A Model Study of Escherichia coli O157:H7 Survival in Fermented Dry Sausages—Influence of Inoculum Preparation, Inoculation Procedure, and Selected Process Parameters

2003 ◽  
Vol 66 (12) ◽  
pp. 2267-2275 ◽  
Author(s):  
FADIA NAIM ◽  
SERGE MESSIER ◽  
LINDA SAUCIER ◽  
GABRIEL PIETTE
Keyword(s):  
Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Pathogen Inactivation ◽  
Fermented Sausage ◽  
E Coli ◽  
Fermentation Temperature ◽  
Model Study ◽  
Inoculation Procedure ◽  
Acidic Conditions ◽  
Inoculum Preparation

The influence of inoculum preparation, inoculation level, and inoculation procedure on Escherichia coli O157:H7 inactivation during the manufacture of fermented sausage was evaluated in a model study. Prior growth in glucose-enrichedtryptone soya broth, which provided exposure to mildly acidic conditions (pH 4.8), had no effect on the later survival of E. coli O157: H7 strains 5-1 and ATCC 43894 under extremely acidic conditions (pH 2), but the same strains became sensitive to acidity after 7 days of incubation on the surface of refrigerated beef (as per the normal contamination route from slaughter to further processing). In subsequent sausage production trials, the extent of destruction observed for E. coli O157:H7 strains F-90, 5-1, and ATCC 43894 inoculated directly into the meat batter was unchanged when the inoculation level was decreased from 7.3 to 4.7 log CFU/g, but the level of inactivation was ca. 1 log higher when the surfaces of beef cuts, rather than the batter, were inoculated 7 days prior to processing. Regardless of processing conditions (fermentation to a pH of ≤5.0 at 24 or 37°C, drying at 14°C to a water activity [aw] value of 0.91 or 0.79), strains F-90, 5-1, and ATCC 43894 showed similar survival capacities during the manufacture of sausage. A ~2-log reduction in pathogen numbers was generally obtained after samples were dried to an aw of 0.91, irrespective of fermentation temperature. The addition of a 5-day predrying holding stage at the fermentation temperature significantly (P < 0.05) increased pathogen inactivation when fermentation was carried out at 37°C (but not when it was carried out at 24°C). However, significant pathogen reductions (4 to 5 log CFU/g) were achieved only for extensively dried products (aw = 0.79).

Survival of Enterohemorrhagic Escherichia coli O157:H7 in Retail Mustard

2001 ◽  
Vol 64 (6) ◽  
pp. 783-787 ◽  
Author(s):  
CAROLYN M. MAYERHAUSER
Keyword(s):  
Escherichia Coli ◽  
Foodborne Illness ◽  
Enterohemorrhagic Escherichia Coli ◽  
Test Strain ◽  
Escherichia Coli O157 ◽  
Time Intervals ◽  
Fermented Sausage ◽  
Apple Cider ◽  
E Coli ◽  
Predetermined Time

Escherichia coli O157:H7 survival in acid foods such as unpasteurized apple cider and fermented sausage is well documented. Researchers have determined that E. coli O157:H7 can survive in refrigerated acid foods for weeks. The potential of acid foods to serve as a vector of E. coli O157:H7 foodborne illness prompted this study to determine the fate of this organism in retail mustard containing acetic acid when stored at room and refrigerated temperatures. Various retail brands of dijon, yellow, and deli style mustard, pH ranging from 3.17 to 3.63, were inoculated individually with three test strains of E. coli O157:H7. Samples were inoculated with approximately 1.0 × 106 CFU/g, incubated at room (25 ± 2.5°C) and refrigerated (5 ± 3°C) temperatures, and assayed for surviving test strains at predetermined time intervals. An aliquot was appropriately diluted and plated using sorbitol MacConkey agar (SMAC). When the test strain was not recoverable by direct plating, the sample was assayed by enrichment in modified tryptic soy broth and recovered using SMAC. Growth of E. coli O157:H7 test strains was inhibited in all retail mustard styles. E. coli O157:H7 was not detected in dijon style mustard beyond 3 h at room and 2 days at refrigerated temperatures. Survival in yellow and deli style mustard was not detected beyond 1 h. Overall, test strain survival was greater at refrigerated than room temperature. Retail mustard demonstrated the ability to eliminate effectively any chance contamination by this organism within hours to days, suggesting that these products are not a likely factor in E. coli O157:H7 foodborne illness.

