جستجوی مقالات مرتبط با کلیدواژه "نایسین" در نشریات گروه "دامپزشکی"

This study aims to compare the antimicrobial properties of nisin and natamycin in pasteurized liquid egg whites. After breaking and processing the eggs and performing operations such as filtration and homogenization, the egg white liquid undergoes pasteurization at 56-57 °C for 10 minutes with a flow rate of 1800 m3/s. Following pasteurization, the liquid is mixed with 0.08% and 0.1% solutions of nisin and natamycin in packaging tanks. Microbial tests are conducted at 0, 7, 14, and 30 days of storage. Based on the results, the antimicrobial effect of both natural preservatives nisin and natamycin in the microbial tests of total count, coliform, mold, and yeast have a significant difference at the probability level of 5%. In the total count test, 0.1% nisin on the seventh day exhibits the lowest total count (1.71 log CFU/gr), while the control sample on the 30th day shows the highest (4/49 log CFU/gr). For natamycin, 0.1% on the seventh day and 0.08% on the seventh day have the lowest counts (2.63 log CFU/gr and 2.67 log CFU/gr) respectively, and the control sample on the 30th day has the highest (4.5 log CFU/gr). No microorganism growth is observed in samples containing nisin and natamycin for coliform, mold, yeast, Escherichia coli, Staphylococcus aureus, and salmonella tests. Nisin demonstrates a more intense reduction in total count compared to natamycin, indicating superior antimicrobial properties and increased shelf life over time.

The aim of this study was to evaluate the effect of bacteriocin-nisin-producing strains of standard pathogenic strains in culture medium and raw chicken meat at 12°C. The number of bacteria studied in the control and experiment groups was measured on days 0, 3, 5 and 7 after inoculation. Protein and pH levels in meat were examined on days 0, 3, 5, 5 and 7 after inoculation and the presence of nisin gene in probiotics were evaluated. The data showed that Lactococcus lactis had significant inhibitory effects (p≤0.05) on the pathogens studied in liquid BHI and chicken meat. The pH of chicken meat inoculated with Lactococcus lactis increased significantly (p<0.05) during 7 days of storage at 12°C, from 5.9 ± 0.1 on day 0 to 6.9± 0.2 on 7th day. The average amount of protein in chicken meat inoculated with Lactococcus lactis at 12°C decreased from 17.93 ± 1.05 on day 0 to 14.23±1.25 on 7th day and this reduction in protein was statistically significant (p<0.05). Regarding to the prevalence of probiotic foods and the emergence of positive potential of this type of food products, the present study showed that lactococcal producing nisin can maintain the freshness of chicken and reduce its spoilage by decreasing population of pathogenic bacteria.

Listeria monocytogenes (Lm) is an important foodborne pathogen that is of great importance in milk and its products. Despite the measures taken to eliminate and control Lm contamination in pasteurized milk products, but due to its high spread in the environment, there is a possibility of secondary contamination in products such as Ultra-filtered (UF) white cheese. This study aimed to investigate the inhibitory effect of nisin-producing Lactococcus lactis on Lm in Ultra-filtered white cheese. Ultra-filtrated and pasteurized cow's milk was inoculated with 3 Log CFU/g of standard or native strains of Lm and control and treatment (containing nisin-producing L. lactis) cheese samples were manufactured. Changes in the population of Lm and nisin concentration were estimated throughout the storage period. According to the results, in all groups, the population of Lm began to decrease from day five onwards. Nonetheless, the decreasing trend in the treatment samples and in parallel with the production of nisin was significant (p < 0.01). The native strain of Lm was significantly (p < 0.01) more resistant than the standard one. Since the nisin-producing L. lactis, despite inhibiting Lm, did not negatively affect the growth of starter bacteria and the resulting pH decline of the cheese samples. Consequently, nisin-producing L. lactis can be used to control some bacterial contamination of the UF white cheese. It is also necessary to study the behavior of native strains isolated from food samples along with laboratory strains in inoculation studies.

