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Journal of Food Safety — Wed, 01 Feb 2012 05:00:00 +0100

(Source: Journal of Food Safety)

Control of listeria monocytogenes in recycled chill brine using ultraviolet light and antimicrobial agents

Journal of Food Safety — Wed, 01 Feb 2012 05:00:00 +0100

ABSTRACTPostprocessing contamination of the products in a processing plant has been identified as one of the major reasons for food contamination with Listeria; brining is one such postprocessing area. Our previous study has shown that the combinations of UV and antimicrobials reduces the number of this organism significantly in fresh brine, but brine is usually recycled from days to weeks depending on its use. Therefore, this study is focused on the reduction of L. monocytogenes in recycled chill brine (obtained from a frankfurter processor) using the combinations of UV and antimicrobial agents, such as citric acid (CA), hydrogen peroxide (HP) and dimethyl dicarbonate (DMDC). Results show that the combinations of UV and 2000 ppm and 4000 ppm HP were the most effective treatments in ...

Composition, antifungal activity and main fungitoxic components of the essential oil of mentha piperita l.

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

This study demonstrates the potential of M. piperita EO as antifungal against C. gloeosporoides, C. musae, F. oxysporum, F. semitectum, A. niger, A. flavus and A. glaucus. Further studies are underway to evaluate M. piperita EO as a feed preservative. In addition, its principal active compounds were isolated and characterized. Identification of such components also helps to understand the mode of action of the extract, which can lead to the discovery of new antifungal compounds. (Source: Journal of Food Safety)

Propionibacterium freudenreichii strains as antibacterial agents at neutral ph and their production on food‐grade media fermented by some lactobacilli

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

In this study, the ability of Propionibacterium freudenreichii Pr4 to retard the growth of Bacillus subtilis, Bacillus cereus, Pseudomonas putida and Escherichia coli at neutral pH was proven. The efficiency of P. freudenreichii culture broth against all these bacteria, except E. coli, was similar to that of the chemical propionate, taken in the same amounts. Consequent cultivation with certain lactic acid bacteria was found to be a convenient way to achieve active growth of P. freudenreichii on food‐grade media. The pregrowth of Lactobacillus acidophilus 146 in skim milk and milk whey stimulated considerably the growth of P. freudenreichii Pr2 and the production of propionate. The final amount of P. freudenreichii Pr2 and L. acidophilus 146 viable cells in this case was 1.5 ...

Detection of enterotoxigenic staphylococci by loop‐mediated isothermal amplification method

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTEnterotoxigenic staphylococcal strains isolated from the food samples in Mysore, Karnataka, India, were evaluated using loop‐mediated isothermal amplification (LAMP) method. The detection limit was 100 colony‐forming units (cfu)/test for LAMP and 10,000 cfu/test for PCR. In the presence of coexisting microbes such as Yersinia enterocolitica, the assays were carried out and the quantified DNA was subjected to LAMP and polymerase chain reaction (PCR) analysis. Despite the presence of Y. enterocolitica genomic DNA, the sensitivity of LAMP remains the same. The detection limits of LAMP and PCR were 100 fg/test and 10 pg/test, respectively. In all cases, LAMP was found to be 100‐fold more sensitive than PCR. No DNA amplification was observed for ent A, ent B, ent C and e...

Structural changes in listeria monocytogenes treated with gamma radiation, pulsed electric field and ultra‐high pressure

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

In conclusion, γ radiation, PEF and UHP targeted different loci in the cell, and thus synergy between these treatments against L. monocytogenes is likely.PRACTICAL APPLICATIONSRecently, there is an increase in the use of gamma (γ) radiation and ultra‐high pressure (UHP) in food processing as alternatives to heat. Other promising technologies, such as pulsed electric field (PEF), are in the experimental stage. This is a side‐by‐side investigation of γ radiation, UHP and PEF that helps in understanding the mechanism of bacterial inactivation by these technologies. The study could also help food processors in determining the suitability of these technologies for particular applications. (Source: Journal of Food Safety)

Properties of durancin gl, a new antilisterial bacteriocin produced by enterococcus durans 41d

