Influence of the packaging systems on the phenolic profile and antioxidant properties of wine pomace used as seasoning in chicken meat.

White wine pomace products (wWPP) represent an innovative strategy as a functional food ingredient to be used as a seasoning both for their technological and functional properties. Nevertheless, the bioactive compounds of wWPP used as a seasoning could be modified during storage. The seasoning in the meat, regardless of the storage method used, modified its phenolic profile and in its bioaccessible fractions, while maintaining a high total antioxidant capacity and total polyphenol content. The contact of the seasoning with the meat can be considered safe as it does not show cytotoxicity in the Caco-2 cells. Additionally, the ability to modulate the cell oxidative stress of the bioaccessible fractions and the potential benefits on microbiota by the colonic fermentation fraction, suggest its potential use as a functional ingredient, without being affected by storage. These results are novel and may help to establish the value of this product as a functional ingredient.

Bread melanoidins as potential new sustainable bakery ingredients: a study using fat and fat-free bakery food models.

Melanoidins isolated from bakery by-products are proposed as new sustainable ingredients for bakery products. The colour, odour profile, texture, water activity, and antioxidant capacity of two bakery food models, fat and fat-free, enriched with 2% and 4% soft bread and common bread melanoidins, were analysed. The colour of the bakery food models with melanoidins was darker than that of the respective control; the fat-free models with melanoidins showed higher values of hardness than the control, while no significant effect was observed in the fat models; the water activity did not change compared to the control; the odour profile was significantly modified with different effects depending on the type of melanoidin quantity added and the food model (fat or fat-free); and the antioxidant capacity increased proportionally to the quantity of melanoidin added. In general, melanoidins from soft bread exhibited a higher effect than the melanoidins from common bread. The melanoidins isolated from both fat and fat-free bakery food models did not show cytotoxicity nor did they modify the levels of reactive oxygen species in Caco-2 cells. Therefore, the results seem to indicate the favourable potential of bread melanoidins as new sustainable ingredients for bakery products.

Antimicrobial Effect of Simira ecuadorensis Extracts and Their Impact on Improving Shelf Life in Chicken and Fish Products.

The objective of this work was to evaluate the antimicrobial potential of different extracts of Simira ecuadorensis, a characteristic plant of Ecuador, and to validate its potential as a food preservative. Four extracts referred to as ethanol, ethanol-water (50:50 v/v), spray-dried, and freeze-dried were obtained under different processes. Initially, their antimicrobial activities were evaluated against a wide group of microorganisms consisting of 20 pathogenic and spoilage microbial strains found in foods through the agar diffusion method. Then, the extracts with the best yields and antimicrobial properties against microorganisms of greatest interest were selected to determine their effect on model foods preserved under normal commercial conditions through challenge tests. Spray-dried and ethanol-water extracts were tested for their ability to inhibit C. jejuni in chicken model products, where is a common pathogen and Shew. putrefaciens in fish model products as it is a spoilage microorganism frequently found in fish. One solid and one liquid were chosen as model foods: burger and broth, respectively. Campylobacter jejuni and Shewanella putrefaciens were effectively inhibited by the four extracts with minimum inhibitory concentration (MIC) of 80 mg/mL. Bacillus cereus, Yersinia enterocolitica, Clostridium perfringens, and Leuconostoc mesenteroides were also inhibited by ethanolic extract. The ethanol-water extract showed greater antimicrobial activity in fish products, whereas spray-dried extract had low growth inhibition of C. jejuni in chicken burgers; however, it was quite effective on C. jejuni in broth. The spray-dried extract significantly decreased the pH of the chicken burgers, while the ethanolic extract had a slight impact on the pH of the fish burgers. The presence of antibacterial effects revealed that the S. ecuadorensis extracts could be potentially used in food preservation and as a natural antimicrobial.

Adjustable Gel Texture of Recovered Crude Agar Induced by Pressurized Hot Water Treatment of Gelidium sesquipedale Industry Waste Stream: An RSM Analysis.

