Effects of temperatures and storage time on resting populations of Escherichia coli O157:H7 and Pseudomonas fluorescens in vitro

Assessment of microbial interactions is crucial for documenting bacterial growth in pure and mixed cultures and their potential for biological applications. Pseudomonas fluorescens (non-plant pathogenic and non-pectinolytic) has been used as a biocontrol microbe for plant pathogens and food-borne bacteria. We determined the growth of Escherichia coli O157:H7 (Ec) and P. fluorescens(Pf) in monocultures and co-cultures in sterile distilled water (SDW), buffered peptone water (BPW) and trypticase soy broth (TSB). The effects of temperatures (5, 10, 15, 20, 25, 35, and 37 °C) and storage time (0, 2, 4, 6, 24, and 48 h) on bacteria populations were assessed. Bacteria counts in monocultures in SDW ranged from 2.14 to 3.03 and 2.54 to 3.31 Log CFU/ml for Ec and Pf; respectively. In BPW, mean bacteria counts (monocultures) ranged from 3.15 to 6.14 and 2.54 to 6.41 Log CFU/ml for Ec and Pf, respectively. Ec populations in co-culture varied with storage temperatures and time. After 48 h, Ec 43894 monocultures in TSB ranged from 2.17 to 8.75 and 2.31 to 8.85 Log CFU/ml at 20 and 35 °C; respectively. In co-cultures with Pf 2-79, Ec 43894 counts ranged from 1.71 to 5.83 (20 °C) and 1.90 to 9.03 Log CFU/ml (35 °C) in TSB. The reductions of Ec by Pf 2-79 varied among strains and generally ranged from 0.20 to 0.90, 0.63 to 1.18, and 0 to 0.56 Log CFU/ml in BPW (10 °C). Substrate availability, storage temperatures, and time significantly (P < 0.05) impacted Ec populations in co-culture. The liquid substrate experiments indicated suppressive conditions of Ec by Pf, however; the reduction of produce contamination by E. coli O157:H7 during transitory temperature abuse conditions such as the transportation of produce from fields needs further investigation.     

Mycological quality and mycotoxin contamination of Sri Lankan peppers (Piper nigrum L.) and subsequent exposure assessment

The aim of the study was to characterize the toxigenic moulds and to screen different mycotoxins in peppers (Piper nigrum L.) of Sri Lankan origin. Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger and Penicillium spp. were found to be the most dominant fungi. Characterization of the moulds was carried out in A. flavus and parasiticus agar (AFPA) and malt extract agar (MEA) in 77 black pepper (BP) and 11 white pepper (WP) samples. In total, 73% of the BP and 64% of the WP samples were contaminated with A. flavus and/or A. parasiticus (AfAp). A BP sample with water activity (a_w) 0.70 recorded the highest count of AfAp (4.3*10⁴ CFU/g). Moreover, 75% of the BP samples exceeded the safe a_w limit (0.65) set by the European Spice Association (ESA). The frequency of occurrence of A. niger in BP was 62% with counts up to 1.3*10³ CFU/g. Penicillium spp. were found in 61% and 55% of the BP and WP samples, respectively. In BP 94% of the samples had a Penicillium contamination below 10³ CFU/g. Other Aspergillus spp, found in peppers included, Aspergillus terrus, Aspergillus tamarii, Aspergillus candidus, Aspergillus penicilloides, Aspergillus sydowii and Aspergillus fumigatus. Mould counts in BP (10²–10⁴ CFU/g) were significantly higher than that of WP (<10² CFU/g). Apart from the occurrence of “classical mycotoxins” of spices, aflatoxins (<LOQ-18 μg/kg) and ochratoxin A (<LOQ-79 μg/kg), other toxins including fumonisin B1 (<LOQ-135 μg/kg), sterigmatocystin (<LOQ-49 μg/kg) and citrinin (<LOQ-112 μg/kg) were detected in peppers. In total, 63% of the BP samples were contaminated with at least one mycotoxin. Mycotoxin contamination in WP was significantly less compared to BP. The exposure to aflatoxins and ochratoxin A by consuming pepper remains harmless considering the existing pepper dietary intake data of the Sri Lankan population.     

