Survival of Listeria monocytogenes in Ground Beef or Liver During Storage at 4 and 25°C.

1989 ◽  
Vol 52 (6) ◽  
pp. 379-383 ◽  
Author(s):  
LEORA A. SHELEF
Keyword(s):  
Listeria Monocytogenes ◽  
Ground Beef ◽  
Plate Count ◽  
C Cells ◽  
Ground Meat ◽  
Potassium Tellurite ◽  
Plate Count Agar ◽  
Natural Microflora ◽  
Survival And Growth ◽  
Selective Environment

Survival and growth of three Listeria monocytogenes strains (Scott A, Brie-1, and ATCC 35152) were studied in ground beef or liver during storage from freshness to spoilage at 4 and 25°C. Cells were enumerated on Plate Count Agar, Trypticase Soy Agar, and selective media, including McBride Listeria Agar (MLA), Cyclohexanedione Nalidixic Acid Phenylethanol Agar (CNPA), LiCl Phenylethanol Moxalactam Agar (LPM), and LPM with potassium tellurite (LPMT). Aerobic natural microflora in the fresh uninoculated samples ranged from 102 to 104 CFU/g, and L. monocytogenes inocula were ca. 103 or 105 CFU/g. Total aerobes after 2 weeks at 4°C were >108 or >107/g in meat or liver respectively, while recovered numbers of L. monocytogenes remained unchanged during a storage of over 30 d in either ground meat or liver. Samples stored at 25°C confirmed recovery but absence of multiplication of the organism. LPM or LPMT provided the best selective environment for direct plating of meat. Despite differences in composition and spoilage pattern of meat and liver, no difference was observed in the fate of L. monocytogenes in these foods.

Lethality of Heat to Escherichia coli 0157:H7: D-Value and Z-Value Determinations in Ground Beef

1991 ◽  
Vol 54 (10) ◽  
pp. 762-766 ◽  
Author(s):  
J. ERIC LINE ◽  
ALFRED R. FAIN ◽  
ALICE B. MORAN ◽  
L. MICHELE MARTIN ◽  
RICHARD V. LECHOWICH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Plate Count ◽  
Ground Meat ◽  
Plate Count Agar ◽  
Death Time ◽  
Lean Beef ◽  
Z Value ◽  
D Values ◽  
D Value

D-values and z-values were determined for lean (2.0% fat) and fatty (30.5% fat) ground beef inoculated with approximately 107 Escherichia coli 0157:H7 cells per g. Inoculated ground meat was sealed in glass thermal death time tubes which were completely immersed in a circulating water bath and held at prescribed temperatures for predetermined lengths of time. Survival was determined by enumeration on plate count agar (PCA) containing 1% sodium pyruvate and by the 2-h indole test of Lee and McClain (7). D-values for fatty ground beef exceeded those for lean ground beef at the temperatures tested. D-values for lean and fatty ground beef at 125°F were 78.2 and 115.5 min, respectively, as enumerated on PCA plus pyruvate. D-values at 135°F were 4.1 and 5.3 min for lean and fatty beef. At 145°F D-values were determined to be 0.3 and 0.5 min. D-values calculated from 2-h indole test data for lean and fatty ground beef at 125°F were 80.1 and 121.0 min, respectively. D-values at 135°F were 4.0 and 7.4 min for lean and fatty beef and at 145°F a D-value of 0.2 min was calculated for lean beef only, due to insufficient survival of E. coli 0157:H7 in fatty beef at this temperature. The z-values determined for lean beef and fatty beef using PCA were 8.3 and 8.4°F respectively. The z-value for lean beef using the 2-h indole data was 7.8°F. No z-value for fatty beef using 2-h indole data could be determined.