A significant amount of bioactive compound-rich solid waste is released during the industrial phycocolloid-centric extraction of Gelidium sesquipedale. The impact of mild pressurized hot water extraction on repurposing this waste for the recovery of agar with an adjustable gel texture is investigated. A two-factor interaction response surface model assessed the influences of the operating temperatures (80 to 130 °C), times (45 and 150 min), pressures (1 to 70 bar), and algae concentrations (3 to 10% (w:v)). At a temperature of 100 °C, a pressure of 10.13 bar, a recovery time of 45 min, and a 10% algae concentration, the working parameters were considered ideal (w:v). Agar with a hardness of 431.6 g, an adhesiveness of -13.14 g.s-1, a springiness of 0.94, a cohesiveness of 0.63, and a gumminess of 274.46 g was produced under these conditions. A combined desirability of 0.78 was obtained for the exposed technology that retrieved gels with a minimum agar yield of 10% and thermal hysteresis between 39 ± 1 and 52 ± 0.5 °C. The fitted design can provide a high techno-commercial value to the agri-food industrial waste stream.

Assessing the pressure resistance of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica to high pressure processing (HPP) in citric acid model solutions for process validation.

Despite the commercial success of high pressure processing (HPP) in the juice industry, some regulatory agencies still require process validation. However, there is a lack of consensus on various aspects regarding validation protocols, including the selection of representative strains to be used in challenge tests. This study characterized the variable response of Escherichia coli O157:H7 (34 strains), Listeria monocytogenes (44 strains) and Salmonella enterica (45 strains) to HPP, and identified potential candidates to use in process validation. Stationary phase cells were submitted to 500 MPa for 1 min at 10 °C in model solutions consisting of tryptic soy broth + 0.6% yeast extract (TSBYE) adjusted to pH 4.5 and 6.0 with citric acid. At pH 6.0, pressure resistance widely varied between species and within strains of the same species. E. coli O157:H7 and L. monocytogenes were the most pressure resistant and showed high variability at strain level, as the total count range given by minimum and maximum counts spread between 2.0 and 6.5 log10 CFU/ml. S. enterica was the least resistant pathogen with more than 82% of the isolates displaying non-detectable counts after HPP. Recovery through storage at 12 °C was also variable for all pathogens, but eventually most strains recovered with median counts on day 14 between 8.3 and 8.9 log10 CFU/ml. For pH 4.5 solutions, 26 E. coli O157:H7 strains displayed survivors after HPP but did not adapt, registering non-detectable counts in the next sampling dates. None of the L. monocytogenes and S. enterica strains survived HPP or incubation at pH 4.5 (<2.0 log10 CFU/ml), suggesting that citric acid at 4.16 g/l is a safe barrier for pathogen control under moderate HPP conditions. Principal component and cluster analyses served to propose strain cocktails for each species based on their pressure resistant and adaptation phenotypes. Additionally, S. enterica was identified as less pressure resistant and less prone to recover following HPP than E. coli O157:H7 and L. monocytogenes, so its relevance in process validation for juices should be questioned. Future work will validate the proposed strain cocktails on real food systems.

Evaluation of factors influencing the growth of non-toxigenic Clostridium botulinum type E and Clostridium sp. in high-pressure processed and conditioned tender coconut water from Thailand.

Bacterial spores survive high pressure processing (HPP). Group II Clostridium botulinum is an obligate anaerobe spore-forming pathogen that can produce the botulinum neurotoxin under refrigeration. This study assessed nontoxigenic type E C. botulinum and Group II Clostridium sp. growth in raw and HPP (550 MPa, 3 min, 10 °C) Thai coconut water (CCW; pH 5.2). No spore germination or growth occurred in HPP CCW inoculated with 105 CFU/ml after 61 days regardless of oxygen concentration (<0.5 - 11 mg/l) or storage temperature (4 and 20 °C). Spore concentration decreased by 3.0 ± 0.1 log CFU/ml in a worst-case scenario consisting of non-HPP filter-sterilized CCW (pH 7.0) under anoxic incubation at 30 °C during 61 days, suggesting spore germination followed by cellular death. Supplementing filter-sterilized CCW (pH 7.0) with selected germinants and free amino acids did not support spore development, but the addition of nutrient-rich laboratory media (TPGY broth) at low concentrations (6.25%) promoted growth, suggesting that a lack of nutrients prevents C. botulinum development in CCW. Further risk assessment will require evaluating other CCW varieties and toxin production.