Inactivation of Escherichia coli O157:H7 in Nonintact Beefsteaks of Different Thicknesses Cooked by Pan Broiling, Double Pan Broiling,or Roasting by Using Five Types of Cooking Appliances

2010 ◽  
Vol 73 (3) ◽  
pp. 461-469 ◽  
Author(s):  
CANGLIANG SHEN ◽  
JEREMY M. ADLER ◽  
IFIGENIA GEORNARAS ◽  
KEITH E. BELK ◽  
GARY C. SMITH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Sodium Tripolyphosphate ◽  
Cooking Methods ◽  
Escherichia Coli O157 ◽  
Target Temperature ◽  
Pathogen Inactivation ◽  
Total Water ◽  
E Coli ◽  
George Foreman

This study compared thermal inactivation of Escherichia coli O157:H7 in nonintact beefsteaks of different thicknesses by different cooking methods and appliances. Coarsely ground beef was inoculated with rifampin-resistant E. coli O157:H7 (eight-strain composite, 6 to 7 log CFU/g) and then mixed with sodium chloride (0.45%) plus sodium tripolyphosphate (0.23%); the total water added was 10%. The meat was stuffed into bags (10-cm diameter), semifrozen (−20°C, 6 h), and cut into 1.5-, 2.5-, and 4.0-cm-thick steaks. Samples were then individually vacuum packaged, frozen (−20°C, 42 h), and tempered (4°C, 2.5 h) before cooking. Partially thawed (−2 ± 1°C) steaks were pan broiled (Presto electric skillet and Sanyo grill), double pan broiled (George Foreman grill), or roasted (Oster toaster oven and Magic Chef standard kitchen oven) to a geometric center temperature of 65°C. Extent of pathogen inactivation decreased in order of roasting (2.0 to 4.2 log CFU/g) > pan broiling (1.6 to 2.8 log CFU/g) ≥ double pan broiling (1.1 to 2.3 log CFU/g). Cooking of 4.0-cm-thick steaks required a longer time (19.8 to 65.0 min; variation was due to different cooking appliances), and caused greater reductions in counts (2.3 to 4.2 log CFU/g) than it did in thinner samples (1.1 to 2.9 log CFU/g). The time to reach the target temperature increased in order of George Foreman grill (3.9 to 19.8 min) < Oster toaster oven (11.3 to 45.0 min) < Presto electric skillet (16.3 to 55.0 min) < Sanyo grill (14.3 to 65.0 min) < standard kitchen oven (20.0 to 63.0 min); variation was due to steak thickness. Results indicated that increased steak thickness allowed greater inactivation of E. coli O157:H7, as time to reach the target internal temperature increased. Roasting in a kitchen oven was most effective for pathogen inactivation.

Inhibition of Escherichia coli O157:H7 in Ripening Dry Fermented Sausage by Ground Yellow Mustard

2008 ◽  
Vol 71 (3) ◽  
pp. 486-493 ◽  
Author(s):  
GARY H. GRAUMANN ◽  
RICHARD A. HOLLEY
Keyword(s):  
Escherichia Coli ◽  
Starter Culture ◽  
Escherichia Coli O157 ◽  
Fermented Sausage ◽  
Yellow Mustard ◽  
E Coli ◽  
Dry Fermented Sausage ◽  
Hydrolysis Of ◽  
Antimicrobial Effectiveness ◽  
Dry Sausage

