Category Archives: Methods

Research – Evaluation of PCR Detection of Salmonella in Alfalfa Sprouts

Posted on February 18, 2013 by | Leave a comment

Ingenta ConnectEurofins

Abstract:

This study evaluated the efficacy of a PCR-based system (DuPont Qualicon BAX) for detection of Salmonella in sprouts and spent irrigation water collected during sprouting of seeds naturally contaminated with Salmonella. Alfalfa seeds were grown in Mason jars at 20 and 30°C for 3 days. Levels of Salmonella present in the water and sprouts were determined by most-probable-number (MPN) analysis. Background microflora levels were also determined. Samples of spent irrigation water and sprouts were enriched overnight individually in tetrathionate broth and in buffered peptone water with novobiocin at 42°C and then run in the BAX system. Samples were also enriched according to the U.S. Food and Drug Administration’s Bacteriological Analytical Manual (FDA BAM) method for Salmonella as a comparison. Salmonella levels were lower at 20°C compared with 30°C for some trials, and background microflora levels ranged from 107 to 108 CFU/g or ml at 20°C and 108 to 109 CFU/g or ml at 30°C. In trials with a Salmonella level >1.1 MPN/g or ml, both the BAX and FDA BAM methods were able to detect Salmonella in all samples. In trials with lower levels (0.21 MPN/g or ml or lower) of Salmonella, BAX was able to detect more positive samples than FDA BAM. For one trial with <0.003 MPN/g or ml of Salmonella, the presence of the pathogen was not indicated by either the BAX or the FDA BAM method. The results suggest that PCR detected low levels of Salmonella in sprouts or spent irrigation water collected from sprouting of naturally contaminated seeds.

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Posted in Bacteria, Food Hygiene, Food Inspections, Food Microbiology, Food Safety, Food Technology, Food Testing, Methods, Microbiology, PCR, Salmonella

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USA – CDC Report Salmonella Heidelburg Outbreak 2012

Posted on February 15, 2013 by | Leave a comment

CDCcdc

Since June 4, 2012, a total of 124 persons infected with the outbreak strain of Salmonella Heidelberg have been reported from 12 states.

32% of ill persons have been hospitalized, and no deaths have been reported.

Most of the ill persons have been reported from two states, Washington (56) and Oregon (38).

State public health officials are interviewing ill persons to obtain information regarding foods they might have eaten and other exposures in the week before illness.

Information available to date indicates that consumption of chicken is the most likely source of infection for many of the ill persons.

Oregon and Washington have identified Foster Farms brand chicken as the most likely source of the infections in their states.

The U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) is currently conducting an investigation to determine the source of infections in this outbreak.

It is not unusual for raw poultry from any producer to have Salmonella. This underscores the importance for consumers to follow food safety tips to help protect themselves and others from foodborne illness.

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Posted in Bacteria, CDC, Food Hygiene, Food Illness, Food Inspections, Food Microbiology, Food Poisoning, Food Safety, Food Testing, Foodborne Illness, Hygiene, Methods, Microbiology, outbreak, Pathogen, Recall

Research – Listeria and Biofilms

Posted on February 15, 2013 by | Leave a comment

Science Direct

Abstract

Listeria monocytogenes is able to form biofilms on surfaces of food industry premises. Once established at certain plant sites, this pathogen can persist there for months or years, risking the transfer to raw materials or processed food by direct contact or other mechanisms. Though persistence of certain strains of L. monocytogenes isolated from food industry surfaces has been reported in several cases, experimental evidence has so far been inconclusive about the association of persistence to features such as better biofilm forming ability or higher resistance to disinfectants. This work has aimed at checking another possible cause of persistence, the ability to recover after exposure to antimicrobial compounds. Damaged cells in the biofilms formed by twelve L. monocytogenes strains previously isolated from an Iberian pig slaughterhouse and processing plant, six persistent and six non persistent, were compared in their recovery of viable cell counts during the 24 h following exposure to chitosan or peracetic acid. Persistent strains showed a better resuscitation rate after chitosan damage.

Highlights

► Persistent strains did not perform better at adherence or biofilm formation. ► Persistent strains biofilms resulted to be no more tolerant to chitosan treatment. ► Persistent strains did resuscitate faster than non persistent ones. ► RR (Recovery Rates) of the persistent group doubled those of the other group.

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Posted in Bacteria, Biofilm, Food Hygiene, Food Microbiology, Food Safety, Food Testing, Listeria, Listeria monocytogenes, Methods, Microbiology, Pathogen, Rotavirus

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Research – Compressed Air – Food Industry

Posted on February 13, 2013 by | Leave a comment

Parker Balston

Understanding the potential risks from compressed air contamination is crucial for developing an effective compliance solution for your plant. Microbial contamination can exist wherever compressed air contacts food either directly or indirectly. As of July 2012, SQF auditors now assess this risk as they perform audits in accordance with the SQF 7th edition code.

