Application of cranberry concentrate (Vaccinium macrocarpon) to control Escherichia coli O157:H7 in ground beef and its antimicrobial mechanism related to the downregulated slp, hdeA and cfa

The possible use of cranberry concentrate (CC) as a natural food preservative was studied by examining its antimicrobial effect on the growth of Escherichia coli O157:H7 inoculated in ground beef, its organoleptical effect on beef patties, and its antimicrobial mechanism on the gene regulation level.     

Antibacterial activity of the extracts from the fruit rinds of Garcinia cowa and Garcinia pedunculata against food borne pathogens and spoilage bacteria

The crude hexane and chloroform extracts from the fruit rinds of Garcinia cowa and Garcinia pedunculata were studied for their antibacterial activity against some foodborne pathogens and spoilage bacteria such as Bacillus cereus, Bacillus coagulans, Bacillus subtilis, Staphylococcus aureus and Escherichia coli. The minimum inhibitory concentrations (MICs) of the extracts determined by the agar dilution method were ranging from 15 to 500 μg/ml and 300 to 1250 μg/ml for G. cowa and G. pedunculata, respectively. However, the hexane and chloroform extracts from the fruit rinds of G. cowa exhibited marked inhibitory effect against all the test organisms and were more effective than that of G. pedunculata extracts. The antibacterial activity of all the extracts was more pronounced against the tested Gram-positive bacteria than the tested Gram-negative bacterium. Furthermore, this study is the first report on the in vitro antibacterial activity of extracts from the fruit rinds of G. cowa and G. pedunculata.     

Anthocyanin composition and content of the Vaccinium uliginosum berry

Anthocyanins are polyphenols that are widely distributed in plants, and contribute to the brilliant blue, red or purple colour in leaves, flowers or fruits. Their attractive colours and their abundance in the north-east of China make the berries of Vaccinium uliginosum a new and excellent source of natural pigments. The pigments were extracted from the V. uliginosum berry using 0.5% TFA in ethanol solution, purified by an X-5 resin column and characterised by HPLC–DAD analysis. All of the peak assignments were confirmed by low-resolution electrospray mass spectrometry. The results showed that 11 anthocyanins and 2 flavonols were present in the V. uliginosum berry.     

Chemical composition,anthocyanins, non-anthocyanin phenolics and antioxidant activity of wild bilberry (Vaccinium meridionale Swartz) from Colombia

Berries of Vaccinium meridionale Swartz native to Colombia were analysed for chemical composition, total phenolic content, anthocyanin content, and antioxidant activity. In addition, high-performance liquid chromatography with photodiode array detection (HPLC–DAD) and HPLC-electrospray ionisation tandem mass spectrometry (ESI–MS/MS) were used to determine anthocyanin and phenolic composition. Anthocyanin content was 329.0 ± 28.0 mg cyanidin 3-glucoside equivalents/100 g (fresh weight) FW and total phenolic content was 758.6 ± 62.3 mg gallic acid equivalent/100 g FW. Cyanidin 3-galactoside was the major anthocyanin while the most abundant non-anthocyanin phenolic was chlorogenic acid.     

Potential roles of essential oil and organic extracts of Zizyphus jujuba in inhibiting food-borne pathogens

This study was undertaken to examine the chemical compositions of essential oil and tested the efficacy of oil and organic extracts from seeds of Zizyphus jujuba against food-borne pathogens. The chemical compositions of the oil was analysed by Null. Twenty three compounds representing 91.59% of the total oil were identified. The oil (5 μl of 1:5 (v/v) dilution of oil with methanol) and extracts of hexane, chloroform, ethyl acetate and methanol (300 μg/disc) of Z. jujuba displayed a remarkable antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19166, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella typhimurium KCTC 2515 and Escherichia coli ATCC 8739. The scanning electron microscopic studies also demonstrated the effect of essential oil on the morphology of Staph. aureus ATCC 6538 at the MIC value, along with the potential effect on cell viabilities of the tested bacteria.     

Antibacterial properties of Polygonum cuspidatum roots and their major bioactive constituents

Antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of crude extract from Polygonum cuspidatum roots were assayed against five common foodborne bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella anatum). The crude extract exhibited potent antibacterial properties. Major bioactive compounds in P. cuspidatum roots were identified as stilbenes (e.g., piceid, resveratroloside, and resveratrol) and hydroxyanthraquinones (e.g., emodin, emodin-1-O-glucoside, and physcion) by LC–ESI-MS. Both stilbenes and hydroxyanthraquinoines greatly contributed to the antibacterial properties. Additionally, scanning electron microscopy was used to observe morphological changes of the bacteria treated with the crude extract and its major antibacterial components. Possible mechanisms of the antibacterial action were also discussed. This study suggests that the roots of P. cuspidatum and its antibacterial components may have potential for use as natural preservatives.     

