Incidence of bacteria of public health interest carried by cockroaches in different food-related environments.

The aim of this study was to determine the incidence of bacteria of public health interest transmitted by cockroaches in different food-related environments. From April to November, cockroaches were trapped in 11 buildings in different urban areas of Western Andalusia (Spain): three hotels, four grocery stores, a catering establishment, a food-industry plant, a health center, and a care home. The presence of a number of bacterial species, including Salmonella, in these food-related environments was confirmed; these species included microorganisms listed in European Union regulations, such as Salmonella spp., Enterobacter sakazakii (Cronobacter spp.), and Escherichia coli. A wide variety of species were isolated, some belonging to different genera that have a significant impact on public health and hygiene, such as Enterobacter and Klebsiella. To ensure adequate elimination of these microorganisms in food-related environments, the control of vectors such as Blattella germanica, Periplaneta americana, and Blatta orientalis, together with a thorough review of hygiene strategies, appears to be fundamental. It is clearly essential to compare the results of hygiene regulations implemented in food-related environments.

Proteolytic activity of lactic acid bacteria strains and fungal biota for potential use as starter cultures in dry-cured ham.

During the processing of dry-cured meat products, sarcoplasmic and myofibrillar proteins undergo proteolysis, which has a marked effect on product flavor. Microbial proteolytic activity is due to the action of mostly lactic acid bacteria (LAB) and to a lesser extent micrococci. The proteolytic capacity of molds in various meat products is of interest to meat processors in the Mediterranean area. Eleven LAB and mold strains from different commercial origins were tested for proteolytic activity against pork myosin, with a view to possible use of these strains as starter cultures for Iberian dry-cured ham. Proteolytic activity was tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The LAB strains with the highest proteolytic activity were Lactobacillus plantarum (L115), Pediococcus pentosaceus (Saga P TM), and Lactobacillus acidophilus (FARGO 606 TM). The best fungal candidate was Penicillium nalgiovense LEM 50I followed by Penicillium digitatum, Debaryomyces hansenii, and Penicillium chrysogenum.

Bactometer system versus traditional methods for monitoring bacteria populations in salchichón during its ripening process.

The performance of the Bactometer system (an impedimetric microbial monitoring system) compared with traditional methods (microbial colony counts) for monitoring bacterial populations (lactic acid bacteria [LAB], Enterobacteriaceae, and coliforms) was studied in 90 samples of an experimental salchichón (a type of Spanish ripened dry sausage) during its ripening process. The population quantitations were carried out with fresh sausage, semiripened sausage (14 days of ripening), and finished product (28 days of ripening). The results showed a high correlation between the traditional microbial colony count (in CFU per gram) and the impedance detection time: -0.98, -0.97, and -0.94 for coliforms, Enterobacteriaceae, and LAB, respectively (P < 0.01). Considering the results obtained with regard to the enumeration of populations of Enterobacteriaceae, coliforms, and LAB in salchichón during its ripening process, the advantages of impedance with respect to plate counts for monitoring the microbial dynamics of ripening processes are notable, especially in its time-saving aspects: between 19 and 21 h in the case of Enterobacteriaceae, between 7 and 20 h for coliforms, and between 32 and 46 h for LAB.

Comparison between the Vitek Immunodiagnostic Assay System and PCR for the detection of pathogenic microorganisms in an experimental dry sausage during its curing process.

The comparison between the Vitek Immunodiagnostic Assay System (VIDAS) and PCR methods for the detection of the pathogenic microorganisms Salmonella Typhimurium, Listeria monocytogenes, Escherichia coli O157:H7, Clostridium perfringens, and Staphylococcus aureus in salchich6n (a type of Spanish fermented dry sausage) was studied. The automated mini-VIDAS method and the PCR method were used to detect the presence of these microorganisms in 90 samples grouped into six batches (one control batch, and five batches inoculated with Salmonella Typhimurium, L. monocytogenes, E. coli O157:H7, S. aureus, and C. perfringens, respectively). The determinations were carried out on fresh sausage, semicured (14 days), and finished product (28 days of curing). The concordance between both methods was 100%. For salchichón-type sausage samples, both the VIDAS method and PCR (in comparison to traditional methods) permit a significant reduction in the time required for the detection of the pathogens assayed. The absence of Salmonella Typhimurium, E. coli O157:H7, L. monocytogenes, S. aureus, their enterotoxins, and C. perfringens were verified in the control batch. Conversely, for batches inoculated with these pathogens, the results were positive in the fresh sausage up to 14 days of curing and in the finished product; this demonstrated the null or scant influence of the curing conditions and the constitutive lactic acid biota on the pathogens investigated.