How can you ensure your air filtration meets the most discriminating industry
standards and ensures compliance with ALL published GMPs? Proper filtration at point-of-use will minimize your contamination risks. Read this GMP Template for Food Plants that use risk-based systems including HACCP Procedures and GFSI – SQF Code.

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Posted in Bacteria, Food Hygiene, Food Inspections, Food Safety, Food Technology, Food Testing, Methods, Microbiology, Research

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Research – Ozone to Extend Shelf Life

Posted on February 12, 2013 by | Leave a comment

The Engineer

A device developed in Scotland uses ozone to make food safer for consumers  and extend the shelf-life of food products by one day.

Dr Declan Diver and Dr Hugh Potts of Glasgow University’s School of Physics  and Astronomy have prototyped a system to rapidly, safely and temporarily turn  some of the oxygen inside the sealed packaging into ozone, which acts as a  germicide.

Plasma generated by a retractable device held briefly against the surface of  plastic or glass packaging splits the bonds between oxygen molecules inside the  packaging which then reform as ozone.

Read more:  http://www.theengineer.co.uk/device-improves-safety-and-shelf-life-of-food-products/1015509.article#ixzz2KhKAIIeS

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Posted in Bacteria, Food Chemistry, Food Hygiene, Food Inspections, Food Safety, Food Technology, Food Testing, Hygiene, Methods, Microbiology, Pathogen, Research

Research-Decontamination of Leafy Green Vegetables Using Edible Plant Extracts

Posted on February 12, 2013 by | Leave a comment

Journal of Food Science

Abstract

Fresh cilantro, parsley, and spinach are products that are regularly consumed fresh, but are difficult to decontaminate, as a result, they are common vehicles of transmission of enteropathogenic bacteria. In this study, the efficacy of plant extracts as alternatives for disinfection of cilantro, parsley, and spinach that were artificially contaminated with Salmonella, Escherichia coli O157:H7, and Shigella sonnei was determined. Edible plant extracts obtained using ethanol as the extraction solvent were tested to determine the minimum bactericidal concentration (MBC) and those that exhibited the lowest MBC were selected for further studies. Leaves of fresh greens were washed with sterile water and dried. For seeding, leaves were submerged in suspensions of 2 different concentrations of bacteria (1.5 × 108 and 1 × 105), dried, and then stored at 4 °C until use. To determine the effects of the extracts, inoculated leafy greens were submerged in a container and subjected to treatments with chlorine, Citrol®, or selected plant extracts. Each treatment type was stored at 4 °C for 0, 1, 5, and 7 d, and the bacterial counts were determined. From the 41 plant extracts tested, the extracts from oregano leaves and from the peel and pulp of limes were found to be as effective as chlorine or Citrol® in reducing by > 2 logs, the population of pathogenic bacteria on leafy greens and therefore, may be a natural and edible alternative to chemicals to reduce the risk of Salmonella, E. coli O157:H7 and S. sonnei contamination on leafy vegetables.

Practical Application:  The antimicrobial efficacy of the extracts of Mexican lime and oregano was clearly demonstrated on cilantro, parsley, and spinach. The extracts of Mexican lime and oregano provide alternatives to chlorine to significantly reduce bacterial pathogens that have been associated with outbreaks from contaminated leafy green vegetables. A simple, low cost, and labor-saving extraction system for production of the extracts was used.

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Posted in Bacteria, Food Hygiene, Food Poisoning, Food Safety, Food Technology, Food Testing, Methods, Microbiology, Pathogen, Research

Research – Antilisterial Properties of Marinades

Posted on February 12, 2013 by | Leave a comment

Journal of Food Science

Abstract

This study evaluated growth of Listeria monocytogenes inoculated on cooked chicken meat with different marinades and survival of the pathogen as affected by microwave oven reheating. During aerobic storage at 7 °C, on days 0, 1, 2, 4, and 7, samples were reheated by microwave oven (1100 W) for 45 or 90 s and analyzed microbiologically. L. monocytogenes counts on nonmarinated (control) samples increased (P < 0.05) from 2.7 ± 0.1 (day-0) to 6.9 ± 0.1 (day-7) log CFU/g during storage. Initial (day-0) pathogen counts of marinated samples were <0.5 log CFU/g lower than those of the control, irrespective of marinating treatment. At 7 d of storage, pathogen levels on samples marinated with tomato juice were not different (P ≥ 0.05; 6.9 ± 0.1 log CFU/g) from those of the control, whereas for samples treated with the remaining marinades, pathogen counts were 0.7 (soy sauce) to 2.0 (lemon juice) log CFU/g lower (P < 0.05) than those of the control. Microwave oven reheating reduced L. monocytogenes counts by 1.9 to 4.1 (45 s) and >2.4 to 5.0 (90 s) log CFU/g. With similar trends across different marinates, the high levels of L. monocytogenes survivors found after microwave reheating, especially after storage for more than 2 d, indicate that length of storage and reheating time need to be considered for safe consumption of leftover cooked chicken.

