جستجوی مقالات مرتبط با کلیدواژه « فعالیت ضد میکروبی » در نشریات گروه « صنایع غذایی »

In this research, in-vitro time- kill curve effect of nano-ZnO loaded nanoliposomes against Bacillus cereus (ATCC 11778) and Pseudomonas aeruginosa (ATCC 9027) were evaluated. Thin layer hydration sonication and heat methods were evaluated to preparation of nano-ZnO loaded nanoliposomes at different level of lecithin: nano-ZnO ratio (5:1, 15:1, and 25:1 w/w). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of nano-ZnO loaded nanoliposomes and free nano-ZnO against Bacillus cereus and Pseudomonas aeruginosa were determined. Results showed that the encapsulation of nano-ZnO in nanoliposome systems significantly increased their antimicrobial activities. Nano-ZnO loaded nanoliposomes were prepared at the highest ratio of lecithin: nano-ZnO ratio (25:1 w/w) showed higher antimicrobial activity compared to those prepared by heat method. From the time- kill curves, the log phase growth of Escherichia coli (8 hours) and Staphylococcus aureus (7 hours) in the medium containing nano-ZnO loaded nanoliposomes prepared through the thin layer hydration sonication at the highest level of lecithin: nano-ZnO ratio (25:1 w/w) at MIC and MBC values decreased to 3 and 3 hours and to 1 and less than 1 hours, respectively.

In this study, the extract of Hypericum Perforatum aerial organs was prepared by hydro alcoholic solvent and the extract was coated in calcium alginate nanoparticles and the antimicrobial properties of the extract and nanoparticles on four gram-positive, gram-negative yeast and mold groups were investigated and Nanocapsules containing extract were evaluated on the shelf life of white cheese. To prepare Nano-extracts, the emulsion production method of alginate-calcium Nanocapsules containing the extract was used. The production of Nanocapsules containing the extract was done by adding calcium chloride nanoparticles to the alginate Nanoemulsion containing the extract in a ratio of 1 to 6 for 4 hours. To prepare the cheese, Staphylococcus aureus, Escherichia coli, and Candida albicans yeast are inoculated separately into the milk at a rate of 103 CFU / ml and then added calcium chloride, Rennet enzyme, extract and Nanocapsules containing extract to milk were done and the microbial properties of the cheese samples were evaluated on the day of production and up to seven days after. The results of particle size determination, particle size dispersion index, and potential and efficiency of encapsulation for the production of Nanocapsules containing Hypericum Perforatum extract and its microscopic examination confirmed the production of nanoparticles with appropriate efficiency of encapsulation. Also, the results showed that for all three microorganisms tested, the sample containing Nano-extract was able to reduce about one logarithmic cycle of the inoculated microorganism and during the shelf life of gram-positive, gram-negative and yeast had a downward trend (P <0.05). The results of the present study showed that using plant extracts containing antimicrobial compounds such as extracts of aerial organs of Hypericum Perforatum plant, especially in Nanoparticle and in appropriate quantities, as an alternative to synthetic preservatives, produce a healthy food product and with longer shelf life, it will be possible.

In this study, the antimicrobial properties of bacterial cell and cell free culture supernatant of Lactobacillus helveticus was investigated both in vitro and in vivo (food). For this purpose, at first, cell free culture supernatant (CFS) was prepared from the mentioned Lactobacillus strain and then divided into three groups (control, treated by heat (100 °C for 15 min) and neutralized by NaOH). Antimicrobial activity of supernatant treated or no treated was investigated utilizing agar well diffusion and Disk diffusion method against two pathogenic bacteria including Salmonella enterica subsp. enterica and Staphylococcus aureus. Moreover, the antimicrobial activity of L. helveticus in cherry juice was evaluated during 24 h of incubation. The results showed that unheated and heated CFS were able to inhibit both pathogenic bacteria, but neutralized CFS had no antimicrobial activity. Inoculation of L. helveticus in cherry juice effectively (P <0.05) prevented the growth of Salmonella and Staphylococcus during the fermentation period. Therefore, based on the results, L. helveticus and its CFS can be used as an alternative to chemical preservative and as a natural antimicrobial source in the food industry.