Occurrence of toxigenic fungi and ochratoxin A in Ethiopian coffee for local consumption

Information on the presence of ochratoxin A (OTA) in local Ethiopian coffee is scarce. Therefore, the objective of this study was to type the fungal and mycotoxin contamination levels in Ethiopian coffee consumed by the local community. Coffee samples were collected from six major coffee growing districts in Jimma zone of Oromiya regional state in Ethiopia. Total fungal incidence mounted up to 87% and Aspergillus (79%), Fusarium (8%) and Penicillium (5%) were the predominant toxigenic genera. OTA producing species A. westerdijkiae, Aspergillus ochraceus, and Aspergillus steynii were identified for the first time in Ethiopia and were shown to be the predominant species while aflatoxin (AF) producing Aspergillus species were scarce. Using an in vitro approach, the OTA production potential was assessed under standardized conditions. Based on this experiment, it was concluded that Aspergillus westerdijkiae isolates were clearly the most potent producers of OTA. The median OTA level in the locally sold Ethiopian coffee was 1.53 μg/kg. Notwithstanding this low median value, significant differences in fungal and toxin incidences were observed between the different coffee processing types, coffee sample types, and storage characteristics.     

Mycoflora and absence of aflatoxin contamination of commercialized cassava chips in Benin, West Africa

Studies conducted in Benin, in which the main staple foods are maize, cassava, groundnuts and yams, showed high levels of aflatoxin residues in blood of the exposed population. The natural contamination with fungi and aflatoxins in cassava chips sold at markets in Benin, West Africa was investigated. A total of sixty samples were sampled from open markets in 11 districts of 3 agroecological zones and analyzed for the presence of mycoflora and aflatoxin B₁, B₂, G₁ and G₂. Fourteen genera of fungi were associated with marketed dried cassava chips. Within these, twenty- two isolates were identified to species level, whereas four were identified only to genus. The dominating fungal species isolated were Rhizopus oryzae, Nigrospora oryzae, Chrysonilia sitophila, Cladosporium resinae, Cladosporium herbarum, Apergillus niger and Aspergillus flavus. Fifty-four out of sixty samples were contaminated with A. flavus. The rate of occurrence in CFU/g of A. flavus fungi was lower than for all other fungal species together. Aflatoxin was not detected in any of the samples analyzed using HPLC with post-column photochemical derivatization and fluorescence detection. The limit of detection (LOD) was 0.1 μg/kg. Results from this study suggest cassava chips are unlikely to be a source of aflatoxin in Benin, and that other staples such as maize and groundnuts are more important in aflatoxin exposure. Therefore it can be speculated that staples like maize and groundnut are more important in aflatoxin exposure.     

Reduction of Escherichia coli O157:H7 and Salmonella enteritidis on mung bean seeds and sprouts by slightly acidic electrolyzed water

High microbial populations on mung beans and its sprouts are the primary reason of a short shelf life of these products, and potentially present pathogens may cause human illness outbreak. The efficiency for inactivating Escherichia coli O157:H7 (E. coli O157:H7) and Salmonella enteritidis (S. enteritidis), which were artificially inoculated on mung bean seeds and sprouts, by means of slightly acidic electrolyzed water (SAEW, pH 5.0 to 6.5) generated through electrolysis of a mixture of NaCl and hydrochloric acid solution in a non-membrane electrolytic chamber, was evaluated at the different available chlorine concentrations (ACCs, 20–120 mg/l) and treatment time (3–15 min), respectively. The effect of SAEW treatment on the viability of seeds was also determined. Results indicate that the ACC had more significant effect on the bactericidal activity of SAEW for reducing both pathogens on the seeds and sprouts compared to treatment time (P < 0.05). The seeds and sprouts treated with SAEW at ACCs of 20 and 80 mg/l resulted in a reduction of 1.32–1.78 log₁₀ CFU/g and 3.32–4.24 log₁₀ CFU/g for E. coli, while 1.27–1.76 log₁₀ CFU/g and 3.12–4.19 log₁₀ CFU/g for S. enteritidis, respectively. The germination percentage of mung bean seeds was not significantly affected by the treatment of SAEW at an ACC of 20 mg/l for less than 10 min (P > 0.05). The finding of this study implies that SAEW with a near-neutral pH value and low available chlorine is an effective method to reduce foodborne pathogens on seeds and sprouts with less effects on the viability of seeds.     

