) and natural populations of aerobic plate counts, coliforms, and E. coli. Antimicrobial solutions were applied to beef surfaces via a portable, pressurized hand-held spray tank, and treated surfaces were subjected to appropriate methods for the enumeration and isolation of pathogens and hygiene indicators. Relative antimicrobial effectiveness was determined (from greatest to least): (i) organic acids, (ii) peroxyacetic acid, (iii) chlorinated compounds, and (iv) aqueous ozone. Using the equipment described, a 2% lactic acid rinse provided 3.5- to 6.4-log CFU/cm2 reductions across all bacterial populations studied. Conversely, aqueous ozone yielded 0.02- to 2.9-log CFU/cm2 reductions in pathogens and hygiene indicators, and did not differ significantly from a control tap water rinse (P = 0.055 to 0.731). This 2% lactic acid rinse will be subsequently combined with a previously described water wash to create a multistep antimicrobial intervention that will be examined under laboratory conditions and validated in very small meat plants.

scholarly journals Evaluating the Effects of Chlortetracycline on the Proliferation of Antibiotic-Resistant Bacteria in a Simulated River Water Ecosystem

2007 ◽  
Vol 73 (17) ◽  
pp. 5421-5425 ◽  
Author(s):  
Jeannette Muñoz-Aguayo ◽  
Kevin S. Lang ◽  
Timothy M. LaPara ◽  
Gerardo González ◽  
Randall S. Singer
Keyword(s):  
River Water ◽  
Biological Activities ◽  
Aerobic Bacteria ◽  
Resistant Bacteria ◽  
Bacterial Populations ◽  
Bacterial Colony ◽  
Water Ecosystem ◽  
Low Levels ◽  
And Control

ABSTRACT Antibiotics and antibiotic metabolites have been found in the environment, but the biological activities of these compounds are uncertain, especially given the low levels that are typically detected in the environment. The objective of this study was to estimate the selection potential of chlortetracycline (CTC) on the antibiotic resistance of aerobic bacterial populations in a simulated river water ecosystem. Six replicates of a 10-day experiment using river water in continuous flow chemostat systems were conducted. Each replicate used three chemostats, one serving as a control to which no antibiotic was added and the other two receiving low and high doses of CTC (8 μg/liter and 800 μg/liter, respectively). The addition of CTC to the chemostats did not impact the overall level of cultivable aerobic bacteria (P = 0.51). The high-CTC chemostat had significantly higher tetracycline-resistant bacterial colony counts than both the low-CTC and the control chemostats (P < 0.035). The differences in resistance between the low-CTC and control chemostats were highly nonsignificant (P = 0.779). In general a greater diversity of tet resistance genes was detected in the high-CTC chemostat and with a greater frequency than in the low-CTC and control chemostats. Low levels of CTC in this in vitro experiment did not select for increased levels of tetracycline resistance among cultivable aerobic bacteria. This finding should not be equated with the absence of environmental risk, however. Low concentrations of antibiotics in the environment may select for resistant bacterial populations once they are concentrated in sediments or other locations.

Comparison of Recovery Methods for Freeze-Injured Listeria monocytogenes, Salmonella Typhimurium, and Campylobacter coli in Cell Suspensions and Associated with Pork Surfaces

2003 ◽  
Vol 66 (5) ◽  
pp. 798-803 ◽  
Author(s):  
V. P. CHANG ◽  
E. W. MILLS ◽  
C. N. CUTTER
Keyword(s):  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Pathogenic Bacteria ◽  
Cell Suspensions ◽  
Campylobacter Coli ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Media ◽  
Agar Layer ◽  
Recovery Methods

