نشریه بهداشت مواد غذایی
سال پنجم شماره 2 (پیاپی 18، تابستان 1394)

Regarding the harmful effects of chemical foods preservatives on human body, it is crucial to find out safe antimicrobials among essential oils and herbs. This study aimed to address the effects of different essential oils on various bacterial species through a systematic review. A wide range of published papers in national and international data bases have been searched for the relevant articles. For this reason, the keywords used in searching were: "essential oils in food", "antimicrobial effect" and "vegetable oils". Among 462 retrieved articles, 76 papers were selected for further reviewing based on their title and abstracts. Based on results, the antimicrobial effects of different essential oils on pathogenic and spoilage organisms were compared. Moreover, the most effective as well as the least effective essential oils on microbial growth were identified. It was concluded that essential oils are more effective on gram positive bacteria rather than gram negatives. Besides, it was evident that some essential oils negatively affected the useful organisms such as lactobacilli.

Essential oils (EOs) have long been applied as flavoring agents in foods. Nowadays, due to the antimicrobial properties of EOs, they have been used as natural food preservatives. In this study, initial experiments were performed in order to elucidate the minimum bactericidal concentration of Rosmarinus officinalis L.EO on Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes. Thereafter, PMA-qPCR was applied in order to selectively quantify living cells within a bacterial population treated with rosemary EO. Inactivation was obtained at EO concentrations of 1%, 0.45%, 0.9% for L. monocytogenes, E. coli O157:H7 and S. enterica, respectively. L. monocytogenes were totally killed within 45 min while it took 90 min for E. coli O157:H7and S. enterica. It was concluded that rosemary EO has the potential to be used as a natural food additive or bio-preservative since it was able to irreversibly inactivate the three tested pathogens at lower concentrations and short exposition times in comparison with the other EOs. In addition, PMA-qPCR approach proved quantitatively precise and specific to selectively detect live pathogenic bacteria in vegetables following inactivation with rosemary EO.

In recent years, plant extracts have been used as antimicrobial agents. One of these extracts is olive leaf extract, which has antimicrobial properties due to its phenolic compounds. In current study the leaf extract of four olive (Olea europaea) cultivars (Shiraz, Zard, Roghani and Dezfool) was extracted by different solvents (acetone, methanol and ethanol) using microwave-assisted extraction method. Then the antibacterial activity of the extracts was assessed on Bacillus cereus. The antibacterial activity of the extracts was determined using the standard and micro broth-dilution methods. All experiments were carried out in triplicate. Minimum inhibitory concentration (MIC) of eleven extracts was estimated as 20 mg/ml, and only MIC of the methanolic extract of Roghani cultivar was 10 mg/ml. Bacterial growth curve of B. cereus in the presence of olive leaf extracts was drawn after 24 h incubation at 37 °C and the mean percentage of growth inhibition of each extract was measured after 24 hours. The results showed that in comparison with the other cultivars, the methanolic extract of Roghani cultivar with the percentage of growth inhibition of 91.3% and 87.8% (in the concentrations of 10 and 20 mg/ml, respectively), demonstrated stronger antibacterial effect on B. cereus. This study indicated that olive leaf extract from inexpensive agricultural waste might be a valuable bioactive source with antibacterial activity, and seem to be applicable as a safe food additive.

Zearalenone is a mycotoxin that poses a risk to human health due to its oestrogenic, immunotoxigenic, teratogenic and carcinogenic effects. This study was undertaken to determine the concentration of zearolenone in different types of bread consumed in Isfahan. In a descriptive study, a total of 60 samples consisting of wheat, oat and maize breads was obtained from Isfahan retails from October 2011 to December 2012. Using ELISA method the samples were surveyed for the presence of zearalenone. According to the results, concentration of zearalenone in positive samples ranged between 0.35 and 45.38 ng/g. Moreover, the mean and standard deviation of zearalenone concentration in wheat, oat and maize breads were estimated as 3.94 ± 6.21, 8.52 ±12.81 and 9.53 ±10.35 ng/g, respectively. Any positive sample contained zearalenone concentration more than the maximum level of 50 ng/g set by the European Regulation for zearalenone in cereals and bread. However, it is essential to continuously monitor the zearalenone contamination level in cereals and particularly in wheat.