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

This study describes the initial characterization of an apparently novel bacteriocin, durancin GL, which is produced by a strain of Enterococcus durans found in artisanal Mexican cheese samples. The bacteriocin was shown to effectively inhibit the growth of several L. monocytogenes strains, including the nisin‐resistant variant, L. monocytogenes NR30. The results suggest that durancin GL may be developed to serve as a food‐grade preservative to inhibit the growth of nisin‐resistant Listeria. (Source: Journal of Food Safety)

Antifungal activities of clove oil against rhizopus nigricans, aspergillus flavus and penicillium citrinum in vitro and in wounded fruit test

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTIn this article, in vitro and in vivo antifungal activities of clove oil to inactivate Aspergillus flavus, Penicillium citrinum and Rhizopus nigricans were investigated. The result showed that eugenol (approximately 83.02%) is the main constituent of clove oil. The minimum inhibitory concentrations of clove oil against A. flavus, P. citrinum and R. nigricans were 25, 25 and 50 µL/mL, respectively. In an in vitro experiment, the results revealed that clove oil possessed stronger antifungal activities against A. flavus and P. citrinum than against R. nigricans, and the antifungal activity improved with increasing its concentration. In an in vivo study, clove oil treatments significantly reduced fungal decay, and clove oil at a concentration of 3.0% showed complete cont...

Evaluation of plant essential oils for control of postharvest brown and gray mold rots on apricot

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

In this study, antifungal activities of Thymus vulgaris L., Eugenia caryophyllata L., Cinnamomum zeylanicum Blume and Carum copticum L. essential oils against Monilinia fructicola and Botrytis cinerea, two important postharvest pathogens of stone fruit, were investigated under in vivo studies. Results showed that the essential oil treatments, especially T. vulgaris and E. caryophyllata oils, had a good antifungal activity in reduction of both disease incidence and disease severity of brown and gray mold rots caused by M. fructicola and B. cinerea on apricots, respectively. Gas chromatography (GC) and GC/mass spectrometry analysis of tested essential oils showed that thymol (37.55%), eugenol (48.76%), cinnamaldehyde (90.33%) and thymol (50.88%) were the main components of T. vulga...

Influence of ethylenediamine‐n,n′‐disuccinic acid (edds) concentration on the bactericidal activity of fatty acids in vitro*

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTThe antibacterial activity of mixtures of ethylenediamine‐N,N′‐disuccinic acid (EDDS) and antibacterial fatty acids (FA) was examined using the agar diffusion assay. Solutions of caproic, caprylic, capric and lauric acids dissolved in potassium hydroxide (KOH) were supplemented with 0, 5 or 10 mM of EDDS and adjusted to pH 11.0 with citric acid. Wells made in agar media seeded with one of nine bacterial isolates were filled with FA‐KOH or FA‐KOH‐EDDS solutions. After incubation of agar plates, zones of inhibition of bacterial growth around the agar wells were measured. Results indicated that caproic‐KOH‐EDDS and caprylic‐KOH‐EDDS inhibited growth of more bacterial isolates than caproic‐KOH and caprylic‐KOH, respectively. Although, capric‐KOH and lauric�...

Evaluation of intestinal invasion in germ‐free mice challenged with acid‐adapted and nonacid‐adapted salmonella enteritidis se86 and salmonella typhimurium st99

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

This study focused on investigating in vivo the influence of SE86 acid adaptation capability on its pathogenic characteristics to explain why this microorganism is predominantly involved in foodborne salmonellosis in southern Brazil. (Source: Journal of Food Safety)

Plant extracts as potent biopreservatives for salmonella typhimurium control and quality enhancement in ground beef

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTPlants are continually the generous source to supply man with valuable bioactive substances. Six plant extracts were evaluated as potential biopreservatives to solve the catastrophe of beef contamination with Salmonella Typhimurium and improve ground beef overall quality. Five of the examined plant extracts exhibited remarkable antibacterial activities, using different assays, against three S. Typhimurium strains. Supplementation of experimentally inoculated beef trimmings with pomegranate peel extract (PPE) and cinnamon bark extract (CBE) resulted in a sharp reduction in bacterial cell counts during storage period for 7 days. Blending of ground beef with the double minimal inhibitory concentration (MIC) from PPE or with a combination from PPE and CBE, at their MIC values, complete...