The aim of this study was to determine the functional groups and qualitative identification, the amount of phenolic and flavonoid compounds, antioxidant and antimicrobial activity of Lavandula stricta essential oil. Essential factor groups were determined by Fourier transform infrared (FTIR) spectroscopy in the wavelength range of 500–4000 cm-1. Total phenols and flavonoids were measured by Folin-Ciocalteu and aluminum trichloride colorimetry, respectively. Antioxidant activity was also determined by two methods of free radical scavenging DPPH and ABTS. The peaks observed in Lavandula stricta essential oil confirmed the presence of O-H, C-H, C=O, C=C, C-C and C-O functional groups of bioactive compounds. The amount of phenol and flavonoids in total essential oil was 68.60±0.68 mg GAE/g and 19.10±0.52 mg QE/g, respectively. Antioxidant activity was also obtained based on the percentage of free radical scavenging DPPH and ABTS equal to 59.50±0.63 and 67.68±0.53, respectively. The antimicrobial activity of essential oil was evaluated by four methods disk diffusion, agar well, minimum inhibitory concentration and minimum bactericidal concentration. The results of measuring the antimicrobial activity of essential oil by disk diffusion and agar well showed that Gram-positive bacterium Staphylococcus aureus is the most sensitive strain to Lavandula stricta essential oil. The minimum inhibitory concentration of essential oil for Salmonella typhi, Pseudomonas aeruginosa, Listeria innocua, Staphylococcus aureus and Escherichia coli was equal to 3.125 mg/ml and for Bacillus cereus it was equal to 6.25 mg/ml. The minimum bactericidal concentrations for Listeria innocua, Pseudomonas aeruginosa and Salmonella typhi was equal to 100, 200 and 400 mg/ml, respectively, and for other bacteria (Staphylococcus aureus, Bacillus cereus and Escherichia coli) it was more than 400 mg/ml.

The toxic effects of synthetic antimicrobial and antioxidant compounds have led to an increase in the use of natural types, such as plant extracts. In this study, the antimicrobial effect of Lawsonia inermis aqueous extract was investigated against Escherichia coli, Salmonella typhimurium, Staphylococcus epidermidis, and Listeria innocua, by disc diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration methods. The higher concentrations of the extract showed higher antimicrobial effects against S. epidermidis and L. innocua compared to E. coli and S. typhimurium. Moreover, the total phenolic and flavonoids contents of the extract were 59.45±1.12 mg gallic acid per gram of extract and 40.35±0.70 mg quercetin per gram of extract, respectively. The antioxidant properties of aqueous extract were measured based on the DPPH and ABTS free radical scavenging activities. It was found that the antioxidant activity increased significantly as a function of L. inermis aqueous extract concentration. The antimicrobial and antioxidant properties of L. inermis leaf aqueous extract could make it a natural bioactive compound to be used as in food and medicinal products.

