The biofilm forming potential of bacterial species in the genus Campylobacter

The biofilm forming abilities of 16 strains representative of 14 of the 16 species comprising the genus Campylobacter were determined on glass, stainless steel, and polystyrene plastic. The formation of biofilms has been suggested as a means by which Campylobacter is able to persist within an inhospitable environment. Of the eight microaerophilic Campylobacter species, including two strains each of Campylobacter jejuni and Campylobacter fetus, only C. jejuni strain 81–176 reliably produced a visible biofilm on multiple surfaces. Alternately, all six strains of the anaerobic Campylobacter species reliably produced visible biofilms on multiple surfaces. Electron micrographs of the individual biofilms showed relatively homogeneous biofilms produced by the anaerobic strains, while the microaerophilic C. jejuni strain 81–176 produced a biofilm containing similar quantities of both the spiral and coccoid forms. This survey suggests a difference in the biofilm forming potentials and the morphologies of the bacteria comprising the biofilms between anaerobic and microaerophilic species of Campylobacter. Additionally, differences observed in the biofilm forming ability of two strains of C. jejuni suggest the need for a further investigation of the biofilm forming potential of this species using a larger number of strains.     

In vitro antimicrobial activity of essential oil from endemic Origanum minutiflorum on ciprofloxacin-resistant Campylobacter spp.

This study evaluated the antimicrobial activities of an essential oil of Origanum minutiflorum (O. Schwarz and P.H. Davis) against ciprofloxacin-resistant Campylobacter spp., by broth microdilution and agar well-diffusion methods. Moreover, O. minutiflorum oil was analyzed by gas chromatography/mass spectrometry (GC/MS). Twenty-nine components were identified, representing 98.7 of the oil. The oil yield from the plants was 4.0–4.4% v/w. The major components of O. minutiflorum oil were carvacrol (73.9%) and p-cymene (7.20%). The oil has lower contents of carvacrol methyl ether (0.05%), heptadecanol (0.06%) and carvacryl acetate (0.06%). Twenty-one Campylobacter spp. (12 C. jejuni, 5 C. lari and 4 C. coli) strains using in this study were selected among 300 isolates according to their resistance to ciprofloxacin. The minimum inhibitory concentration (MIC) values for bacterial strains, which were sensitive to the essential oil of O. minutiflorum, were in the range of 7.8–800 μg/ml. The essential oil obtained showed strong antimicrobial activity against all of the tested ciprofloxacin-resistance Campylobacter spp. These results suggest that the essential of O. minutiflorum may be used as a natural preservative in food against food-born disease, such as Campylobacteriosis.     

PorA specific primers for the identification of Campylobacter species in food and clinical samples

Campylobacteriosis is a public health problem with considerable socio-economic impact. As the European Food Safety Authority has emphasized the importance of a surveillance programme for campylobacteriosis, the aim of the present study was the optimization of a specific and sensitive PCR protocol able to detect Campylobacter species responsible for gastrointestinal infections. Raw poultry meat samples were analysed for the presence of Campylobacter sp., by plating onto mCCD (Modified Charcoal-Cefoperazone-Deoxycholate) Agar and Campylobacter Selective Preston Agar and using four sets of species-specific primers for Campylobacter jejuni, Campylobacter coli, Campylobacter upsaliensis and Campylobacter lari designed to bridge the porA gene. The resulting primers demonstrated a sensitivity of 0.01 ng/μl for the C. coli-specific, C. lari-specific, and C. upsaliensis-specific primer sets and 0.5 ng/μl for the C. jejuni-specific primer sets using DNA from pure cultures. Non-specific amplification of non-target DNA was not observed indicating excellent specificity. The primers were useful for the analyses of poultry meat samples both for direct plating onto mCCDA, and for DNA extracted directly from the cells grown for 48 h in Preston enrichment broth. The sets of primers were also useful when used for species identification of human isolates.     

