JOURNAL OF FOOD MICROBIOLOGY
Year:2018 | Volume:5 | Issue:1 |Papers Count:9

Kombucha is a non-dairy fermented drinks which the raw material for its production usually is sweetened black tea with sugar. The aim of the present study was to produce a new product from white tea and apple vinegar, which has high antioxidant properties. For this purpose, effect of date syrup (40-100%W/V) as a carbon source of Kombucha fermentation, apple vinegar (15-30%) and ginger (0. 25-0. 75 g/L) on microbial quality, chemical properties and nutritional characteristics of Kombucha during fermentation period (1-15 days) using Box-Behnken design was investigated. The results showed that acidity and cellulosic layer increased during the fermentation period but pH decreased which statistically affected by date syrup concentration and fermentation time (p<0. 05). Moreover, the maximum polyphenol content and antioxidant activity were observed in 15th day that the effect of the fermentation time was statistically significant (p<0. 05). The results of this study showed that the fermentation time was only factor that had significant effect on all characteristics of the Kombucha beverage that produced by white tea and date syrup, which contains ginger and apple cider vinegar (p<0. 05). Also, it can be concluded that except ginger, which reduced yeast count (p<0. 05), other factors had no significant effect on the characteristics of Kombucha tea (p>0. 05).

Listeria monosytogenes is one of food borne pathogens that presence in raw foods and capable of growth during cold storage and cause infection in consumers. Raw milk is one of the most particular foods associated with listeria contamination. Reemerging listerial infection increased because of increase the consumer interest to consume of raw milk in last years. This study was conducted to evaluate the anti-listerial effect of nisin, rosemary extract and mixed of them in milk at refrigerator temperature (4± 1º C). Five treatments of milk were prepared; control sample with no nisin and rosemary extract (A), milk contain 0. 5% rosemary extract (B), milk contain 1% rosemary extract (C), milk contain 1000 IU nisin (D) and milk contain 0. 5% rosemary extract + 500 IU nisin (E). 107 cfu/ml Listeria monosytogenes was inoculated in each sample. All samples were exanimate for Listeria monosytogenes count on day 0, 1, 2, 3, 4 and 5. Based on results; rosemary extract and nisin reduced the listerial growth. Highest anti-listerial activity was shown in sample E, D and C respectively. The antimicrobial effect of rosemary extract at high concentration significantly (p<0. 05) was higher than low concentration. Nisin had synergist effect on anti-listerial properties of rosemary extract.

The aims of this study were to evaluate the probiotic and antibacterial properties of Lactobacillus paraplantarum and Pediococcus pentosaceus isolated from wheat bran and rice bran sourdoughs. For mentioned purpose, survival of the isolates in simulated conditions of gastrointestinal tract, their antagonistic activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coliand Pseudomonas putida as foodborne indicator bacteria, ability of aggregation with E. coli as an infection agent of intestine and profile resistance of these lactic acid bacteria (LAB) isolates against some of routine antibiotics and their hemolysis activity were also investigated. Based on the results, the highest sensitivity of the bacterial indicators towards LAB isolates was observed in L. monocytogenes. Furthermore, the highest inhibition of LAB cell-free culture filtrate (CCF) were belonged to L. paraplantarumlogarithmic and stationary CCF, against L. monocytogenes and P. pentosaceus stationary CCF, against P. putida. The survival of L. paraplantarum was also significantly (P<0. 05) more than the other LAB isolate in pH=3 and 0. 3% bile salt. Furthermore, the LAB isolates were resistant to Vancomycin, Sterptomycin, Nalidixic Acid, Ciprofloxacin and Gentamycin antibiotics. Aggregation ability of L. paraplantarum and P. pentosaceus with E. coli were respectively equal to 31. 52 and 16. 9% and the LAB isolates hadn’ t hemolysis activity.

Antimicrobial agents can be incorporated into edible films and coatings to reduce the risk of microbial growth on food surfaces. This offers advantages such as the use of small antimicrobial concentrations and low diffusion rates. Therefore, this study aimed to determine the antifungal effect of Pistacia atlantica subsp. Kurdica essential oil in sodium alginate coating against Penicillium chrysogenum growth in bread. First, minimum inhibitory concentration of essential oil (EO) against mold was determined by agar dilution method. Then, the EO with or without alginate coating was applied on bread surface and the percent inhibition of radial growth was determined. The results showed that Bene’ s EO at concentration of 25 mL/L inhibits the mold growth. At concentration of 125 mL/L of EO on bread surface, without alginate coating 71. 28% and with alginate 74. 45% mold growth inhibition was observed.

