Residues of tetracycline (TC) groups were quantified in 120 broiler chickens carcasses (including breast, liver and thigh tissues) by high performance liquid chromatography (HPLC) and also four-plate test (FPT) and ELISA methods as primary screening tests. Results of FPT showed that 25% of carcasses were polluted by antibiotic residues. The ELISA assay indicated that out of 30 positive samples in FPT, 21 liver, 16 thigh and 12 breast muscle samples were positive for TC residues. Frequency of TC-like residues and their concentration ranges in ELISA-positive samples were determined by HPLC method. In comparison between the results of these methods, the correlation between FPT and HPLC (0.940) was higher than ELISA and HPLC methods (-0.726). Moreover, this study revealed that an inhibition test with a medium at pH 6 which seeded with Bacillus subtilis had highest sensitivity for detecting of TC residues.
Background: Essential oils usually exhibit different characteristics such as antimicrobial and flavoring effects. The aim of the present study was to investigate chemical composition and in vitro antibacterial activity of the essential oil of Ferulago angulata (Schlecht.) Boiss aerial parts against bacterial food-borne pathogens (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli O157:H7). Methods: The chemical composition of the essential oil was analysed by gas chromatograph coupled with mass spectrometer detector (GC-MS). The antibacterial activity of the essential oil was assessed using broth micro-dilution and agar disk diffusion methods. Results: According to results of GC-MS analysis, 33 constituents were identified. The dominant components were α-pinene (28.43%), (Z)-beta-ocimene (20.12%), bornyl acetate (7.92%), ɣ-terpinene (5.72%), germacrene D (5.63%), myrcene (4.67%) and p-cymene (2.17%). The results obtained in this study showed that L. monocytogenes and B. cereus had the most sensitivity to the essential oil (MIC and MBC= 40µg/mL; Inhibition zone: 9mm). Conclusions: Our results indicated that F. angulata essential oil might be a potential rich source of compounds with antibacterial properties against food-borne bacteria.
The aim of the present study was incorporation of Mentha spicata essential oil (MSO) at three different concentrations (0.5, 1, and 1.5% vol/wt) into raw minced camel meat to extend shelf life and evaluate its antibacterial activity against Listeria monocytogenes for 12 days at refrigerated temperature. Final microbial population (total mesophilic and psychrotrophic bacteria, Pseudomonas spp., Enterobacteriaceae, and L. monocytogenes) decreased approximately 1-4 log CFU/g in treated samples compared to control. The initial total volatile base nitrogen was 8.86 6 0.33 mg/ 100 g and after 12 days reached to 39.2 6 0.13 mg/100 g in control, while it was lower than 25 mg/100 g for treated samples with 1 and 1.5% MSO. At the end of storage time in control samples peroxide value reached to 2.57 6 0.01 meq peroxide/1,000 g lipid, while the values for the treated samples remained lower than 2 meq peroxide/1,000 g lipid. Moreover, during 12 days of storage, odor, color and also appearance of the minced camel meat treated with 0.5% MSO were superior.
Practical applicationsToday as people tend to consume natural foods due to health concerns, the use of natural preservatives such as essential oils is increasing. Around the different parts of Iran Mentha spicata plant is known as a popular flavoring ingredient in home food making. In the present study, M. spicata essential oil as a natural substance could successfully extend the shelf life and control Listeria monocytogenes in fresh minced camel meat stored at refrigerated temperature for 12 days of storage. M. spicata essential oil can be used as a replacement to synthetic preservatives as well as synthetic flavorings in minced camel meat.
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