Molecular characterization and antibiotic resistance profiling of Campylobacter isolated from cattle in Polish slaughterhouses

A total of 812 samples from bovine hides and the corresponding carcasses collected at the slaughterhouse level in the eastern part of Poland were examined for the presence of Campylobacter jejuni and Campylobacter coli. Recovered isolates were confirmed using species-specific PCR, characterized by the presence of 11 putative virulence genes and antimicrobial susceptibility was determined using a microbroth dilution method. Furthermore, the genotypic relatedness of the isolates was determined by PFGE profiling and virulence pattern cluster analysis. The prevalence of Campylobacter was 25.6% and 2.7% in bovine hide and carcass samples, respectively. The presence of virulence markers varied between C. jejuni and C. coli species however, the majority of strains possessed the cadF, flhA, flaA genes, irrespective of the bacterial species and origin. The lower number of the strains was positive for the invasive associated markers – virB11 and wlaN. Antibiotic profiling showed that campylobacters were most frequently resistant to quinolones and fluoroquinolones (nalidixic acid and ciprofloxacin, 38.3% of each, respectively) followed by streptomycin (24.3%) and tetracycline (20.9%). Resistance to erythromycin and gentamicin was demonstrated in 4.3% and 2.6% of strains, respectively. Comparisons of the PFGE and virulence marker profiles of the isolates reflected the high genetic diversity of Campylobacter tested. Moreover, a poor correlation between the PFGE type, pathogenic gene marker and antimicrobial resistance patterns was observed.     

Effect of sample preparation and bacterial concentration on Salmonella enterica detection in poultry meat using culture methods and PCR assaying of preenrichment broths

We evaluated the sensitivity of a PCR assay in the detection of Salmonella enterica at the broth preenrichment step of poultry meat. A total of 162 retail poultry meat samples, which were prepared by manual massaging, stomacher or no homogenization were compared for Salmonella recovery. Using these homogenization methods, the PCR assay at the broth preenrichment step detected Salmonella in, respectively, 48.9%, 62.2% and 50.0% of meat and giblet samples detected as Salmonella-positive using the culture method. In ground chicken, however, Salmonella was detected in 21.7% of samples treated by stomacher homogenization, compared to 40.7% and 48% of untreated and hand-massaged samples, respectively. These results suggest that stomaching of ground chicken causes excessive effusion of food constituents, which affects PCR results. Using the most probable number (MPN) technique, Salmonella was detected at under 1.0 CFU/g in 12 ground chicken samples and under 10³ CFU/ml of broth in seven of the 12 broth-enriched samples, which considered the minimum concentration detectable by PCR assay. These results show that Salmonella detection using routine PCR assays is difficult in poultry meat, and in particular ground chicken, due to low amounts of Salmonella and the presence of inhibitors.     

Influence of flavonoids from Phellinus igniarius on sturgeon caviar: Antioxidant effects and sensory characteristics

The antioxidant differences between two flavonoid extracts from fruiting body and fermentation broth of Phellinus igniarius were determined, and the effects of flavonoid addition on the sensory characteristics of sturgeon caviar were investigated. Both extracts exhibited moderate antioxidant activity with EC₅₀ values of 4.98 and 2.39 mg/mL, the extract of fermentation broth exhibiting higher antioxidant efficiency. Flavonoids were added at 0.01% and 0.02% to sturgeon caviars, which were then stored at 4 or 20 °C for 12 days. Peroxide values (meq/kg) were determined after regular intervals. The 0.02% level of flavonoids from fermentation broth of P. igniarius had stronger antioxidant effect than vitamin C, very close to that of butylated hydroxyanisole (BHA). Flavonoid addition improved the sensory profile of caviar, and the flavonoid extract from the fermentation broth had a more desirable effect on flavour and aroma than that from fruiting bodies.     

