Reflecting the importance of food safety, the number of peer-reviewed papers is huge, to such an extent that it is frequently difficult for those working in the field to keep up with the literature. As a special service to our readers, FEI presents a selection of literature abstracts, chosen by our editorial board as being particularly worthy of attention.
Control of food-borne pathogens on ready-to-eat roast beef slurry by epsilon-polylysine.
This study evaluates the antimicrobial effectiveness of epsilon-polylysine against Escherichia coli O157:H7, Salmonella typhimurium and Listeria monocytogenes in laboratory media and roast beef slurry. Epsilon-Polylysine supplemented laboratory medium and roast beef slurry were inoculated with three-strain cocktails of each pathogen and survival was periodically monitored using conventional spread plating. Inoculated laboratory medium was stored at room temperature for 48h, and inoculated roast beef slurry was stored at 4 °C for up to seven days. Maximum log reductions in laboratory media/roast beef slurry were 6.01+/-1.43/3.81+/-0.37, >7.82+/-0.05/5.23+/-0.08, and 4.58+/-0.86/5.83+/-0.48 for E. coli O157:H7, S. tyhimurium, and L. monocytogenes, respectively. Injured cells were produced as a result of exposure to polylysine. This study confirms the effectiveness of polylysine against pathogens in laboratory media, and demonstrates its potential as a novel antimicrobial agent in complex food matrices such as roast beef.
Chang SS, Lu WY, Park SH, Kang DH. Int J Food Microbiol. 2010 May 31.
Inactivation of Bacillus cereus by Na-chlorophyllin-based photosensitisation on the surface of packaging.
This study was focused on the possibility of inactivating the food-borne pathogen Bacillus cereus by Na-chlorophyllin (Na-Chl)-based photosensitisation in vitro and after attachment to the surface of packaging material. Bacillus cereus in vitro or attached to the packaging was incubated with Na-Chl (7.5 x 10-8 to 7.5 x 10-5 mol L-1) for 2-60 min in phosphate buffer saline. Photosensitisation was performed by illuminating cells under a light with a lambda of 400 nm and an energy density of 20 mW cm-2. The illumination time varied 0-5 min and subsequently the total energy dose was 0-6 J cm-2. The results showed that B. cereus vegetative cells in vitro, or attached to the surface of packaging after incubation with 7.5 x 10-7 mol l-1 Na-Chl, were inactivated by 7 log following illumination. The photoinactivation of B. cereus spores in vitro by 4 log required higher (7.5 x 10-6 mol L-1) Na-Chl concentration. Decontamination of packaging material from attached spores by photosensitisation reached 5 log at 7.5 x 10-5 mol L-1 Na-Chl concentration. Comparative analysis of different packaging decontamination treatments indicates that washing with water can diminish pathogen population on the surface by <1 log, 100 ppm Na-hypochlorite reduces the pathogens about 1.7 log and 200 ppm Na-hypochlorite by 2.2 log. Meanwhile, Na-Chl-based photosensitisation reduces bacteria on the surface by 4.2 orders of magnitude. These data support the idea that Na-Chl-based photosensitisation has great potential for future application as an environment-friendly, non-thermal surface decontamination technique.
Luksiene Z, Buchovec I, Paskeviciute E. J Appl Microbiol 2010 May 22.
Cell-based biosensor for rapid screening of pathogens and toxins.
The development and validation of a mammalian cell-based biosensor for application in food defense and food safety was investigated. Three prototypes of the biosensor capable of handling different sample types were developed and tested with food and beverages. The sensing element was a B lymphocyte Ped-2E9 cell-line, encapsulated in a collagen matrix in a 3D scaffold. The uniqueness of this biosensor is that it detects analyte interaction with mammalian cells and is able to distinguish pathogenic from non-pathogenic, and active from inactive toxins, rendering accurate estimation of the risk associated with the agents. This sensor gave a positive signal for a broad range of bacterial pathogens including Listeria monocytogenes, enterotoxigenic Bacillus, Vibrio, Micrococcus and Serratia, and toxins; alpha-hemolysin from Staphylococcus aureus, phospholipase C from Clostridium perfringens, cytolysin from sea anemone Stoichactis helianthus, listeriolysin O from L. monocytogenes, and enterotoxin from Bacillus. The detection limit for the toxins was 10-40ng in 2h. A model bacterial pathogen, L. monocytogenes, produced 103 -104 CFU/mL in 4-6h, even in the presence of a mixture of higher concentrations of non-pathogenic species of the same genera or common background microflora. With inoculated food and beverage, the sensor detected L. monocytogenes and Bacillus cereus at a low initial concentration of 102-104 CFU/g from ready-to-eat meat and rice, and only active toxins at nanogram quantities from rice, milk and water samples. Though all the three prototypes performed well with beverages, Devices II & III are most suitable for testing particulate foods. These data present promising evidence for the possible application of this biosensor for rapid detection of multiple pathogens or toxins for food defense and food safety application.