Behavior of Listeria monocytogenes in Skim Milk during Fermentation with Mesophilic Lactic Starter Cultures

1988 ◽  
Vol 51 (8) ◽  
pp. 600-606 ◽  
Author(s):  
MICHELLE M. SCHAACK ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Skim Milk ◽  
Starter Cultures ◽  
Plate Count ◽  
Inoculum Level ◽  
Plate Count Agar ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris

The ability of Listeria monocytogenes to grow and compete with mesophilic lactic acid bacteria was examined. Autoclaved skim milk was inoculated with 103 cells of L. monocytogenes (strain V7 or Ohio)/ml, and with 5.0, 1.0, 0.5 or 0.1% of a milk culture of either Streptococcus cremoris or Streptococcus lactis. Inoculated milks were fermented for 15 h at 21 or 30°C, followed by refrigeration at 4°C. Samples were plated on McBride Listeria Agar to enumerate L. monocytogenes and on either APT Agar or plate count agar to enumerate lactic acid bacteria. L. monocytogenes survived in all fermentations, and commonly also grew to some extent. Incubation at 30°C with 5% S. lactis as inoculum appeared to be the most inhibitory combination for strain V7, causing 100% inhibition in growth based on maximum population attained. S. cremoris at the 5.0% and 0.1% inoculum levels, was slightly less inhibitory to L. monocytogenes at 37°C, but it was slightly more inhibitory to L. monocytogenes at the 1.0% inoculum level than was S. lactis. In general, S. lactis reduced the pH of fermented milks more than did S. cremoris. The population of L. monocytogenes began to decrease before 15 h in only one test combination, which was use of a 5.0% inoculum of S. cremoris and 30°C incubation. In most instances, growth of the pathogen appeared to be completely inhibited when the pH dropped below 4.75.

Incidence and Survival of Listeria monocytogenes in Ready-To-Eat Seafood Products

1997 ◽  
Vol 60 (4) ◽  
pp. 372-376 ◽  
Author(s):  
SUSAN A. MCCARTHY
Keyword(s):  
Listeria Monocytogenes ◽  
Storage Time ◽  
Storage Temperature ◽  
Storage Conditions ◽  
Plate Count ◽  
Standard Plate Count ◽  
Smoked Salmon ◽  
Standard Plate ◽  
Seafood Products ◽  
Survival And Growth

The effects of processing and postprocess storage conditions on the incidence and survival of Listeria monocytogenes on crawfish (Procambaris sp.), crabmeat (Callinectus sapidus), and smoked salmon (Salmo salar) were evaluated. L. monocytogenes was recovered from 3% of whole boiled market crawfish samples and 17% of frozen vacuum-packaged partially cooked crawfish tail meat, but not from boiled crabmeat or smoked salmon. Contamination was most likely due to postprocess handling as commonly used methods of cooking (5 min boil or 20 min steep) reduced L. monocytogenes to nondetectable levels in laboratory-contaminated crawfish. In postprocess storage temperature abuse studies, cooked whole crawfish were inoculated internally and externally with 3.0 log CFU of L. monocytogenes per g and incubated at 22 or 30°C for 6 h. The greatest increase in numbers of cells, 1.9 log CFU/g (determined by standard plate count), occurred at 30°C on externally contaminated crawfish. There was little change in numbers of L. monocytogenes during cold storage (6°C, 5 days; −20°C, 15 days). There was little change in cell numbers associated with products stored at 22 or −20°C. At 6°C, numbers of cells associated with crabmeat increased by 3.8 log MPN/g after 6 days; however, there was no increase in numbers of cells associated with salmon. The results show that the survival and growth characteristics of L. monocytogenes are dependent on storage time and temperature and the nature of the seafood product.

Evaluation of Dichloran-Rose Bengal Agar for Enumeration of Fungi in Foods1

1985 ◽  
Vol 48 (7) ◽  
pp. 562-563 ◽  
Author(s):  
J. A. KOBURGER ◽  
F. C. CHANG ◽  
C. I. WEI
Keyword(s):  
Rose Bengal ◽  
Bacterial Contamination ◽  
Plate Count ◽  
Corn Meal ◽  
Ground Meat ◽  
Plate Count Agar ◽  
Standard Procedures

Samples of flour, corn meal, ground meat and carrots were analyzed by standard procedures for presence of fungi using both Dichloran-Rose Bengal (DRBC) and Plate Count agar with antibiotics. Bacterial contamination was so extensive with ground meat and carrot samples on DRBC that meaningful fungal counts could not be obtained. Therefore, DRBC is not recommended for routine enumeration of fungi in foods.

