This study aimed to develop the reliable technique called ethidium bromide monoazide-random amplified polymorphic DNA-PCR (EMA-RAPD-PCR) for detection of only viable Salmonella cells due to PCR cannot distinguish DNA from viable and dead cells. In EMA-RAPD-PCR, EMA was used to intercalate the DNA obtained from 1.2 × 10⁶ cells of viable and heat-killed Salmonella Typhimurium and Salmonella Enteritidis. The optimized conditions of EMA treatment for an effective prevention of DNA amplification from dead cells by RAPD-PCR were as follows: the minimum amount of 3 μg/mL EMA; the suitable light exposure time of at least 5 min; and the optimum light exposure distance of 20 cm. To improve a reliability in specific detection of viable Salmonella cells in food samples, use of an optimized 20-h preenrichment in nutrient broth followed by EMA-RAPD-PCR could inhibit the DNA amplification of the dead cells in all artificially and naturally Salmonella-contaminated chicken products tested.

The developed Ethidium Bromide Monoazide-Random Amplified Polymorphic DNA-Polymerase Chain Reaction (EMA-RAPD-PCR) involving 20-h culturing in preenrichment medium is an efficient, reliable and economical procedure to detect only viable Salmonella spp. in food samples. This technique has demonstrated effectiveness in preventing the DNA amplification of dead Salmonella cells. Moreover, the EMA-RAPD-PCR has the potential for use as a rapid, simple and reliable monitoring tool of Salmonella spp. prevalence along the food production chain.

The chemical composition and the biological activities of Mentha pulegium leaves extracts were evaluated. The main components of M. pulegium EO were menthone (41.7%), cis-isopulegone (31.71%) and isomenthone (15.03%). The methanol extract of M. pulegium was rich in phenols and flavonoids. The EO showed much better antioxidant activity than the methanol extract against the DPPH and ABTS radicals scavenging. The EO showed strong antibacterial and antifungal activities against 10 tested microorganisms (Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Pseudomonas aeruginosa, Aeromonas hydrophila, Listeria monocytogenes, Bacillus cereus, Aspergillus niger, Aspergillus flavus, Candida albicans) tested whereas the methanol extract almost remained inactive. The IZ diameters and minimal inhibitrice concentration values for tested microorganisms were in the range of 15–30 mm and 0.05–0.8% (v/v), respectively. Future studies should focus on to determine the usage ability of M. pulegium EO in foods as natural preservative in effective dose.

The replacement of synthetic additives by natural active compounds fosters research on the screening of medicinal plants as sources of new antioxidants. Moreover, such compounds can be used for extension of product shelf life by inhibiting the growth of foodborne spoilage bacteria. This study focused on the evaluation of biological activities of M. pulegium EO because of its application in food industries as a reasonably safe agent.

Thus, this species might be a good candidate for further investigation in developing new antioxidants, as well as preservatives in food against the well-known causal agents of foodborne diseases and food spoilage, particularly E. coli, S. typhimurium, L. monocytogenes, P. aeruginosa and S. aureus.

Morganella morganii was subjected to cold shock treatment at 10C for 2 h or heat shock treatment at 42C for 45 min. The effect of these shock treatments on the viability of M. morganii under adverse conditions was investigated. Viability of M. morganii cells during storage at 4C was slightly affected by cold shock treatment under the conditions tested (P > 0.05). However, a significant increase in the viable population of the cold-shocked cells was found in the subsequent challenge of −18C, as compared with the nonshocked cells (P < 0.05). In addition, cold-shocked cells became more susceptible to high incubation temperature (P < 0.05). Nevertheless, cold shock treatment did not alter the susceptibility of this bacterium to 1.0 mM H₂O₂, 20% NaCl and low pH (pH, 3.5). On the contrary, heat shock treatment increased the susceptibility of M. morganii to low incubation temperatures and H₂O₂, while made the cells more resistant to high temperature. As in the cold shock treatment, heat shock treatment under the conditions tested did not affect the susceptibility of M. morganii to NaCl and low pH.

These findings may be of significant importance with regard to food safety because cooling chains and heating regimes do exist in the food industry, which could potentially induce a cold or heat shock phenomenon.