Safety of a street vended traditional maize beverage,ice-kenkey,in Ghana

Ice-kenkey is a chilled cereal beverage sold as street food in some open markets in Ghana. It is produced by mashing and sweetening kenkey, a stiff dumpling produced from fermented maize meal. The safety of street vended ice-kenkey was assessed by microbiological, elemental and myco-toxicological analysis of ice-kenkey and intermediary products obtained from 16 producers in four open markets in the Accra and Tema metropolis. A tenfold increase in counts of aerobic mesophiles, and yeast and moulds were recorded during the production of ice-kenkey. Coliform bacteria, E. coli and Staphylococcus aureus which were not detected in the starting materials were found partway through production or in the final product. The mean microbial counts in the packaged ice-kenkey were 10⁶–10⁷ CFU/g for aerobic mesophiles, 10⁴–10⁵ CFU/g for yeast and moulds, 10–1000 CFU/g for total coliforms and 10–100 CFU/g for S. aureus. E. coli counts of 10 CFU/g were recorded in samples from three out of the four markets. The microbial load could be eliminated by pasteurizing ice-kenkey at 80 °C for 15 min. The mean concentration in mg/kg of Fe was between 15.97 and 29.48, Cu, 0.57 to 1.41, Mn, 0 to 2.55, Pb 0 to 1.25 and Zn 0.47 to 6.17. Total aflatoxins content in samples ranged from 7.04 to 22.17 μg/kg and included a range of 7.01–20.54 for aflatoxin B₁, 0.51 to 1.63 for aflatoxin B₂ and 0–0.47 μg/kg for aflatoxin G_I. Aflatoxin G₂ was not detected in any of the samples. A simplified training module based GMP, GHP and a HACCP plan was developed and used to train ice-kenkey producers in Accra in collaboration with municipal authorities.     

Microbiological evaluation of fresh-cut organic vegetables produced in Zambia

This study was undertaken to assess the microbiological quality of fresh-cut organic vegetables produced in Zambia. Fresh-cut organic mixed vegetables and green beans produced in Zambia were analysed for aerobic plate counts, coliforms, Enterobacteriaceae, Escherichia coli, Bacillus cereus, Clostridium perfringens, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, and yeast and mould counts. The study included 160 samples for most of the parameters. The vegetables were grown on farms meant primarily for the export market. The vegetables were treated/washed with 150 μg ml⁻¹ chlorine solution at the processing plant prior to sampling. The aerobic plate count ranged between 3 log₁₀ and 9.7 log₁₀ CFU/g, with the highest count recorded for green beans. The largest grouping (26.1%) of vegetable samples fell between 3 and 4 log₁₀ CFU/g. Coliform counts were between 1.0 log₁₀ and 7.7 log₁₀ CFU/g. The highest incidence level was 31.4% for total coliform counts between 3 log₁₀ and 4 log₁₀ CFU/g. E. coli was only detected on mixed vegetables in the range of 0.6 log₁₀ to 3 log₁₀ CFU/g, while Enterobacteriaceae counts ranged between 1.6 log₁₀ and 9.8 log₁₀ CFU/g with the highest counts being found on green beans. The highest incidence level was of 25.8% for counts within the same range as the aerobic plate counts. Yeast and mould counts showed the highest incidence level between 5 log₁₀ and 6 log₁₀ CFU/g with an overall range between 1.5 log₁₀ and 5.6 log₁₀ CFU/g. L. monocytogenes, Salmonella spp. and S. aureus were detected in 20%, 23.1% and 83.9% of samples, respectively . C. perfringens and B. cereus were not detected in any of the samples analysed.     

