Development and optimization of an ELISA based method to detect Listeria monocytogenes and Escherichia coli O157 in fresh vegetables

Food-borne pathogen contamination of fresh produce represents a crucial problem in terms of food safety and economic losses. To avoid outbreaks and release of contaminated products in the market, food producers must assure that safety and control measures are followed throughout the production chain. Since traditional methods are complex and time consuming, the use of rapid and reliable methods is needed for a reproducible detection of low pathogen levels prior to packaging. To respond to this need, an indirect ELISA assay was developed to detect the presence of Listeria monocytogenes and Escherichia coli O157. Bacteria isolation procedure, antibody working concentration and limit of detection were studied and optimized to verify the presence of the two bacteria on cucumber. Incubation times for antigen (overnight, 4 \ub0C), antibodies (60 minutes, 25 \ub0C) and for substrate reaction (30 min, 25 \ub0C) were selected. Results show that the ELISA method was highly sensitive with a detection limit lower than 103 CFU g 121 and relatively fast because bacteria isolation was achieved from 1 to 7 hours

Labelling Assessment of Greek “Quality Label” Prepacked Cheeses as the Basis for a Branded Food Composition Database

A labelling assessment study of Greek prepacked “quality label” cheeses was conducted with a view to provide an overview of the whole category. In total, 158 prepacked products belonging to 19 “quality label” cheeses were identified in the Greek market. Among them, Feta had the highest share followed by Kasseri, Graviera Kritis, Kefalograviera and Ladotyri Mitilinis with 81, 16, 15, 11 and 9 products found in the market, respectively. For the rest of the 14 cheeses, the share was limited, ranging from 1 to 4. All labelling indications, nutritional information, claims and other labelling data were recorded and analysed in relation to their compliance against European food law requirements. The results of the analysis showed that for only 6 of the 19 cheeses, all products fully complied with EU labelling legislation. Among the 14 mandatory labelling requirements, the lowest overall compliance was observed for allergens declaration (65%). The analysis of the nutritional data showed a remarkable variability between cheeses and products. Differences in the nutritional characteristics were more pronounced among soft, semi-hard, hard and whey cheese. The above data were entered into an archival database. Application of global harmonisation and standardisation guidelines and tools lead to the initialisation of a branded food composition database (BFCD), conceptualising a specialised database for “quality label” foods

Applicability of an Arrhenius Model for the Combined Effect of Temperature and CO(2) Packaging on the Spoilage Microflora of Fish

The temperature behavior of the natural microflora on the Mediterranean fish red mullet (Mullus barbatus) was examined as a case study. The growth of the spoilage bacteria Pseudomonas spp., Shewanella putrefaciens, Brochothrix thermosphacta, and lactic acid bacteria was modeled as a function of temperature and the concentration of carbon dioxide in modified atmosphere packaging. Combined models were developed and comparatively assessed based on polynomial, Belehradek, and Arrhenius equations. The activation energy parameter of the Arrhenius model, E(A), was independent of the packaging atmosphere and ranged from 75 to 85 kJ/mol for the different bacteria, whereas the preexponential constant decreased exponentially with the packaging CO(2) concentration. We evaluated the applicability of the models developed by using experimental bacterial growth rates obtained from 42 independent experiments performed with three Mediterranean fish species and growth rates predicted from the models under the same temperature and packaging conditions. The accuracy factor and bias factor were used as statistical tools for evaluation, and the developed Arrhenius model and the Belehradek model were judged satisfactory overall