The effects of stainless steel finish on Salmonella Typhimurium attachment,biofilm formation and sensitivity to chlorine

Bacterial colonization and biofilm formation on stainless steel (SS) surfaces can be sources for cross contamination in food processing facilities, possessing a great threat to public health and food quality. Here the aim was to demonstrate the influence of surface finish of AISI 316 SS on colonization, biofilm formation and susceptibility of Salmonella Typhimurium to disinfection.     

Control of foodborne pathogens on fresh-cut fruit by a novel strain of Pseudomonas graminis

The consumption of fresh-cut fruit has substantially risen over the last few years, leading to an increase in the number of outbreaks associated with fruit. Moreover, consumers are currently demanding wholesome, fresh-like, safe foods without added chemicals. As a response, the aim of this study was to determine if the naturally occurring microorganisms on fruit are “competitive with” or “antagonistic to” potentially encountered pathogens. Of the 97 and 107 isolates tested by co-inoculation with Escherichia coli O157:H7, Salmonella and Listeria innocua on fresh-cut apple and peach, respectively, and stored at 20 °C, seven showed a strong antagonistic capacity (more than 1-log unit reduction). One of the isolates, CPA-7, achieved the best reduction values (from 2.8 to 5.9-log units) and was the only isolate able to inhibit E. coli O157:H7 at refrigeration temperatures on both fruits. Therefore, CPA-7 was selected for further assays. Dose-response assays showed that CPA-7 should be present in at least the same amount as the pathogen to adequately reduce the numbers of the pathogen. From the results obtained in in vitro assays, competition seemed to be CPA-7's mode of action against E. coli O157:H7. The CPA-7 strain was identified as Pseudomonas graminis. Thus, the results support the potential use of CPA-7 as a bioprotective agent against foodborne pathogens in minimally processed fruit.     

Free radical scavenging capacity and antioxidant enzyme activity in deerberry (Vaccinium stamineum L.)

Fruit from three genotypes (‘B-76’, ‘B-59’ and ‘SHF-3A’) of deerberry [Vaccinium stamineum L.] were evaluated for fruit quality, total anthocyanin and phenolic contents, antioxidants, antioxidant capacity, and antioxidant enzyme activity. The fruit soluble solids, titratable acids, total anthocyanins, and total phenolic contents varied with genotypes. Cyanidin 3-galactoside and cyanidin 3-arabinoside were the two predominant anthocyanins. Resveratrol was also found in deerberries. Among the three genotypes, ‘B-76’ had higher amount of anthocyanins, phenolic compounds and resveratrol than ‘B-59’ and ‘SHF-3A’. Deerberries contained potent free radical scavenging activities for 2,2-Di (4-tert-octylphenyl)-1-picrylhydrazyl (DPPH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS⁺), peroxyl radical (ROO), superoxide radicals (), hydrogen peroxide (H₂O₂), hydroxyl radicals (OH), and singlet oxygen (¹O₂) radicals and also had high activities of antioxidant enzymes including glutathione-peroxidase (GSH-POD), glutathione reductase (GR), superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD), guaiacol peroxidase (G-POD), monodehydroascorbate radical reductase (MDAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR)] and non-enzyme antioxidants [ascorbic acid (ASA) and reduced glutathione (GSH)]. Antioxidant capacities were highly correlated to antioxidant enzymes activities. Among the three genotypes, ‘B-76’ had the highest level of antioxidants and antioxidant enzyme activity.     

Phytochemical composition of the essential oils from three Apiaceae species and their antibacterial effects on food-borne pathogens

Essential oils (EOs) of three Apiaceae species, including Bunium persicum, Cuminum cyminum and Carum copticum, extracted by hydrodistillation, were analyzed by gas chromatography (GC) and GC/mass spectrometry. The main components of EOs of B. persicum were γ-terpinene (44.2%), cuminaldehyde (16.9%), γ-terpinen-7-al (10.5%), and ρ-cymene (8%). The major constituents of Cu. cyminum were cuminaldehyde (30.2%), ρ-cymene (14.1%), γ-terpinene (12.8%), and safranal (9.4%), while those of Ca. copticum were thymol (48.4%), ρ-cymene (21.8%) and γ-terpinene (21.3%). The antibacterial effects of the EOs were assessed on several food-borne pathogens, namely Staphylococcus aureus, Bacillus cereus, Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes. The ranges of minimum inhibitory concentration (MIC) of the oils were 0.03–0.5, 0.18–3.0, and 0.37–3.0 mg/ml, respectively, for Ca. copticum, B. persicum and Cu. cyminum. Moreover, the combination of B. persicum and Cu. cyminum EOs confirmed synergistic and additive activities against the pathogens.     