Evaluation of antimicrobial activity and phenolic compounds of alcoholic citron (Citrus medica l.) peel inner layer extract in the lemon carbonated drinks Citrus fruits are rich sources of different vitamins, minerals, and fibers. In recent years, more attention has been paid to the antibacterial properties of non-edible parts of fruits (Tavasoli et al., 2009). Citron (Citrus medica L.) is one of the species of citrus fruits (Dalia, 2014). Flavored essential oils of this fruit (located in the outermost layer, pigmented layer of peel) are also regarded as an antibiotic. The citron juice along with honey is also known as an effective antidote to poisons. Citron peel contains citronellal, terpenes, aldehydes, ketones, esters, alcohols, and organic acids. Limonene neutralizes the effect of pathogenic microbes. Geraniol and other monoterpenes found in the extract of citron peel have also anti-cancer properties (Mina et al., 2011). Carbonated beverages are products made by a mixture of water, carbon dioxide, additives, and sugar, or other sweeteners (Elhami Rad & Mohammadi, 2006). The harmful effect of consuming industrial soft drinks can be examined from different perspectives (Bawa, 2005). There are some reports that show benzene forms by a reaction between benzoate in soft drinks and ascorbic acid, which is a cancer-causing compound. Due to the health risks attributed to consumption of industrial soft drinks, many researchers are looking for ways to optimize the consumption of natural drinks, as synthetic materials make up most of the compounds used in industrial soft drinks (hunter, 2003). In this study, given the beneficial effects of citron, the ethanolic extract of citron peel was used as a preservative compound in the formulation of lemon soft drinks, and its antimicrobial activity against microorganisms contaminating soft drinks was studied in a culture medium and lemon carbonated beverages. In this study, the ethanolic extract of citron peel with concentrations of 0, 0.8, 1, 1.5, and 2 mg/ml, as a preservative composition, was added to the formulation of lemon soft drinks, and its antimicrobial activity against the microorganisms contaminating the soft drinks, including Lactobacillus delbrueckii, Leuconostoc mesenteroides, Saccharomyces cerevisiae, Candida krusei, was investigated. The total amount of phenolic compounds in the produced lemon soft drinks was also measured based on the Folin-Ciocalteu method (Lin & Tang, 2007). The characteristics of color, taste, and flavor, and the overall acceptability of the produced samples were evaluated using 10 evaluators by the hedonic method and through completing the assessment questionnaire (Karami et al., 2012). Data were analyzed based on a completely randomized design, with the help of ANOVA, and using SPSS ver. 19 software. The charts were plotted using Excel software. The statistical comparison of results was also conducted at a 95% confidence level. The results showed that the ethanolic extract of citron peel exhibited an inhibitory effect on the microorganisms studied. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Lactobacillus delbrueckii bacteria against the citron peel extract were assessed as 0.6 mg/ml and 0.8 mg/ml, respectively, whereas, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Leuconostoc mesenteroides bacteria were the same, 1 mg/ml. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of yeast saccharomyces cerevisiae and candida krusei were evaluated as the same value of 0.8. The ethanolic extract of citron peel exhibited an inhibitory effect on microorganisms of Lactobacillus delbrueckii, Leuconostoc mesenteroides bacteria, saccharomyces cerevisiae, and yeast candida krusei. The results of the total count of mesophilic aerobic bacteria (CFU/ml) indicated the antimicrobial activity of citron peel extract in lemon soft drinks. The citron peel extract, with its antibacterial properties, was able to reduce the microbial load of the samples containing the extract by approximately the same amount as the sample containing sodium benzoate. The count of acid-resistant microorganisms showed that the citron peel extract has an antimicrobial activity in the lemon soft drink. In the control and T_4 (2 mg/ml) treatment samples, in which there was a high concentration of the citron peel extract, the count of acid-resistant bacteria dropped to zero over the time of storage, and no growth was observed in them. The results indicated the antimicrobial activity of citron peel extract in the lemon soft drink (yeast and molds count (CFU/ml). There was no significant difference between the produced treatments and the control sample at day 0 (P>0.05). The T_1, T_2, and T_3 treatments, which had lower amounts of the extract, had a significant difference with other samples at day 30, 60, and 90 of the test, and they also had higher colony counts than the control and T_4 (2 mg/ml) treatment samples (p < 0.05). In all the studied treatments, expect for T_4 treatment, there was an increasing trend in the amount of yeast and molds, and then over time, the amount of yeast and molds dropped to zero in the control and T_4 (2 mg/ml) treatment samples, so that the yeast and molds count for these treatments at day 90 of the test reached the range declared by Institute of Standards and Industrial Research of Iran (negative), which shows the antibacterial properties of citron peel extract. The results of studying the amounts of phenolic compounds of the produced soft drinks showed that by increasing the amount of citron peel extract, the amount of phenolic compounds in the produced soft drink also increased, which can be due to the rich content of phenolic compounds in the citron peel extract. Considering the acidic pH, the amount of phenolic compounds in the produced lemon soft drinks containing citron peel extract retained during the storage period, and significantly increased after 30 days, and then remained constant. There was a significant difference between the produced treatments and the control samples at day 0 and other studied times, and the amount of phenolic compounds measured in all the treatments containing the citron peel extract was significantly higher than that of the control sample (p < 0.05). By increasing the amount of the citron peel extract, the amount of phenolic compounds also increased. The results of sensory evaluation showed that there was no significant difference between all the treatments containing the citron peel extract and the control sample in terms of taste, flavor, and color (P>0.05). By increasing the amount of citron peel extract, the rates of taste, flavor, and overall acceptability decreased compared to the control sample, however, this rate was not evaluated as significant by the evaluators (P>0.05). The evaluators were not able to detect a difference with the control sample in terms of color, and this parameter had no significant difference with the control sample (P>0.05). The results of this study indicated that the citron peel extract, by having antimicrobial, phenolic, and antioxidant properties, has an antimicrobial activity against the microorganisms contaminating soft drinks. The results showed that, by adding the citron peel extract with a rate of 2 mg/ml, lemon soft drinks with more desirable microbial quality and chemical properties can be produced that can compete in terms of sensory evaluation with the lemon soft drinks containing sodium benzoate. Keywords: Lemon Soft Drink, Extract, Citron Peel, Phenolic Compounds, Antimicrobial Activity

