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Assuring Growth Inhibition of Listerial Contamination during Processing and Storage of Traditional Greek Graviera Cheese: Compliance with the New European Union Regulatory Criteria for Listeria monocytogenes
11/18/2009
Samelis, John; Giannou, Eleni; Lianou, Alexandra
Journal of Food Protection®, Volume 72, Number 11, November 2009 , pp. 2264-2271(8)
Abstract:
The current microbiological regulatory criteria in the European Union specify a maximum Listeria monocytogenes population of 100 CFU/g allowable in ready-to-eat foods provided the product will not exceed this limit throughout its shelf life. The aim of this study was to validate the manufacturing method for traditional Greek Graviera cheese produced from thermized milk. Initial challenge experiments evaluated the fate of inoculated L. monocytogenes (ca. 4 log CFU/ml, three-strain cocktail) in thermized Graviera cheese milk (TGCM; 63°C for 30 s) in the presence and absence of a product-specific starter culture (SC) in vitro. Milk samples were incubated for 6 h at 37°C and then for 66 h at 18°C. Experiments were conducted to evaluate the fate of a cocktail of three nonpathogenic L. monocytogenes and L. innocua indicator strains inoculated (ca. 3 log CFU/g) in Graviera cheeses commercially manufactured from TGCM+SC. Cheeses were brined, ripened at 18°C and 90% relative humidity for 20 days, and stored at 4°C for up to day 60 under vacuum. In TGCM, L. monocytogenes increased by ca. 2 log units, whereas in TGCM+SC L. monocytogenes growth was retarded (P < 0.05) after a ca. 1-log increase within 6 h at 37°C. Populations of Listeria indicator strains did not grow in TGCM+SC cheeses at any stage; they declined 10-fold in fresh cheeses within 5 days and then survived with little death thereafter. Thus, growth inhibition but not inactivation of potent natural Listeria contaminants at levels below 100 CFU/g occurs in the core of traditional Greek Graviera cheese during fermentation, ripening, and storage.
Assessing Interventions by Quantitative Risk Assessment Tools To Reduce the Risk of Human Salmonellosis from Fresh Minced Pork Meat in Belgium
11/18/2009
Delhalle, L.; Saegerman, C.; Messens, W.; Farnir, F.; Korsak, N.; Van der Stede, Y.; Daube, G.
Journal of Food Protection®, Volume 72, Number 11, November 2009 , pp. 2252-2263(12)
Abstract:
The risk of human salmonellosis through the consumption of minced pork meat in Belgium was assessed via a modular risk model covering pork meat production from lairage to human consumption. The main goal of the model was to give concrete options to reduce effectively the risk of human salmonellosis through the consumption of minced pork meat. These options (scenarios) were elaborated with reference to the international situation and the literature to give concrete and realistic possibilities for improving the microbiological quality of pork meat and to reduce the number of human salmonellosis cases per year in Belgium. The model estimates 15,376 cases of human salmonellosis per year in Belgium due to the consumption of minced pork meat. The results of the scenarios showed that the risk of human salmonellosis could be significantly reduced by efforts all along the pork meat production chain but also by efforts made by consumers. The responsibility of food business operators for the pork meat production chain is high in relation to the microbiological quality of meat delivery, especially at the slaughterhouse. Consumers also need to be aware of good hygiene practices during preparation of the meat at home. Cross-contamination with raw food can be avoided by changing the habits and the behavior of the household cook. The results of these scenarios would be useful for the food business operators involved in the pork meat chain and for public health authorities.