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Posted in Food Hygiene, Food Safety, Food Technology, Food Testing, Methods, Microbiology, Research

Research – Bacteriocidal Properties of Health Promoting Powders

Posted on February 12, 2013 by | Leave a comment

Journal of Food Science

Abstract

We evaluated the relative bactericidal activities (BA50) of 10 presumed health-promoting food-based powders (nutraceuticals) and, for comparison, selected known components against the following foodborne pathogens: Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. The relative activities were evaluated using quantitative bactericidal activity [(BA50 value, defined as the percentage of the sample in the assay mixture that resulted in a 50% decrease in colony forming units]. The BA50 values were determined by fitting the data to a sigmoidal curve by regression analysis using concentration–antimicrobial response data. Antimicrobial activity is indicated by a low BA50 value; meaning less material is needed to kill 50% of the bacteria. Olive pomace, olive juice powder, and oregano leaves were active against all 4 pathogens, suggesting that they behave as broad-spectrum antimicrobials. All powders exhibited strong antimicrobial activity against S. aureus. The following powders showed exceptionally high activity against S. aureus (as indicated by the low BA50 values shown in parentheses): apple skin extract (0.002%); olive pomace (0.008%); and grape seed extract (0.016%). Listeria bacteria were also highly susceptible to apple skin extract (0.007%). The most active substances provide candidates for the evaluation of antimicrobial effectiveness in human food and animal feed.

Practical Application: Plant-derived health-promoting food supplements, high in bioactive compounds, are candidates for use as antimicrobials in food.

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Posted in Bacteria, Food Safety, Listeria, Methods, Microbiology, Pathogen, Research

Research – FDA Risk Assessment of Listeria monocytogenes in Cheese

Posted on February 10, 2013 by | 2 comments

FDA FDA

The U.S. Food and Drug Administration announced a draft quantitative assessment of the risk of listeriosis from soft-ripened cheese consumption in the United States and Canada. The risk assessment is a joint effort between FDA and Health Canada. View the Federal Register Notice for the assessment.

The new FDA/Health Canada draft risk assessment found that the risk of listeriosis from soft-ripened cheeses made with raw milk is estimated to be 50 to 160 times higher than that from soft-ripened cheese made with pasteurized milk. This finding is consistent with the fact that consuming raw milk and raw milk products generally poses a higher risk from pathogens than do pasteurized milk and its products.

While raw milk and raw milk products put all consumers at risk, the bacteria they may contain can be especially dangerous to people with weakened immune systems, older adults, pregnant women and children. View guidelines for avoiding illness by choosing milk and milk products carefully.

FDA invites comments that can help FDA and Health Canada improve:

  • the approach used;
  • the assumptions made;
  • the modeling techniques;
  • the data used; and
  • the clarity and transparency of the draft quantitative risk assessment documentation.

To submit comments electronically, go to docket FDA-2012-N-1182 on regulations.gov. The comment period opens February 11, 2013 for 75 days.

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Posted in Bacteria, FDA, Food Hygiene, Food Inspections, Food Poisoning, Food Safety, Food Technology, Food Testing, Foodborne Illness, Listeria, Listeria monocytogenes, Methods, Microbiology, Pathogen, Research

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Research – Flash Drying Poultry Cages – Reduces Campylobacter Levels

Posted on February 10, 2013 by | Leave a comment

Food Poisoning Bulletin Campylobacter

Campylobacter is a bacteria that is commonly found in the intestines of poultry and shed  in their feces. During slaughter, these bacteria sometimes make their way onto cuts of meat, posing a health threat to consumers.

Sometimes these bacteria are spread from infected birds to healthy ones during transport. For example, a healthy bird may be placed in a poultry cage whose previous occupant was infected, or the healthy bird’s poultry cage may be placed beneath an infected bird’s cage on a truck. Despite the risk to consumers, there hasn’t been much progress in reducing the presence of the pathogen in poultry, according to the Centers for Disease Control and Prevention (CDC).

A few years ago, researchers discovered that drying the cages for 24-48 hours after washing them, cut down and even eliminated Campylobacter levels in poultry cages. But these drying times were found to be overly long and impractical by the industry. So  microbiologists Mark Berrang and Richard Meinersmann at the US Department of Agriculture’s  Agricultural Research Service and their colleague Charles Hofacre at the University of Georgia in Athens researched a shorter drying time with a blast of hot air.

They found that flowing hot air for 15 minutes on cages that had been spray washed with water “lowered the numbers of Campylobacter to an undetectable level,” according to a report of their study published in the January 2013 edition of Agricultural Research, a USDA publication. No word  yet on how the poultry industry views the breakthrough.

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Posted in Bacteria, Campylobacter, Food Hygiene, Food Illness, Food Inspections, Food Poisoning, Food Safety, Food Technology, Methods, Microbiology, Pathogen, Research

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