In this study, ZnO nanoparticles less than 30 nm in spherical shape and using simple and eco-friendly method was fabricated. ZnO nanoparticles in between of metal oxides have maximum interest because they are inexpensive to produce, safe and can be prepared easily. This metal oxid has potential applications like antibacterial, antifungal, anti-diabetic, anti-inflammatory, wound healing, and antioxidant. In the present article, Zinc oxide nanoparticles were synthesized by both chemical and green methods. Thymus pubescens leaf extract was used as a reducing agent and stabilizer in the green synthesis of ZnO nanoparticles. The crystalline structure, chemical elements, morphology, weight variations, functional groups, and optical characteristics of the fabricated ZnO nanoparticles were characterized by XRD, EDX, SEM, TGA, FT-IR, and UV-vis DRS instruments. The results of the XRD and SEM were confirmed the size and morphology of nanoparticles less than 30 nm in spherical shape. Furthermore, the presence of some biocompounds from the extract on the prepared nanoparticles was recorded by TGA, FT-IR, and UV-vis DR spectra. The anti-bacterial activities of the nanomaterials were studied by CFU method. The biological function of the synthesized ZnO nanoparticles showed a favorable anti-microbial efficacy against gram-negative (E. coli) and gram positive (S. aureus) bacteria. Our results indicated that the fabricated ZnO nanoparticles using Th. pubescens leaf extract, against E. coli (13.1 ± 0.46) have the highest anti-bacterial activity than that of S. aureus (17.8 ± 0.35). Therefore, the ZnO nanoparticles can be introduced as a potential proficient disinfectant.

In this study, the extract components, antioxidant properties, total phenol, antimicrobial activity, alpha-glucosidase inhibition of the leaf and seed extract of Moringa Peregrina were measured. Essential oil extracted from Moringa seeds and leaves were placed in an ultrasonic bath for 40 minutes and then distilled in a Clevenger apparatus for 3 hours. Flame detector gas chromatograph was used to identify the percentage of essential oil component in Moringa Peregrina seed and leaf. Antioxidant activity of the essential oil was determined by ABTS free radical scavenging method. Also, the total phenol content was measured by Folin-Ciocalteu reagent. Antimicrobial activity of the essential oil was evaluated by disk diffusion method for Staphylococcus aureus, Escherichia coli, Bacillus cereus and Penicillium notatum. PNPG was used as a substrate to determine the inhibitory property of α-glucosidase. The results showed that the use of ultrasonic pretreatment significantly increased the extraction rate of leaf and seed extract of Moringa (p<0.05). The percentage of essential oil extracted from Moringa Peregrina leaves was higher than the essential oil extracted from Moringa Peregrina seeds (p<0.05). The main constituent in the essential oil of this plant seed is isothiocyanic acid (41.44%) and the main composition of the essential oil of Moringa Peregrina leaf, farnesyl acetone (22.72%). The essential oil of leaf and seed of Moringa Peregrina has free radical scavenging properties and phenolic compounds (0.025 mg/ml Gallic acid) that can be considered as antioxidant plant. The essential oil of Moringa Peregrina seed has anti-microbial properties against the bacteria Staphylococcus aureus and Escherichia coli and the fungus Penicillium nutatum. The essential oil of Moringa leaf showed no antimicrobial activity. The concentration of essential oils of leaf and seed of Moringa Peregrina that IC50 (alpha-glucosidase 50% inhibition) was 0.03 mg/ml. The essential oil of this plant can be used to produce functional foods.