Fifty-three lactic acid bacteria (LAB) strains from five species of bacteria were isolated and identified from yogurt and Chinese pickled vegetables. Susceptibility of all the isolates to five antibiotics (ampicillin, erythromycin, tetracycline, vancomycin, streptomycin) was tested with disc diffusion methods. All LAB were resistant to streptomycin. Thirty-seven strains were resistant to vancomycin, seven strains were resistant to tetracycline and erythromycin, and six strains were resistant to ampicillin. The corresponding genetic determinants were characterized by polymerase chain reaction. No antibiotic resistant gene was detected among all resistant strains. Biofilm-forming ability was monitored by a modified crystal violet staining method. Among the 53 strains, 32 strains showed different levels of biofilm-forming ability, while 21 strains did not form biofilms. The minimal inhibitory concentration of antibiotics (MIC) and the biofilm inhibitory concentration (BIC) were determined in the 32 strains which can form biofilms. There are significance correlations between biofilm formation and BIC/MIC for all antibiotics (P < 0.05) except vancomycin. Biofilms exhibited increased antimicrobial resistance compared with planktonic isolates, but the extent of enhanced antibiotic resistance in biofilms is different with different antibiotics.

Recently, there are increasing researches focusing on the safety of LAB, due to their antibiotic resistance. However, effects of antibiotic resistance in LAB were different in different application fields. So it is necessary to understand the mechanism of resistance all sidedly. In this study, we found those LAB isolates, which exhibiting antibiotics resistance in the susceptive tests, carried no transferable antibiotic resistance determinant, while there was a significant positive correlation between four antibiotics resistance and biofilm-forming ability. Data derived from this study can be used as a basis for assessing the safety of LAB applied in fermented food.

Along with the popularity of raw sprouts in the food baskets, the outbreaks associated with the consumption of the contaminated sprouts increased. In the present study, the antibacterial effect of the essential oil of Satureja khuzistanica in reducing the Escherichia coli O157:H7 population on alfalfa seeds prior to sprouting was evaluated.

The essential oil (EO) was analyzed by gas chromatography/mass spectrometry. Alfalfa seeds were inoculated with E. coli O157:H7. The inoculated seeds were then treated with different concentrations of the essential oil of S. khuzistanica. The surviving populations of E. coli O157:H7 were enumerated by direct plating of the seeds on tryptic soy agar.

The oil was rich in carvacrol. Direct surface-plating on selective media showed the treatment resulted in a significant (P ≤ 0.05) reduction of E. coli O157:H7 population in a dose-dependent manner. Increasing the washing time revealed a significant effect on reduction of E. coli O157:H7 population.

The considerable antibacterial activity of the oil might be due to the high concentration of carvacrol. As the S. khuzistanica EO did not adversely affect alfalfa seed germination and had a strong antibacterial activity, the oil might be used as a natural antimicrobial product to overcome bacterial contamination of sprouts without compromising the viability.

During the past decades, existing of chemical antibacterial has become increasingly unpopular in food industries. Consumers presume that these chemicals are threats to human health, because of their carcinogenicity, allergenicity, toxicity and environmental contaminations. For these reasons, nowadays, using of organic products is becoming more popular. Moreover, many foodborne pathogens are genetically adapted to synthetic antimicrobial compounds, thereby reducing the efficacy of such preventatives.

It has been known that EOs have antimicrobial activities, rendering these natural products as good alternatives to synthetic bactericides. S. khuzistanica, with high concentration of carvacrol which is classified as GRAS (generally regarded as safe), could be one of these potential alternatives. This antimicrobial property favors its application in food industries as a reasonably safe agent.

The confirmed antibacterial activities of S. khuzistanica, recommends its possible application in the field of food preservation for prolonging the shelf life of sprouts during postharvest and marketing processes.

The viability of a five-strain cocktail of Listeria monocytogenes or Escherichia coli O157:H7 was separately evaluated in/on goetta, a sausage-like meat product, both during extended refrigerated storage and following cooking. At 4C, L. monocytogenes numbers increased from ca. 1.4 to 8.4 log cfu/g over 90 days, whereas E. coli O157:H7 numbers remained relatively unchanged. At 12C, L. monocytogenes and E. coli O157:H7 numbers increased from ca. 1.4 to 9.0 log cfu/g over 28 days. After cooking for 2 to 6 min per side at an external temperature of 176.7C, reductions of 0.7 to 6.6 log cfu/g were observed for L. monocytogenes and E. coli O157:H7. Although goetta supported the growth/survival of L. monocytogenes and E. coli O157:H7 during refrigerated storage, a ≥5-log reduction of both pathogens was achieved by cooking the product for at least 5 min per side at the manufacturer's recommended internal temperature of 73.8C.