Bacterial Dynamics in Model Cheese Systems, Aiming at Safety and Quality of Portuguese-Style Traditional Ewe's Cheeses
11/18/2009
Pereira, Cláudia I.; Graça, João A.; Ogando, Natacha S.; Gomes, Ana M.P.; Malcata, F. Xavier
Journal of Food Protection®, Volume 72, Number 11, November 2009 , pp. 2243-2251(9)
Abstract:
An experiment using model ewe's milk cheeses was designed to characterize microbial interactions that arise in actual raw milk cheese environments. These model cheeses were manufactured according to Portuguese artisanal practices, except that the microbial load and biodiversity were fully controlled: single potential pathogens and spoilage bacteria, or a combination thereof, were combined at various initial inoculum levels in sterilized raw ewe's milk with several lactic acid bacteria (LAB) normally found in traditional cheeses. Viable microbial counts were monitored throughout a 60-day ripening period. Two alternative mathematical approaches were used to fit the experimental data generated in terms of population dynamics: percent of inhibition and D-values. These were able to explain the complex competitive interactions between the contaminant microorganisms and the LAB adventitious populations. In general, the tested LAB were less able to inhibit contaminants present in combination and in higher concentrations. Lactococcus lactis, with its strong acidifying potential, was the most effective factor in controlling the unwanted bacterial population, especially single Staphylococcus aureus. The two lactobacilli studied, especially Lactobacillus brevis, were shown to be less effective; Escherichia coli and Listeria innocua were the contaminants least inhibited by the LAB.
Transfer of Bacillus cereus Spores from Packaging Paper into Food
11/18/2009
Ekman, Jaakko; Tsitko, Irina; Weber, Assi; Nielsen-LeRoux, Christina; Lereclus, Didier; Salkinoja-Salonen, Mirja
Journal of Food Protection®, Volume 72, Number 11, November 2009 , pp. 2236-2242(7)
Abstract:
Food packaging papers are not sterile, as the manufacturing is an open process, and the raw materials contain bacteria. We modeled the potential transfer of the Bacillus cereus spores from packaging paper to food by using a green fluorescent protein-expressing construct of Bacillus thuringiensis Bt 407Cry- [pHT315O(papha3-gfp)], abbreviated BT-1. Paper (260 g m-2) containing BT-1 was manufactured with equipment that allowed fiber formation similar to that of full-scale manufactured paper. BT-1 adhered to pulp during papermaking and survived similar to an authentic B. cereus. Rice and chocolate were exposed to the BT-1-containing paper for 10 or 30 days at 40 or 20°C at relative air humidity of 10 to 60%. The majority of the spores remained immobilized inside the fiber web; only 0.001 to 0.03% transferred to the foods. This amount is low compared with the process hygiene criteria and densities commonly found in food, and it does not endanger food safety. To measure this, we introduced BT-1 spores into the paper in densities of 100 to 1,000 times higher than the amounts of the B. cereus group bacteria found in commercial paper. Of BT-1 spores, 0.03 to 0.1% transferred from the paper to fresh agar surface within 5 min of contact, which is more than to food during 10 to 30 days of exposure. The findings indicate that transfer from paper to dry food is restricted to those microbes that are exposed on the paper surface and readily detectable with a contact agar method.
Read the whole story: Transfer of Bacillus cereus Spores from Packaging Paper into Food
Agriculture chief promises better food alerts to schools
11/18/2009
Peter Eisler and Blake Morrison
USA Today
WASHINGTON — Agriculture Secretary Tom Vilsack pledged Tuesday that the government will do a better job alerting schools across the nation when it suspects that food for school lunches might be contaminated.
"We understand and appreciate that there has been a … gap in communication, which results in school districts not getting information on a timely basis," Vilsack told lawmakers during a Senate Agriculture Committee hearing on child nutrition programs.
Vilsack's comments came during questioning by Sen. Kirsten Gillibrand, D-N.Y., who asked about a USA TODAY investigation published Tuesday. The newspaper reported that schools know almost nothing about where the food they serve comes from, even when government regulators are aware it may be contaminated.
For the complete news item, please visit http://www.usatoday.com/news/education/2009-11-17-school-lunches_N.htm?csp=34
Read the whole story: Agriculture chief promises better food alerts to schools
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