Banerjee P, Bhunia AK. Biosens Bioelectron 2010; May 19.
Analytical testing as a tool for the enforcement of future regulatory thresholds for food allergens.
Food allergen labelling regulations have been implemented in several countries since 2006. Currently, experts are still discussing the introduction of thresholds or action levels, which should lead to the reduction of the widespread use of advisory statements (e.g., “may contain”) for the benefit of the allergic consumer. However, the establishment of a threshold requires supporting analytical methodologies to enforce and comply with the regulations. This article discusses the possibilities and limitations of existing and emerging methodologies for the purpose of enabling compliance with, and enforcement of, allergen action levels.
Diaz-Amigo C, Popping B. J AOAC Int. 2010;93(2):434-41.
Review: highlights in recent applications of electronic tongues in food analysis.
This paper examines the main features of modern electronic tongues (e-tongues) and their most important applications in food analysis. The components of an e-tongue (automatic sampler, array of chemical sensors, and data processing system) are described. Applications discussed include process monitoring, freshness evaluation and shelf-life investigation, authenticity assessment, foodstuff recognition, quantitative analysis and other quality control studies. Finally, the strengths and weaknesses of e-tongues in food analysis are also discussed.
Escuder-Gilabert L, Peris M. Anal Chim Acta. 2010;665(1):15-25.
Review of rapid tests available for measuring the quality changes in frying oils and comparison with standard methods.
Repeated use of oils and fats for the frying of food brings about many changes in their physical and chemical properties. Due to increasing health concerns, the assessment of the quality of reused oils has received much attention, since such assessment is useful in determining the discarding point of the oils. The official analytical methods used in laboratories for this purpose need skill, time and a large amount of solvents. To make oil testing simpler, several rapid test kits have been developed based on either physical parameters, such as viscosity or dielectric changes, or chemical parameters, such as free fatty acids, oxidised fatty acids, or carbonyl compounds. These test kits usually comprise a portable instrument or colorimetric reaction sticks, capable of providing a direct or indirect measurement of a single parameter. The review presented in this paper evaluates the use of such rapid test kits and highlights the need to develop multi-parameter test kits in order to establish the quality of reused oil and the point at which it should be discarded. The review also encompasses pertinent details on the standard analytical methods, and deterioration of frying oils that occur during and after their use, as well as the associated health consequences.
Bansal G, Zhou W, Barlow PJ, Joshi PS, Lo HL, Chung YK. Crit Rev Food Sci Nutr. 2010;50(6):503-14.
Quality and safety aspects of meat products as affected by various physical manipulations of packaging materials.
This article explores the effects of physically manipulated packaging materials on the quality and safety of meat products. Recently, innovative measures for improving quality and extending the shelf-life of packaged meat products have been developed, utilising technologies including barrier film, active packaging, nanotechnology, microperforation, irradiation, plasma and far-infrared ray (FIR) treatments. Despite these developments, each technology has peculiar drawbacks which will need to be addressed by meat scientists in the future. To develop successful meat packaging systems, key product characteristics affecting stability, environmental conditions during storage until consumption, and consumers’ packaging expectations must all be taken into consideration. Furthermore, the safety issues related to packaging materials must also be taken into account when processing, packaging and storing meat products.
Lee KT. Meat Sci. 2010 Apr 28.
Safety and quality of ready-to-eat dry fermented sausages subjected to E-beam radiation.
The inactivation kinetics in the death of Listeria innocua NTC 11288 (more radio-resistant than five different strains of Listeria monocytogenes), Salmonella enterica serovar Enteritidis and S. enterica serovar Typhimurium by E-beam irradiation were studied in two types of vacuum-packed RTE dry fermented sausages (“salchichon” and “chorizo”) in order to optimise the sanitation treatment of these products. A treatment of 1.29kGy was calculated to reach the food safety objective (FSO) according to the “zero tolerance” criterion for the three strains. No irradiation treatment was necessary to meet the 102 CFU/g microbiological criterion for L. monocytogenes. Dry fermented sausages treated with 2kGy had negligible sensory (appearance, odour and taste) modifications. This treatment produces safe, dry, fermented sausages with similar sensory properties to the non-irradiated product.
Cabeza MC, de la Hoz L, Velasco R, Cambero MI, Ordóñez JA. Meat Sci. 2010 Jun 6.