Assessing relationships between microbiota and food handler practices in delicatessen sections: an interdisciplinary approach

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTThe interactions between microbiota and food handler practices in the delicatessen sections of a major retail group in the Western Cape were investigated in order to establish possible relationships between food handler practices and microbial contamination. The microbiota analyzed included total viable counts, total coliforms, Escherichia coli, members of the family Enterobacteriaceae and Staphylococcus aureus on hands and aprons of food handlers. Various groups of food handler practices were identified, using a questionnaire, and compared with microbial counts on hands and/or aprons by means of the Kruskal–Wallis and Mann–Whitney tests. Variables were described by means, standard deviations, medians and percentiles. A statistically significant difference occurred with regard ...

Impact of proton: a food handler certification course on food handlers' knowledge, attitudes and behaviors

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTWe conducted an evaluation of our food handler certification program, PROTON. Research examined changes in knowledge, attitude and behavior of participants as a result of completing the course. Participants completed a pre‐test assessing the three variables related to food safety at time of registration. One month following the completion of the program, participants completed an identical post‐test. A total of 1,042 pre‐tests and 320 post‐tests were completed. Scores in the pre‐test (6.3/10) and mean score for the post‐test (7.6/10) rendered a mean difference of 1.3 (95% confidence interval = 1.1 to 1.6; P < 0.0001) demonstrating an increase in knowledge by participants after taking the course. Significant increases for two attitudinal statements related to ...

Comparison of excision, swabbing and rinsing sampling methods to determine the microbiological quality of broiler carcasses

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

The objective of this study was to compare the three different sampling methods for enumeration and monitoring of bacteria on broiler carcasses. Total viable counts, Pseudomonas spp., lactic acid bacteria, Brochothrix thermosphacta and Enterobacteriaceae recovered by each sampling method were enumerated using the pour plate technique. Rinsing and excision recovered a similar level (P > 0.05) of the total viable counts, whereas swabbing yielded a lower level (P < 0.05). For Pseudomonas spp., lactic acid bacteria and B. thermosphacta, rinsing recovered the highest counts, followed by excision and finally the swabbing. There was no significant difference (P > 0.05) to detect Enterobacteriaceae by the three methods. Polymerase chain reaction–denaturing gradient gel ele...

Evaluation of antimicrobial activity of a polyhexamethylene biguanide‐coated textile by monitoring both bacterial growth (iso 20743/2005 standard) and viability (live/dead baclight kit)

Journal of Food Safety — Sun, 11 Dec 2011 05:00:00 +0100

ABSTRACTAntimicrobial textiles (65% cotton – 35% polyester) were functionalized using a patented technology that combines an antimicrobial molecule – polyhexamethylene biguanide (PHMB) and a precipitating agent – sodium laurylsulphate. Surface characterization was performed by x‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry, and both techniques made clear signatures of PHMB at the top surface of treated textiles. Washing led to a strong decrease of PHMB concentration at the surface. Comparison of textile surface analysis and antimicrobial tests indicated that the amount of PHMB at its extreme surface of textiles after five or 10 industrial washings was sufficient to inhibit Listeria innocua but not Pseudomonas aeruginosa growth. The viability...

Source diversity of toxoplasma gondii infection during meal preparation

Journal of Food Safety — Wed, 09 Nov 2011 05:00:00 +0100

ABSTRACTPotential sources of Toxoplasma gondii infection, as a foodborne zoonotic disease, and suggested control strategies, were investigated. Samples of fresh buffalo meat (FBM) and imported frozen buffalo meat (IFBM), raw vegetables (RVs) and irrigation water (IW) were examined for the presence of T. gondii infective stages. Serum samples from housewives, regarding their gloves usage, were serologically inspected for T. gondii antibodies. The prevalence of T. gondii tissue cysts in FBM and IFBM were 15.4 and 0%, respectively. FBM had an increased risk of 18.60 times than IFBM. The prevalence of T. gondii tissue cysts in RV and IW were 13 and 16.7%, with 0.78 times increased relative risk, respectively. The total antibodies were significantly differed between nonglove users and g...

Development and clinical validation of a multiplex polymerase chain reaction‐denaturing high‐performance liquid chromatography method for the identification of foodborne diarrheagenic escherichia coli

Journal of Food Safety — Wed, 09 Nov 2011 05:00:00 +0100

ABSTRACTA multiplex polymerase chain reaction (PCR) combined with denaturing high‐performance liquid chromatography (DHPLC) method to simultaneously detect foodborne enterotoxigenic Escherichia coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC) and enteroinvasive E. coli (EIEC) were described. Following the design of PCR primer pairs specific for ETEC, EPEC, EHEC and EIEC, respectively, the multiplex PCR was developed, and then PCR products were subjected to DHPLC analysis under nondenaturing condition. The specificity and potential diagnostic capability of the multiplex PCR‐DHPLC method were evaluated, and results demonstrated that the multiplex PCR‐DHPLC is an effective method to rapidly identify the major four categories of diarrheagenic E. coli...