Although there have been no reported recalls/illnesses associated with goetta, a specialty/ethnic meat enjoyed as a breakfast item, information is lacking to confirm if goetta would support the growth/survival of foodborne pathogens such as L. monocytogenes and E. coli O157:H7. Thus, we determined if goetta would provide a favorable environment for persistence of these pathogens and, if so, would consumer reheating/storage practices be sufficient to kill any cells of either pathogen that might be present. Our data highlight the importance for proper storage and cooking of specialty/ethnic products such as goetta to extend shelf life and ensure wholesomeness. In this regard, it is significant from a public health perspective that goetta supported growth/survival of L. monocytogenes and E. coli O157:H7, and more importantly that cooking goetta at specific time/temperature combinations can achieve a ≥5-log reduction of both pathogens. These data may be useful for establishing consumer guidelines for storing and cooking/reheating goetta prior to consumption.

Application of natural antimicrobial essential oils (EOs) against foodborne pathogens has been recently developed due to consumer demand. In this study, at first step, the highest concentration of Bunium persicum (Black zira) EO without any undesirable effect on sensory properties on fillet was determined, and then the antimicrobial effect of this EO at 0.05, 0.2 and 0.4% against Listeria monocytogenes was examined in fish model systems for 12 days at 4C. Fish peptone broth, kutum broth and cold smoked kutum broth were inoculated with 10⁴ cfu/mL L. monocytogenes. Black zira EO demonstrated strong inhibitory activity against L. monocytogenes in fish peptone broth, this efficacy significantly decreased in kutum and cold smoked kutum broth (P < 0.05). Black zira EO performance significantly stimulated in broth with 4% NaCl. L. monocytogenes growth rate in cold smoked kutum broth was significantly lower than in kutum broth. Combination of Black zira EO, smoke component, NaCl and low temperature as a Hurdle system has noticeable inhibition on L. monocytogenes growth.

L. monocytogenes is one of the most important biological hazards in marine products and control of this foodborne pathogen via application of antimicrobial EOs could have a great impact on safety promotion of sea foods. This study focused on B. persicum (Black zira) because of its pleasant and proper flavor which supports the application of this EO in fish and fish products traditionally from the past times till now.

The demonstrated antibacterial activity of B. persicum EO against L. monocytogenes, recommends its application as a natural food preservative. Moreover synergistic effect between NaCl, smoke compounds and the EO in a Hurdle system increased the antibacterial activity of Black zira against L. monocytogenes.

The study concerns the presence of Brucella spp. in the stretched curd cheese produced in an area characterized by the presence of a relevant number of herds infected with Brucella spp. One hundred ninety-one cheese samples made with milk from different species were tested by two molecular assays. Positive samples were further submitted to sequence analysis of the IS711 gene. Eleven out of 98 of the samples made with buffalo milk alone resulted contaminated. The prevalence in cheese samples from cow milk alone and milk from cow and buffalo was 2.7% and 10.5%, respectively. No sample was positive to the microbiological Office International des Epizooties detection tests of Brucella spp.

The aim of the study is to evaluate the use of molecular assays as a tool to support microbiological and immunological tests carried out to eradicate brucellosis. Molecular assays shows to be a useful aid for the monitoring of herds health and the safety of dairy products evaluation; furthermore, their application to dairy products allows the implementation of the procedures to trace those infected farms that supply milk to dairies.

Using national polling data from the U.S.A., this study assessed differences between older (>64) and younger (18–64) adults in their levels of concern about getting sick from a hypothetical outbreak and their likelihood of adopting each of several protective behaviors in response to a warning and a recall. Concern levels among older adults were lower than younger adults when outbreak-related illnesses were reported in the same state or town as the respondent, but concern among both increased as cases were reported in closer geographic proximity. Majorities of both older and younger adults reported that they were very likely to adopt a range of recommended protective behaviors, but older adults were less likely to adopt many. For example, if the outbreak was described as mild (no deaths), older adults were less likely to stop purchasing affected items and throw out affected items in the home. Under a severe scenario (with deaths), older adults were also less likely to take several actions, including throwing out the affected item, not purchasing the affected item at stores that sell groceries and not ordering the affected item in restaurants.