Influence of low concentrations of an acid preservative on sponge cakes under different storage conditions.

In a previous study, we demonstrated the efficiency of an acid test preservative at concentrations higher than 10 g/kg of product. The aim of the current study has been to assay, in a pilot plant, a preservative at lower and different doses than tested in the aforementioned study, in contrast with different storage temperature and relative humidity (RH) conditions and to check the possibilities of the growth of molds with a toxigenic capacity. The effect of the test preservative is not demonstrable at very low concentrations, as occurs in batch 2. In this case, the influence of the other storage parameters, temperature and RH, has a mixed effect, which makes it difficult to draw conclusions about the convenience of the preservative. In our opinion, the minimal concentration of the test preservative to reach readable results is 4 g/kg, but it is not enough to guarantee a longer shelf life. Regarding the mycotoxigenic study, the majority of molds obtained in the isolations from the cakes after their macroscopic identification corresponded to the genera Aspergillus and Penicillium. Only 5 turned out to be mycotoxigenic, with citrinin and viridicatumtoxin being detected.

Prevalence of Salmonella in a poultry slaughterhouse.

The prevalence of Salmonella on surfaces, water, and broiler chicken (carcasses, parts, viscera, and spoils) taken from a poultry slaughterhouse located in the south of Brazil was studied. The automated mini-VIDAS system (a variation of the basic enzyme-linked immunosorbent assay) was used to screen for the presence of this microorganism in 615 samples, and the traditional culture method was used in 470 samples. We detected Salmonella in the following sampling points by the VIDAS Salmonella test: transport cages (16.7%), boxes (10%), scalding water (16.7%), chilled water (6.7%), carcass before evisceration (6.7%), carcass after chilling (3.3%), fresh breast (3.3%), fresh leg (10%), frozen wing (13.3%), frozen leg (13.3%), intestines (6.7%), skin of breast and leg (10%), and skin of neck (6.7%). Nevertheless, with the traditional culture method we only detected salmonellae in the following sampling points: scalding water (10%), fresh leg (6.7%), frozen wing (10%), skin of breast and leg (20%), and skin of neck (10%). Finally, 5.4% (33 of 615) of the samples analyzed by the VIDAS Salmonella system were positive, whereas the positive percentage with the traditional method was 2.6% (12 of 470). The results showed that transport cages, scalding water, frozen wing, frozen leg, and skin of breast and leg were the sampling points that demonstrated the greatest prevalence.

Behaviour of the constitutive biota of two types of Spanish dry-sausages ripened in a pilot-scale chamber.

The behaviour of the constitutive biota in eighty four samples belonging to two different types of Spanish dry-cured sausages during the ripening process in a pilot-scale chamber was investigated. Samples were analyzed in three stages during production: fresh product, first drying stage and finished product. Lactic acid bacteria (LAB) and Coagulase-negative cocci (CNC) were identified by the API system. In general, evolution of LAB and CNC during the ripening process of Spanish dry-cured sausages increased during the first days after which numbers of these organisms remained stable. Pediococcus pentosaceus and Staphylococcus xylosus, were the dominant species. Lactobacillus plantarum, Staphylococcus saprophyticus Staphylococcus simulans and Kocuria varians were also present. The results obtained show that the ripening process in a pilot-scale chamber under controlled conditions contributes to a more homogeneous behaviour of the constitutive biota, in comparison with commercial production standards.

Influence of a test preservative on sponge cakes under different storage conditions.