The use of plastic wrap for foodstuff is very common in the world. Plastic wrap is impermeable to air, oils, greases, and more importantly, bacteria which makes it useful for food packaging. Bacillus cereus and Staphylococcus aureus are of important pathogens and the most common cause of food-borne disease. Ten Iranian plastic wraps with different brands were chosen and identification was done by biochemical test and serial dilution methods. After microorganism identification, selective and differential medium cultures were used to confirm bacteria. Among ten Iranian plastic wrap; seven samples were devoid of any contamination, while two samples had Bacillus cereus contamination and one plastic wrap sample had Staphylococcus aureus contamination. According to the result of serial dilution, 1. 6X104 CFU and 2. 1X102 CFU Bacillus cereus and 1. 7X101 CFU Staphylococcus aureuswas counted. Acceptable microbial limits for Bacillus cereus and Staphylococcus aureus per gram of plastic wrap need to be established by international organizations for standardization. Besides, the presence of Bacillus cereus and Staphylococcus aureuson plastic wrap surface and related disease in food contact plastic wrap needs to have a continuous investigation.

Sodium dodecyl sulfate (SDS) is one of the strong alkaline sulfates germicidal which is used in health and beauty purposes. In this study, the effect of minimum bactericidal concentration of SDS on 4 major foodborne pathogens including Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Listeria monocytogenes in normal saline was studied. Different concentration of SDS was made and based on standard methods the level of MIC and MBC for all strains was measured. Then the least bactericidal concentration of SDS on viability of strains in 4 and 25° C in different time's periods was studied. MIC and MBC results showed that E. coli and S. typhimurium have a similar sensitivity to SDS; meanwhile L. monocytogenes is so sensitive to SDS among the studied strains. The rate of viability of the strains is much higher in cold condition than in ambient temperature. SDS has an effective role in reducing the population of studied bacteria in different temperatures and time. Raising the temperature increases the antibacterial effect of the SDS. Also Listeria monocytogenes is very more sensitive to SDS in comparison to other studied bacteria. So according to the results of the study, sodium dodecyl sulfate could be useful for reducing population of pathogenic bacteria especially Listeria monocytogenes on surfaces, foodstuffs and equipment.

Yogurt gels are a type of soft solid. Streptococcus thermophilus and Lactobacillus bulgaricus are yogurt starter cultures widely used in the dairy industry. Co-culture of these bacteria leads to higher biomass yield than their separate single strain culture. Incubation temperature also affected some physicochemical and sensory features of yogurt, so the aim of this work is to determined physicochemical and sensory features of yogurt containing different concentrations starter and different incubation temperatures made from sheep’ s milk. The preparation of all treatments(T) as follows, Yogurt produced from: 2% starter culture and incubation temperature 42˚ C, T(A); 1% starter culture and incubation temperature 37˚ C, T(B); 1% starter culture and incubation temperature 42˚ C, T(C: as a Control); 2% starter culture and incubation temperature 37ᵒ C, T(D); 3% starter culture and incubation temperature 42˚ C, T(E) and 3% starter culture and incubation temperature 37˚ C, T(F). the results indicated that fat%, dry matter% and moisture% did not change during 22 days of storage period and parallel to drop of pH, acidity (Dornic scale) continuously increased. The protein content of treatments B, C; continuously increased during 22 days storage period. The starter culture bacterial counts of yogurt showed that both Streptococcus thermophilus and Lactobacillus bulgaricus decreased during storage period. Sensory evaluation was performed for two features (flavor and texture). The scores for these features decreased during storage period but scores that allocated for treatment D were highly similar to control sample. According to above mentioned, it was concluded that treatment D was more similar to treatment C as a control sample.

Brucellosis or Malta-Fever, is a zoonotic disease that cause by gram negative brucella bacteria and is a serious health problem in the Mediterranean area. It usually transmitted to humans from livestock or tainted livestock products. Brucellosis in humans followed by consumption of raw milk, its products and soft cooked meat. It’ s endemic as well as in our country and it has increased in recent years. Regarding the health of milk and its products due to the high value in humans food is paramount important and contamination of milk and its products from important ways of disease transferring, therefore in this article provides overview of dairy-products contamination as one the important transfer ways since 1948 to 2016. There are several methods to diagnose, but in recent years, according to the molecular methods such as PCR or serology ones as ELISA due to the sensitivity and a high degree of accuracy are payed attention. Prevention, control and eradicate program of brucellosis have been different according to the economic condition various in countries and broadly eradicate and control of brucellosis is important from tow aspects of health and economic. Raise up awareness of poultry-mans and educating consumers by the mass media and raise up awareness about transferable disease from milk and its products can be useful.