Due to the synthetic and chemical nature of antibiotics and the phenomenon of body resistance against them, using herbal compounds to cure infections and diseases are being noticed a lot, today. In this study, extracting the herbs was done by soaking in 80% ethanol. Berberis Vulgaris (Barberry root)by HPTLC and Foeniculum vulgare (F. vulgare). Mill (Fennel seed)by GC/MS methods were analyzed. Disk diffusion and micro dilution methods were used to detection of the antibacterial effect in triplicate. Minimal of inhibitory concentration (MIC) between the antibacterial effects of Berberis vulgaris (B. vulgaris) and F. vulgare Mill extracts individually and combined with nisin and sodium diacetate showed a significant difference against Yersinia enterocolitica. Among the studied factors, nisin had the most antibacterial effect and followed by the extract of B. vulgaris and F. vulgare Mill respectively. The antibacterial effect of sodium diacetate against Y. enterocolitica was the lowest. These results were almost consistent with those achieved by disk diffusion method. Our results indicated that MIC of sodium diacetate and nisin combined with the extracts of B. vulgaris and F. vulgare mill had a remarkable decrease compared to each one's effect individually (P<0.05). Results were similar about minimal bactericidal concentration (MBC), which showed simultaneous usage of sodium diacetate with these extracts can decrease the use of sodium diacetate a lonely and its complications. Moreover, combined consumption of extracts with nisin decreases the use of the extracts and the resultant organoleptic changes.

Lactococcusis disease due to Lactococcus garvieae, one of the most important zoonotic bacterial diseases. The purpose of this study was to evaluate the effect of Cinnamon essential oil and Nisin on the growth of Lactococcus garvieae. The effect of cinnamon essential oil with concentrations of 0, 0.25 and 0.75%, and Nisin 0, 0.4 and 0.8 μg/mL on growth of this bacteria at 4 and 8 °C during 0, 3, 6, 9, 12, 15 days of storage was investigated. The results of this study showed that on samples kept at 4 °C, bacterial growth was delayed until the fifteenth day using cinnamon essential oil or Nisin, and in the case of cinnamon, the growth rate of bacteria in the ninth and fifteenth days was below 2 log cfu/g. While the combination of 0.8 μg/ml Nicin and 0.75% essential oil of cinnamon postponed growth on the third day. At 8 °C, Nisin, the cinnamon essential oil alone and in combination (similar to 4 ºC) until the sixth day prevented bacterial growth. Compared to the control treatment, the concentration of Nisin and cinnamon essential oil had a significant difference in inhibitory bacterial growth (P<0.05). The results also showed that the combination of Nisin and cinnamon essential oil, had a significantly higher effect than their single state. Results indicate that Nisin and cinnamon essential oil effectively inhibit the growth of Lactococcus garvieae in the rainbow trout fillet.

Nisin is an antimicrobial peptide used in food industry as preservative. However, this peptide has no considerable effect on gram negative bacteria. In this study the effect of glycation on antimicrobial activity of gram negative bacteria was elucidated against gram negative bacteria. Solution of nisin and fivefold concentration of glucose, lactose and dextran and solution of nisin without any sugar were prepared in phosphate buffer and were lyophilized. The lyophilized powder was exposed to 60°C temperature and 70% humidity for 7 days. Every 24 hours, one sample was collected and dissolved in distilled. Equal molar concentration of native and conjugated nisin were made. Percent of glycation was measured by OPA (ortho-phthalaldehyde) method. MIC50 of nisin was assayed by microdilution method against Escherichia coli and Salmonella typhimurium. The result of this study has revealed that percentage of glycation is conversely related to the size of carbohydrates in which nisin-glucose had the highest and nisin-dextran had the least percentage of glycation. Glycation of nisin increased the MIC50 of nisin against E. coli after seven days. MIC50 of native nisin and glycated nisin had no difference against S. typhimurium. From this study it was concluded that conjugation of nisin with carbohydrates is not able to extend the antimicrobial activity of nisin to gram negative bacteria.

In this study, strains of lactic acid bacteria capable of bacteriocin production were isolated from Lighvan cheese samples obtained from East Azerbaijan, Iran. Among 16 isolates initially identified as Lactococcus lactis, four isolates were phenotipically determined as bacteriocinogenic. The isolates showed inhibitory effect on the growth of Gram-positive food borne pathogens including Staphylococcus aureus, Bacillus cereus, Clostridium perfringens and Listeria monocytogenes by the agar spot test. Selected isolates were PCR-positive for nisin-encoding gene. The strains produced antibacterial substances resistant to α-amylase but sensitive to trypsin and proteinase K. Thermo-stability was indicated after treatment at 100 °C for 30 minutes. The antibacterial activity was pH dependent and occurred in pH 3 and 6, but at pH 9 the antibacterial activity was mainly restricted. No loss in antibacterial activity was recorded after treatment with SDS, Tween20, Tween 80, Triton X-100, urea and EDTA. The results suggest the potential application of these isolates as biopreservatives in food products.