Aflatoxin determination in black tea (camellia sinensis) – status and development of a protocol

Journal of Food Safety — Wed, 09 Nov 2011 05:00:00 +0100

ABSTRACTAflatoxins, toxic mold metabolites, are naturally contaminants of food and have been reported on tea (Camellia sinensis), but there are no validated methods published for its determination. A method has been standardized incorporating Tween‐20, a nonionic surfactant in the extraction solvent, with use of an immunoaffinity column for cleanup followed by postcolumn photochemical derivatization reversed‐phase high‐performance liquid chromatography. Acceptable recoveries of 76–100% were observed when spiked with aflatoxins B1, B2, G1 and G2. Analysis of market samples of black tea showed the presence of aflatoxigenic molds in 25.9% of samples, and aflatoxin B1 was detected in one sample at a level of 19.2 µg/kg. Aflatoxin production was observed in tea samples artificially i...

Expression of virulence genes of listeria monocytogenes in food

Journal of Food Safety — Tue, 01 Nov 2011 04:00:00 +0100

This study adds new information regarding the heterogeneity within this species. Moreover, it highlights the need to better understand the influence of the different food matrices on the expression of virulence and stress response genes in L. monocytogenes. The reverse transcription‐quantitative polymerase chain reaction approach developed and exploited in this study has the potentials to be applied in the field of food safety in order to provide additional insights regarding the virulence of L. monocytogenes. Such information could be useful in implementing control strategies. (Source: Journal of Food Safety)

Foodborne yeasts serve as reservoirs of helicobacter pylori

Journal of Food Safety — Tue, 01 Nov 2011 04:00:00 +0100

ABSTRACTIt is not clear where Helicobacter pylori establishes in the environment and how it is transmitted to humans. Fifteen yeasts were isolated from 15 food samples. Microscopic examination of yeasts revealed fast‐moving bacterium‐like bodies (BLBs) inside the vacuoles of yeasts. Yeasts were identified as Candida species. Polymerase chain reaction (PCR) was recruited to detect H. pylori‐specific ureAB (urease) and babAB (BabA/B adhesins) genes in the total DNAs of yeasts. The ureAB gene was amplified from 9/15 yeasts and babAB from 2/15. Sequencing of the PCR products of ureAB (406 bp) and babAB (980 bp) genes that were amplified from one yoghurt yeast showed 98% homology with those of control H. pylori. Fluorescent microscopy of stained yeasts showed live BLBs inside the ...

Perspectives on the use of essential oils as antimicrobials against campylobacter jejuni cect 7572 in retail chicken meats packaged in microaerobic atmosphere

Journal of Food Safety — Tue, 01 Nov 2011 04:00:00 +0100

ABSTRACTThe chemical composition of the essential oils (EOs) of Inula graveolens, Laurus nobilis, Pistacia lentiscus and Satureja montana was analyzed using a gas chromatography‐mass spectrometry technique. The main components of EOs obtained were, respectively, bornyl acetate, 1,8‐cineole, β‐myrcene and carvacrol. EOs were screened for their ability to inhibit the growth of Campylobacter jejuni CECT 7572 using the standard agar‐disk diffusion assay. The results obtained, followed by measurements of minimal inhibitory concentrations, indicated that I. graveolens was most active (Φ = 53.3 mm), with the lowest MIC value against C. jejuni (2 µL/mL). EOs were tested in chicken stored in microaerobic conditions at 3 ± 2C, experimentally inoculated with the pathogen a...