Antimicrobial packaging has a potential to prevent pathogenic microorganisms and also increases the shelf life of meat products. The aim of this study was to determine mechanical and physical properties of Carboxymethyl Cellulose (CMC) containing Trachyspermum ammi and Myrtus Communis essential oils (0.1, 0.3, 0.6 and 1%). Then antimicrobial packaging with optimum concentration of essential oil (0.6 and 1%) was selected to evaluate the effect of packaging on microbial and physical properties of turkey meat during storage at refrigerator. The results showed that tensile strength decreased and percentage of film elongation increased significantly. Water absorption, moisture content, solubility and water vapor permeability decreased when the concentration of the essential oils increased. Film prepared using Trachyspermum ammi essential oil had high antimicrobial activity compared with Myrtus Communis essential oil. Turky meat which packed using film containing 0.6% Trachyspermum ammi essential oil was more effective against total bacterial count than 1% essential oil. In contrast, the film containin 1% essential oil showed high antimicrobial activity against coliform and E.coli. Therefore, the film containing essential oil increased the shelf life of turkey meat, and application of 0.6% Trachyspermum ammi essential oil film as an effective treatment is recommended.

In this study, the chemical compositions, total phenolic content, antioxidant power and the antimicrobial effect of Heracleum lasiopetalum essential oil on Enterobacter aerogenes, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria innocua and Candida albicans were determined. The essential oil was extracted by hydrodistillation. Its chemical composition was determined through gas chromatography-mass spectrometry in comparison with standard mass spectra. Total phenolic content and antioxidant activity were measured using the Folin-Ciocalteu and DPPH scavenging methods. The essential oil antimicrobial activity was quantified by disk diffusion, well diffusion agar, minimum inhibitory concentration and minimum bactericidal/fungicidal concentration methods. Eucalyptol was the major constituent of the essential oil with a percentage of 30.75. The total phenolic content and antioxidant power of the essential oil were 35/44±0.95 mg GAE/g and 24.20±1.60 mg/ml respectively. The antimicrobial activity based on disk diffusion and agar well showed that Candida albicans was the most sensitive species to the essential oil. The minimum inhibitory concentration of the essential oil was equal to 16, 16, 4, 8 and 4 mg/ml for Pseudomonas aeruginosa, Enterobacter aerogenes, Staphylococcus aureus, Listeria innocua and Candida albicans respectively. The results of the bactericidal and fungicidal concentrations were totally equal to or higher than those of the minimum inhibitory concentration. The results revealed that Heracleum Lasiopetalum essential oil has appropriate antioxidant power and is able to control the growth of foodborne pathogens and can be utilized as a natural preservative in food industry.

Evaluation of the antimicrobial activity of plant extracts and essential oils has grown dramatically in recent years. In this study, the antimicrobial effect of Cardin extract (Biarum bovei) in vitro and hamburger on Escherichia coli and Staphylococcus aureus bacteria and total countt is investigated. At first, different concentrations of Cardin hydroalcholicextract was prepared. Antibacterial effects of extracts were evaluated by agar method (disc and wells), minimum inhibitory concentration and minimum bactericidal concentration (by dilution method) and time-killing curves. Antimicrobial activity of extract against Escherichia coli, Staphylococcus aureusand its effect on total microbial count in hamburger at -12 °C during storage (0, 15, 30 and 45 days) was studied. In diffusion method, with increasing concentration, the diameter of inhibition increased. MIC of extract for Escherichia coli and Staphylococcus aureus, was 25 and 12.5 mg/ml and MBC was 50 and 50 mg/ml, respectively. After treatment the hamburger samples with different concentrations of the extract, it was found that antimicrobial activity increased with increasing the concentration and decreasing the temperature. Thus, it can be concluded that hydroalcoholic Cardinextract can be replaced by synthetic materials as a natural antimicrobial compoundto improve durability.