The Response to Oxidative Stress in Listeria monocytogenes Is Temperature Dependent.

The stress response of 11 strains of Listeria monocytogenes to oxidative stress was studied. The strains included ST1, ST5, ST7, ST6, ST9, ST87, ST199 and ST321 and were isolated from diverse food processing environments (a meat factory, a dairy plant and a seafood company) and sample types (floor, wall, drain, boxes, food products and water machine). Isolates were exposed to two oxidizing agents: 13.8 mM cumene hydroperoxide (CHP) and 100 mM hydrogen peroxide (H2O2) at 10 °C and 37 °C. Temperature affected the oxidative stress response as cells treated at 10 °C survived better than those treated at 37 °C. H2O2 at 37 °C was the condition tested resulting in poorest L. monocytogenes survival. Strains belonging to STs of Lineage I (ST5, ST6, ST87, ST1) were more resistant to oxidative stress than those of Lineage II (ST7, ST9, ST199 and ST321), with the exception of ST7 that showed tolerance to H2O2 at 10 °C. Isolates of each ST5 and ST9 from different food industry origins showed differences in oxidative stress response. The gene expression of two relevant virulence (hly) and stress (clpC) genes was studied in representative isolates in the stressful conditions. hly and clpC were upregulated during oxidative stress at low temperature. Our results indicate that conditions prevalent in food industries may allow L. monocytogenes to develop survival strategies: these include activating molecular mechanisms based on cross protection that can promote virulence, possibly increasing the risk of virulent strains persisting in food processing plants.

Genotyping, virulence genes and antimicrobial resistance of Campylobacter spp.isolated during two seasonal periods in Spanish poultry farms.

Campylobacter spp. are the leading causes of bacterial human gastroenteritis worldwide; being poultry farms the main source of infections. In order to obtain information on prevalence and diversity of Campylobacter-infected flocks in the North of Spain, fourteen farms were studied between autumn and spring in 2014 and 2015, respectively. Moreover, virulence genes involved in pathogenicity and antimicrobial resistance were investigated. A survey about preventive hygiene practices at farms was performed to determine the risky practices that could contribute to the presence of Campylobacter in this step of the poultry food chain. Testing the presence of Campylobacter spp. showed 43 % of the farms were positive during autumn, whereas only 31 % were positive in spring. A very high prevalence within-flock was observed (43.1 % to 88.6 %) and C. jejuni was the most prevalent species in both periods. Genotyping by pulsed field gel electrophoresis (PFGE) showed a high heterogeneity among farms (309 isolates clustered into 21 pulsotypes). Virulence genes were present in all C. jejuni isolates while cdtA and cdtC were absent in C. coli. On the contrary, the latter showed higher antimicrobial resistance than C. jejuni. This study suggests that environment might be one of the main sources for Campylobacter transmission, as water supply seemed to be a clear cause of the contamination in a specific farm. However, in other farms other environmental factors contributed to the contamination, confirming the multifactorial origin of Campylobacter colonization in broilers. Therefore, biosecurity measures in farms are crucial to reduce Campylobacter contamination, which may have important implications for human and animal health.

Characterization of Virulence and Persistence Abilities of Listeria monocytogenes Strains Isolated from Food Processing Premises.