Rapid and simultaneous detection of Salmonella,Shigella, and Staphylococcus aureus in fresh pork using a multiplex real-time PCR assay based on immunomagnetic separation

The incidence of foodborne infections caused by Salmonella sp., Shigella sp. and Staphylococcus (S.) aureus in fresh pork is increasing each year, which poses a great potential threat to public health. In this study, a rapid and simultaneous detection for these three pathogens from fresh pork samples was developed by combining immunomagnetic separation (IMS) with multiplex real-time PCR (RT-PCR). Magnetic beads coated with specific antibodies were used to capture and purify the pathogens from 250 mL matrix prepared by both spiked and commercial samples, followed by DNA extraction. Then, multiplex RT-PCR was applied with three sets of specific primers and probes. The limit of detections were evaluated in 67 spiked pork samples and were 2.0 CFU/g for Salmonella, 6.8 CFU/g for Shigella, and 9.6 CFU/g for S. aureus. The sensitivity, specificity, and accuracy of IMS-multiplex RT-PCR method were 99.2%, 100%, and 99.5%, respectively. One hundred fifty-one samples were tested using the IMS-multiplex RT-PCR and culture methods, and a comparison of the results showed that the former was a potentially reliable method for rapid and effective detection of Salmonella sp., Shigella sp., and S. aureus in fresh pork.     

Reduction of Campylobacter jejuni counts on chicken meat treated with different seasonings

To analyze the potential of various seasoning combinations in reducing Campylobacter jejuni counts on fresh chicken meat, fresh chicken drumstick samples were inoculated with a mixture of two C. jejuni strains at log 4–5 CFU/g and subsequently treated with six different seasonings. After addition as a dry powder to the meat’s surface, all seasoning combinations adsorbed water from the meat and formed a gel on the meat’s surface. The samples were placed in individual packages containing a modified gas atmosphere (N₂ 80% and CO₂ 20%) and stored at 4 °C for seven days and C. jejuni counts in CFU/g were determined at the beginning, after 15 min, 1 h, 1 day and 7 days. The most effective seasoning combination contained, among other ingredients and food additives, sodium lactate and potato protein fractions; it reduced counts by mean 1.52 to 1.66 log CFU/g in seven days. The other seasoning combinations without potato protein fractions decreased counts in the range of mean 1.05 to 1.16 log CFU/g; simultaneously, the counts in control meat samples decreased by mean 0.21 log CFU/g. The death rate estimates after 1 h storage was in the range of ?0.25 log CFU/g/h to ?0.34 log CFU/g/h.In conclusion, various combinations of seasonings decreased the counts of C. jejuni, with the highest C. jejuni death rate during the first hour and further minor reductions in C. jejuni counts with additional storage time. These types of treatments may decrease human exposure to Campylobacter from fresh poultry meat.     

Incidence and consumer awareness of toxigenic Aspergillus section Flavi and aflatoxin B1 in peanut cake from Nigeria

Peanut cake samples were collected from major markets in five states of Nigeria and evaluated for incidence of toxigenic Aspergillus section Flavi populations, and aflatoxin B₁ (AFB₁) levels by liquid chromatography tandem mass spectrometry (LC–MS/MS). The awareness of consumers to the presence of aflatoxin in the snack and potential health risks of its regular ingestion was evaluated by questionnaire analysis. Aspergillus section Flavi populations were recovered from 83% of the peanut cake samples. Aspergillus flavus L-strain was the most predominant (>56%) across the states while Aspergillus tamarii had the least mean incidence (2.7%). The incidence of atoxigenic strains was significantly (p < 0.05) higher than that of toxigenic strains in samples from Lagos and Kaduna, while the toxigenic strains had a significantly (p < 0.05) higher incidence than the atoxigenic strains in Niger. All analyzed cake samples contained AFB₁ in concentrations exceeding the NAFDAC recommended level for AFB₁ in food and reaching up to 2824 μg/kg. There was a weak positive correlation (r = 0.32, p = 0.03) for the relationship between the incidence of toxigenic strains in the samples and AFB₁ concentration. The consumer awareness data showed that 64% of the respondents consumed peanut cake; majority of who are youth of economic and reproductive age. Eighty-five percent of the consumers lacked awareness of aflatoxin contamination in the snack and possible health risks associated with its ingestion.     

