[Effect of zataria multiflora boiss essential oil and nisin on shelf life in light salted fish fillet of silver carp [hypophthalmichthys molitrix]]

Zataria multiflora is medical plants in Traditional Medicine of Iran. It is necessary to study on antimicrobial effects of essential oil on foodborne pathogens. Nisin is bacteriocin, antimicrobial food preservative. It is regarded as natural because it is a polypeptide produced by certain strains of Lactococcus lactis subsp. lactis [hereafter referred to as L. lactis], during fermentation. This study was performed to evaluate the antimicrobial effects of Zataria multiflora Boiss essential oil and Nisin on the shelflife of light salted fish fillet, silver carp. Effects of different concentrations, Zataria multiflora Boiss essential oil [0, 0.045, 0.135, 0.405 and 0.810%] and Nisin [0, 0.25 microg/ml] were studied on shelf life in light salted fish fillets of silver carp at unfavourable refrigeration storage temperature [10 C] by measuring of microbial flora and chemical values such as pH, thiobarbituric acid [TBA] and total volatile basic nitrogen [TVB-N] and perioxide compared with control group. The results showed that higher used concentrations of Zataria multiflora essential oil [0.135, 0.405 and 0.810%] and Nisin [0.25%] had a significant effect on the shelf life of fish fillets [p> 0.05]. The results showed that Z. multiflora essential oil and nisin have antimicrobial effects and are as a food natural preservative in fish fillet. Also, Total volatile basic nitrogen [TVB-N] increased with growth of microbial flora and TVN in the study was best factor for shelf life changes

Isolation and identification of Campylobacter jejuni from poultry carcasses using conventional culture methods and multiplex PCR assay

Campylobacter jejuni is a major cause of food-borne diarrhea in many countries. Poultry and poultry products are known as important sources of human campylobacteriosis. In this study, conventional culture and multiplex PCR methods were compared for the detection of C. jejuni isolated from poultry carcasses. A total of 100 samples, representing 20 broiler flocks, were collected from poultry carcasses after the evisceration stage in the processing line at a commercial broiler slaughtering facility in Mashhad, Iran. In the conventional culture method, samples were processed by enrichment followed by selective plating, and then suspected colonies were isolated on sheep blood agar and tested for morphology, motility, Gram staining, biochemical properties and hippurate hydrolysis activity. For the identification of the Campylobacter genus and its jejuni serovar by molecular methods, a multiplex PCR assay [m-PCR] with two sets of specific primers was used. In the hippurate hydrolysis test of suspected colonies, 76% of the samples were determined as positive, while in the m-PCR assay 28% of cultures harvested were identified as C. jejuni. Two percent of hippurate hydrolyze negative colonies were found positive in the m-PCR test. It appears that the conventional method, based on the hippurate hydrolysis test for detection of C. jejuni, is a less reliable test. The use of the m-PCR method, based on amplification from conserved genes, allows reliable detection and identification of C. jejuni

[Effect of Zataria multiflora Boiss. essential oil on the behavior of Vibrio parahaemolyticus in salted fish]

Thyme [Zataria multiflora Boiss.] is one of the Iranian traditional spices and it has antimicrobial effect on the pathogenic bacteria which are agents for some current food borne intoxications. The aim of this study was to evaluate the antimicrobial activity of Zataria multiflora Boiss. essential oil on V. parahaemolyticus in salted [8% Nacl in tissue] silver carp. Effect of different concentrations of this Essential oil [0.0%, 0.045%, 0.135%, 0.405%, 0.810%] on behavior of V. parahaemolyticus in two temperatures [15, 25 C] was determined by evaluation of the bacterial growth in salted fish fillets. The essential oil in used concentrations had significant inhibitory effect on the growth of V. parahaemolyticus in salted fish compare with control treatment during the storage time [p<0.05]. There was no significant difference between all treatments. The results showed that Zataria multiflora Boiss. Essential oil had inhibitory effect on V. parahaemolyticus, therefore it can be considered as a natural preservative in salted fish

[Study on the growth of Staphylococcus aureus in processed fillets of silver carp with salt and nisin]

There is increasing demand for use of natural preservatives such as bacteriocins to control foodborne pathogens in seafoods. This study was performed to evaluate the antimicrobial effects of Nisin on Staphylococcus aureus in light and heavy salted silver carp fillets [4 and 8% NaCl]. Effect of different concentrations of Nisin [0, 0.15, 0.25, 0.75, 1.5 micro g/ml] on behavior of S.aureurs at unfavourable refrigeration storage temperature [10 [degree sign]C] was determined by evaluation of the bacterial growth in salted fish fillets. The results showed that used concentrations of Nisin had inhibitory effect on the growth of S.aureus in light and heavy salted fish fillets compared to the control [p<0.05]. This study showed inhibitory effect of Nisin on the growth of S.aureus. Therefore it can be considered as a natural preservative in light and heavy salted fish

Evaluation of Zataria mutiflora boiss. Effect on staphylococcus aureus in Feta Cheese

Thyme [Zataria multiflora Boiss] is one of the Iranian traditional spice and it has antimicrobial effect on the pathogenic bacteria which are agents for some current food borne intoxications. Evaluation of antimicrobial effect of mentioned plant essential oil on Staphylococcus aureus in Feta cheese. The essential oil of this plant was obtained by hydrodistillation and analyzed by GC/MS. Effects of different concentrations of this essential oil on Staphylococcus aureus were determined by evaluation of the microorganism growth on the selective media in laboratory, and these effect on the growth of Staphylococcus aureus and when the mentioned concentrations of the essential oil were used in combination with cheese starter culture, the counts of the pathogen were decreased significantly below its toxic dose in this kind of food product. The antimicrobial effect of Zataria multiflora Boiss. in 300 ppm was higher than its lesser concentrations and with concern to the control groups, the synergistic effect between the starter and the essential oil is necessary to achieve this inhibitory effect