We report the characterization of 15 Listeria monocytogenes strains isolated from various food processing plants by multivirulence locus sequence typing to determine virulence types (VTs) and epidemic clones. Molecular mechanisms involved in adaptation to food processing environments and related to virulence were also studied. Phenotypic behaviors associated with various antimicrobials, biofilm formations, and invasiveness were assessed. There were 11 VTs among the 15 L. monocytogenes strains. Strains belonging to six VTs were stress survival islet 1 (SSI-1) and one strain of VT94 was SSI-2. Tn6188 was found in VT6 and VT94 strains, and bcrABC cassette genes were identified in VT21, VT60, and VT63 strains. Only one strain, in VT20, showed llxS, whereas a full-size inlA was detected in strains belonging to VT8, VT20, VT21, and VT63. VT10, VT20, VT21, VT60, and VT63 strains were the most tolerant to studied disinfectants. A VT6 strain showed the strongest biofilm formation ability in polyvinyl chloride, and strains belonging to VT10, VT11, VT20, and VT94 had moderate abilities. Antimicrobial sensitivity tests showed that all the L. monocytogenes strains were multidrug resistant. F tests revealed that only strains of VT10, VT60, and VT94 were significantly noninvasive (P < 0.05) in Caco-2 cells. Our findings illustrate how L. monocytogenes isolates exploit diverse mechanisms to adapt to adverse conditions. Consequently, detailed characterization of L. monocytogenes isolates is required for comprehensive elimination of this pathogenic bacterium in food processing environments.

Biofilm formation, virulence and antimicrobial resistance of different Campylobacter jejuni isolates from a poultry slaughterhouse.

The fastidious requirement of the zoonotic pathogen Campylobacter jejuni contrasts with its ability to overcome harsh conditions. Different strategies might be involved in the survival and persistence of C. jejuni through the poultry food chain. Therefore, the aims of this study were to get insights in the survival strategies in the poultry slaughterhouse environment by (i) characterizing factors such as biofilm formation, virulence and antimicrobial resistance in environmental isolates and (ii) understanding the possible link between the phenotypic and genetic characterization using whole genome sequencing (WGS). Results have shown that three STs: ST 443 (PFGE A), ST 904 (PFGE C) and ST 3769 (PFGE G), out of the six studied, formed biofilms with variable intensity according to different conditions (temperatures -37 °C, 30 °C, 25°C- and materials -stainless steel and plastic-). High levels of antimicrobial resistance were found in isolates to ciprofloxacin, nalidixic acid and tetracycline as well as to two common detergents used in the slaughterhouse. A combination of several changes in the genome of ST 904 (PFGE C) including mutations, insertions in antimicrobial resistance genes, the presence of T6SS and a set of genes related to virulence factors might explain its ability to form biofilm and persist longer in the environment. However, the complexity of the survival strategies adopted by the different strains of C. jejuni suggests that multiple mechanisms may exist that allow these organisms to persist and ultimately cause disease in humans.

Characterization of Campylobacter species in Spanish retail from different fresh chicken products and their antimicrobial resistance.

Contaminated chicken products have been recognized as the primary vehicles of Campylobacter transmission to human. Pulsed-field gel electrophoresis (PFGE) and antimicrobial resistance of Campylobacter isolates from fresh chicken products at retail were studied. A total of 512 samples including: thigh, breast, marinated and minced chicken were purchased from different retail stores. Half of the samples were packed and the other half were unpacked. The 39.4% of the samples were Campylobacter positive; being unpacked chicken products (45.3%) more contaminated than packed chicken (33.6%). PFGE typing showed a high diversity among isolates; clustering 204 isolates into 76 PFGE types: 55 clusters of C. jejuni, 19 of C. coli and 2 of C. lari. C. coli genotypes showed higher resistance than other Campylobacter species. Although modified atmosphere packaging can reduce the prevalence of Campylobacter spp., it does not avoid their presence in at least 33.6% of packed chicken products analyzed. Some pulsotypes might persist in the processing plant or butcher shops environment for longer than previously thought. More stringent control measures are needed in previous steps of the chicken food chain, in order to avoid the presence of Campylobacter spp. strains at retail that can compromise consumer's safety.