The aim of this study was to determine the effects of nisin (250 international units per gram), chitosan (1%), eringo extract (1%), combination of three material and salt treatment (1.5%) on the quality and sensorial traits of rain bow trout (Oncorhynchus mykiss) roe during refrigerated (4±1 ̊C) storage for 60 days. Lipid, ash, moisture, pH, amount of TVN, TBA, Aerobic mesophilic bacteria, psychrotrophic bacteria, yeast and mold were evaluated at 0, 15, 30, 45 and 60 days. Sensorial analyses of samples were evaluated. The results showed that Chitosan and combinational treatment had significant effect (p≤ 0.05) in decrease of microorganisms after 45 days. In addition, TVN had a significant increase during the time (p≤0.05) but in Chitosan and combinational treatment not observed significant change until 45 days. According to the sensory evaluation, was not significant difference between the chitosan and combination treatments until 45 days. Based on the results of chemical and biological analyses, control, salt, nisin and E.extract were unusable between 0 and 15 days. Therefore, it can be concluded that the use of chitosan improved shelf life and organoleptic properties of fish roes effectively.

Synthetic preservatives have been used as food additives to extend shelf life of foods, but they are strictly regulated due to toxicological concerns and some health problems. So it is increasingly attractive to find out effective and nontoxic measures (e.g. use of natural antimicrobial agent) to delay microbial spoilage. Nisin is a bacteriocin that it is the only bacteriocin permitted for use in foods. And rosemary is one of the medicinal plants. In this study the effect of antibacterial property of various concentration of rosemary extract alone (3 and 4 mg/ml), and with nisin (7 µg/ml nisin 1.5 mg/ml RE and 8 µg/ml nisin 2 mg/ml RE) against Staphylococcus aureus in minced meat were assessed throughout 14 days of storage at 4±1˚C. Leaves and stems of rosemary after drying in the shade were soaking in pure ethanol and alcoholic extract was obtained. The minimum inhibitory concentration (MIC) of RE and nisin were determined against S. aureus using the agar dilution method. Assessment of microbial parameters (total plate count and S. aureus count) was carried out in 0, 1, 3, 7 and 14 days. The data were statistically significant (P

Nisin is a natural preservative produced by strains of Lactococcuslactis subsp. Lactis, has been approved for use in food by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Committee on Food Additives and has been awarded generally recognized assafe (GRAS). It remains the only bacteriocin allowed in food as an addedpreservative. Nisin has a broadspectrum of antimicrobial activity againstgram-positive bacteria, thus one of the problems associated with nisinapplication is inhibition of starter culture and prevention of ripening, which is required for development of cheese characteristics during ripening. In the current study, the effects of different concentrations of nisin and temperature on growth and activity of lactic acid bacteria in model cheeses manufactured fromultrafiltrated milk was evaluated. Cheese samples were supplemented with nisin atconcentrations of 0, 2, 4 and 6 μg/g and stored at 8 and 25 °C up to 60 days. Microbiological and physico chemical properties of the cheese samples were analyzedat 0, 1, 8, 15, 30, 45 and 60 days. Results showed that addition of nisin at concentrations of 4 and 6 μg/g affects (p<0.01) the growth of lactic acid bacteria and so prevents pH reductionduring cheese ripening (p<0.01). Moreover, roomtemperature decreased significantly (p<0.01)nisin activity. According to the results, nisin at concentrations less than 4 μg/g along with refrigeratorstorage temperature could be used as a natural preservative in Cheese manufactured fromultrafiltered milk.

The application of nisin, as one of the most common natural antimicrobial compound, and packaging techniques are effective to extend the shelf-life, preserve the safety and organoleptic characteristics of meat products. In the present study, effect of nisin (30 ppm) on chemical, microbial and sensory properties of emulsion type sausage stored under vacuum packages were investigated. The samples stored for 42 days at 3±1 ºC. One sample from each experiment group was then used every 7 days of storage. Microbial count, pH, CIE L*, a* and b* color parameter, lipid oxidation, production of nitrosomyoglobin and sensory properties were assessed throughout the storage period. The data showed that nisin was able to reduce the growth of mesophilic, psychrotrophic and lactic acid bacteria. But it had not significant effect on pH, color, oxidative reactions, production of nitrosomyoglobin and sensory properties. Therefore, the nisin can lead to better quality preservation of the emulsion type sausages and in extending their shelf life