Site‐directed mutagenesis, isolation and purification of listeria monocytogenes listeriolysin o and its immunogenicity

Journal of Food Safety — Mon, 24 Oct 2011 16:27:21 +0100

ABSTRACTListeria monocytogenes is a food‐borne pathogenic bacterial species that can cause diseases in humans and animals. A rapid and reliable method for detection of L. monocytogenes is crucial in disease control. Listeriolysin O (LLO), encoded by the hly gene, is the most important virulence factor of L. monocytogenes and a useful identifying factor. We studied the protein structure of LLO with the aim of developing an antibody to be used in an enzyme‐linked immunosorbent assay (ELISA) for detection of L. monocytogenes. By in silico analysis, a Leu52Phe modification of LLO sequence was predicted to increase its immunogenicity. The corresponding modification in the hly gene sequence was achieved by site‐directed mutagenesis. The wild‐type and mutated hly genes were cloned a...

Quantification and antibiotic susceptibility profiles of staphylococcus aureus and bacillus cereus strains isolated from biltong

Journal of Food Safety — Mon, 24 Oct 2011 16:27:19 +0100

This study contributes new knowledge to food processors in the central region of S.A. relating to the production of safe dried meat products. (Source: Journal of Food Safety)

Scopoletin in cassava products as an inhibitor of aflatoxin production

Journal of Food Safety — Mon, 24 Oct 2011 16:27:17 +0100

ABSTRACTThe scopoletin level in a cassava variety from Benin, BEN 86052, and the compounds effect on the growth of an Aspergillus flavus isolate from cassava chips were investigated. The influence on the biosynthesis of aflatoxins was also investigated. Scopoletin was quantified using high performance liquid chromatography. An in vitro test was used to evaluate the inhibitory effects of cassava flour extracts and pure scopoletin on growth and biosynthesis. The A. flavus isolate was genetically characterized to be an aflatoxin producer using polymerase chain reaction. Scopoletin was found in roots and chips with a level ranging from 4.9 to 242.5 mg/kg dry weight. Scopoletin induction was noticed after a peeling and drying process (6 days). Aflatoxin production by a strain of A. flav...

A loop‐mediated isothermal amplification assay for rapid detection of listeria monocytogenes

Journal of Food Safety — Mon, 24 Oct 2011 16:27:15 +0100

ABSTRACTBy amplifying part of the hlyA gene, which encodes the virulence factor listeriolysin O of Listeria monocytogenes, we developed a rapid, sensitive loop‐mediated isothermal amplification (LAMP) assay with a high specificity for the detection of L. monocytogenes in both its pure culture and artificially contaminated chicken specimens. The LAMP assay was highly specific for four strains of L. monocytogenes but not for 16 Listeria spp. and 13 non‐Listeria strains. The LAMP assay, which required a total of 90 min for the whole procedure, was significantly faster than the conventional polymerase chain reaction (PCR) assay, which usually took 160 min. We could also directly identify the presence of L. monocytogenes through the white precipitate of magnesium pyrophosphate in ...

Ochratoxigenic mold and ochratoxin a in fermented sausages from different areas in northern italy: occurrence, reduction or prevention with ozonated air

Journal of Food Safety — Mon, 24 Oct 2011 16:27:13 +0100

ABSTRACTMycotoxigenic molds can grow on the surface of sausages and can influence their safety for consumption. The aim of this study was to investigate the presence of ochratoxin A (OTA) and ochratoxin‐producing molds on the surface of traditional sausages in areas in Northern Italy, including the Central Alps, the Prealps, the Apennines, the Central Padana Valley and the Northeast. We then sought methods for preventing the growth of ochratoxigenic molds and for eliminating them. Our results demonstrated that 24% of the sampled sausages were OTA‐positive, and Penicillium verrucosum, Penicillium nordicum and Aspergillus ochraceus were the main ochratoxigenic molds isolated. Brushing and washing treatments reduced the OTA concentrations on sausage casings to below the Italian law limit ...

Concurrent use of ultraviolet light and citric acid, dimethyl dicarbonate or hydrogen peroxide to inactivate listeria monocytogenes in chill brine

Journal of Food Safety — Mon, 24 Oct 2011 16:27:12 +0100

ABSTRACTChill brine used during ready‐to‐eat meat processing is an important source of postprocessing contamination by Listeria monocytogenes. The efficacy of UV in combination with citric acid (CA; 0.2 and 0.5%), dimethyl dicarbonate (DMDC; 250 and 500 ppm) or hydrogen peroxide (2,000 and 4,000 ppm) was determined to reduce L. monocytogenes in chill brine to below detectable levels after enrichment. Fresh brine solution was inoculated with L. monocytogenes and exposed to UV and/or antimicrobial agent at −1C in a recirculating UV treatment unit. When L. monocytogenes was no longer detectable via direct plating on MOX, enrichment in brain–heart infusion broth was performed, and suspect colonies were confirmed using API Listeria. The combinations of UV + 0.5% CA and UV�...