A study was performed on 240 samples, divided into four batches, of sponge cakes baked following their industrial recipe to which different concentrations of a test preservative, mainly lactic acid and propylene glycol, were added. Each batch was submitted to three different temperature and relative humidity conditions. The counts of mesophilic aerobic bacteria, enterobacteria, enterococci, staphylococci, clostridia, lactic acid bacteria, and yeasts were less than 1 log CFU/g in all the batches studied and throughout the 120 days of study. Depending on batches and conditions, the mold counts were between less than 1 and 6.40 log CFU/g. Aspergillus, Eurotium, Penicillium, and Wallemia were detected and were potentially toxigenic in two cases. The test preservative added at 18 g/kg produced the greatest preserving effect, prolonging the product's shelf life by more than 4 months and showing itself to be effective at the other concentrations, especially at 15 degrees C and at 80 and 51% relative humidity.

Occurrence of Campylobacter and Listeria monocytogenes in a poultry processing plant.

The occurrence of Campylobacter and Listeria monocytogenes was studied in 645 samples from surfaces, water, and poultry products (chicken carcasses, chicken parts, viscera, and spoils) in a poultry processing plant in southern Brazil. The automated mini-VIDAS system was used to detect the presence of Campylobacter and L. monocytogenes on the samples. The positive samples were confirmed by conventional methods. Campylobacter and L. monocytogenes were found in 16.6 and 35.6% of the analyzed samples, respectively. The sampling points with the highest Campylobacter incidence were intestine (63.3%, 19 of 30 samples), gallbladder (46.7%, 14 of 30), carcasses before evisceration (33.33%, 10 of 30), and carcasses after plucking (30%, 9 of 30). For L. monocytogenes, the majority of positive samples were from frozen breast (100%, 15 of 15 samples), frozen wing (93.3%, 14 of 15), fresh breast (83.3%, 25 of 30), fresh wing (80%, 24 of 30), skin of breast and leg (76.7%, 23 of 30), frozen leg (60%, 9 of 15), and fresh leg (50%, 15 of 30).

Population dynamics of the constitutive biota of French dry sausages in a pilot-scale ripening chamber.

The population dynamic of constitutive biota on 84 samples belonging to two different types of French fermented dry sausages during the ripening process in a pilot-scale ripening chamber was investigated. Samples were analyzed in three steps of their production: fresh product, first drying stage, and finished product. In addition, 180 strains of lactic acid bacteria were identified using a miniaturized biochemical procedure of characterization. In general, the number of lactic acid bacteria that evolved during the ripening process of French dry sausages increased during the first days of the process after which the number of these organisms remained constant at approximately 8 log CFU/g. Lactobacillus sakei and Pediococcus pentosaceus, bacteria added as starter, were the dominant species. Pediococcus urinaeequi, Pediococcus acidilactici, and particularly Lactobacillus curvatus were also present. Finally, we have to take into account that the controlled conditions of the pilot plant generally contribute to the homogenization of the behavior of the starter biota.

Occurrence and behavior of Enterobacteriaceae and enterococci in mediterranean dry sausages during ripening in a Pilot-Scale chamber.

The occurrence and evolution of Enterobacteriaceae, coliforms, Escherichia coli, and enterococci in 252 samples of six types of Mediterranean dry-ripened sausages during maturation was investigated. The changes of the pH values were also recorded. Samples were analyzed in three steps of the ripening process: fresh product, first drying stage, and finished product. In all six sausages, Enterobacteriaceae, coliforms, and E. coli counts were characterized by high initial concentrations that significantly decreased during ripening. However, the initial counts of enterococci remained stable throughout the experiments in all sausages types. The average pH values of finished sausages ranged from 4.54 to 5.31.

Differentiation of Clostridium perfringens and Clostridium botulinum from non-toxigenic clostridia, isolated from prepared and frozen foods by PCR-DAN based methods.

During the elaboration process of prepared and frozen foods, Clostridium sp. have been reported. From those microorganisms, C. perfringens and C. botulinum may pose a high risk for the consumers. To avoid these pathogenic organisms an HACCP program should be implemented, but in addition sensitive and moderately time consuming microbiological methods for monitoring C. perfringens and C. boulinum should be established. In this work, an RFLP analysis of the 16S rDNA will be developed to differentiate C. perfringens from other Clostridium sp. In addition, a PCR protocol, will be assayed to detect C. botulinum. Both two methods will be compared with biochemical characterization by API system. The restriction analysis of the 16S rDNA with Taq I and Rsa I showed at least the same sensitivity to differentiate C. perfringens from clostridial isolates as biochemical identification. However, the former method takes only 8-10 h of analysis as compared with 24-48 h required for biochemical characterization. With the specific PCR protocol to detect C. botulinum a band of 1.1 kbp was obtained derived from the specific amplification of BoNT genes, taking 6-8 h for analysis. Both two molecular DNA based methods should be considered as verification techniques of pathogenic clostridia in the HACCP program.