Compounds generated by the enzymatic hydrolysis of glucosinolates naturally present in mustard powder are potently bactericidal against Escherichia coli O157:H7. Because E. coli O157:H7 can survive the dry fermented sausage manufacturing process, 2, 4, and 6% (wt/wt) nondeheated (hot) mustard powder or 6% (wt/wt) deheated (cold) mustard powder were added to dry sausage batter inoculated with E. coli O157:H7 at about 7 log CFU/g to evaluate the antimicrobial effectiveness of the powders. Reductions in E. coli O157:H7 populations, changes in pH and water activity (aw), effects on starter culture (Pediococcus pentosaceus and Staphylococcus carnosus) populations, and effects of mustard powder on sausage texture (shear) were monitored during ripening. Nondeheated mustard powder at 2, 4, and 6% in dry sausage (0.90 aw) resulted in significant reductions in E. coli O157:H7 (P < 0.05) of 3.4, 4.4, and 6.9 log CFU/g, respectively, within 30 days of drying. During fermentation and drying, mustard powder did not affect P. pentosaceus and S. carnosus activity in any of the treatments. Extension of drying to 36 and 48 days reduced E. coli O157:H7 by >5 log CFU/g in the 4 and 2% mustard powder treatments, respectively. The 6% deheated mustard powder treatment provided the most rapid reductions of E. coli O157:H7 (yielding <0.20 log CFU/g after 24 days) by an unknown mechanism and was the least detrimental (P < 0.05) to sausage texture.

Predicting Survival of Escherichia coli O157:H7 in Dry Fermented Sausage Using Artificial Neural Networks

2008 ◽  
Vol 71 (1) ◽  
pp. 6-12 ◽  
Author(s):  
A. PALANICHAMY ◽  
D. S. JAYAS ◽  
R. A. HOLLEY
Keyword(s):  
Escherichia Coli ◽  
Neural Networks ◽  
Artificial Neural Networks ◽  
Statistical Model ◽  
Allyl Isothiocyanate ◽  
Escherichia Coli O157 ◽  
Fermented Sausage ◽  
E Coli ◽  
Dry Fermented Sausage ◽  
Artificial Neural

The Canadian Food Inspection Agency required the meat industry to ensure Escherichia coli O157:H7 does not survive (experiences ≥ 5 log CFU/g reduction) in dry fermented sausage (salami) during processing after a series of foodborne illness outbreaks resulting from this pathogenic bacterium occurred. The industry is in need of an effective technique like predictive modeling for estimating bacterial viability, because traditional microbiological enumeration is a time-consuming and laborious method. The accuracy and speed of artificial neural networks (ANNs) for this purpose is an attractive alternative (developed from predictive microbiology), especially for on-line processing in industry. Data from a study of interactive effects of different levels of pH, water activity, and the concentrations of allyl isothiocyanate at various times during sausage manufacture in reducing numbers of E. coli O157:H7 were collected. Data were used to develop predictive models using a general regression neural network (GRNN), a form of ANN, and a statistical linear polynomial regression technique. Both models were compared for their predictive error, using various statistical indices. GRNN predictions for training and test data sets had less serious errors when compared with the statistical model predictions. GRNN models were better and slightly better for training and test sets, respectively, than was the statistical model. Also, GRNN accurately predicted the level of allyl isothiocyanate required, ensuring a 5-log reduction, when an appropriate production set was created by interpolation. Because they are simple to generate, fast, and accurate, ANN models may be of value for industrial use in dry fermented sausage manufacture to reduce the hazard associated with E. coli O157:H7 in fresh beef and permit production of consistently safe products from this raw material.