The findings from this study suggest there need to be improved communications to older adults in regard to foodborne illness outbreaks. Future communications should focus more on providing actionable information regarding ways that consumers can change their behavior to reduce their risk of infection. For example, it may be important to highlight clear directions for identifying recalled units of foods or drinks so older adults can easily find them if they are in their own kitchens. Communications should also include channels that are better targeted toward older consumers, such as networks of senior services. Materials should follow guidelines that have been shown to be effective with older adults, such as including basic changes like larger font sizes and clear graphics on printed materials.

This study investigated the effects of the essential oils from Origanum vulgare L. (oregano [OVEO]) and Rosmarinus officinalis L. (rosemary [ROEO]) on the membrane permeability, morphology and cell viability of Pseudomonas fluorescens ATCC 11253 in a vegetable-based broth after treatment with one essential oil (OVEO: 5 μL/mL; ROEO: 40 μL/mL) and with a combination of both essential oils (OVEO: 1.25 μL/mL + ROEO: 20 μL/mL). Release of cell material was observed immediately after the addition of the essential oils, both singly and as a mixture, in the growth media. Electron microscopy of bacterial cells exposed to OVEO, ROEO and the mixture of both revealed the following morphological changes after 2 and 3 h of exposure: alteration in the cell wall structure, rupture of the plasma membrane, shrinking of the cells, condensation of the cytoplasmic content and leakage of the intracellular material. Confocal scanning laser microscopy revealed increased cell membrane permeability, which resulted in cell death after short exposure times of 15 and 30 min. A combination of sublethal amounts of OVEO and ROEO could be applied to inhibit the growth of P. fluorescens in vegetables.

Pseudomonas fluorescens is of particular concern in vegetable products, such as minimally processed vegetables, because of its ability to survive and grow at cold environments. The special risk posed by P. fluorescens on the storage and consumption of fresh vegetables has provoked studies on development of novel technologies to control this contamination. In this context, plant essential oils have received particular interest for their potential to control this bacterium in these foods. The findings of our study clearly indicate that the essential oil of Origanum vulgare and Rosmarinus officinalis, singly or in combination at sublethal amounts, caused a decrease in cell viability, loss of cellular material and drastic ultrastructural changes in P. fluorescens. These essential oils combined at subinhibitory concentrations could be rationally applied to control the survival of P. fluorescens in fresh vegetables and give the balance of microbial safety and organoleptic acceptability.

This study evaluated the inactivation of Cronobacter spp. on radish seeds using ClO₂ treatment followed by storage in modified atmosphere (MA) for up to 4 days. Radish seeds were inoculated with Cronobacter spp. (6 log cfu/g), adapted to nalidixic acid and treated with a ClO₂ aqueous solution (0, 50 or 100 μL/mL). The seeds were then stored in an ambient air or MA (10% O₂, 10% CO₂ and 80% N₂; 5% O₂, 10% CO₂ and 85% N₂; or 10% O₂, 0% CO₂ and 90% N₂) for up to 4 days. The Cronobacter spp. (6.2 log cfu/g) populations on the radish seeds were reduced to 3.9, 3.8 or 2.6 log cfu/g after treatment with 0, 50 or 100 μL/mL ClO₂, respectively, and then to 3.7, 3.1 or ≤ 1.6 log cfu/g after 2 h of drying. After 2–3 days of storage under MA (5 or 10% O₂ with 10% CO₂), no Cronobacter spp. were detected on the seeds treated with 100 μL/mL aqueous ClO₂. More than 94.3% of the radish seeds germinated after ClO₂ treatment followed by exposure to an MA, regardless of the ClO₂ concentration.

These results indicate that sprout seeds should be treated with sanitizers at an appropriate concentration. Sanitizer treatment of the seeds is more critical than following storage conditions for enhancing microbial safety. In addition, sprout seeds should be dried or stored after ClO₂ treatment to increase its antimicrobial activity because a greater reduction in microbial populations occurred when the seeds treated with ClO₂ were dried or stored than immediately after the treatment.

In this investigation, the effect of chitosan coating containing anti-browning agents and cinnamon oil fumigation on the microbiological and quality safety of fresh-cut pears was evaluated during 15 days of storage at 4C. The results showed that the combined application of chitosan coating and oil fumigation could retard the microbiological deterioration of fresh-cut pears. The L* value of samples treated by chitosan coating + oil fumigation was 61.15 at the end of storage. This combined treatment prevented product weight loss at the largest extent. Titratable acidity, vitamin C content and total phenolic content in treated slices presented the smallest changes throughout the storage time. Polyphenol oxidase activity of the sample treated by chitosan coating + oil fumigation was 26.90 U/g at the end of storage. These treated slices showed the lowest increase in malondialdehyde (MDA) content (2.9 μmol/g) and the highest overall visual quality values (5.6 scores) after 15 days of storage. These results indicated that the combined treatment of coating + oil fumigation could effectively maintain the microbiological and quality safety of fresh-cut pears.