Cells injured as a result of freezing, heating, and acidification treatments may not grow during conventional microbiological procedures owing to the presence of selective agents, compounds, or dyes in the media, impairing the cell's ability to repair itself and grow. Injured cells can be recovered by combining selective and nonselective media into a single system. With such combinations, the diffusion of the selective compounds or dyes is controlled, allowing for the resuscitation of injured cells of interest while also inhibiting the growth of undesirable background microflora. In this study, Listeria monocytogenes, Salmonella Typhimurium, and Campylobacter coli suspended in buffer or associated with pork surfaces were subjected to a freeze-thaw cycle (−15°C for 24 h, 4°C for 4 h). Following treatments, freeze-injured cells were plated on appropriate media for the overlay (OV), thin agar layer (TAL), and Lutri plate (LP) recovery methods. The levels of L. monocytogenes and Salmonella Typhimurium recovered from cell suspensions and pork surfaces by the TAL, OV, and LP methods following freeze treatments were not statistically different (P &gt; 0.05) from recovery levels associated with nonselective media. Conversely, levels of pathogens on selective media were significantly reduced compared with those for the other methods employed. The TAL method's recovery of C. coli was not significantly different from that achieved with the nonselective media. Overall, the results presented in this study demonstrate that the TAL method not only was easier to perform, but also allowed improved isolation of single colonies for further characterization. This study may provide researchers with better methods to determine the effectiveness of industry-employed chilling processes in reducing pathogenic bacteria associated with red meat surfaces.

Investigation of Water Washes Suitable for Very Small Meat Plants To Reduce Pathogens on Beef Surfaces

2010 ◽  
Vol 73 (5) ◽  
pp. 907-915 ◽  
Author(s):  
SALLY FLOWERS YODER ◽  
WILLIAM R. HENNING ◽  
EDWARD W. MILLS ◽  
STEPHANIE DOORES ◽  
NANCY OSTIGUY ◽  
...  
Keyword(s):  
Pilot Study ◽  
Salmonella Typhimurium ◽  
Cold Water ◽  
Hot Water ◽  
Campylobacter Coli ◽  
Bacterial Populations ◽  
E Coli ◽  
Water Washing ◽  
Effective Combination ◽  
Combination Of Methods

Water washing with a handheld hose was performed on beef surfaces to ascertain the most effective combination of methods needed to remove potentially harmful microorganisms. For these experiments, beef brisket surfaces were experimentally inoculated with a fecal slurry containing Escherichia coli O157:H7, Salmonella Typhimurium, Campylobacter coli, and Campylobacter jejuni. In a pilot study, surfaces were washed with cold water (15°C) at various water pressures, spray distances, application times, and drip times, and remaining bacterial populations were determined following the enumeration and isolation of pathogens and naturally occurring hygiene indicators (mesophilic aerobic bacteria, coliforms, and E. coli). The most efficacious combinations of these washing conditions were applied subsequently to artificially contaminated beef brisket surfaces in conjunction with hot (77°C), warm (54°C), and additional cold (15°C) water washes. In the cold water washing pilot study, combinations of physical washing conditions significantly reduced all bacterial populations (P &lt; 0.05). Further studies clearly indicated the superior bactericidal effectiveness of hot water washing; E. coli O157:H7 and Salmonella Typhimurium were reduced by 3.8 and 4.1 log CFU/cm2, respectively. Overall, higher water temperature, longer application times, and shorter spray distances more effectively removed pathogens from inoculated beef surfaces. These findings will be used to formulate water washing recommendations for very small meat processing establishments.

Trihalomethane Formation Potential and Disinfection

1992 ◽  
Vol 27 (1) ◽  
pp. 185-202
Author(s):  
C.R. Erland Jansson
Keyword(s):  
Hydroxyl Radicals ◽  
Giardia Lamblia ◽  
Test Results ◽  
Formation Potential ◽  
Trihalomethane Formation Potential ◽  
Resistant Species ◽  
Low Levels ◽  
High Concentrations ◽  
Operational Data ◽  
Surface Water Supply

Abstract The UVOX process was developed to reduce the high concentrations of trihalomethanes, a potentially hazardous disinfection by-product found in a surface water supply for a community in northeastern Saskatchewan. Pilot plant tests were conducted at a throughput of 1.25 l/s utilizing UV to produce hydroxyl radicals from photolysis of H2O2 with air cooled UV units. These tests continued through 1985 andl986 to provide operational data for all seasons of the year. Test results indicated that the UVOX process was effective in reducing trihalomethane formation potential to very low levels. Recent concerns have also centred on the biocidal effectivenesss of disinfectants, particularly when applied to inactivation of resistant species of microogranisms, such as the cysts of Giardia lamblia. The UVOX process in a single pass configuration slightly enhanced the ability of UV to inactivate Giardia cysts.

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