Prevalence of and risk factors for Campylobacter spp. contamination of broiler chicken carcasses at the slaughterhouse

A study was conducted in 2008 to estimate the prevalence and identify the risk factors for Campylobacter spp. contamination of broiler carcasses during the slaughtering process. A pool of 10 caeca and one carcass were collected from 425 batches of broiler chickens slaughtered in 58 French slaughterhouses over a 12-month period. Potential risk factors were identified according to the Campylobacter contamination status of carcasses and processing variables identified from questionnaires. The statistical analysis took into account confounding factors that have already been associated with the presence of Campylobacter on carcasses such as the slaughter age of the chicken or seasonal variations. Campylobacter spp. were isolated from 77.2% of caeca (95% CI 73.2 to 81.2) and from 87.5% of carcasses (95% CI 84.4 to 90.7). A multiple logistic regression showed 4 parameters as significant risk factors (p < 0.05) for contamination: (I) batches were not the first to be slaughtered in the logistic schedule (OR = 3.5), (II) temperature in the evisceration room was higher than 15 °C (OR = 3.1), (III) dirty marks on carcasses after evisceration were visible (OR = 2.6) and (IV) previous thinning of the flocks, from which slaughtered batches came, had occurred at the farm (OR = 3.3). This last result highlighted the need for sanitary precautions to be taken when catching birds for transport. At the slaughterhouse, evisceration seemed to be the operation contributing most to the spread of contamination. Effective risk management solutions could include the systematic external rinsing of carcasses after evisceration and the implementation of slaughtering schedules according to the Campylobacter contamination status of flocks.     

Model of inactivation of Campylobacter jejuni in poultry scalding

The purpose of this study was to develop a model of inactivation of Campylobacter jejuni in industrial scalding of chickens. Models can be used as a guide for broiler slaughterhouse operations for reducing levels of C. jejuni contamination on broiler carcasses. Mean concentrations of C. jejuni in terms of colony forming units (CFU) in scald tank water and in carcass rinse solution after scalding were 2.90 ± 0.07 and 3.86 ± 0.11 LogCFU/mL, respectively. Scald tank water temperature, flow rate, pH, and total solids in scalding process water were 54.15 ± 0.2 °C, 172.0 ± 8.4 L/min, 8.0 ± 0.01, and 2565 ± 114.3 mg/L, respectively. Inactivation models were developed by using mass balances and literature data for inactivation kinetics, of Campylobacter and the Arrhenius equation. Results of the inactivation models of scalding process indicate that high temperature and short time (less than 2 min) of scalding process were effective in reducing the number of viable cells. For this experimental data more than 50% of the Campylobacter are inactivated on surfaces of the chickens. The model fits the experimental data well and the values of the estimated parameters provide insight for this process. The model can be used for process design and potential process modifications.     

Effect of trisodium phosphate solutions washing on the sensory evaluation of poultry meat

The effect of trisodium phosphate (TSP) solutions treatments on the sensory evaluation of poultry meat has been explored since TSP was recently approved by USDA for its usage in poultry processing to eliminate Salmonella contamination. In the present study, fresh chicken thighs were dipped in water (control sample) and in 8, 10 and 12% TSP solutions (treated samples) for 15 min. Raw samples' color, smell and overall acceptability and cooked thighs' color, smell, flavor, texture and overall acceptability were evaluated by consumer panelists. The evaluation of raw pieces after treatment or after 7 days storage at 2°C revealed that, with the exception of 12% TSP solutions treatment, sensory quality was not adversely affected by TSP. The color, smell and overall acceptability hedonic scores for the boiled thigh meat were not different between the treated samples and the control ones. Only the color, flavor and overall acceptability of thighs dipped in 12% TSP were rated significantly lower than the control sample. These results suggested that TSP solutions have good potential as dips to sanitize chickens carcasses     

Decontamination treatments can increase the prevalence of resistance to antibiotics of Escherichia coli naturally present on poultry

