Irradiation Inactivation of Listeria monocytogenes and Staphylococcus aureus in Low- and High-fat, Frozen and Refrigerated Ground Beef

1994 ◽  
Vol 57 (11) ◽  
pp. 969-974 ◽  
Author(s):  
J. DAVID MONK ◽  
MA. ROCELLE S. CLAVERO ◽  
LARRY R. BEUCHAT ◽  
MICHAEL P. DOYLE ◽  
ROBERT E. BRACKETT
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Gamma Irradiation ◽  
Ground Beef ◽  
Stationary Growth Phase ◽  
High Fat ◽  
Beef Patties ◽  
Treatment Conditions ◽  
Irradiation Treatment ◽  
And Staphylococcus Aureus

The influence of two levels of fat (11.l to 13.9% [low-fat] and 27.1 to 27.9% [high-fat]) and temperature (frozen [−17 to −15°C] and refrigerated [3 to 5°C]) on gamma irradiation (60CO) inactivation of Listeria monocytogenes and Staphylococcus aureus in raw ground beef patties was investigated. Ground beef patties inoculated with stationary growth phase cells of five-strain mixtures of L. monocytogenes or S. aureus were treated with seven mean gamma irradiation doses up to 2.062 or 2.147 kGy, respectively. D10 values ranged from 0.507 to 0.610 kGy and 0.435 to 0.453 kGy for L. monocytogenes and S. aureus, respectively. Neither the fat content of beef nor the temperature during irradiation treatment influenced inactivation rates of the two pathogens. Regression coefficients were high for all treatment conditions, the lowest being 0.984 for L. monocytogenes and 0.990 for S. aureus in high-fat frozen beef. Based on the highest D10 value obtained, a dose of 2.50 kGy would theoretically kill 4.10 log10 L. monocytogenes and 5.12 log10 S. aureus per gram of ground beef. The fact that this investigation was done under commercial processing and irradiation treatment conditions, to the extent possible, makes the significance of the results more meaningful to the beef industry.

Effect of Irradiation Temperature on Inactivation of Escherichia coli O157:H7 and Staphylococcus aureus†

2001 ◽  
Vol 64 (10) ◽  
pp. 1624-1626 ◽  
Author(s):  
DONALD W. THAYER ◽  
GLENN BOYD
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Gamma Radiation ◽  
Gamma Irradiation ◽  
Ground Beef ◽  
Irradiation Temperature ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
And Staphylococcus Aureus

The resistance of Escherichia coli O157:H7 and Staphylococcus aureus in ground beef to gamma radiation was significantly (P < 0.05) higher at subfreezing temperatures than above freezing. Ground beef was inoculated (ca. 2 × 108 CFU/g) with five isolates of either E. coli O157:H7 or S. aureus and subdivided into 25-g samples, vacuum packaged in barrier pouches, and tempered to 20, 12, 4, 0, −4, −12, −20, −30, −40, or −76°C before gamma irradiation. The studies were repeated twice. The D10-values for both of these pathogens increased significantly at subfreezing temperatures, reaching maxima at approximately −20°C. The D10-values for E. coli O157:H7 at 4 and −20°C were 0.39 ± 0.04 and 0.98 ± 0.23 kGy, respectively. The D10-values for S. aureus at 0 and −20°C were 0.51 ± 0.02 and 0.88 ± 0.05 kGy, respectively.

Bacterial Growth in Ground Beef Patties Made with Meat from Animals Fed Diets without or with Supplemental Vitamin E

1998 ◽  
Vol 61 (1) ◽  
pp. 36-40 ◽  
Author(s):  
LAURA CABEDO ◽  
JOHN N. SOFOS ◽  
GARY C. SMITH
Keyword(s):  
Listeria Monocytogenes ◽  
Vitamin E ◽  
Ground Beef ◽  
Major Effect ◽  
Aerobic Bacteria ◽  
Fluorescent Light ◽  
Bacterial Populations ◽  
High Vitamin ◽  
Beef Patties ◽  
Supplemental Vitamin