Effect of modified atmosphere packaging on the shelf life of sliced wheat flour bread.

The application of modified atmospheres packaging (MAP) of sliced bread with different aw, moisture content and pH values, with or without preservative added (calcium propionate) and at different storage temperatures, has been studied with the aim of establishing the effect of MAP on the shelf-life of the selected product. Four atmospheres were tested per batch: 100% N2, 20% CO2/80% N2, 50% CO2/50% N2 and a standard air control. In samples without added preservative in CO2:N2 (50:50), the increases in shelf life were 117% and 158% at 22-25 degrees C and 15-20 degrees C, respectively. In samples with added preservative in 100% N2, shelf life was increased by 116%. Samples with added preservative in 20% CO2:80% N2 increased shelf life by 150% and 131% at 22-25 degrees C and 15-20 degrees C, respectively. By increasing the CO2 concentration to 50%, the increases in shelf life of the samples with added preservative were 167% and 195% at 22-25 degrees C and 15-20 degrees C, respectively.

Evaluation of petrifilm series 2000 as a possible rapid method to count coliforms in foods.

This research note is a preliminary comparison between the Petrifilm 2000 method and a widely used traditional enumeration method (on violet red bile agar); six batches of different foods (egg, frozen green beans, fresh sausage, a bakery product, raw minced meat, and raw milk) were studied. The reliability of the presumptive counts taken at 10, 12, and 14 h of incubation using this method was also verified by comparing the counts with the total confirmed counts at 24 h. In all the batches studied, results obtained with Petrifilm 2000 presented a close correlation to those obtained using violet red bile agar (r = 0.860) and greater sensitivity (93.33% of the samples displayed higher counts on Petrifilm 2000), showing that this method is a reliable and efficient alternative. The count taken at 10-h incubation is of clear interest as an early indicator of results in microbiological food control, since it accounted for 90% of the final count in all the batches analyzed. Counts taken at 12 and 14 h bore a greater similarity to those taken at 24 h. The Petrifilm 2000 method provides results in less than 12 h of incubation, making it a possible rapid method that adapts perfectly to hazard analysis critical control point system by enabling the microbiological quality control of the processing.

Evaluation of microbial hazards during processing of Spanish prepared Flamenquín.

Flamenquín is a traditional, prepared, frozen meat product from the south of Spain made with minced pork, chicken, and cooked ham. Since it is a prepared raw meat product some microbial hazards could be associated with the process of making it. Microbiological analyses have been performed throughout the various steps of processing over a 1-year period to evaluate microbial hazards in the commercial process. High levels of microorganisms were observed all through the processing of this product, the mincing and mixing steps being where major microbial contamination was observed. Pathogenic bacteria such as Staphylococcus aureus, Clostridium perfringens, Escherichia coli and Pseudomonas aeruginosa were detected during processing. Raw materials and food handlers were the principal sources of microbial contamination. A modification of processing to include a heating step after mincing and mixing and an improvement in hygiene practices could eliminate the microbial hazards. Both modifications should be noted for the implementation of a hazard analysis of critical control points (HACCP) program in commercial flamenquín processing.

Aflatoxin-Producing Strains of Aspergillus flavus Isolated from Cheese.

Contamination by fungi of the genus Aspergillus with special reference to the possible detection of aflatoxin-producing strains of Aspergillus flavus was studied in 52 samples of commercial cheeses made with different types of milk (8 of cow's milk, 12 of ewe's milk, 13 of goat's milk, and 19 of milk mixtures of various species: cow, ewe, and goat) produced in Southern Spain. The frequency of appearance of various species of Aspergillus , A. glaucus , A. niger , A. nidulans , A. sulphureus , A. Terreus , and A. flavus , in the different types of cheese was determined. In 4 (2 of goat's milk cheese and 2 of cheeses made with milk from various species) out of 52 samples (7.69%), aflatoxin-producing strains of A. flavus were detected.

