JOURNAL OF FOOD MICROBIOLOGY
Year:2016 | Volume:3 | Issue:1|Papers Count:8

The need to replace synthetic preservatives with a natural resource has caused the food manufacturers to use from the medicinal plants as a reservoir. The present study was carried out to evaluate the antimicrobial effects of essential oils extracted from Origanum vulgare, Mentha piperita and Carum carvi on the Escherichia coli, Staphylococcus aureus and Salmonella typhimurium isolated from food products. After preparation of medicinal plants, essence extraction was done using the Clevenger device and antimicrobial effects of essences were evaluated on Escherichia coli, Staphylococcus aureus and Salmonella typhimurium isolated from raw milk and meat. Diameter of inhibition zone each essence was determined using the simple disk diffusion method on Mueller-Hinton agar. Bacterial isolates of meat were more resistant to all tested essences but the pattern of the effectiveness of essential oils on isolated strains was similar in both sources. Essential oil extracted from Origanum vulgare had the highest antimicrobial effect on S. aureus and the lowest on E. coli, Mentha piperita had the highest antimicrobial effect on E. coli and the lowest on S. aureus and Carum carvi had the highest antimicrobial effect on S. aureus and the lowest on S. typhimurium. According to the antibacterial effects of the mentioned essential oils, the possibility of their application as an antimicrobial preservative in meat and its products and also dairy products dairy is existing.

From desirable characteristics of electrolyzed water could be noted to inexpensive, safe, and no adverse impact on the environment. The aim of this study was to evaluate the influence of exposure time to neutral electrolyzed water on the reduction of contamination to Salmonella typhimurium and E. coli on skin and fresh poultry fillets. The neutralized electrolyzed water with 100 ppm free available chlorine was used for the exposure times of 1, 5, 10, 15 and 30 minutes on the inoculated skin (6 log/cm2) and chicken fillets (6 log/g) with mentioned bacteria. The results showed that the reduction of studied bacteria in skin and poultry fillets exposed to neutral electrolyzed water were statistically significant in comparing to distilled water (P<0.01). According to the results, the treated fillets with neutral electrolyzed water for 15 minutes lead to the complete disappearance of E. coli in such a way that the bacterium was not detectable in surface plating. The most reduction of E. coli in treated skin with neutral electrolyzed water was 2.63 log/cm2 after 30 minutes. Also the most reduction of salmonella typhimurium in treated fillets and skin with neutral electrolyzed water after 30 minutes were 2.51 log/g and 2.54 log/cm2 respectively. In brief, the obtained results show that the usage of neutral electrolyzed water for washing of slaughtered poultry carcasses in the lines and chillers of slaughterhouses could be in consideration as a suitable method of disinfection.

In spite of novel progresses in the methods for foodstuff’s preparation and production, consumer’s health and safety in the public hygiene import increasingly. One of the ways to control pathogenic microorganisms is the use of chemical preservatives in food. This study was done for determining antibacterial effects of Digitalis nervosa extracts on Staphylococcus aureus pathogenic bacteria. In this study the antibacterial effects of ethanolic extract of D. nervosa alone and in combination with Ciprofloxacin were evaluated on gram-positive bacteria, S. aureus (ATCC25923), by micro broth dilution method. MIC test results for D. nervosa extract and Ciprofloxacin were 4.9 and 0.5 mg/ml, respectively. Combined effects of antibiotic and the extract revealed that S. aureus was inhibited by the ethanolic extract and Ciprofloxacin respectively at 3.5 and 0.28 mg/ml. MBC were measured 7.1 and 1 mg/ml respectively against ethanolic extract and Ciprofloxacin. Simultaneous application of the extract at 1 mg/ml and Ciprofloxacin at 0.14 mg/ml destroyed S. aureus. Results showed that simultaneous use of alcoholic extract and Ciprofloxacin, reduced antibiotic usage by 48% to inhibit S. aureus and also the concomitant use of alcoholic extract and antibiotic, caused 86% reduction in antibiotic use to reach MBC point against S. aureus.