The growth of food-spoilage microorganisms and surface browning are the major causes of quality loss of fresh-cut pear during the storage time. Chitosan coating with anti-browning agents is useful for inhibiting the browning of tissue surface and keeping the nutrients in fresh-cut fruits. On the other hand, cinnamon oil inhibits the growth of bacteria and molds on sample slices. In this study, the combined application of chitosan coating and cinnamon oil fumigation could significantly control the browning and rot of fresh-cut pear. It could potentially be useful as a technology in maintaining the microbiological and quality safety of fresh-cut fruits.

A total of 339 Enterococcus faecalis strains were isolated from pork production chain, slaughterhouses, processing plants and retails, and were compared with human infection strains for investigating the transmission from animal to human via food production chain. From slaughterhouses to retails, most of antimicrobial resistances and multidrug resistance rates decreased or were not changed significantly. Meanwhile, the prevalence rate of strong or moderate biofilm-forming isolates was highest at retails. In the result of random amplified polymorphic DNA-polymerase chain reaction analysis, there was no strain persisting along the pork production chain or being similar to human strains. Consequently, it is suggested that E. faecalis strains from pork meat would not be delivered to humans by consumption of pork.

Through investigation of antimicrobial resistant bacteria of the pork production chain of Korea, more information and relief would be provided to consumers and its results could help policy making in public health and food safety.

This study investigates the antibacterial mechanism of action of Allium sativum rhizome essential oil (ASEO) against foodborne pathogens. The ASEO was obtained by hydrodistillation of A. sativum rhizome using a microwave-assisted extraction technique. The ASEO (1,000 μg/disk) showed potential antibacterial effect as diameters of inhibition zones against the tested foodborne pathogens including American Type Culture Collection (ATCC) strains Bacillus cereus ATCC 13061, Escherichia coli ATCC 43889, Listeria monocytogenes ATCC 7644, Salmonella Typhimurium ATCC 43174 and Staphylococcus aureus ATCC 12600, which were found in the range of 11.0 ± 0.1–24.0 ± 0.1 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of ASEO against the tested bacteria were found in the range of 62.5–500 μg/mL. At the MIC concentration, ASEO had potential inhibitory effect on the cell viability of the tested bacteria. In addition, the scanning electron microscopy analysis showed the inhibitory effect of ASEO as confirmed by the considerable morphological alterations on the cell walls of B. cereus ATCC 13061 and E. coli ATCC 43889. Moreover, the ASEO revealed its mode of action on membrane integrity as confirmed by the release of extracellular adenosine 5′-triphosphate, 260-nm absorbing materials and potassium ions efflux against tested pathogens. These findings suggest that ASEO showed its effect on membrane permeability and surface characteristics.

Foodborne pathogens are the leading causes of illness in the developed countries. These pathogens are responsible for millions of cases of infectious diseases each year, costing billions of dollars in medical care. New foodborne pathogens and foodborne diseases are likely to emerge driven by factors such as pathogen evolution, changes in food manufacturing practices, and changes to the human host status. Fuelled by these concerns, research on biologically active natural compounds to control the foodborne pathogens has escalated to unprecedented levels in recent years. Plant-based antimicrobials such as essential oils have been found to suppress the growth of foodborne pathogens in various in vitro and in vivo models. These findings clearly indicate that essential oil derived from the rhizome of A. sativum confers its mode of action on membrane integrity, hence, could be used as an affective candidate to control the growth of certain important foodborne pathogens in practical applications.

The objectives of this study were to quantify enteric viruses in shellfish along the Chinese coast and find an indicator of viral contamination in shellfish. One hundred sixty-two samples were collected in August from 10 cities. Hepatitis A virus (HAV), norovirus (NV), rotavirus (RV), poliovirus (PV), astrovirus (AsV) and adenovirus (AdV) were detected by polymerase chain reaction (PCR) and confirmed by sequencing. The percentage of positive samples for each virus was as follows: HAV 5%, NV 12%, RV 7%, PV 15%, AsV 6% and AdV 9%. The six species of shellfish were contaminated with different viruses. PV showed a significant correlation with other viruses, with the exception of RV (P < 0.05). Contamination of shellfish with human enteric viruses was common across a large geographical region of China, indicating a potential public health threat from seafood. The data confirm the potential to monitor the food safety of shellfish by using PV as an index of enteric virus contamination.