Characterization of the quinolone resistance mechanism in foodborne Salmonella isolates with high nalidixic acid resistance

Sixteen Salmonella strains resistant to nalidixic acid isolated from kimbab, the most popular ready-to-eat (RTE) food in Korea, and chicken meat were selected for this study. The resistant strains were shown to have high minimal inhibitory concentrations (MICs) against nalidixic acid (512 ~ 4096 μg/mL). Among them, 4 Salmonella enterica serovar Haardt isolates showed multi-drug resistance (MDR) patterns with reduced susceptibility to fluoroquinolone (0.5 μg/mL of ciprofloxacin MICs). The mechanisms of quinolone resistance in the nalidixic acid resistant strains were characterized by PCR and sequence analysis. The presence of plasmid-mediated quinolone resistance (PMQR) genes and amino acid changes in the quinolone resistance determining region (QRDR) were investigated by PCR-based detection and sequencing, and the efflux pump inhibition test was also done using phe-arg-β-naphthylamide (PAβN). Although PMQR genes were not detected in any of the tested strains, the QRDR mutations were found in this study: single mutation in gyrA (Asp87Tyr, Asp87Gly, and Asp87Asn), double mutations in gyrA (Ser83Thr) and parC (Thr57Ser), and single mutation in parC (Thr57Ser). MICs of nalidixic acid were reduced by 2- to 32-folds by the efflux pump inhibitor, PAβN. Pulsed-field gel electrophoresis (PFGE) was carried out to confirm the epidemiological relationship between the nalidixic acid resistant strains. The PFGE patterns were classified into 6 groups at cutoff level of 70 ~ 100% correlation on the dendrogram. Some strains of serotype Haardt and Enteritidis showed several values of genomic identity in accordance with strains, sources, and isolation year. We suggest that point mutation on QRDR and efflux pump systems involved in antimicrobials had independent effects on drug-resistance regardless of bacterial genomic variation.     

2017—2021年河南省肉与肉制品食源性致病菌监测及部分肠杆菌耐药特征分析

目的 了解河南省肉制品中食源性致病菌的污染状况,并对肠杆菌进行血清学分型和耐药特征分析。方法 收集2017—2021年河南省郑州市等21个监测点的1 934份肉与肉制品,参考《国家食品污染物和有害因素风险监测工作手册》和《河南省食品微生物风险监测工作手册》进行沙门菌、致泻大肠埃希菌、小肠结肠炎耶尔森菌、产气荚膜梭菌、单核细胞增生李斯特菌、金黄色葡萄球菌和空肠弯曲菌等7种食源性致病菌的检测,使用微量肉汤稀释法对致泻大肠埃希菌和沙门菌进行药敏试验,分析耐药率和耐药谱等特征。结果 1 934份样品中检出478株致病菌,其中沙门菌96株,共26个血清型,以肠炎沙门菌为主;致泻大肠埃希菌82株,以肠集聚性大肠埃希菌为主;产气荚膜梭菌68株,小肠结肠炎耶尔森菌38株,空肠弯曲菌33株,单核细胞增生李斯特菌140株和金黄色葡萄球菌21株。致病菌总检出率为24.72%,调理肉制品检出率最高达到89.00%,其次为生禽肉（36.79%）和生畜肉（22.35%）。96株沙门菌对氨苄西林（71.88%）、萘啶酸（63.54%）及四环素（58.33%）高水平耐药;82株致泻大肠埃希菌对四环素（84.38%）、...     

Insecticidal and antifeedant effects of Junellia aspera (Verbenaceae) triterpenes and derivatives on Sitophilus oryzae (Coleoptera: Curculionidae)

Triterpenes from Junellia aspera (Gillies ex Hook) (Verbenaceae) and chemical derivatives were evaluated for their antifeedant and toxic effects against adults of Sitophilus oryzae (L.). Five triterpenoids were acutely toxic by ingestion. The compounds maslinic acid (II), daucosterol (III), and 3β-hydroxy-12α-bromine-(28→13)-oxide-oleanane (IX) showed the highest toxic effects, while oleanolic acid (I) and oleanonic acid (VII) showed less toxicity. Daucosterol also exhibited important feeding deterrence activity. No toxicity was observed when the assayed compounds were topically applied.     