The purpose of this study was to evaluate the antimicrobial activity of four different strains of lactobacillus-plantarum isolated from several sources of food (fermented olives, sour dough, cottage cheese and camel milk) against four bacterial pathogens including Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Salmonella Enteritidis and two food spoilage fungi (Aspergillus flavus and Aspergillus niger ). Antibacterial and antifungal activity of each strain and its cell free supernatant (CFS) was tested in well diffusion, overlay and agar spore spot, respectively . To determine the nature of the antimicrobial compounds, CFS of Lactobacillus plantarum strains were also used for different thermal and enzymatic treatments and neutralization. The results showed that all strains had good antimicrobial activity against all bacteria and fungi and the activity level was different depending on the strain. Also, there was no significant difference between antimicrobial activity of active culture suspension and cell-free supernatant in well diffusion method, and the highest inhibition zone was observed against E.coli (13.67 ± 0.57). The high antifungal activity was observed in strains isolated from sour dough. Also, A.flavus was more sensitive to antimicrobial compounds of CFSs than A.niger. Thermal treatment of CFS did not have any effect on the reduction or increase of antimicrobial properties, while neutralization omit antimicrobial activity. Also, except two strains antimicrobial activity of all supernatants was affected by Proteinase K treatment. The results of this study showed that indigenous strains of Lactobacillus plantarum and their antimicrobial compounds have a good potential for use as a natural preservative in food.

Nowadays, consumers' awareness about the dangers of using synthetic colors has been led to increasing demand for natural colors in various food industries. In this research, in order to study the antibacterial efficacy of bixin against S.aureus, E.coli and L. Innocoa, its inhibition zones, MIC and MBC were determined against selected bacteria. After that bixin as a natural color additives in different concentration (0.14, 0.28, 0.42%) were added in the formulation of snacks.Color properties including L*,a*,b* were determined by hunter lab andorganoleptic propertiesas aroma, color, texture, shape and overall acceptance in 5-point hedonic scale and microbial features of samples including total count, yeast and mold, Enterobacteriaceae, Ecoli were investigated with standard methods. According to the results,bixin showed significant inhibitory effects on all three microorganisms and its inhibitory effects up to 1.2 mg / ml on S.aureus were more pronounced than two other bacteria.Increasing the concentration of bixin caused higher value of a* (redness) and lower values of L* and b* (yellowness and brightness) in samples. The differences between samples containing various concentrations of bixin in organoleptic characteristics such as aroma, texture, appearance and overall acceptability were not significant . Overall, panelists gave more scores for all organoleptic properties to the samples containing 0.42% bixin. Also, in samples containing bixin significant decrease in total count as well as mold and yeast growth were observed.

In this study the antimicrobial potential of Lactobacillus plantarum strains isolated from goat,s milk was evaluated. Sixty seven goat,s milk samples were collected from Tehran and Karaj and screened for the presence of lactic acid bacteria (LAB). Among the isolated LAB, 18 strains were identified as Lactobacillus plantarum by their carbohydrate fermentation pattern and 16S rRNA sequencing. Antimicrobial activity of the isolatedLactobacillus plantarum strains against a number of pathogens including Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Listeria monocytogenes and Escherichia coli was evaluated by agar spot and well diffusion method. Results indicated 10 of theLactobasillusplantarum strains to possess inhibitory activity towards the tested pathogens, while 6 of these strains were shown to have wide spectrum of inhibitory activity and were able to inhibit the growth of the entire tested gram positive and gram negative pathogens. The antibacterial activity demonstrated by these 6 strains was further analyzed by subjecting their supernatant fluid to various physico-chemical treatments. The supernatant fluid of these strains retained their antagonistic action even after neutralization, while only 2 strains (LP4 and LP14) retained their antimicrobial activity after treatment with 1 mg/ml catalase. The supernatant fluids of the respected isolates LP4 was resistant to enzyme Lysozyme and lipase, while proteolytic enzymes like pepsin, trypsin and proteinase K completely destroyed its antibacterial potential. The isolates were resistant to their own antagonistic action. The bacteriocin like substance produced by LP4 was pH and heat resistant as it resisted wide pH range of 3-8 and autoclave temperatures of 121ºC for 15 min. This substance after 4 weeks storage at -20 0C still retained its antimicrobial activity and after treating by concentration of 7 percent NaCl, it was still active.