Impact of Preinoculation Culture Conditions on the Behavior of Escherichia coli O157:H7 Inoculated onto Romaine Lettuce (Lactuca sativa) Plants and Cut Leaf Surfaces

2009 ◽  
Vol 72 (7) ◽  
pp. 1553-1559 ◽  
Author(s):  
CHRISTOPHER G. THEOFEL ◽  
LINDA J. HARRIS
Keyword(s):  
Escherichia Coli ◽  
High Standard ◽  
Culture Conditions ◽  
Escherichia Coli O157 ◽  
Late Stationary Phase ◽  
Romaine Lettuce ◽  
Preparation Methods ◽  
E Coli ◽  
Leaf Surfaces ◽  
Inoculum Preparation

Inoculum preparation methods can impact growth or survival of organisms inoculated into foods, thus complicating direct comparison of results among studies. The objective of this study was to evaluate preinoculation culture preparation for impact on Escherichia coli O157:H7 inoculated onto leaves of romaine lettuce plants and cut leaf surfaces. E. coli O157:H7 was grown quiescently or shaken at 15, 25, or 37°C to different growth phases in tryptic soy or M9 minimal salts broth or agar. Cells were harvested, washed, and suspended in 0.1% peptone, Milli Q water, or well water and refrigerated for 0 or 18 h. Prepared inoculum was spotted onto cut romaine lettuce (10 μl; 3 × 104 CFU/10 g) or onto romaine lettuce plants (20 μl; 3 × 106 CFU per leaf). Cut lettuce was sealed in 100-cm2 bags (made from a commercial polymer film) and incubated at 5 or 20°C. Lettuce plants were held at 23°C for 24 h. For all tested conditions, levels of E. coli O157:H7 increased at 20°Concut lettuce and decreased on cut lettuce stored at 5°C or on leaves of lettuce plants. At 20°C, preinoculation culture conditions had little impact on growth of E. coli O157:H7 on cut lettuce. However, survival at 5°C was significantly better (P < 0.05) for cultures grown at 15 or 37°C in minimal medium and to late stationary phase. Impact of preinoculation handling on survival on lettuce plants was less clear due to relatively high standard deviations observed among samples.

Ammonia sanitization of blackwater for safe use as fertilizer

2015 ◽  
Vol 71 (5) ◽  
pp. 795-800 ◽  
Author(s):  
Jörgen Fidjeland ◽  
Sven-Erik Svensson ◽  
Björn Vinnerås
Keyword(s):  
Escherichia Coli ◽  
Treatment Time ◽  
Escherichia Coli O157 ◽  
Storage Facility ◽  
Egg Viability ◽  
Pathogen Inactivation ◽  
E Coli ◽  
Available Nutrients ◽  
Manure Slurry ◽  
The Impact

Source-separated blackwater from low-flush toilets contains plant-available nutrients and can be used as a fertilizer. The aim of the study was to evaluate the impact on pathogen inactivation when treating blackwater with urea and/or lime. Blackwater was spiked with Salmonella typhimurium, Escherichia coli O157, Enterococcus faecalis, and Ascaris suum eggs, and treated with urea and/or lime in concentrations up to 0.1% w/w. The bottles were kept in a storage facility (manure slurry tank) for 102 days while monitoring the pathogen concentrations. The treatment time needed to meet the requirement for Salmonella and E. coli reduction could be reduced at least six-fold. The enterococci were more persistent, and only the highest treatment doses had a significantly higher inactivation than the controls. The Ascaris egg viability was only reduced by around 50%, so higher urea/lime doses and/or longer treatment times are required to fulfill the treatment requirements of 3 log10 reductions of parasite eggs.