Potential for microbial contamination of spinach through feedyard air/dust growing in close proximity to cattle feedyard operations

Journal of Food Safety — Mon, 24 Oct 2011 16:27:10 +0100

ABSTRACTTo determine if spinach grown near cattle feedyards can become contaminated with microorganisms, fresh spinach bundles were set upright in polyvinyl chloride pipes within a feedyard. Bundles were located at 0, 20 and 50 yards from the cattle loadout area (dust generation). Control samples were in a Rubbermaid box (Rubbermaid, Huntersville, NC) to prevent environmental contamination. All samples were tested for generic Escherichia coli, E. coli O157 and Salmonella after 6, 12 and 24 h of feedyard exposure. Generic E. coli levels in exposed spinach placed at 0 yards increased by 2.5, 2.6 and 2.7 logs after 6, 12 and 24 h, respectively. These increases were significant when compared with control samples (P = 0.0456). At 20 and 50 yards, there was an increase in generic E...

Occurrence and antibiotic resistance of vibrio vulnificus in seafood and environmental waters in korea

Journal of Food Safety — Mon, 24 Oct 2011 16:27:08 +0100

In this study, we detected high percentages of antibiotic resistance, as well as the presence of V. vulnificus in seafood and environmental waters including the cold‐water seasons. These data can be used in risk assessment protocols designed to establish safety in seafood against V. vulnificus in Korea. (Source: Journal of Food Safety)

Application of supercritical carbon dioxide for microorganism reductions in fresh pork

Journal of Food Safety — Mon, 24 Oct 2011 16:27:06 +0100

This study was conducted to examine the inhibitory effects of supercritical carbon dioxide (SC‐CO2) on microorganisms in fresh pork. With SC‐CO2 treatment at 120 bar and 40C for 30 min, the initial mesophilic plate counts were reduced from 6.23 to 4.54 log colony‐forming units (cfu) per cm2, and the reduction levels of microorganisms, including nonpathogenic Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium and E. coli O157:H7, ranged from 1.99 to 2.51 log cfu/cm2. Even though SC‐CO2 treatment at 120 bar resulted in higher reductions than treatment at 80 bar, the higher temperature or longer exposure times did not always present greater inhibitory effects than the lower temperature or shorter exposure times. Therefore, from an economic point of view, SC�...

Synergistic inhibition of listeria monocytogenes by nisin and green onion extract

Journal of Food Safety — Mon, 24 Oct 2011 16:27:04 +0100

ABSTRACTThe aim of this study was to determine the synergistic effect of nisin and green onion extract (GOE) on the inhibition of Listeria monocytogenes cocktail found in full‐fat milk (M1), fat‐free milk (M2), nano‐calcium milk (M3) and nano‐iron milk (M4). GOE at concentrations of 2, 5 and 8% revealed significant antilisterial effect against L. monocytogenes cocktail in all retail milk. The addition of nisin at concentrations of 75, 150, 225 and 300 IU/mL also showed a good antilisterial effect compared with the control group. Combination of GOE (2 and 5%) and nisin (75, 150, 225 and 300 IU/mL) resulted in synergistic antilisterial activity in all samples tested (M1∼M4) at 14 days. The synergistic antilisterial ability shows the potential application of combining GOE and ni...

An indirect competitive elisa for determination of citrinin

Journal of Food Safety — Mon, 24 Oct 2011 16:27:02 +0100

ABSTRACTCitrinin (CIT)–protein artificial antigen was prepared by conjugating CIT with keyhole limpet hemocyanin by 1,4‐butanediol diglycidyl ether. By immunization and fusion, a hybridoma cell line named K2‐F3, which stably secreted the monoclonal antibody (McAb) against CIT was obtained. The titer of the CIT‐ specific McAbs purified by affinity chromatography came to 1:1.38 × 105. The indirect competitive enzyme‐linked immunosorbent assay (ELISA) showed that the detection limit of CIT was 0.01 ng/mL, with a good linearity ranging from 0.01 to 1.0 ng/mL. The McAb was highly specific and cross‐reactivity rate was less than 0.01%. The data showed that the ELISA developed could accurately determine CIT in the real contaminated red yeast rice samples. The systematic error...