Yoghurt drink or Doogh has gained great attention in recent years in different countries. On the other hand, this desirable commodity has showed some drawbacks especially from microbial point of view. One of the main problems in Doogh production and storage is considered to be the presence and activity of gas producing microorganisms especially in warm conditions and environments. From the consumer point of view, blowing of container is not acceptable and is regarded as a defect. Since lactic acid bacteria (LAB) possess the potential use as adjunct or co-culture in fermented dairy products for inhibition of gas – producing microorganisms’ especially gas-producing yeasts in doogh, inclusion of these bacteria (LAB) can be a solution for this problem in aforementioned product. In this study, antimicrobial effects of two selected strains of Lactobacillus brevis assigned as M2 and M4 isolated from Motal cheese were investigated on the gas-producing and food spoilage microorganisms in Doogh. Two strains of lactobacillus namely M2 (Lactobacillus brevis KX572376) and M4 (Lactobacillus brevis KX572378) were selected from traditional Motal cheese isolates. Doogh production was carried out according to National Iranian Standard No. 2453. Each of these two strains was inoculated in Doogh at two levels of 106 and 108 cfu / ml and control sample was taken without inoculation followed by subjecting to microbial and sensory analysis at three temperatures of 4, 25 and 37°C, at intervals of 10, 7 and 7 days, respectively. Microbial profiles including coliforms, E. coli, Mold & yeast and Staphylococcus aureus were determined according to National Iranian Standard Number (2 and 1) –5486, 5234 and 5486, 997 and 6806, respectively. Sensory evaluation was carried out according to Iranian National Standard No. 4691. Sensory evaluation parameters such as taste, texture, color and total acceptance were evaluated by 10 senior food industry students. The results showed that sample inoculated with M4106 strain, received the highest score for antimicrobial activity at all three storage temperatures. Results demonstrated that, at 4 ° C, the control sample was contaminated (spoiled) on 50th day and was positive for mold and yeast count, but sample inoculated with M4106 was acceptable (negative) for mold and yeast count. At 25 C, mold growth was detected in control sample on the 14th day of storage, but the sample inoculated with M4106 remained completely un-spoiled until the 21st day. At 37°C, the control sample on day 7 was positive for mold and yeast count, but the sample inoculated with M4106, mold and yeast was not detected until the 14th day. Coliform, Staphylococcus and Escherichia coli counts in M4106 sample were negative. Sensory evaluation was carried out according to Iranian National Standard No. 4691.Sensory evaluation data showed that samples inoculated with M4106 were superior to the control sample. Doogh samples inoculated with Lactobacillus brevis strains experienced acceptable sensory evaluation so that they gained better score than control sample. The highest score was obtained for the M4106 sample. The texture of the Doogh samples showed a decreasing trend at all three temperatures during the storage period. Moisture and pH are factors influencing texture changes during the initial stages of storage. Based on the taste evaluation results, at 4°C, the highest score was related to M4108 until day-20, but from the 20th to the 60th day of storage, the M4106 has gained the highest one. At 25°C until day 7, the highest score belonged to sample M4108 but from this day on, M4106 has been more favorable. At 37°C on production day, highest score for the M4108 sample but on day- 7 and 14, the M4106 took the highest score. Regarding to color index, M2108 has gained the highest score at all 3 temperatures on the production day and for the rest of storage time, the highest scores were obtained for the M4108 and M4106 samples. Maximum total acceptance, was obtained for M2108 on the production day but this was replaced by M4106 for the rest of the time .The results showed that the Lactobacillus strain M4106 strain had the highest antimicrobial activity and the optimum score for sensory evaluation, as well as a significant increase in Doogh shelf life and reduced gas production in the bottle.

Mentha Piperita belonging to the family of Lamiaceae, is a usable medicinal herb that has therapeutic effects that essential oil has various applications in pharmaceutical industries and food. The aim of this study was to investigate the antioxidant properties, phytochemical constituents and antimicrobial effects of Mentha Piperita “in vitro”. Antioxidant activity was evaluated through 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and ß-carotene/linoleic acid assay. The essential oil was individually tested by disc diffusion assay and evaluating minimum inhibitory concentration (MIC) by method micro dilution broth and agar dilution. The minimum bactericidal/fungicidal concentration (MBC/MFC) and phytochemical constituents were tested. The results of the Kirby-Baur test showed that the maximum diameter of inhibition zone of Mentha piperita to the Candida albicans and the minimum zone diameter was associated with Salmonella typhi. The MIC of Mentha piperita for Staphylococcus epidermidis, Listeria innocua, Salmonella typhi and Candida albicans were 9.2, 18.4, 73.6 and 4.6 mg/ml, respectively. The IC50 and B-CL of Mentha piperita essential oil were equal to 1300 μg/ml and 41.3% respectively. Preliminary phytochemical analysis demonstrated the presence of most of the phytochemicals including flavonoids, saponins, flavone, saponins, tannins and alkaloids in the essential oil tested. Based on the present study, the essential oil from Mentha piperita antioxidant activity and antimicrobial activity against several clinical isolates tested and thus can be a good source of food industrial.