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.     

Antimicrobial activity of some plant extracts and essential oils against foodborne pathogens in vitro and on the fate of inoculated pathogens in chocolate

The efficacy of commercially available plant extracts and essential oils used extensively as flavour ingredients in confectionery products were used as antimicrobials in laboratory media against the following microorganisms: Escherichia coli O157:H7, Salmonella Enteritidis, Salmonella Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. Using the disc diffusion method, inhibition zones in diameter >20 mm were observed by adding 10 μl of each antimicrobial substance on the following microorganisms: lemon flavour applied on E. coli O157:H7, lemongrass essences against S. aureus, plum using a B. cereus strain and strawberry flavour using a L. monocytogenes strain. E. coli O157:H7 strains were the most susceptible microorganisms inhibited by 18 extracts, followed by S. Typhimurium and S. aureus which were inhibited by 17 extracts. Lemon flavour, lemongrass essences, pineapple and strawberry flavour inhibited the foodborne pathogens at the lowest concentration (5 ml/100 ml). Plant extracts and essential oils with potent antimicrobial activities were tested in chocolate held at different temperatures (7 and 20 °C) in dry or humidified environment, which resulted in different a_w values of the product (i.e. 0.340, 0.450, and 0.822), in order to determine their efficacy on the fate of the inoculated pathogens. The most inhibitory action was observed by lemon flavour applied on chocolate inoculated with E. coli cocktail culture after storage at 20 °C for 9 days. Plant extracts tested on chocolate show an enhanced inhibitory effect during storage at 20 °C indicating that their application may provide protection in case of storage at the above temperature or even higher.     

Antagonistic effect of Pseudomonas graminis CPA-7 against foodborne pathogens in fresh-cut apples under simulated commercial conditions

Recently, we reported that the application of the strain CPA-7 of Pseudomonas graminis, previously isolated from apple, could reduce the population of foodborne pathogens on minimally processed (MP) apples and peaches under laboratory conditions. Therefore, the objective of the present work was to find an antioxidant treatment and a packaging atmosphere condition to improve CPA-7 efficacy in reducing a cocktail of four Salmonella and five Listeria monocytogenes strains on MP apples under simulated commercial processing. The effect of CPA-7 application on apple quality and its survival to simulated gastric stress were also evaluated. Ascorbic acid (2%, w/v) and N-acetyl-l-cysteine (1%, w/v) as antioxidant treatments reduced Salmonella, L. monocytogenes and CPA-7 recovery, meanwhile no reduction was observed with NatureSeal^® AS1 (NS, 6%, w/v). The antagonistic strain was effective on NS-treated apple wedges stored at 10 °C with or without modified atmosphere packaging (MAP). Then, in a semi-commercial assay, efficacy of CPA-7 inoculated at 10⁵ and 10⁷ cfu mL⁻¹ against Salmonella and L. monocytogenes strains on MP apples with NS and MAP and stored at 5 and 10 °C was evaluated. Although high CPA-7 concentrations/populations avoided Salmonella growth at 10 °C and lowered L. monocytogenes population increases were observed at both temperatures, the effect was not instantaneous. No effect on apple quality was detected and CPA-7 did not survived to simulated gastric stress throughout storage. Therefore, CPA-7 could avoid pathogens growth on MP apples during storage when use as part of a hurdle technology in combination with disinfection techniques, low storage temperature and MAP.     

A filtration-based real-time PCR method for the quantitative detection of viable Salmonella enterica and Listeria monocytogenes in food samples

We developed a novel filtration-based method that can eliminate dead or severally damaged Salmonella enterica and Listeria monocytogenes in food samples. This new method can recover all viable bacteria in less than 30 min, and can be coupled with a subsequent bacterial DNA extraction and real-time PCR. No statically significant differences (p < 0.01) were found between real-time PCR results obtained separately from S. enterica and L. monocytogenes when different ratios of living and dead cells were used. The analytical sensitivity in both cases was 1 genome equivalent (GE), and the quantification was linear (R² > 0.9969) over a 5-log dynamic range with PCR efficiencies >0.9754. When compared with the standard microbiological methods for the detection of these foodborne pathogens, the relative accuracy was excellent ranging from 95.72% to 104.48%. Finally, we applied the pre-treatment method to the direct detection of viable forms of these foodborne pathogens in food samples using yogurt as a model, the results being similar to those obtained using pure cultures.     