Nowadays use of natural antimicrobial compounds such as herbal powders and extracts in food storage is important; therefore, in this study, the antimicrobial effects of plant powder Kelussia Odoratissima Mozaff in at the levels of 0.1, 0.2 and 0.3 on preventing the growth of mold, yeast and coliforms; as well as the, overall acceptability, pH and acidity of Borujerd domestic cheese samples during the cold storage were studied. For this purpose, raw sheep's milk was heated to a temperature of35-37°C, and fungal rennet was added at a rate of0.06%. plants powders studied, after blanching with steam, was added with fungal rennet to milk. After clotting for one hour at room temperature, curds were poured in to a clean cloth to squeeze. After 12hours, the curds were sectioned and transferred to12% salt water, and were stored at 4°C during 60 days. The findings showed that with increasing the percentage of Kelussia Odoratissima Mozaff powder in cheese samples, the number of coliform and mold and yeast, titratable acidity and overall acceptability significantly decreased (p <0.05); and pH significantly increased (p <0.05). Finally, the sample containing 0.1% Kelussia Odoratissima Mozaff had more utility in sensory properties than the others that containing it.

Replacing a part of fat and sugar in ice-cream by inulin and lactulose as prebiotic may create a healthier product. Two low-fat and two low-sugar synbiotic ice-cream samples were manufactured inoculated with Lactobacillus acidophilus or Bacillus coagulans. The physicochemical, textural and sensorial characteristics of the samples were compared with regular ice-cream as control. Low-fat and low-sugar synbiotic ice-cream formulations were prepared by replacing 5% of the fat and sugar contents of the control formula by inulin and lactulose, respectively. According to the results, although the total solids of the ice-cream mixes did not differ significantly, there were significant (p<0.05) differences among fat and sugar contents. By replacing vegetable fat with inulin in low-fat synbiotic ice-creams, overrun, viscosity, hardness, adhesiveness and cohesiveness were increased significantly (p < 0.05). Replacing lactulose by sugar significantly (p<0.05) decrease the hardness. After 5 days of frozen storage, the taste score of synbiotic ice creams was significantly (p<0.05) lower than control group. However after 90 days of storage, sensory scores of treated and control samples were comparable. It was shown that the type of probiotic microorganism had no effect on studied characteristics. Low-fat or low-sugar synbiotic ice-creams can be produced in small scale because they had acceptable physicochemical, textural and sensorial characteristics; however it needs more studies to recommend for commercial production.

The aim of this study was to compare the concentration of Cadmium (Cd) and its weekly intake among imported rice and the rice samples cultivated in Isfahan and Borojerd in 2011. For this reason, a total of 30 Indian imported rice samples together with 5 Iranian rice specimens were obtained from Hamedan and Tehran retails. The samples were subjected to acid digestion and afterwards the Cd concentrations were determined using ICP-OES. According to the results the mean ± SD values of Cd concentrations in imported and Iranian rice samples were determined as 107.60 ± 19.54 and 44.760 ± 12.55 µg/kg dry weight, respectively. Moreover, comparison of the mean concentrations of Cd in recent study with FAO/WHO permissible limits revealed that the Cd concentrations were below the approved limit. Data suggested that weekly intake of Cd through the consumption of imported and Iranian rice samples was 2.07 and 0.86 µg/kg body weight, respectively which was below the WHO/FAO limit. Based on the results of this study, both imported and Iranian rice do not pose a Cd-related health problem for the consumers. However, long-term accumulation of Cd in critical tissues could have health consequences.

Giardiasis has a close relation with improper sanitation, consumption of contaminated water and foods and might be lead to malabsorption syndrome and nutritional deficiency. Therefore, this study aimed to estimate the occurrence of giardiasis among the food staff in Bandarabbas and also to determine the concentration of serum albumin in infected individuals. In a cross-sectional study which was conducted in a 6 months period, a total of 11080 fecal samples of the food staff rerrered to the Research Center of Hormozgan University of Medical Sciences, was examined. Then, 30 Giardia-positive together with 30 Giardia-negative individuals were chosen for further investigation. At this step, the concentration of serum albumin were evaluated in both groups. According to the results, 30 (0.27%) of the samples were positive for Giardia lamblia. The level of serum albumin in infected and healthy people were determined at 46.8 g/l and 53.9 g/l, respectively. Moreover, 66% of the fecal samples had normal condensation and 76% were intensively contaminated. Results revealed that 90% of the infected cases were male, urban and vegetable consumers. In addition, the age of 66% of the cases was between 20 to 30. The concentration of serum albumin in patients with giardiasis was significantly (p< 0.05) lower than the control group which might be related to malabsorption. Based on results, the consumption of raw vegetable seems to play an important role in transmission of Giardia infection. In addition, high occurrence of intensively contaminated patients together with the high rate of the individuals without clinical manifestations, reveals the Giardia hidden carriers. Regarding the occurrence of giardiasis among the food staff and considering the importance of their role in public health, the necessity for hygienic measures are reemphasized.