Retention of Acid Tolerance and Acid Shock Responses of Escherichia coli O157:H7 and Non-O157:H7 Isolates

1997 ◽  
Vol 60 (12) ◽  
pp. 1478-1482 ◽  
Author(s):  
DONNA MAE GARREN ◽  
MARK A. HARRISON ◽  
SCOTT M. RUSSELL
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Acid Tolerance ◽  
Escherichia Coli O157 ◽  
Adaptation Period ◽  
E Coli ◽  
Acid Shock ◽  
Acidic Conditions ◽  
Temperature Levels ◽  
Over Time

Escherichia coli O157:H7 and non-O157:H7 survival due to induced acid tolerance or shock responses when exposed to lactic acid over time was studied. Induced acid tolerance or shock responses could allow pathogens, like E. coli O157:H7, to survive acidic conditions in foods during storage. Escherichia coli O157:H7 isolates 932 and E009 and a non-Ol57:H7 strain, 23716, were grown to stationary phase at 32°C and exposed to one of two treatments: acid shock or acid adaption. Acid-shocked cells were exposed to lactic acid at pH 3.5 or 4.0. Acid-adapted cells were exposed to pH 5.5 for an adaptation period and then exposed to an acid challenge of pH 3.5 or 4.0. Samples were incubated at either 25 or 32°C and survival of the isolates at 0, 3, 24, 48, 72, and 168 h (7 days), 336 h (14 days), and 504 h (21 days) was determined. All three isolates survived longer with larger populations at pH 4.0 and 25°C compared to the other treatments. In cases where a difference was observed in the two responses, acid-shocked cells had a higher survival rate (typically less than 2 logs) than acid-adapted cells in most cases. Isolate differences were observed at the two pH and temperature levels. Isolate 932 was the most resistant to the acidic conditions during the incubation period, E009 intermediate, and strain 23716 was the most sensitive.

Dynamic Effects of Free Chlorine Concentration, Organic Load, and Exposure Time on the Inactivation of Salmonella, Escherichia coli O157:H7, and Non-O157 Shiga Toxin–Producing E. coli†

2013 ◽  
Vol 76 (3) ◽  
pp. 386-393 ◽  
Author(s):  
CANGLIANG SHEN ◽  
YAGUANG LUO ◽  
XIANGWU NOU ◽  
QIN WANG ◽  
PATRICIA MILLNER
Keyword(s):  
Escherichia Coli ◽  
Organic Matter ◽  
Exposure Time ◽  
Shiga Toxin ◽  
Contact Time ◽  
Organic Load ◽  
Escherichia Coli O157 ◽  
Pathogen Inactivation ◽  
Dynamic Effects ◽  
E Coli

This study evaluated the dynamic effects of free-chlorine (FC) concentration, contact time, and organic load on the inactivation of Salmonella, Escherichia coli O157:H7, and non-O157 Shiga toxin–producing E. coli (STEC) in suspension. Bacterial cells from four strains each of Salmonella, E. coli O157:H7, and non-O157 STEC were inoculated separately or as a multistrain cocktail into solutions with varying FC concentrations. Lettuce or tomato extract was used to simulate the organic matter present during commercial fresh and fresh-cut produce wash operations. After exposure to FC for various lengths of time, the bacterial survival and water-quality changes were determined. In the absence of organic matter in a wash solution, pathogen inactivation is primarily a function of initial FC concentration (P < 0.0001), exposure time (P < 0.0001), and pathogen strains (P < 0.0001). In general, an over 4.5-log CFU/ml pathogen reduction was found after exposure to >0.5 mg/liter FC for over 30 s, or to >1.0 mg/liter FC for over 5 s. When the combination of FC concentration and contact time were less than or equal to the above conditions, survival of pathogens was strain dependant and ranked as: Salmonella > E. coli O157:H7 > non-O157 STEC. When organic matter was present in the wash solution, pathogen inactivation efficacy was specifically dependent on the residual FC concentration, which directly relates to both the initial FC concentration and the organic load. Prevention of pathogen survival in chlorinated produce wash solutions can be achieved by maintaining sufficient FC concentration and reducing the accumulation of organic matter.