Food-borne illnesses are major international public health concern and significant cause of reduced economic growth. Contaminated food is the usual source of human infections, and poultry and beef meat are considered the major infectious route for humans. Each year, millions of persons become ill from foodborne diseases, though many cases are not reported. To assess the microbiological quality and safety of beef and poultry meat and try to achieve the connection of its contamination with hygienic conditions of packaging and without packaging of food in this study we analyzed food borne pathogens (Salmonella, Staphylococcus aureus and Bacillus cereus) in Gilan Province. A total number of 380 beef and poultry meat samples (with packing and without packaging) were collected and studied. Out of which 5/5 percent were founded contaminated with Salmonella 20.5 percent were founded contaminated with Staphylococcus aureus while 11.8 percent were founded contaminated with Bacillus cereus. Also 13.9 percent (beef meat) and 23.9 percent (poultry meat) were contaminated. The study confirmed the presence of Salmonella, Staphylococcus aureus and Bacillus cereus in beef and poultry meat which is potential threat to consumer health. To reduce of contamination, good hygiene practices are necessary from processing to storage.

In today's world, there is a growing tendency towards producing healthy and nutritious food. Mint is a genus of plants that its healthy and nutritious effects have been proved. Adding probiotic bacteria to yogurt increases its nutritious benefits. This study aims at adding the extract and fiber of mint stalk to stirred yogurt containing Bifidobacterium Lactis bacteria (BB-12) as well as examining the viability of this bacterium. To do so, the response surface methodology and the central composite rotatable design were employed. The findings obtained from the analysis showed that there was a significant relationship between different concentrations of fiber and extract, and the viability of B. Lactis bacteria in the first day to the 21st day (P<0.01). Having applied the response surface method, the optimization depicted that the maximum viability of B. Lactis bacteria is only achieved when the concentration of extract and fiber are 0.1 and 1.3 percent, respectively. In these conditions, the utility of the model equals 0.94 and the number of B. Lactis bacteria is 7.11±0.005 log cfu/ml in the first day, 6.49± 0.035 log cfu/ml in the 7th day, 6.24±0.055 log cfu/ml in the 14th day, and 5.41±0.17 log cfu/ml in the 21st. Since the produced yogurt under the condition of optimization contained at least 106 colony of bacteria per milliliter, the said product was called functional.

Nowadays, application of antimicrobial films for food packaging have been increased. The present study was carried out in order to investigate the antimicrobial activity of chitosan films containing 1-4% (v⁄v) Lavandula stoechas essential oil (EO) on some food-borne pathogenic bacteria (Listeria monocytogenes, Bacillus cereus, Vibrio parahaemolyticus, Staphylococcus aureus and Escherichia coli O157:H7). Circular discs of chitosan films containing different concentration of Lavandula stoechas essential oil were placed on bacterial lawn. The result of this study showed Incorporation of chitosan film with EO showed significant antimicrobial effects (P<0.05). Chitosan films incorporated with 4% v⁄v of EO inhibited the growth of all tested pathogenic bacteria. Maximum and minimum antimicrobial effect of chitosan films containing Lavandula stoechas essential oil was achived for Vibrio parahaemolyticus and Escherichia coli O157:H7 Transparency of film was reduced by increasing of EO. These results showed that Chitosan films containing Lavandula stoechas EO can be used for packaging foods.

Campylobacter spp. infections are of the most important foodborne diseases in many countries causing diarrhea in consumer. In this study, a total of 100 edible mushrums (Agaricus mushrooms) were purchase in order to detection and identification of Campylobacter jejuni and Campylobacter coli at 2014 year in retail market of Shahrekord city, Central of Iran. All of the samples were cultured in enrichment and specific bacteriological media and then used for Polymerase Chaine Reaction (PCR) method for detection of C. jejuni and C. coli. Out of 100 samples, 15 % were found to be contaminated with Campylobacter spp. From 15 positive samples, 13.3 % and 86.7 % were positive for C. jejuni and C. coli, respectively. Therefore the consumption of raw edible mushrum to C. jejuni and C. coli constitutes health hazard for human in this city.

The purpose of this study is to provide a predictive model of Escherichia coli growth undr different conditions such as heat storage (8o and 37oC) and pH (4, 5 and 6) in a commercial chicken extract. For this purpose, a commercial extract of chicken prepared using acetic acid and 0/1 normal profit on the desired pH was adjusted. The level of 105 cfu / ml of E. coli extracts prepared to be inseminated. 8 and 37oC extracts were kept at two different temperatures and at different times of the sampling, dilution and the surface culture on Mac conkey Agar was developed. The results showed growth at pH 4 to 5 and 6 was significantly less than pH and reduces the growth of bacteria at temperatures of 8 and 37oC with no significant difference.