Campylobacter jejuni survival in a poultry processing plant environment.

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Consumption of poultry, especially chicken's meat is considered the most common route for human infection. The aim of this study was to determine if Campylobacter spp. might persist in the poultry plant environment before and after cleaning and disinfection procedures and the distribution and their genetic relatedness. During one month from a poultry plant were analyzed a total of 494 samples -defeathering machine, evisceration machine, floor, sink, conveyor belt, shackles and broiler meat- in order to isolate C. jejuni and C. coli. Results showed that C. jejuni and C. coli prevalence was 94.5% and 5.5% respectively. Different typing techniques as PFGE, MLST established seven C. jejuni genotypes. Whole genome MLST strongly suggest that highly clonal populations of C. jejuni can survive in adverse environmental conditions, even after cleaning and disinfection, and persist for longer periods than previous thought (at least 21 days) in the poultry plant environment. Even so, it might act as a source of contamination independently of the contamination level of the flock entering the slaughter line.

Improvement of the microbiological quality of ready-to-eat peeled shrimps (Penaeus vannamei) by the use of chitosan coatings.

Chitosan coatings incorporated with 0.5% of oregano and thyme EO were applied onto ready-to-eat peeled shrimp tails and packed under MAP conditions. The growth of naturally present spoilage microorganisms was evaluated for 12days during chilled storage (4°C). Coatings containing thyme EO were more effective in inhibiting the microbial species studied, specially lactic acid and psychrotrophic bacteria. As carrier of EOs, chitosan was more effective in inhibiting the growth of bacteria present in peeled shrimps than the direct application of an oil-water (O/W) emulsion. Finally, results from sensory analysis showed that the sensorial quality was affected by the chitosan-thyme coatings despite characteristics like firmness and colour were kept. The present work demonstrates the effectiveness of chitosan enriched coatings, offering a promising alternative to control the growth of spoilage and pathogen microorganisms on peeled shrimps during refrigeration storage.

Rye and Wheat Bran Extracts Isolated with Pressurized Solvents Increase Oxidative Stability and Antioxidant Potential of Beef Meat Hamburgers.

Rye and wheat bran extracts containing phenolic compounds and demonstrating high DPPH• (2,2-diphenyl-1-picrylhydrazyl), ABTS(•+) (2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) scavenging and oxygen radical absorbance capacities (ORAC) were tested in beef hamburgers as possible functional ingredients. Bran extracts significantly increased the indicators of antioxidant potential of meat products and their global antioxidant response (GAR) during physiological in vitro digestion. The extracts also inhibited the formation of oxidation products, hexanal and malondialdehyde, of hamburgers during their storage; however, they did not have significant effect on the growth of microorganisms. Hamburgers with 0.8% wheat bran extract demonstrated the highest antioxidant potential. Some effects of bran extracts on other quality characteristics such as pH, color, formation of metmyoglobin were also observed, however, these effects did not have negative influence on the overall sensory evaluation score of hamburgers. Consequently, the use of bran extracts in meat products may be considered as promising means of increasing oxidative product stability and enriching with functional ingredients which might possess health benefits.

Effect of edible chitosan/clove oil films and high-pressure processing on the microbiological shelf life of trout fillets.