A study was designed to determine populations of aerobic bacteria, coliforms, sorbitol-negative bacteria, and Listeria monocytogenes during display at 4 and 12°C of ground beef patties made with meat from animals fed diets supplemented daily (for 100 days) with 0, 1,000, or 2,000 IU of vitamin E. The patties (113.5 g) were either left uninoculated or were inoculated with Escherichia coli O157:H7 or L. monocytogenes and were tray-overwrapped and stored (at 4 or 12°C for 8 to 10 or 4 to 6 days, respectively) while being continuously exposed to fluorescent light in a display setting. Patties were visually evaluated for overall appearance (based on color and/or discoloration) twice a day and analyzed for microbiological counts at 2-day intervals during display at 4°C and at 0, 1, 2, 3, 4, and 6 days during display at 12°C. Use of beef from animals fed supplemental vitamin E (“high-vitamin E beef”) resulted in ground beef patties which, when stored at 4°C, maintained visually acceptable color longer than did patties made from control beef (from animals not fed supplemental vitamin E), but effects on microbial growth were less pronounced. In general, use of high-vitamin E beef versus control beef in patty manufacture had no major effect on populations of aerobic bacteria, coliforms, sorbitol-negative bacteria, or L. monocytogenes in ground beef patties displayed at 4 or 12°C. Listeria monocytogenes multiplied at 12°C, but growth was similar among ground beef patties made from high-vitamin E beef versus control beef. Overall, changes in bacterial populations were similar in ground beef patties derived from meat from animals with or without added vitamin E in their diets, but control ground beef became visually unacceptable sooner.

Comparison of Four Commercial DNA Extraction Kits for PCR Detection of Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Staphylococcus aureus in Fresh, Minimally Processed Vegetables

2008 ◽  
Vol 71 (10) ◽  
pp. 2110-2114 ◽  
Author(s):  
P. ELIZAQUÍVEL ◽  
R. AZNAR
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Dna Extraction ◽  
Pcr Detection ◽  
Escherichia Coli O157 ◽  
Minimally Processed ◽  
Green Pepper ◽  
Minimally Processed Vegetables ◽  
And Staphylococcus Aureus

Four commercial DNA extraction methods, PrepMan Ultra (Applied Biosystems), InstaGene Matrix (BioRad), DNeasy Tissue kit (Qiagen), and UltraClean (MoBio), were tested for PCR detection of Listeria monocytogenes, Escherichia coli O157: H7, Salmonella, and Staphylococcus aureus in fresh, minimally processed vegetables. For comparative purposes, sensitivity assays with specific PCRs were carried out after DNA extraction with the four methods in green pepper, broccoli, and onion artificially inoculated with the four pathogens separately. As confirmed by statistical analysis, the DNeasy Tissue kit rendered the highest sensitivity values in the three matrices assayed for Salmonella, L. monocytogenes, and E. coli O157:H7 and in onion for S. aureus. Despite being the most expensive of the methods compared, the DNeasy Tissue Kit can be successfully applied for any of the four most commonly studied pathogens, thus saving time and overall reducing the cost of the analysis.

Inactivation of Salmonella enterica serovar Typhimurium and Staphylococcus aureus in rice by radio-frequency heating

2021 ◽  
Author(s):  
Ki-Ok Jeong ◽  
Sang-Soon Kim ◽  
Sang-Hyun Park ◽  
Dong-Hyun Kang
Keyword(s):  
Staphylococcus Aureus ◽  
Radio Frequency ◽  
Heating Rate ◽  
Foodborne Pathogens ◽  
Color Change ◽  
Oryza Sativa L ◽  
Rf Heating ◽  
Pathogen Inactivation ◽  
Treatment Conditions ◽  
And Staphylococcus Aureus