Behavior of Listeria monocytogenes in the Presence of Flavobacteria in Skim Milk at 7 or 13°C

1991 ◽  
Vol 54 (9) ◽  
pp. 677-680 ◽  
Author(s):  
SEHAM A. FARRAG ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Skim Milk ◽  
Mixed Cultures ◽  
Plate Count ◽  
Time Intervals ◽  
Plate Count Agar ◽  
Pure Cultures

Sterile samples of skim milk were inoculated with Listeria monocytogenes (strain Scott A, California, or V7), Flavobacterium lutescens or Flavobacterium species, or a combination of L. monocytogenes plus flavobacteria and incubated at 7 or 13°C for 8 weeks. McBride Listeria agar was used to determine populations of L. monocytogenes at 0, 7, 14, 28, 42, or 56 d, and plate count agar was used to enumerate flavobacteria at the same time intervals. Growth of L. monocytogenes was significantly (P<0.05) enhanced during incubation at 7 or 13°C in mixed cultures with F. lutescens. When tested with Flavobacterium sp. ATCC 21429, numbers of L. monocytogenes decreased insignificantly (P<0.05) in mixed cultures compared to pure cultures. L. monocytogenes did not affect growth of flavobacteria; also, no marked changes in pH of the milk were caused either by L. monocytogenes alone or by mixed cultures.

Effects of Diacetyl and Carbon Dioxide on Spoilage Microflora in Ground Beef

2002 ◽  
Vol 65 (3) ◽  
pp. 523-527 ◽  
Author(s):  
ANISHA M. WILLIAMS-CAMPBELL ◽  
JAMES M. JAY
Keyword(s):  
Ground Beef ◽  
Plate Count ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Plate Count Agar ◽  
Plate Counts ◽  
Meat Samples ◽  
Spoilage Microflora

The effect of CO2 and diacetyl, alone or in combination, on spoilage microflora in ground beef was determined. Ground beef was treated with 20, 30, or 40% CO2 for 22 days (study I); 20, 50, or 100 μg/g diacetyl for 26 days (study II); or a combination of 20% CO2 and 100 μg/g diacetyl for 40 days (study III). Antimicrobial effectiveness was determined by aerobic plate counts (log10 CFU/g) using plate count agar (total aerobic bacteria), deMan Rogosa Sharpe (MRS) Lactobacillus agar (gram-positive bacteria), MacConkey agar (gram-negative bacteria), pH, and informal organoleptic assessments (by appearance and by odor). In study I, total bacteria and pH increased by day 4 in control meat samples. For all CO2 levels, gram-negative bacteria decreased and gram-positive bacteria increased compared with untreated controls. The pH remained constant for CO2-treated meat. Control samples had an off-odor and a brown appearance, while CO2-treated samples had no off-odor but did have a brown appearance. For samples treated with diacetyl (study II), spoilage was evident by day 7 for samples treated with 0, 20, and 50 μg/g diacetyl for all parameters examined. Ground beef treated with 100 μg/g diacetyl was spoiled on day 12. Diacetyl was detected (by odor) in samples that were treated with 100 μg/g diacetyl and had a brown appearance. Meat samples treated with the combination of CO2 and diacetyl (study III) showed that the addition of diacetyl did not have an additive effect on microbial growth. Combination-treated meat maintained a red appearance and no off-odor. Diacetyl and CO2 could be used in combination to maintain a red color and inhibit spoilage microorganisms.