Enteric viruses are one of foodborne pathogens transmitted by bivalve shellfish, which pose a severe potential risk for consumers, as well as a serious problem facing researchers. China leads the worldwide production of shellfish. Therefore, the safety of shellfish harvested in China is particularly important. Norovirus, hepatitis A virus, rotavirus, adenovirus, poliovirus and astrovirus are introduced to assess the seafood safety by documenting risks for transmission of enteric viruses in shellfish along the Chinese coast. Of which, poliovirus could be one of these potential indicator to present human enteric virus contamination in the countries where oral polio vaccines are used.

A rapid procedure for two-dimensional pulsed field minigel electrophoresis (2D-mini-PFGE) with high throughput sample format was standardized to separate chromosomal DNA molecules of yeast. Molecules separation in the first dimension (1D) was done in 4.5 h using the contour-clamped homogeneous electric field minichamber. 1D-minigel was negatively stained with zinc-imidazole and the lanes containing the chromosomal bands were excised from the 1D-minigel. The strips were loaded into the second dimension (2D) minigel(s). 2D runs were performed in the single or multiple minigels of the transversal alternating field electrophoresis (TAFE) or multi-TAFE minichamber, respectively, for 7 h. Total running time (1D + 2D) was 11.5 h. The 2D-mini-PFGE resolved co-migrating molecules in the Saccharomyces cerevisiae 1D-electrophoretic karyotypes and detected chromosome length polymorphisms in three distinct strains. Also, the multi-TAFE minichamber allowed obtaining up to 12 2D-DNA patterns simultaneously. This procedure could be suitable for monitoring of industrial yeast strains by molecular methods.

This work reports the standardization of a rapid and economic two-dimensional pulsed field minigel electrophoresis procedure with high throughput sample format to separate DNA molecules with chromosomal sizes. This procedure enhances the resolution of chromosomal DNA molecules in the 1D-electrophoretic karyotypes from microorganisms and reveals chromosome length polymorphisms of different yeast strains without using restriction enzymes. The procedure also includes the staining of the 1D-minigels with zinc-imidazole. It avoids the environmental pollution caused by the ethidium bromide when the 1D-DNA molecules are visualized and prevents DNA damages due to UV-irradiation. The procedure permits to analyze from 1 to 12 DNA samples by 2D-PFGE simultaneously. It could be suitable for maintenance, monitoring and control of industrial yeast strains by molecular methods.

The study aimed to evaluate the efficacy of plant essential oils and their mixtures and to investigate the effect of γ-irradiation on their antibacterial activity. About 2 kGy (C₂) and 4 kGy (C₄) in cumin essential oil, 4 kGy (T₄) in thyme essential oil, and 6 kGy (R₆) in rosemary essential oil were the effective antibacterial dose against Escherichia coli, Salmonella typhimurium, Bacillus cereus and Staphylococcus aureus. The checkerboard method was used to quantify the efficacy of mixtures made from cumin, thyme and rosemary. Fractional inhibitory concentrations were calculated and interpreted as synergy, addition, indifference or antagonism. Most of the mixtures showed indifference efficacy against selected strains. (R₆ × T₄) and (C₄ × R₆) represented additive efficacy against B. cereus and S. typhimurium, respectively. Synergistic effect was observed against B. cereus and E. coli in (C₀ × R₀). (C₂ × T₄) represented a higher minimum inhibitory concentration than (C₀ × T₀). The mixtures of essential oils either irradiated or nonirradiated could be used to minimize essential oil concentrations and to reduce any adverse sensory impact on food.

Essential oils would have to be used in considerable concentrations to achieve an antibacterial potential. Thyme essential oil is individually defined as a higher antibacterial agent against wide spectrum of pathogenic bacterial strains, while cumin and rosemary showed limited antibacterial activity compared to thyme essential oil. The levels of essential oils necessary to inhibit microbial growth are higher in foods than in culture media, thus the quantity of essential oil to be used has a distinctive bitter flavor. The changes made by gamma irradiation increased the antibacterial activity of essential oil at lower doses. The finding of our study clearly indicates that the possibility of using mixtures of essential oils, either irradiated or nonirradiated, would have a synergistic effect and that lower concentrations of the oils could therefore be used.