The objectives of this study were to determine the effect of the milling degree (MD) of Oryza sativa L. (Korean rice) on the heating rate, pathogen inactivation (Salmonella Typhimurium and Staphylococcus aureus), and color change resulting from radio-frequency (RF) heating. Rice samples inoculated with pathogens were placed in a polypropylene jar and subjected to RF heating for 0-75 s. The heating rate of rice with a 2% MD was the highest during RF heating, followed by those with a 0, 8, and 10% MD, and the reduction of pathogens showed the same trend. The reduction of the levels of pathogens in rice with a MD 0 and 2% was significantly higher than that observed for rice with a MD of 8 and 10% under the same treatment conditions. For example, log reductions of S. Typhimurium in rice by 55 s RF heating were 3.64, 5.19, 2.18, and 1.80 for milling degree of 0, 2, 8, and 10%, respectively. At the same treatment conditions, log reduction of S. aureus were 2.77, 5.08, 1.15, and 0.90 for milling degree of 0, 2, 8, and 10%, respectively. The color of rice measured according to L*, a*, and b* was not significantly altered after RF heating, regardless of the MD. Therefore, the MD of rice should be considered before RF heating is applied to inactivate foodborne pathogens.

Bacteriological Evaluation of Retail Ground Beef, Frozen Beef Patties, and Cooked Hamburger

1977 ◽  
Vol 40 (6) ◽  
pp. 378-381 ◽  
Author(s):  
C. L. DUITSCHAEVER ◽  
D. H. BULLOCK ◽  
D. R. ARNOTT
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Fast Food ◽  
Ground Beef ◽  
Frozen Ground ◽  
E Coli ◽  
Beef Patties ◽  
Plate Counts ◽  
Bacteriological Evaluation ◽  
G 28

A total of 108 samples of fresh refrigerated ground beef, 99 samples of frozen hamburger patties, and 107 fried hamburgers, purchased from retail stores and fast-food outlets in Ontario, were analyzed for their bacteriological quality. About 44% of non-frozen ground beef samples had aerobic plate counts exceeding 50 million/g; 50 of 108 samples (46.3%) contained Staphylococcus aureus and 46 of these 50 samples (88%) exceeded 1000 organisms/g; 43 of 108 samples were positive for Escherichia coli with 38 samples (88.4%) exceeding 500 organisms/g. About 19% of frozen hamburger patties had aerobic plate counts in excess of 10 million/g; 93 of 99 samples (93.9%) contained S. aureus with 83 of these samples (89.3%) exceeding 1000 organisms/g; 28 of 99 samples were positive for E. coli with 7 of these samples (25%) exceeding 500 organisms/g. About 96.3% of fried hamburger samples had aerobic plate counts of less than 10,000/g.

Viability Loss of Salmonella Species, Staphylococcus aureus, and Listeria monocytogenes in Complex Foods Heated by Microwave Energy

1996 ◽  
Vol 59 (8) ◽  
pp. 813-818 ◽  
Author(s):  
RONALD A. HEDDLESON ◽  
STEPHANIE DOORES ◽  
RAMASWAMY C. ANANTHESWARAN ◽  
GERALD D. KUHN
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Chemical Composition ◽  
Food Systems ◽  
Sodium Content ◽  
Salmonella Spp ◽  
Uht Milk ◽  
Mixed Mean ◽  
Liquid Whole Egg ◽  
And Staphylococcus Aureus

The chemical composition of five foods (UHT milk, beef broth, pudding, cream sauce, and liquid whole egg) was examined to determine factors important in achieving uniform temperatures within foods heated in a 700 W microwave oven. Proximate analyses were performed on all food systems to relate their chemical composition to temperatures and to destruction of microwave-heated Salmonella species, Listeria monocytogenes Scott A and V7 and Staphylococcus aureus ATCC 25923. Microwave heating times were chosen such that the final mixed mean temperature achieved by systems was 60°C for Salmonella spp. and L. monocytogenes, and 65°C for S. aureus. The amount of destruction of Salmonella spp. varied from 3.17 log CFU/ml in UHT milk to 0.44 log CFU/ml in beef broth. L. monocytogenes strains incurred the greatest amount of destruction in pudding (2.39 log CFU/g), while the least amount of destruction was observed in cream sauce (1.63 log CFU/ml). There were no significant differences in the amount of destruction of S. aureus heated in the five foods. The pH and aw of these foods did not affect survival of thermally stressed Salmonella, L. monocytogenes, or S. aureus cells. Of the food components examined, sodium content was the primary influence on the uniformity of temperatures achieved within foods, and, in turn, on the survival of bacteria.

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