BACKGROUND: The inhibitory effect of chitosan films with clove oil (0-50 g kg(-1) ) was evaluated on a range of ten representative food spoilage and pathogenic bacteria. RESULTS: The most sensitive bacteria to the films was Shewanella putrefaciens and the most resistant was Aeromonas hydrophila (inhibition was apparent only at 50 g kg(-1) clove essential oil (CEO)). Films with 20 g kg(-1) CEO inhibited nine of ten of the bacteria tested. Chitosan films with 20 g kg(-1) CEO were combined with high-pressure (HPP) processing as treatments for trout fillets, and changes in physicochemical parameters and microbial load were evaluated at 4 °C over 22 days of storage. The films reduced weight loss and water activity compared to fresh and treated samples (HPP and cooking). Results showed that microbial load (total aerobic mesophilic, lactic acid bacteria and total coliform) of the trout fillets covered with chitosan films was lower than that for HPP-treated samples, and similar to cooked samples, except for coliform counts. CONCLUSION: The use of 20 g kg(-1) CEO-chitosan films showed a further improvement in the shelf-life of trout fillets when compared to that obtained with HPP and cooking treatment.

Characterization by culture-dependent and culture-independent methods of the bacterial population of suckling-lamb packaged in different atmospheres.

This study offers insight into the dynamics of bacterial populations in fresh cuts of suckling lamb under four different atmospheric conditions: air (A), and three Modified Atmosphere Packaging (MAP) environments, 15%O2/30%CO2/55%N2 (C, commercial), 70%O2/30%CO2 (O), and 15%O2/85%CO2 (H) for 18 days. Microbial analyses by both conventional methods and PCR-DGGE were performed. Controversial and surprising results emerged from comparing both methods in relation to the genus Pseudomonas. Thus, conventional methods detected the presence of high numbers of Pseudomonas colonies, although PCR-DGGE only detected this genus in air-packaged samples. PCR-DGGE detected higher microbial diversity in the control samples (A) than in the modified atmospheres (C, O, H), having atmosphere H the fewest number of species. Brochothrix thermosphacta, LAB (Carnobacterium divergens and Lactobacillus sakei), and Escherichia spp. were detected in all the atmospheres throughout storage. Moreover, previously undescribed bacteria from lamb meat such as Enterobacter hormaechei, Staphylococcus equorum and Jeotgalicoccus spp. were also isolated in this study by DGGE. Additionally, qPCR analysis was used to detect and characterize strains of Escherichia coli. Virulence genes (stx1, stx2 and eae) were detected throughout storage in 97% of the samples. A high CO2 atmosphere was the most effective packaging combination doubling storage time in comparison with commercial atmosphere.

Tracing Campylobacter jejuni strains along the poultry meat production chain from farm to retail by pulsed-field gel electrophoresis, and the antimicrobial resistance of isolates.

In this study Campylobacter jejuni isolates were recovered from birds, carcasses and carcass portions from two broiler chicken flocks and from equipment used for carcass and meat processing along the production chain from farms to retail stores. Isolates were subjected to pulsed-field gel electrophoresis (PFGE) using SmaI and KpnI restriction enzymes and their antimicrobial susceptibilities were determined. C. jejuni was recovered from product and equipment used with both flocks at each point in the production chain. The prevalence of C. jejuni in poultry products at retail stores was 58.97% (flock 1) and 69.23% (flock 2). SmaI divided 122 C. jejuni strains from flock 1 and 106 from flock 2 into 17 and 13 PFGE types, respectively. PFGE types H and F were present at all steps along the chain, from farms to retail products. Similarly, for both flocks PFGE type D was detected in crates, slaughterhouse and retail stores. Moreover, the PFGE types were highly diverse at the processing and retail steps. Most PFGE types were resistant to ciprofloxacin (95.45%) and tetracycline (81.82%); and multidrug resistant PFGE types were found in the final products. Our study showed that there were several points of cross-contamination of product along the chain, and a high diversity of PFGE types with antimicrobial resistance to ciprofloxacin and tetracycline in the retail products.

Behaviour of non-stressed and stressed Listeria monocytogenes and Campylobacter jejuni cells on fresh chicken burger meat packaged under modified atmosphere and inoculated with protective culture.

