JOURNAL OF FOOD MICROBIOLOGY
Year:2014 | Volume:1 | Issue:2|Papers Count:8

Generally, yogurt has the highest consumption among all fermented milk products in the world and has significant nutritional value, particularly protein and calcium. Yogurt due to having higher acid, often suffer micro-organism infections resistant to acid such as molds and yeasts. But main surface spoilage in yogurt occurs by mold. The present study was done between the years 2012 to 2014 on pasteurized yogurt samples collected from 9 dairy products industry of Zanjan Province for the purpose of monitoring the quality of products. The results showed that from among 50 samples of pasteurized yogurt, all of them in terms of acidity, pH and solids-not-fat (SNF) properties were consistent with national standards. Also in investigating the total bacteria count, no infection was observed with pathogenic micro-organisms. Findings from the study showed that most of the pasteurized yogurt produced in the Province of Zanjan in terms of the quality and biological characteristics is suitable and compliant with standards.

Alicyclobacillus is an endospore forming and heat resistant bacterium that can cause changes in odor and color of fruit juice and make significant losses to juice industries. The purpose of this study was to identify this bacterium from different juices by PCR using specific primers. To do so, DNA extraction and PCR was done after culture and incubation. Of 24 tested samples, 5 cases were examined. As a consequence of enzymatic digestion with EcoR1 and electrophoresis, 118 and 528 bp fragments were obtained that are in accordance with RFLP pattern of Alicyclobacillus acidoterrestris. With regard to the obtained results, it can be claimed that contamination to this bacterium makes some problems in fruit juice industry. To diagnosis it better, PCR with high sensitivity can be used since it reduce the expenditures and save the time.

Aeromonas hydrophila is one of the most important pathogens of acute bacterial gastroenteritis particularly in young children and elderly which is transmitted mostly via water and food originating from animals. This study was conducted to determine the contamination rate of A. hydrophila in fish, shrimp and lobster caught off the south coast of Iran. After microbial culture, biochemical protocol was applied for identification of A. hydrophila. The results showed that from a total of 180 samples including, 110 fish, 40 shrimp and 30 lobsters from summer 1389 to spring 1390, 14 fish samples (12.7%) and 4 shrimp (10%) were positive and no contamination with A. hydrophila was found in the lobsters. The highest contamination of A. hydrophila occurred in summer (17.5%) followed by fall (10.1%) and winter (4.9%). The results of this study revealed the presence of A. hydrophila in fish and shrimp in Iran.

In this study the efficiency of two commercial anti-bacterial compounds comprising hydrogen peroxide and Nanosil D2 for reducing of bacterial population on egg shell surface was compared. Thus, 90 eggs were prepared and divided into 3 groups. In first group, Nanosil, in second group, hydrogen peroxide and in third group sterile water (as control) were sprayed on outer surface of egg shell. After 30 minutes, crushed egg shells were cultured. After preparation of serial dilution, Escherichia coli colonies were identified and counted according to usual bacteriological procedures. The results revealed there are no significant differences in amount of E. coli colonies between eggs exposed to Nanosil and hydrogen peroxide. The eggs exposed to Nanosil and hydrogen peroxide showed significant lower infectivity comparing to the control group. Thus, it seems that Nanosil can be used as a disinfectant of eggs.

In Iran, herbal waters are as traditional medicinal products and are widespreadly consumed. Therefore, microbial quality of these products in terms of public health is important. The aim of this study was evaluation of microbial quality of Herbal waters distributed in Kashan 2012. In this descriptive study, the number of 132 herbal waters samples (27 traditional samples and 105 industrial samples) distributed in Kashan during 2012 year were purchased and transferred to laboratory. Then microbial tests such as total aerobic bacterial count, mold and yeast count, total coliforms, detection of enterococcus, Pseudomonas aeruginosa and sulphite reducing clostridia were evaluated based on national standard of Iran. The results showed that any one samples not contaminated to coliforms, E. coli and Sulphite reducing clostridia. 51.52% and 11.6% of samples were demonstrated total mesophilic bacteria and yeast counts more than the standard, respectively. Also, based on national standard of Iran, 57 industrial herbal waters samples (54.29%) and 4 traditional herbal waters samples were usable. Based on obtained results and contamination of some of these products to mold and yeast as well as high count of total aerobic mesophilic bacteria, pasteurization, good packaging material and good hygiene in processing procedure is recommended.

Using the potential of natural materials as special food additives for reducing the use of chemical preservatives in production of food stuff, considering their antimicrobial properties, is of great importance. In this research, the in vitro antibacterial effects of Pelargonium graveolens essential oil on Staphylococcus aureus, Escherichia Coli, Salmonella enterica and Listeria monocytogenes were studied. To do so, 4ml of the essence was prepared using Clevenger. Afterward, MIC and MBC were determined. MIC of S. aureus and E. coli was equal to 62.5 ppm and this figure for S. enterica and L. monocytogenes was 125 and 31.25 ppm, respectively. The results showed that, comparing to gram-negative bacteria, the gram-positive bacteria were more sensitive to this essential oil. The most sensitive tested microorganisms were L. monocytogenes, S. aureus, E. coli, and S. enterica. Finally, we found that the use of some ornamental plants for inhibiting bacteria can be a helpful approach in future researches.

The aim of the present study was to examine the presence of P. aeruginosa and E. coli in packed mineral and drinking water by using Polymerase Chain Reaction and microbial culture methods. In this study, 142 packed water samples were collected from active productive factories in various Provinces. Isolating and diagnosing the bacteria P. aeruginosa and E. coli were done by microbial culture and Polymerase Chain Reaction and the results were compared. E. coli contamination in PCR method, were evaluated as positive in 12 samples (14.6%) of mineral water, while all the samples in the microbial culture were negative (p=0.000). The results of study the contamination to E. coli in drinking water samples were negative based on PCR and microbial culture methods. Contamination of Pseudomonas aeruginosa was positive in 10 samples (12.1%) and 7 samples (8.5%) based on PCR and microbial culture methods, respectively (p=0.176). This value was 2 (3.3%) and 0 in drinking water by PCR and culture method, respectively (p=0.496). The results of this study indicates that Polymerase Chain Reaction can be high sensitive, specific, fast and easy method for identification.

This study was conducted to determine the contamination of Escherichia coli O157:H7 in traditional cheeses in villages of Maragheh City. A total of 100 cheese samples were cultured in Tryptic Soy Broth containing cefixime and in Mac conkey sorbitol agar containing cefixime and potassium tellurite. Suspicious colonies were stained (Gram staining) and IMVC and other tests were performed on them. The isolated Escherichia coli were tested for detection of O and H serotypes by direct agglutination method. Cheese samples were also examined for pH and NaCl content. Antibiogram test was done on Escherichia coli isolates from cheese samples by Kirby-bauer’s method. According to the results, no case of E. coli O157:H7 was detected in the studied samples, although 32 cases of non O157 serotypes of E. coli including enteropathogenic (O55, O127, O86, O114, O44, O126, O125), enterotoxigenic (O20, O128) and verotoxigenic (O26, O111) serotypes were identified. All of the isolated strains were resistant to Ampicillin and Polymyxin B. The effect of prevalence ratio of E. coli serotypes from pH and NaCl content was not significant statistically (p>0.05). From the results of this study it is concluded that traditional cheese could be a potent carrier to transmit the various serotype of E. coli and cause disease in human.