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To predict Listeria monocytogenes population during storage (8 °C) as a function of time (1–16 days), cinnamon essential oil (EO), ZnO nanoparticles (NPs; 10–30 nm), and two different genotypes in liquid microbiological medium, an adaptive neuro fuzzy inference system (ANFIS) was developed. For this purpose, 32 modeling scenarios were investigated. The ANFIS scenarios were fed with 4 inputs of EO concentration (0, 0.8, 1.6, and 2.4%), ZnO NPs (0, 5, 10, and 15 mg/ml), strain (2 strains), and storage time (1–16 days). Our findings demonstrate that the final ANFIS architecture with triangular-shaped membership function (MF) provides the best prediction accuracy (RMSE = 0.214; R2 = 0.974) over models with other MFs. Moreover, the effects of antibacterial activity of cinnamon EO were investigated in a food model system, vegetable broth. The bacterial counts decreased with increasing cinnamon oil and ZnO NPs concentrations; however, some strain variation was observed. These observations demonstrate the reliability of the ANFIS model for prediction of L. monocytogenes population and confirm its potential use as a supplemental tool in predictive microbiology.

The virulence potential of Listeria monocytogenes is not a stable property and can be greatly affected by diverse environmental conditions and stresses. For example, the addition of essential oils (EOs) into the formulation of foods, as well as the time and temperature of the treatment process, can affect the virulence gene expression of L. monocytogenes. The aim of the present study was to assess the transcriptomic response of L. monocytogenes isolate on the exposure to Zataria multiflora Boiss. essential oil (ZEO) in fish storage resembling conditions. The expression of four different genes of L. monocytogenes (hly, prfA, inlA, and inlB) was assessed by the reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) during growth in two different growth mediums (broth and minced rainbow trout fish), treated by sub inhibitory concentrations (subMIC) of ZEO at select times (0 h, 24 h and 48 h) and temperatures (12 °C, 22 °C and 37 °C). The mixed responses of gene regulation for L. monocytogenes were obtained in response to the differences in the type of growth medium, dose of ZEO, time, and temperature of treatment. Our results show that the application of EO at acceptable sensory amounts (

The overall objective of this study was to develop antimicrobial nanocomposite films to control the growth of foodborne pathogens. In the first step, the antibacterial effects of clove, coriander, caraway, marjoram, cinnamon, and cumin essential oils were studied against three important food pathogens, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes by application of agar diffusion assay. The intensity of antimicrobial efficacy was in the following order: marjoram > clove > cinnamon > coriander > caraway > cumin. In the next study, the three most potent essential oils were subsequently incorporated into alginate/clay nanocomposite films. The antibacterial effectiveness of the prepared films against E. coli, S. aureus, and L. monocytogenes was studied during 12 days. The antibacterial activity of the essential oils was maintained when incorporated into the nanocomposite film. The nature and amount of the essential oils play an important role in the film’s antimicrobial activity. In all film matrices, marjoram showed the highest antimicrobial activity. Films with 1.5% marjoram decreased the numbers of L. monocytogenes, E. coli, and S. aureus populations with respect to the control up to 6.33, 4.52, and 5.80 log, respectively.

Food poisoning caused by Listeria monocytogenes leads to a 30% rate of mortality among patients. The antibacterial activity of cinnamon, thyme, and rosemary essential oils (EOs) and shallot and turmeric extracts was tested against L. monocytogenes using agar well and disc diffusion techniques. Results showed that thyme EO had the highest antimicrobial activity, followed by cinnamon and rosemary EOs, respectively. The antilisterial activity of thyme EO at 0.4%, 0.8%, and 1.2% levels, nisin at 500 or 1000 IU/g level, and their combination against L. monocytogenes was examined in minced fish samples. The antilisterial properties of nisin were also investigated in cooked minced fish treatments. Nisin at 500 or 1000 IU/g in the minced fish meat demonstrated bacteriostatic activity against L. monocytogenes. The use of thyme EO at 0.8% and 1.2% reduced the L. monocytogenes viable count below 2 log cfu/g after 6 days. Furthermore, simultaneous use of thyme EO at 0.8% and 1.2%, and nisin at 500 or 1000 IU/g level, reduced the L. monocytogenes viable count below 2 log cfu/g after the second day of storage. The antilisterial activity of nisin in the cooked minced fish samples was slightly stronger than that of the raw group.

Iranian Kefir type drink (IKTD) is a highly consumed, traditional Iranian, fermented milk product. To improve monitoring procedures for food safety 32 industrial Kefir type drinks from 4 brands and 8 different production dates as well as 32 samples from pasteurized milk of the same Kefir manufacturers and air of the production sites were analyzed for contaminations. 16S rDNA extraction from Kefir samples as well as 16S rDNA obtained from samples incubated on Columbia agar were analyzed using PCR/DGGE, cloning, sequencing and phylogenetic classification. Already DGGE analysis indicated contaminations including Bacillus strains. Subsequently analysis of cultured clones indicated contaminations with Bacillus sp. including Bacillus cereus, Bacillus thuringiensis and Paenibacillus sp. in 9 (28%) from all analyzed samples. Also 38% of pasteurized milk samples were contaminated with B. cereus. The average count of B. cereus was 74 ± 19 cfu/ml. B. cereus and B. thuringiensis were found as contaminant bacteria in the air of the all manufacturing sites. These results suggest that milk is one of the most important sources of contamination with Bacillus sp., especially B. cereus for Kefir products in Iran. But bacterial contamination in Kefir samples might also originate from the air of the production sites. 16S rDNA analysis accelerates monitoring strategies.

Shrimp is one of the most important fishery products of Persian Gulf coastal provinces of Iran. Sea foods are prone to bacterial contamination and could cause health risk to the consumers. To examine shrimp caught off the south coast of Iran, 770 samples of fresh shrimp collected from either sea or shrimp farm were tested for possible presence of Vibrio spp. Twenty-five grams of homogenized sample diluted with 225 ml of alkaline peptone water contains 1% NaCl, pH=8.6 and remained in 37 °C for 6–8 h. After primary enrichment, TCBS was used as selective medium for separation of Vibrios colonies. Vibrio spp. were separated from 16 samples out of 770 sample that represent for 2.1% of collected shrimp samples. Separated Vibrio spp. were V. parahaemolyticus , V. damsela , V. alginolyticus and V. fluvialis . However, no contamination of shrimp with V. cholerae was observed. It should be mentioned that Vibrios such as V. damsela , V. alginolyticus and V. fluvialis are indigenous to the marine environment and shrimps. Cultivated shrimp in Iran is washed with fresh water contains 2–7 ppm chlorine and freeze at −40 °C.