Surface enhanced Raman scattering (SERS) with biopolymer encapsulated silver nanosubstrates for rapid detection of foodborne pathogens

A biopolymer encapsulated with silver nanoparticles was prepared using silver nitrate, polyvinyl alcohol (PVA) solution, and trisodium citrate. It was deposited on a mica sheet to use as SERS substrate. Fresh cultures of Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus and Listeria innocua were washed from chicken rinse and suspended in 10 ml of sterile deionized water. Approximately 5 μl of the bacterial suspensions was placed on the substrate individually and exposed to 785 nm HeNe laser excitation. SERS spectral data were recorded over the Raman shift between 400 and 1800 cm^− 1 from 15 different spots on the substrate for each sample; and three replicates were done on each bacteria type. Principal component analysis (PCA) model was developed to classify foodborne bacteria types. PC1 identified 96% of the variation among the given bacteria specimen, and PC2 identified 3%, resulted in a total of 99% classification accuracy. Soft Independent Modeling of Class Analogies (SIMCA) of validation set gave an overall correct classification of 97%. Comparison of the SERS spectra of different types of gram-negative and gram-positive bacteria indicated that all of them have similar cell walls and cell membrane structures. Conversely, major differences were noted around the nucleic acid and amino acid structure information between 1200 cm^− 1 and 1700 cm^− 1 and at the finger print region between 400 cm^− 1 and 700 cm^− 1. Silver biopolymer nanoparticle substrate could be a promising SERS tool for pathogen detection. Also this study indicates that SERS technology could be used for reliable and rapid detection and classification of food borne pathogens.     

Factors affecting growth of foodborne pathogens on minimally processed apples

Escherichia coli O157:H7, Salmonella and Listeria innocua increased by more than 2 log₁₀ units over a 24 h period on fresh-cut ‘Golden Delicious’ apple plugs stored at 25 and 20 °C. L. innocua reached the same final population level at 10 °C meanwhile E. coli and Salmonella only increased 1.3 log₁₀ units after 6 days. Only L. innocua was able to grow at 5 °C. No significant differences were observed between the growth of foodborne pathogens on fresh-cut ‘Golden Delicious’, ‘Granny Smith’ and ‘Shampion’ apples stored at 25 and 5 °C. The treatment of ‘Golden Delicious’ and ‘Granny Smith’ apple plugs with the antioxidants, ascorbic acid (2%) and NatureSeal^® (6%), did not affect pathogen growth. The effect of passive modified atmosphere packaging (MAP) on the growth of E. coli, Salmonella and L. innocua on ‘Golden Delicious’ apple slices was also tested. There were no significant differences in growth of pathogens in MAP conditions compared with air packaging of ‘Golden Delicious’ apple plugs, but the growth of mesophilic and psychrotrophic microorganisms was inhibited. These results highlight the importance of avoiding contamination of fresh-cut fruit with foodborne pathogens and the maintenance of the cold chain during storage until consumption.     

Antimicrobial activity of the essential oils of Brazilian species of the genus Cunila against foodborne pathogens and spoiling bacteria

The essential oils from aerial parts of six Brazilian species of the genus Cunila Mill. (Lamiaceae) currently used in beverages and food preparation, and in folk medicine, were obtained by steam distillation and analyzed by GC and GC/MS. The main components of the oils were: Cunila galioides citral (citral −77.9%), C. galioides menthene (mentha-trans-2,8-dienol −20.0%, limonene −13.6%, trans-ocimene −13.0%), C. incisa (1,8-cineole −42.9%, α-terpineol −14.0%), C. spicata (1,8-cineole −47.9%, α-terpineol −37.5%), C. menthoides (menthene −77.8%), C. angustifolia (sabinene −41.4%, γ-terpinene −11.4%), and C. microcephala (menthofuran −94.90%). These oils were screened for antibacterial activity against 15 bacterial species. The oil of C. galioides citral efficiently controlled the growth of Bacillus sp., L. monocytogenes, S. aureus, A. hydrophila, and E. faecalis, showing both contact and gaseous activity. Although less efficient, the other essential oils studied were effective against Bacillus species, S. aureus, and other specific bacteria. MIC and MCC values support their popular use, and indicate that they can be an efficient alternative for the control of foodborne and spoiling bacteria.