The main objective of this study was to determine the ability of various decontaminants to increase the prevalence of resistance to antibiotics in Escherichia coli populations on poultry. Chicken legs were dipped for 15 min into aqueous solutions (wt/vol) of trisodium phosphate (TSP; 12%), acidified sodium chlorite (ASC; 1200 ppm), ascorbic acid (AA; 2%) or citric acid (CA; 2%), or tap water (control). Samples were analyzed immediately after treatment (day 0) and after five days of storage at 7 ± 1 °C. A total of 250 E. coli isolates (50 from each group of samples; 25 on day 0 and 25 on day 5) were tested against twelve antibiotics of clinical significance by means of a standard disc-diffusion technique. A high prevalence of resistance to antibiotics was observed for E. coli strains from control samples, with three (6.0%) isolates sensitive, three (6.0%) resistant to one antibiotic and 44 (88.0%) isolates resistant to two or more antibiotics. Isolates from control samples had a lower prevalence of resistance than those from treated samples to ampicillin-sulbactam (P < 0.01, samples treated with TSP), amoxicillin-clavulanic acid (P < 0.001, ASC, AA and CA), cephotaxime (P < 0.05, TSP), trimethoprim-sulphamethoxazole (P < 0.05, AA; P < 0.01, CA), tetracycline (P < 0.01, CA), ciprofloxacin (P < 0.001, ASC; P < 0.05, AA; P < 0.01, CA) and nitrofurantoin (P < 0.01, TSP). These results suggest that the chemical decontaminants tested could favor the emergence, selection and/or proliferation of antibiotic-resistant strains in microbial populations on poultry meat.     

Effect of pork lard content on the chemical, microbiological and sensory properties of a typical fermented meat product (Pitina) obtained from Alpagota sheep

The aim was to investigate the physicochemical, microbiological and sensory properties of Pitina, a typical fermented meat product and evaluate the effect of two levels of pork lard content (Low Fat, LF, 10% vs. High Fat, HF, 30%) on its attributes. HF attained lower pH than LF Pitina, which reached lower water activity. LAB comprised the major flora with substantial counts of micrococci, enterococci and mould and yeast. Gram negative Enterobacteria were recovered as coliforms and faecal coliforms. Listeria monocytogenes was also isolated. The lard level influenced the count of micrococci and some sensory attributes. LF attained higher scores for both hardness and cohesiveness and differed from HF in having a more marked odour of ewe and smoke and sweeter taste. HF had a more pronounced odour and taste of garlic and mould than LF.     

A comparison of the physicochemical and sensory characteristics of alheira samples from different-sized producers

Alheira is a traditional Portuguese meat product made from boiled meat, usually pork and/or poultry, and bread. The physicochemical and sensory properties of alheira were analyzed to determine the relationships between them and to evaluate how they are affected by the product’s origin i.e. if is produced on a small or industrial scale. The most important variables used to characterize alheira are: color, visual evaluation of the amount of meat and bread, paprika aroma, clamminess and fibrousness, water activity, moisture, fat, carbohydrate content, hardness and color parameters (L^∗, a^∗,  and b^∗). Principal component analysis demonstrated that drying has a major effect on these characteristics, as it plays a part in the product’s physical make-up. Using these parameters it was possible to ascertain that industrial products enjoyed higher levels of consumer acceptability, given that they contain a higher proportion of meat and undergo a shorter drying process.     

Effects of post-processing treatments on sensory quality and Shiga toxigenic Escherichia coli reductions in dry-fermented sausages

The effects of post-processing treatments on sensory quality and reduction of Shiga toxigenic Escherichia coli (STEC) in three formulations of two types of dry-fermented sausage (DFS; salami and morr) were evaluated. Tested interventions provided only marginal changes in sensory preference and characteristics. Total STEC reductions in heat treated DFS (32 °C, 6 days or 43 °C, 24 h) were from 3.5 to > 5.5 log from production start. Storing of sausages (20 °C, 1 month) gave > 1 log additional STEC reduction. Freezing and thawing of sausages in combination with storage (4 °C, 1 month) gave an additional 0.7 to 3.0 log reduction in STEC. Overall > 5.5 log STEC reductions were obtained after storage and freezing/thawing of DFS with increased levels of glucose and salt. This study suggests that combined formulation optimisation and post-process strategies should be applicable for implementation in DFS production to obtain DFS with enhanced microbial safety and high sensory acceptance and quality.     