Numerous investigations have provided evidence that chicken products are a source of Listeria monocytogenes and Campylobacter jejuni. Different strategies applied in final products are needed to prevent consumers' contamination. In this work, the combination of modified atmosphere packaging (MAP) and protective culture to control the growth of freeze stressed and non-stressed L. monocytogenes and C. jejuni on fresh chicken meat burger was studied. Meat burgers were inoculated with L. monocytogenes, C. jejuni and Leuconostoc pseudomesenteroides PCK 18, as protective strain against L. monocytogenes. Prior to the addition of the protective culture, half of the L. monocytogenes and C. jejuni - inoculated meat was frozen at -18°C for 48 h to subject cells to stress. Following the addition of the protective culture, meat burgers were packaged in air or MAP (50% CO(2)/50% O(2)) and stored under refrigeration conditions. L. monocytogenes counts were not reduced by the freezing temperature applied; however, the addition of Lc. pseudomesenteroides PCK 18 reduced its counts for 0.90 log cfu/g when chicken meat burgers were packaged under MAP. Furthermore, freezing stress was an effective strategy to reduce C. jejuni counts but only in combination with a high-O(2) MAP, it was completely eliminated. Chicken meat burgers' shelf-life under aerobic packaging conditions was reduced by the effect of freeze-thawing, while the use of MAP extended the product's shelf-life till 21days. Therefore, the combination of freezing, protective culture and MAP could extend the shelf-life and enhance the food safety of this kind of chicken products.

Comparison between conventional and qPCR methods for enumerating Campylobacter jejuni in a poultry processing plant.

Campylobacter jejuni is worldwide recognized as a human foodborne pathogen. It is widely present in poultry meat and slaughterhouses, but little is known about its fate during the processing of poultry meat preparations. In stress conditions, this pathogen can enter into a viable but non-culturable state, where quantitative PCR (qPCR) becomes more convenient for its detection. In this study, two different pairs of primers, targeting the rpoB and the hipO genes, were compared for its detection and quantification by PCR. Two calibration curves were prepared: one for the meat samples and the other for the environmental samples. rpoB primers showed higher sensitivity with a quantification limit of 1 log cfu/g or ml. Microbial Assessment Scheme (MAS) was used to select the Critical Sampling Locations (CSLs) along the poultry processing line. Forty-six out of 48 samples were positive by qPCR after enrichment (t = 48 ) while only 6 samples were positive by ISO 10272-1:2006. Forty-three samples showed positive signal without enrichment (t = 0 h), however only 16 samples could be quantified. These results showed the high prevalence of C. jejuni in the poultry industry and the need for new, rapid and sensitive techniques, such as qPCR, for the detection and quantification of C. jejuni in meat and environmental samples.

The influence of different preservation methods on spoilage bacteria populations inoculated in morcilla de Burgos during anaerobic cold storage.

Blood sausage is a widely consumed traditional product that would benefit from an extended shelf life. The two main spoilage bacteria in vacuum-packaged morcilla de Burgos are Weissella viridescens and Leuconostoc mesenteroides. This study examines the way in which three preservation treatments--organic acid salts (OAS), high-pressure processing (HPP) and pasteurization--influence these bacterial populations and their spoilage behaviour. HPP and pasteurization treatments were found to inhibit growth of the inoculated species and delay sensory spoilage of the product. In both treatments, L. mesenteroides was observed to have a longer recovery time; even so, once its growth started, it grew faster than W. viridescens. This longer recovery time might be due to metabolic modification following treatment, which would affect the production of metabolites such as acetic acid and some aldehydes. W. viridescens was the first strain to recover from the two treatments. It preserved its spoilage behaviour and even increased the production of certain compounds such as acetoin or ethanol. The extended product shelf life following HPP and pasteurization treatments might be due to a combination of various factors such as the fall in both microbial populations, as well as the delay in spoilage caused by damage to L. mesenteroides cells, as this strain is the fastest-acting, most intensive spoilage microorganism. It was observed that the addition of organic salts neither diminished nor delayed the growth of the two inoculated species. Nevertheless, the results also indicate that this treatment inhibits the metabolic activity of L. mesenteroides, resulting once again in an extended product shelf life.