In this study after molecular identification of dominant Lactobacillus isolated from whole barley sourdough, antimicrobial properties of the isolate and it’s cell free culture filtrate (CCF) as native (natural pH) and neutralized obtained from logarithmic and stationary phases against some of food borne bacteria and fungi were investigated. For statistical analysis a completely randomized design with factorial arrangement was used. By sequencing of specific PCR products, mentioned isolate was identified as Lactobacillus brevis. For evaluation of antibacterial properties of the isolate, disc diffusion and microdilution and also for antifungal study, overlay and agar spore spot methods were used. Based on the results of disc diffusion, the highest and lowest antagonistic effects of L. brevis were observed against Bacillus subtilis and Escherichia coli, respectively. According to microdilution results, the highest effect of CCF on indicator bacteria was also observed in native CCF obtained from L. brevis logarithmic phase which reduced 79.55% of B. subtilis population. Furthermore, antifungal activity of L. brevis against Aspergillus flavus and Aspergillus niger was confirmed based on results of overlay method. The antifungal activity of the isolate was not different significantly (α

As the technological point of view, cheese is a nutritious environment for growth of several of foodborne pathogens such as Staphylococcus aureus. Although, application of chemical and natural preservatives is common in prolongation of shelf-life of dairy products, so many researches are still running to find alternatives solutions. In this study, the effect of three strains of lactococcus lactis named as JP51, FK23 and DC103 was evaluated on viability of S. aureus in cheese. The produced cheese samples were analyzed for chemical composition and viability of S. aureus during period of 20 days of storage. The results showed that all three strains were able to significantly reduce the number of viable S. aureus in comparison to control. According to our results, the cheese manufactured by strain JP51 had the lowest number of S. aureus (2.00 log cfu/g) after 20 days of storage. Subsequently, current study showed that L. lactis isolate JP51 can be considered as potent natural antibacterial starters for cheese production. However, it would be necessary to evaluate its effect on physical and sensorial properties of cheese.

In this study, the antimicrobial effect of HPEO was evaluated on Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans through the methods of disk diffusion agar, well diffusion agar, minimum inhibitory concentration (micro dilution broth), and minimum bactericidal/fungicidal concentration. Antioxidant potential and total phenolic content were examined through the method of 2,2-diphenyl-1picrylhydrazyl (DPPH) and Folin-Ciocalteu method, respectively. Plantago major seed mucilage (PMSM) edible coatings were prepared at four different concentrations of the HPEO, including 0, 1, 1.5 and 2 percent. The control and the coated beef samples were analyzed periodically for microbiological (total viable count, psychrotrophic bacteria, Escherichia coli, Staphylococcus aureus and fungi), chemical changes (thiobarbituric acid, peroxide value and pH) and sensory attributes (color, odor and total acceptability) of the beef slices coated with pure PMSM at 4°C for 15 days (0, 3, 6, 9, 12 and 15). The minimum inhibitory concentration of the HPEO varied from 0. 5 mg/ml to 4 mg/ml. The total phenolic content (TPC) and antioxidant power were equal to 9.50 mg GAE/g and 57.25 ± 0.2 mg/ml, respectively. PMSM extended the microbial shelf life of beef by 3 days, whereas the PMSM incorporated with (1, 1.5 and 2) HPEO resulted in a significant shelf life extension of the beef by 3, 6 and 9 days, respectively, as compared to the control samples. Thus, PMSM containing HPEO could be used as an active packaging to maintain quality and extend the shelf life of the beef at 4◦C.