Microbiological Survey of Frozen Ground Meat and a Proposed Standard

1983 ◽  
Vol 46 (2) ◽  
pp. 87-89 ◽  
Author(s):  
A. MATES
Keyword(s):  
Staphylococcus Aureus ◽  
Ground Beef ◽  
Limiting Distribution ◽  
Plate Count ◽  
Ground Meat ◽  
Frozen Ground ◽  
Streptococcus Faecalis ◽  
Aerobic Plate Count

A microbiological survey of frozen ground meat was conducted during a period of five years, 1975–1980. Five hundred and nineteen samples of frozen ground beef and 172 samples of frozen ground fowl were examined. Bacteriological tests performed included aerobic plate count (APC), Staphylococcus aureus, Streptococcus faecalis and Salmonella. A proposed standard limiting distribution of the various bacteria found in frozen ground meat was proposed. The data indicated that frozen ground fowl was heavily contaminated (33%) with Salmonella, therefore according to our findings, this product should not be processed.

Lethality of Heat to Listeria monocytogenes Scott A: D-Value and Z-Value Determinations in Ground Beef and Turkey

1991 ◽  
Vol 54 (10) ◽  
pp. 756-761 ◽  
Author(s):  
ALFRED R. FAIN ◽  
J. ERIC LINE ◽  
ALICE B. MORAN ◽  
L. MICHELE MARTIN ◽  
RICHARD V. LECHOWICH ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Ground Beef ◽  
Ground Meat ◽  
Circulating Water ◽  
Death Time ◽  
Lean Beef ◽  
Z Value ◽  
D Values ◽  
Thermal Death Time ◽  
D Value

D-Values and z-values for Listeria monocytogenes strain Scott A were determined in lean (2.0% fat) and fatty (30.5%) ground beef inoculated with approximately 107cells/g. Inoculated ground meat was sealed in glass thermal death time tubes which were completely immersed in a circulating water bath and held at prescribed temperatures for predetermined lengths of time. Survival was determined by enumeration on Columbia CNA agar base containing 1% sodium pyruvate with a CNA + 4% horse blood overlay (CBNA) and on Listeria Plating Medium (LPM). D-values for L. monocytogenes in lean and fatty ground beef at 125° were 81.3 and 71.1 min, respectively, as enumerated on CBNA plus pyruvate. D-values at 135°F were 2.6 and 5.8 min in lean and fatty beef. At 145°F, D-values were determined to be 0.6 and 1.2 min. D-values calculated from LPM recovery data from fatty ground beef at 125°F were 56.1 and 34.5 min, respectively. D-values at 135°F were 2.4 and 4.6 min in lean and fatty beef. At 145°F a D-value of 0.5 min was calculated in lean beef and a D-value of 1.1 min was determined in fatty beef. The z-values determined in lean beef and fatty beef using CBNA recovery data were 9.3 and 11.4°F, respectively. The z-value in lean beef using LPM recovery data was 9.8°F. The z-value in fatty beef using LPM recovery data was 13.2°F. A D-value for ground turkey meat at 160°F could not be determined under the conditions of this study. Problems encountered are discussed.

scholarly journals THE MICROBIOLOGICAL STUDY OF MINCED MEAT IN SOME MARKETS IN ALEXANDRIA WITH REFERENCE TO ESCHERICHIA COLI O157 H: 7

2017 ◽  
Vol 5 (9) ◽  
pp. 26-35
Author(s):  
Aiada Daw Mohamed
Keyword(s):  
Microbiological Quality ◽  
Ground Beef ◽  
Total Coliform ◽  
Cross Sectional Study ◽  
Plate Count ◽  
Ground Meat ◽  
Frozen Ground ◽  
Cross Sectional ◽  
E Coli ◽  
Meat Samples

This cross sectional study was carried out during a four months period from December, 2012 to March, 2013. A total of 140 fresh and frozen ground beef samples were purchased from local butchers and supermarkets in Alexandria. Each of the ground beef sample was analyzed for its microbiological quality (Aerobic plate count, total coliform count and E. coli count) as well as for the presence of E. coli O157:H7. Out of the 140 studied ground meat samples, 75(53.6%) proved to be unsatisfactory according to the three tested parameters. None out of 140 examined ground meat samples showed E. coli O157:H7.

Sign in / Sign up

Export Citation Format

Share Document