Multimycotoxin analysis of sorghum (Sorghum bicolor L. Moench) and finger millet (Eleusine coracana L. Garten) from Ethiopia

The natural contamination of sorghum and finger millet by toxigenic fungi and associated mycotoxins has been studied. All the tested sorghum and finger millet samples were found to be contaminated by Fusarium and Aspergillus species. Sorghum was considerably more likely to be contaminated by both genera than finger millet. Penicillium, Alternaria, Rhizopus and Epicoccum species were also present in both grains albeit at lower frequencies. Multimycotoxin analysis using LC–MS/MS revealed the contamination of sorghum and finger millet by 84 and 62 metabolites, respectively. The prevalence of major mycotoxins was lower than 15% in sorghum except zearalenone that occurred in one third of the samples at average level of 44 μg/kg. In finger millet major mycotoxins occurred at a prevalence of 6–52% with zearalenone being the dominant and occurring at average level of 76 μg/kg. Aflatoxins B₁, B₂, G₁, G₂ and M₁ were detected in at least one sorghum sample while only aflatoxins B₁ and G₁ were present in finger millet samples. The average aflatoxins B₁ and G₁ concentrations in sorghum have been higher than European standards. But the level of B₂, G₂ and M₁ in sorghum and that of B₁ and G₁ in finger millet have been lower. Apart from aflatoxin precursors and other Fusarium metabolites, a broad range of additional metabolites were detected in sorghum and finger millet.     

Occurrence and diversity of Bacillus cereus and moulds in spices and herbs

Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems for consumers and contribute to food spoilage and shelf-life reduction. The aims of the present work were (i) to determine the occurence and levels of B. cereus and moulds; (ii) to charactize the incidence and diversity of B. cereus emetic toxin (ces, CER), and diarrhoeal toxin-encoding genes (entFM, nheA, hblC, cytK) and toxigenic potential of Hbl toxin-producing B. cereus strains. Black ground pepper samples showed the most contamination with the highest concentration of B. cereus 2.49 log₁₀ CFU/g. Moreover, cumin contained the most prominent mould concentration level of 3.6 log₁₀ CFU/g. The most common moulds were Aspergillus and Penicillium spp. Compared to packaging type, all products acquired from the local market, except curry for B. cereus, exchibited high concentrations of B. cereus and moulds. Four genes were identified – 96% of B. cereus strains contained entFM, 94% nheA, 56% hblC, 42% cytK. None of the samples contained emetic toxin-encoding genes (ces, CER). Toxigenic potential of Hbl toxin was found in 72% of B. cereus strains. Different temperature, moisture levels and hygiene practices were observed at places of sale in local markets thus facilitating contamination and development of moulds. Moreover, the presence of B. cereus and its ability to produce toxins in spices and herbs, may suggest the need to establish microbiological criteria for mould and spore-forming bacteria in spices and herbs.     

Biological activities of Boswellia sacra extracts on the growth and aflatoxins secretion of two aflatoxigenic species of Aspergillus species

Aflatoxins are the most serious carcinogenic, hepatotoxic, teratogenic and mutagenic secondary metabolites which adversely affect human and animal health. This study was designed to evaluate the in vitro inhibitory effect of different concentrations of Boswellia sacra resin (2.5, 5, 7.5 and 10 g/100 ml), leaf extract (5, 7.5, 10, 12.5 and 15 ml/100 ml), and essential oil (1, 2, 3, and 4 ml/100 ml) on the growth and aflatoxins production by two species of Aspergilli, namely Aspergillus flavus (SQU21) and Aspergillus parasiticus (CBS921.7). Resin of B. sacra caused 57.9–92.1% inhibition of aflatoxin secretion by A. flavus and 43.6–95.7% for A. parasiticus. However, the mycelial dry weights were significantly increased by 20.9–52.7% for A. flavus, and 8.9–68.5% for A. parasiticus. The leaf extract of B. sacra apparently enhanced aflatoxins production by 20–50%, and mycelial dry weight by 25.5–29.1% for A. flavus and A. parasiticus. The essential oil of B. sacra at different concentrations similarly inhibited the fungal growth and aflatoxins production by 45.8–83.7% for A. flavus and 41.3–83.5% for A. parasiticus which indicates the antifungal activity of this oil. None of the B. sacra extracts detoxified pure aqueous aflatoxin B₁. We have concluded that B. sacra resin and essential oil possess biological activity against biochemical synthesis and metabolic pathway of aflatoxin production of the two Aspergillus species. Therefore, the resin and essential oil of B. sacra can be recommended as safe plant based bioreservatives to enhance shelf life of food and feed products with reference to adverse effect of physical and synthetic chemical preservatives and their antimicrobial and aflatoxins inhibition activity.     