Evaluation of sequential inoculation of Saccharomyces cerevisiae and Oenococcus oeni strains on the chemical and aromatic profiles of cherry wines

The current study was carried out to elucidate the effect of sequential inoculation of Saccharomyces cerevisiae (RC212, D254) and Oenococcus oeni (SG26, Lalvin 31 and Uvaferm Alpha) on the production of cherry wines, especially on the chemical and aromatic characteristics. SI-D culture required the shortest period (23 d) to complete the fermentation, while other inoculations needed longer time. Analysis from chemical composition showed that titratable acidity and content of l-malic acid exhibited evident differences among the samples after MLF. For volatile compounds, 49 major components were identified, mostly comprising of alcohols, acids and esters. Cherry wines obtained from SI-B and SI-C showed higher contents of total volatile alcohols, and SI-D wines produced the greatest amount of volatile acids. According to the odour active value (OAV), 9 out of 49 studied volatile components had OAV >1 in all the analyzed wines, while six volatile components showed OAV >1 only for some of them. Furthermore, a sensory analysis was performed to compare the sensory profile of these cherry wines, and results evidenced that wines resulting from different inoculations presented diverse sensory profiles. These findings suggest that sequential inoculations posed a great potential in affecting and modulating the aromatic profile of cherry wines.     

Identical plasmid AmpC beta-lactamase genes and plasmid types in E. coli isolates from patients and poultry meat in the Netherlands

The increasing prevalence of third-generation cephalosporin-resistant Enterobacteriaceae is a worldwide problem. Recent studies showed that poultry meat and humans share identical Extended-Spectrum Beta-Lactamase genes, plasmid types, and Escherichia coli strain types, suggesting that transmission from poultry meat to humans may occur. The aim of this study was to compare plasmid-encoded Ambler class C beta-lactamase (pAmpC) genes, their plasmids, and bacterial strain types between E. coli isolates from retail chicken meat and clinical isolates in the Netherlands.     

Protective action of Lactobacillus curvatus CRL705 on vacuum-packaged raw beef. Effect on sensory and structural characteristics

Lactobacillus curvatus CRL705 was examined for its effectiveness as protective culture in the biopreservation of vacuum-packaged fresh beef stored during 60 days at 2 °C. For this purpose, L. curvatus CRL705, producer of lactocin 705 and lactocin AL705, was inoculated on the meat surface (10⁶ cfu g⁻¹). This microorganism became the dominating population throughout the storage period controlling the growth of Brochothrix thermosphacta and spoilage lactic acid bacteria naturally present on the meat. When the microstructural characteristics of the meat were evaluated using light microscopy, beef samples inoculated with the bioprotective culture showed a 10 days delay for the appearance of tissue degradation signs. Sensory analysis demonstrated that beef samples treated with L. curvatus CRL705 only developed an “acid” off-flavor after 60 days of refrigerated storage, and no undesirable off-odors were found. Therefore, inoculation with this bacteriocinogenic strain would provide an additional hurdle to improve storage life of refrigerated vacuum-packaged beef without affecting its sensory and structural characteristics.     