Reduction of Escherichia coli O157:H7 and Salmonella enterica Serovar Enteritidis in Chicken Manure by Larvae of the Black Soldier Fly

2004 ◽  
Vol 67 (4) ◽  
pp. 685-690 ◽  
Author(s):  
MARILYN C. ERICKSON ◽  
MAHBUB ISLAM ◽  
CRAIG SHEPPARD ◽  
JEAN LIAO ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Feeding Activity ◽  
Chicken Manure ◽  
Escherichia Coli O157 ◽  
Pathogen Inactivation ◽  
Salmonella Enterica Serovar Enteritidis ◽  
E Coli ◽  
Fly Larvae

Green fluorescent protein–labeled Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis were inoculated at 107 CFU/g into cow, hog, or chicken manure. Ten- or 11-day-old soldier fly larvae ( Hermetia illucens L.) (7 to 10 g) were added to the manure and held at 23, 27, or 32°C for 3 to 6 days. Soldier fly larvae accelerated inactivation of E. coli O157: H7 in chicken manure but had no effect in cow manure and enhanced survival in hog manure. The initial pH values of the hog and chicken manure were 6.0 to 6.2 and 7.4 to 8.2, respectively, and it is surmised that these conditions affected the stability of the larval antimicrobial system. Reductions of E. coli O157:H7 populations in chicken manure by larvae were affected by storage temperature, with greater reductions in samples held for 3 days at 27 or 32°C than at 23°C. Pathogen inactivation in chicken manure by larvae was not affected by the indigenous microflora of chicken manure, because Salmonella Enteritidis populations in larvae-treated samples were approximately 2.5 log lower than control samples without larvae when either autoclaved or nonautoclaved chicken manure was used as the contaminated medium during 3 days of storage. Extending the storage time to 6 days, larvae again accelerated the reduction in Salmonella Enteritidis populations in chicken manure during the first 4 days of storage; however, larvae became contaminated with the pathogen. After 2 days of feeding on contaminated manure, Salmonella Enteritidis populations in larvae averaged 3.3 log CFU/g. Populations decreased to 1.9 log CFU/g after 6 days of exposure to contaminated chicken manure; however, the absence of feeding activity by the maggots in later stages of storage may be responsible for the continued presence of Salmonella Enteritidis in larvae. Transfer of contaminated larvae to fresh chicken manure restored feeding activity but led to cross-contamination of the fresh manure.

Modeling the Survival of Escherichia coli O157:H7 in Uncooked, Semidry, Fermented Sausage

2001 ◽  
Vol 64 (6) ◽  
pp. 759-766 ◽  
Author(s):  
TREVOR J. POND ◽  
DIANE S. WOOD ◽  
ISMAIL M. MUMIN ◽  
SHAI BARBUT ◽  
MANSEL W. GRIFFITHS
Keyword(s):  
Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Time Model ◽  
Fermented Sausage ◽  
E Coli ◽  
Log Reduction ◽  
Predicted Values ◽  
Using Data ◽  
Model C ◽  
Temperature Time

The data collected from studies to monitor inactivation of Escherichia coli O157:H7 in uncooked fermented salami were used to develop models to describe survival of the organism. Three models were developed that included different variables to best describe E. coli O157:H7 reduction. Model A included the variables water activity (aw), pH, time, and quadratic variables pH and time. Model B separated the processing stages into fermentation and drying. The fermentation included the variables pH and temperature × time (ttarea) and interaction between the two variables. The drying stage was modeled using the variables time and aw and interaction between the two. Model C looked at variables aw and the time at pH 5.3 to achieve a 2-D log reduction of E. coli O157:H7 and the interaction between the variables. The variables selected for inclusion in all the models were significant at the P < 0.0001 level. The predicted values for all models correlated well to the observed values with R2 of 0.888, 0.828, 0.836, and 0.818 for models A, Bferm, Bdrying, and C, respectively. The models were validated using data from a trial not used to develop the model. In general the predicted reduction in E. coli O157:H7 count in uncooked fermented salami was greater than for the observed E. coli O157:H7 log reductions for all models, but the relation between the two was linear. The results demonstrate that modeling can be a useful tool in assessing manufacturing practices for uncooked fermented salami processes.

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