EFFECTS OF ORANGE JUICE pH ON SURVIVAL, UREASE ACTIVITY AND DNA PROFILES OF YERSINIA ENTEROCOLITICA AND YERSINIA PSEUDOTUBERCULOSIS STORED AT 4C

Journal of Food Safety — Mon, 24 Oct 2011 16:27:01 +0100

The objective of this study was to determine the survival, growth rate and possible cellular adaptation mechanisms of Yersinia pseudotuberculosis and Yersinia enterocolitica in orange juice under different pH conditions. Yersinia was inoculated in orange juice with adjusted pH levels of 3.9, 4.0 and 7.0 and stored at 4C for 3, 24, 72 and 168 h. The inter‐and intraspecies variation is significant to the pH and time of incubation variables (P < 0.05). At 3.9 pH the cfu (colony forming units) count decreased significantly.At pH 3.9 and 4.0, Y. enterocolitica and Y. pseudotuberculosis survived for at least 30 and 15 days, respectively. Yersinia that survived under low pH in orange juice revealed enhanced urease activity within 12 h of incubation. The attachment gene (ail) could ...

Validation of heating conditions in production of direct acidified venison with beef fat summer sausage for elimination of escherichia coli o157:h7

Journal of Food Safety — Mon, 24 Oct 2011 16:26:59 +0100

ABSTRACTEffectiveness of a typical production process for eliminating Escherichia coli O157:H7 in directly acidified venison with beef fat summer sausage was evaluated for formulations of different fat content (approximately 10.5 and 18%) and type of direct acidulant (encapsulated citric or lactic acid). Raw batter inoculated with E. coli O157:H7 to an initial level of c. 7.4 log cfu/g was stuffed into 64‐mm casings and processed according to a thermal processing schedule used by a small commercial processor for directly acidified summer sausage products (maximum internal product temperature [I.T.] of 68.3C, followed by cold showering). For all venison sausage, log reductions were 5.8 cfu/g when product reached 64.4C I.T., 6.1 cfu/g when product reach 68.3C I.T., and 5.9 cfu/g when...

Inactivation of pathogenic bacteria by fd&c red no. 3 and high‐pressure processing combination treatment in food systems

Journal of Food Safety — Mon, 24 Oct 2011 16:26:57 +0100

The objective of this study was to determine the efficacy of HPP‐Red 3 to inactivate Listeria monocytogenes and Escherichia coli O157:H7 in two food systems. Sterile carrot juice and turkey product were inoculated with stationary‐phase cells and treated with HPP‐Red 3. Red 3 concentrations of 10–100 ppm in carrot juice with HPP (500 MPa, 1 min, 23C) produced synergistic inactivation of L. monocytogenes. HPP‐Red 3 (100 ppm) combinations in carrot juice caused synergistic inactivation of E. coli. HPP was ineffective at reducing L. monocytogenes in pre‐cooked luncheon turkey product. HPP reduced E. coli in turkey product (3.9 log reduction); however, combination treatment did not significantly increase lethality, regardless of Red 3 concentration. Food systems significantl...

Enhancement of antimicrobial activities of naturally occurring phenolic compounds by nanoscale delivery against listeria monocytogenes, escherichia coli o157:h7 and salmonella typhimurium in broth and chicken meat system

Journal of Food Safety — Mon, 24 Oct 2011 16:26:55 +0100

ABSTRACTPhenolic compounds commonly occurring in fruits, vegetables and tea were studied for their effects on Listeria monocytogenes (L.m.), Escherichia coli O157:H7 (E.c.) and Salmonella Typhimurium (S.T.) in brain–heart infusion broth (BHI) and meat system. Incubated at 37C for 72 h in BHI, gentistic, benzoic and vanillic acids inhibited L.m., E.c and S.T. at 5,000 µg/mL by 2.8 to 3.0 log CFU/mL, 2.8 to 3.0 log CFU/mL and 2.7 to 2.9 log CFU/mL, respectively. Encapsulation of benzoic acid (1,100 µg/mL) in polylactic‐co‐glycolic acid nanoparticles inhibited 6.5 log CFU/mL of L.m. and S.T., and 6.0 log CFU/mL of E.c. at 48 h. In raw and cooked chicken meat systems, nanoparticle delivery of benzoic acid was effective against S.T. and L.m. (1.0 and 1.6 log CFU/g reduction of S...