Relation among taste-related compounds (phenolics and caffeine) and sensory profile of erva-mate (Ilex paraguariensis)

Erva-mate (Ilex paraguariensis St. Hil.) is a native species from temperate regions of South America, such as Brazil, Paraguay, and Argentina, that is consumed as a beverage known as mate. The objective of this research was to determine the content of caffeic acid, catechin, chlorogenic acid, caffeine, and gallic acid in mate to explain their influence in beverage taste and sensory differences between native and reforested plants, as well as between beverages from plants of different regions of Brazil (Santa Catarina and Rio Grande do Sul states). Compounds were determined by HPLC and results were related to a sensory evaluation performed by trained tasters. Tasters considered the beverage from reforested plants to be more bitter than the beverage from native plants. Beverages from reforested plants had significantly higher caffeic acid and lower catechin, chlorogenic acid, caffeine, and gallic acid content than native plants. Beverages from plants of Santa Catarina state had significantly higher catechin, caffeine, and gallic acid content than plants from Rio Grande do Sul state.     

Textural and sensory quality of poultry meat batter containing malva nut gum, salt and phosphate

The effect of crude malva nut gum (CMG) addition to poultry breast meat batters formulated with different salt levels (0-3 g/100 g NaCl) and phosphate (0 and 0.5 g/100 g) was studied. Increasing the salt level resulted in an overall increase of cook yield, and the addition of CMG (0.2 g/100 g) further improved yield at all salt levels. The cooked batter with 2 g/100 g NaCl and phosphate showed the highest values for all of textural parameters. However, the cohesiveness and chewiness were reduced by the addition of 0.2 g/100 g CMG. In addition, the effect of incorporating CMG (0.0, 0.2 and 0.6 g/100 g) into commercial type frankfurters, made from mechanically deboned chicken meat (MDCM), was evaluated. Frankfurters with 0.2 g/100 g CMG showed low cooking loss and had better textural properties than the frankfurters without CMG. Frankfurters lightness and redness were reduced due to CMG. Sensory analysis results indicated that the frankfurters with 0.2 g/100 g CMG were more firm and elastic. Overall, the study indicates the potential use of CMG to improve yield and textural parameters of meat products.     

Phage inactivation of foodborne pathogens on cooked and raw meat

Phages infecting Salmonella Typhimurium PT160 and Campylobacter jejuni were added at a low or high (10 or 10(4)) multiplicity of infection (MOI) to either low or high (<100 or 10(4)cm(-2)) densities of host bacteria inoculated onto raw and cooked beef, and incubated at 5 and 24 degrees C to simulate refrigerated and room temperature storage. Counts of host bacteria were made throughout the incubation period, with phages being counted at the first and last sampling times. Host inactivation was variable and depended on the incubation conditions and food type. Significant host inactivations of the order of 2-3 log(10)cm(-2) at 5 degrees C and >5.9 log(10)cm(-2) at 24 degrees C were achieved compared to phage-free controls using the Salmonella phage under optimal conditions (high host cell density and MOI). These results alongside those already published indicate that phages may be useful in the control for foodborne pathogens.     

Phytochemical,sensory attributes and aroma stability of dense phase carbon dioxide processed Hibiscus sabdariffa beverage during storage

The effect of dense phase carbon dioxide (DPCD) processing (34.5 MPa, 8% CO₂, 6.5 min, and 40 °C) on phytochemical, sensory and aroma compounds of hibiscus beverage was compared to a conventional thermal process (HTST) (75 °C for 15 s) and a control (untreated beverage) during refrigerated storage (4 °C). The overall likeability of the hibiscus beverage for all treatments was not affected by storage up to week 5. DPCD process retained more aroma volatiles as compared to HTST. Aroma profiles in the beverages were mainly composed of alcohols and aldehydes with 1-octen-3-ol, decanal, octanal, 1-hexanol, and nonanal as the compounds with the highest relative percentage peak areas. A loss of only 9% anthocyanins was observed for the DPCD processed hibiscus beverage. Phytochemical profiles in the hibiscus beverage included caffeoylquinic acids, anthocyanins, and flavonols. No major changes in total phenolics and antioxidant capacity occurred during the 14 weeks of storage.