Effects of high pressure processing on immunoreactivity and microbiological safety of crushed peanuts

Peanuts are a common economical food source consumed worldwide but exist health concern of food allergy and are particularly susceptible to infection by the mold fungus Aspergillus flavus during storage, accumulating highly toxic substance aflatoxin. In this study, the effect of high pressure treatments on peanut immunoreactivity, peanut amino acid composition, A. flavus growth and aflatoxin contents on crushed peanuts was evaluated. Results showed that immunoreactivity of peanuts treated with 600 MPa and 800 MPa for 10 min was significantly lower (P < 0.05) than those of the control group by 69.2 ± 5.3% and 73.3 ± 1.9%, respectively. High pressure treatment at 800 MPa decreased total essential amino acid content as well as two nutritional indexes, the chemical score and the essential amino acid index, by 32.4 ± 2.1% and 31.1 ± 3.2%, respectively. The growth of aflatoxigenic fungi was inhibited in peanuts with aflatoxin accumulation that were subjected to different levels of pressure treatments during 30 days of storage. Peanuts treated with 600 MPa and 800 MPa had considerably lower aflatoxin levels, 0.26 μg/g and 0.22 μg/g in wet basis, respectively, than the control peanut aflatoxin level (9.08 μg/g) on day 30. Results were demonstrated that high pressure treatment had a significant inhibitory effect on A. flavus growth in peanuts and this contributes to reduction of aflatoxin production and accumulation instead of directly destroy aflatoxin. Taken together, the findings of this study indicated that high pressure treatment could preserve peanut quality by reducing food immunoreactivity and by eliminating A. flavus in peanuts.     

Lactic acid bacteria in cooked hams – Sources of contamination and chances of survival in the product

The aim of this study is microbiological analysis of individual technological operations during the industrial production of cooked hams, focusing on lactic acid bacteria (LAB). Samples were during the course of the entire cooked ham production cycle in May–June (Experiment I) and November–December (Experiment II). A total of 215 samples were taken and subsequently tested. The difference in the occurrence of LAB in meat before thermal processing resulted from the initial level of contamination of the raw material. A reduction to the number of LAB from 4.0 to 5.0 log CFU/g of meat to a value of practically zero occurred during the thermal processing. The LAB population increased during storage of the finished products. A level of 7.0 log CFU/g was reached in slices of ham in the modified atmosphere after three (Experiment I) or two (Experiment II) weeks of storage, respectively. LAB of the genera Leuconostoc (Leuc. carnosum, Leuc. mesenteroides and Leuc. gelidum) occurred most frequently in samples of cooked ham after thermal processing. These species were also isolated from the production environment. Lactobacillus sakei, Lbc. curvatus and Weissella viridescens were other species of LAB that were isolated from samples after thermal processing.     

Rapid real-time loop-mediated isothermal amplification combined with coated activated carbon for detection of low numbers of Salmonella enterica from lettuce without enrichment

A real-time loop amplified (Rti-LAMP) DNA assay system was developed for the rapid detection of low numbers of Salmonella enterica ser. Enteritidis (S. enterica) on the leaves of romaine lettuce without enrichment. The assay involved seeding 50 g portions of leaves with various numbers of S. enterica CFU. The lowest level of DNA consistently detected by the Rti-LAMP assay was that from 25 CFU per 50 g (0.5 CFU/g) of lettuce equivalent to the DNA from 6 CFU per Rti-LAMP reaction. A standard curve was generated by plotting the Tp values (min) against the log of 6, 25, 60 and 250 CFU of S. enterica seeded onto 50 g of lettuce. The entire assay could be completed in 3.5 h.7     

Potential of Escherichia coli as a surrogate indicator for postchill broiler carcasses with high Campylobacter counts