Irrigation water as a potential preharvest source of bacterial contamination of vegetables

Journal of Food Safety — Mon, 24 Oct 2011 16:26:53 +0100

ABSTRACTThe aim of this research is to determine the bacteriological quality of the irrigation canal from Loskopdam, the two rivers that feed it and vegetables (broccoli and cauliflower) in Mpumalanga, South Africa and also to predict the presence of selected bacterial pathogens in irrigation water and on vegetables with logistic regression analysis. Water and vegetable samples were examined for the presence of total coliforms, fecal coliforms, Escherichia coli, Listeria monocytogenes, Salmonella sp., Enterococcus, Staphylococcus aureus, aerobic spore formers, anaerobic spore formers and aerobic colony counts were done. Apart from bacterial analysis, the following physicochemical tests: temperature, pH, turbidity and chemical oxygen demand (COD) were determined in water samples. The averag...

In vivo effect of mint (mentha viridis) essential oil on growth and aflatoxin production by aspergillus flavus isolated from stored corn

Journal of Food Safety — Mon, 24 Oct 2011 16:26:52 +0100

ABSTRACTThe effect of mint (Mentha viridis) essential oil (EO) on Aspergillus flavus growth and aflatoxin production was investigated in stored corn and evaluated. A. flavus was isolated from stored corn and identified as an aflatoxigenic strain. Conical flasks of 250 mL each containing 100 g of corn were sterilized by autoclave (121C, 15 lbs/in2 for 15 min) and artificially inoculated with A. flavus approximately 106 cfu/mL (control sample). Other samples were inoculated in the same manner as the control, but with the addition of different values of mint EO (50, 100, 200, 300, 500 and 700 µL/100 g corn). Mint EO was fungistatic at all concentrations, fungicidal and antiaflatoxigenic at 300, 500 and 700 µL/100 g corn from 7 days storage up to the end of storage at 21 da...

Genetic variability of toxigenic and nontoxigenic isolates of aspergillus flavus and aspergillus parasiticus by rapd marker

Journal of Food Safety — Mon, 24 Oct 2011 16:26:50 +0100

In this study, we determined the genetic relations between toxigenic and nontoxigenic Aspergillus flavus and Aspergillus parasiticus by random amplified polymorphic DNA (RAPD) markers. Eighteen samples from all 18 pistachio storages of Kerman City (the capital city of Kerman Province) were collected. A total of 51 fungi related to the flavi group were isolated, of which 17 were A. flavus, while the other 34 isolates were A. parasiticus. The amount and type of aflatoxin in all 51 samples were determined by high‐performance liquid chromatography method. Randomly six isolates of A. flavus and 13 isolates of A. parasiticus were selected for further molecular study. The DNA of these isolates was extracted and RAPD was done by five random primers. Data analysis showed that two of 19 isolates c...

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Journal of Food Safety — Mon, 24 Oct 2011 16:26:46 +0100

(Source: Journal of Food Safety)

Enterotoxin gene profile and antibiogram of bacillus cereus strains isolated from raw meats and meat products

Journal of Food Safety — Mon, 01 Aug 2011 04:00:00 +0100

ABSTRACTThe present investigation was undertaken to study the incidence and antibiogram of enterotoxigenic Bacillus cereus in raw meats and meat products. B. cereus was isolated from 97 (37.45%) of the 259 samples analyzed. Recorded incidences of B. cereus from chicken, chevon, mutton, meat products and swab samples were 33.33, 37.20, 39.47, 51.85 and 26.08%, respectively. Screening of isolates by multiplex polymerase chain reaction revealed the overall distribution of various enterotoxin genes hblD, hblA, hblC, nheA, nheB, nheC, cytK and entFM as 64.94, 64.94, 68.04, 97.83, 95.87, 93.81, 65.98 and 100%, respectively. Sensitivity of isolates to a panel of 10 antimicrobial agents revealed gentamicin (100%), ciprofloxacin (98.97%), chloramphenicol (89.69%) and streptomycin (85.56%) to ...

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Journal of Food Safety — Sun, 31 Jul 2011 23:00:00 +0100

(Source: Journal of Food Safety)

Granularity and antibacterial activities of ultra‐fine cinnamon and clove powders