Occurrence of Aflatoxin M1 in Cheeses from the South of Spain.

Thirty-five samples of commercial cheeses, 9 fresh, 9 semicured or semiripened and 17 ripened made with different types of milk (cow, ewe, goat and mixtures of milk of various species) produced in the South of Spain were analyzed for the presence of aflatoxin M1 (AFM1) by high-performance liquid chromatography, In 16 of the 35 samples (45.71%) the presence of AFM1 was detected in concentrations ranging between 20 and 200 ng/g of cheese, In the positive cases, the mean levels of AFM1 were 105.33 ng/g in ripened cheeses, 73.80 ng/g in semiripened cheeses and 42.60 ng/g in fresh cheeses.

Comparison of Petrifilm method to conventional methods for enumerating aerobic bacteria, coliforms, Escherichia coli and yeasts and molds in foods.

The Petrifilm plates method was compared to conventional methods (PCA, VRBA, Levine EMB agar and OGYE agar) for enumeration of mesophilic aerobic bacteria, coliforms, Escherichia coli, and yeasts+molds in six homogeneous lots of different food groups (pasteurized milk, yoghurt ice cream, eggs, minced meat, fresh strawberries and frozen green beans). For all the microbiological criteria except for yeasts and molds and mesophilic aerobic bacteria in frozen green beans, the mean values of counts with Petrifilm plates were higher than those obtained with traditional methods. The correlation coefficient of Petrifilm aerobic bacteria, coliforms, and yeasts + molds v. PCA, VRBA and OGYE agar for each microbiological criterion for a composite of six food products were 0.897, 0.861 and 0.981, respectively.

Population Dynamics of Constitutive Microbiota in BAT Type Fermented Milk Products.

Seventy samples from two batches of commercially produced fermented milk were analyzed for constitutive microbiota. Five samples were tested on the day of collection and the others analyzed after 10, 17, 24, 28, 31 and 36 days of storage at 7°C. M17 agar was used to enumerate Streptococcus salivarius subsp. thermophilus . MRS (de Man, Rogosa, Sharpe) agar was used to enumerate Lactobacillus acidophilus . For the enumeration of Bifidobacterium spp. MRS agar to which antibiotic substances were added was used. In the case of Batch A, streptococci, lactobacilli and bifidobacteria were initially present at levels of 231.2 × 106, 0.677× 106 and 1.558 × 106, respectively. The initial pH of 4.48 decreased to 4.12 after 24 days. For Batch B, streptococci, lactobacilli and bifidobacteria were initially present at levels of 858 × 106, 190.7 × 106 and 1.644 × 106, respectively. The initial pH of 4.23 decreased to 4.07 and 3.84 after 24 and 36 days, respectively. The fall in the counts throughout refrigerated storage time showed some irregularities which, in our opinion, indicate a lack of control over the ecological aspects which affect the interrelation between the microorganisms involved. The statistical significance of the differences between the different trials was established throughout the time.

Survival of Constitutive Microflora in Commercially Fermented Milk Containing Bifidobacteria During Refrigerated Storage.

The survival of constitutive microflora was studied in one batch (n = 50) of fermented milk containing bifidobacteria produced in Spain during storage at 7°C. Levels of Streptococcus salivarius subsp. thermophilus , Lactobacillus delbrueckii subsp. bulgaricus , and Bifidobacterium spp. and the pH of the product were determined on the day of collection and after 10, 17, 24, 28, 31, 36, 42, 51, and 84 d of storage. Initial populations of streptococci, lactobacilli, and bifidobacteria were 2.6 × 108, 5.1 × 107, and 7.4 × 106 CFU/g, respectively. The S. salivarius subsp. thermophilus population increased slightly after 10 d and then decreased during further refrigerated storage. Numbers of Bifidobacterium and L. delbrueckii subsp. bulgaricus decreased faster during storage. After 24 d (the reported shelf life of the product), levels of streptococci decreased only 10.7% as compared to decreases of 85.4 and 92.6% for lactobacilli and bifidobacteria, respectively. The pH values were between 4.57 and 3.81.