Surrogating Campylobacter contamination level in broiler carcasses with other bacterial indicators, used to evaluate the hygienic status of the slaughterline operations, might be stimulation to the broiler meat industry to improve control of Campylobacter during slaughter. Theoretically, Escherichia coli might have some practical merits as a potential indicator for carcasses contaminated with Campylobacter. This study investigates the correlation between the counts of E. coli and Campylobacter in 231 postchill broiler carcasses. The impact of setting a process hygiene target based on E. coli counts on reducing the frequency of carcasses contaminated with Campylobacter at level of ≥3 log₁₀ CFU/g was also investigated. Almost half (48.9% (46/94)) of the carcasses with enumerable Campylobacter (≥1 log₁₀ CFU/g) had E. coli counts between 3 and 4 log₁₀ CFU/g. In addition, 54.8% (17/31) of the carcasses contaminated with Campylobacter of ≥3 log₁₀ CFU/g were correlated with E. coli count range of ≥3 & <4 log₁₀ CFU/g. A theoretical scenario assuming that hygiene and processing measures could allow achieving a target for E. coli that not exceeding 3 log₁₀ CFU/g showed a parallel impact on Campylobacter contamination in broiler carcasses. In such scenario, the overall number of Campylobacter-positive carcasses could be dropped from 40.6% to 12.5%; in addition, 80.6% (25/31) of the carcasses contaminated with Campylobacter of ≥3 log₁₀ CFU/g could be eliminated. Findings from this study reveal that a hygiene target based on E. coli count could be used as an indirect sanitary tool for reducing the level of Campylobacter contamination in postchill broiler carcasses.     

Influence of temperature and surface kind on biofilm formation by Staphylococcus aureus from food-contact surfaces and sensitivity to sanitizers

This study aimed to assess the adhesion, detachment kinetic and biofilm formation of Staphylococcus aureus isolates from food services surfaces on stainless steel and polypropylene surfaces when cultivated in a vegetable-based broth at 7 and 28 °C, and the efficacy of peracetic acid (30 mg/L) and sodium hypochlorite (250 mg/L) in removing the bacterial cells from the matrix of the preformed biofilm. The isolates adhered over 4 Log cfu/cm² regardless the surface kind and incubation temperature. Cell detachment was around 3 Log cfu/cm² over the first six contacts with agar characterizing a high persistence of cells on the tested surfaces. Number of cells (5-7 Log cfu/cm²) needed for biofilm formation was noted at all experimental systems already after 3 days of incubation. A range of 2.0-3.3 and 1.5 to 2.1 Log cfu/cm² was observed in the reduction of cells in biofilm matrix caused by peracetic acid and sodium hypochlorite, respectively. The isolates of S. aureus revealed high capability to adhere and form biofilm on the tested surfaces in both assayed incubation temperature.     

General patterns of background microbiota and selected bacterial pathogens during production of fermented sausages in Serbia

The presence of Salmonella spp. or Escherichia coli O157 and background microbiota, pH and a_w were determined in raw fermented sausages produced from pork or beef and without lactic acid bacteria starters. The investigation was conducted at five meat processing plants, and the sampling was done at five steps of the production process at each plant. In meat trimmings, total viable count (TVC) ranged around 6 log CFU/g and around 5–6 log CFU/g in the pork and the beef sausages, respectively. Enterobacteriaceae count (EBC) ranged in the vicinity of 3–4 log CFU/g, whilst E. coli count (ECC) ranges were comparably lower (by 1–2 logs). During chopping of both the pork and the beef trimmings, the levels of TVC, EBC and ECC increased by 1–1.5 logs. After the additives and the spices were added, background microbiota tended to slightly decrease, generally more noticeably in pork sausages and with ECC. During the fermentation-drying stage, in both pork and beef sausages, initial TVC levels (6–7 log CFU/g) increased by the mid-process (by approximately 1.5–2 logs) and remained at those levels in finished products. During the same period, lactic acid bacteria (LAB) increased from initial levels of 5.5–6 log CFU/g to around 7–8 log CFU/g in pork and around 8–9 log CFU/g in beef sausages, and became the predominant microbial group. Salmonella spp. was found in the first three stages of the production process (trimmings, trimmings chopping, mixing with additives/spices), in two of three meat processing plants, but not at later stages of the production process. E. coli O157 was found only in one sample of chopped trimmings in one meat processing plant. The background microbiota patterns and levels were, generally, similar to those commonly reported for raw fermented sausages in other published studies. The initial presence of foodborne pathogens in raw fermented sausage production may be considered as a potential meat safety risk, because in the case of high initial pathogen counts, their total elimination cannot be assumed.