نشریه بهداشت مواد غذایی
سال نهم شماره 4 (پیاپی 36، زمستان 1398)

In animal and food products, different types of chemical preservatives and antibiotics are used to inhibit the growth of Aspergillus flavus and other toxicogenic fungi. The aim of this study was to investigate the antifungal activity of Lactic Acid Bacteria Isolated from Masske, Chal, and local yogurt against Aspergillus flavus and Aspergillus niger. For this purpose, isolates previously tested for antibacterial effects were used. The isolates of Lactobacillus plantarum B38, Enterococcus faecium 8C and Lactobacillus ramonosus Y89 with the highest inhibitory effect on pathogenic bacteria were selected and their antifungal effects against toxin-producing molds were evaluated using the overlay method. The results showed that lactic acid isolates at the end of the fourth day prevented the growth of Aspergillus niger and Enterococcus faecium, Lactobacillus rhamnosus and Lactobacillus plantarum showed 70.84%, 37.65% and 43.31% of inhibitory activity, respectively. The results also showed that Lactobacillus rhamnosus had the highest (62.35%) inhibitory effect on Aspergillus niger (P< 0.05). The results of the study on the effect of lactic acid isolates on the growth of Aspergillus flavus showed that all tested bacteria had inhibitory properties on the molds and Lactobacillus rhamnosus with 83.8% had the highest inhibitory effect on Aspergillus flavus (P< 0.05). Consequently, due to the inhibitory ability of the lactic acid bacteria, they can be used as bio-preservatives along with synthetic preservatives in the food industry.

In this research, the daily intake and risk assessment of grape fruit withtheperspectiveofheavy metal contamination were measured in Malayer city. For sampling, five villages were selected. The concentrations of heavy metals were determined by atomic absorption spectrophotometry with flame and graphite furnace technique. For assessment the contamination level of each metal, the single factor index (SFI), and for assessment of the cumulative contamination of heavy metals, the integrated pollution index (IPI) were applied.The concentration level of heavy metals in the grape cultivars was found in the decreasing order as Cu>Mn>Zn>Ni>Pb and lower than the maximum permissible levels recommended by FAO/WHO. Among the studied cultivars, Askari cultivar contained higher heavy metal concentrations compared to the other two cultivars and Fakhri cultivar showed the lowest concentrations. In general, lead concentration was found to be low in the three grape cultivars. The integration pollution index (IPI) of heavy metals was higher in cv. Askari, as compared with the two other cultivars, although the IPI of heavy metals in three grape cultivars were at safe level. In general, the highest DIR was obtained for the Askari cultivar. The THQ of all metals were < 1. The integrated pollution index of heavy metals in three grape cultivars was low and heavy metals pollution was within the safe limits with IPI ≤ 0.7. The DIR and THQ showed that the consumption of grape cultivars pose no risk to health.

The aflatoxin M1 (AFM1) is present in the milk of livestock fed on contaminated feed. This study was conducted based on the fact that milk is one of the main sources of aflatoxin contamination in human. In order to record the frequency of AFM1, a total of 207 milk samples including 153 raw milk samples from 12 different regions of Kerman province and 54 pasteurized milk samples produced in 10 dairy factories of Kerman province were checked by Elisa. Results showed that the concentration of AFM1 in 41.2% of raw and 35.2% of the pasteurized samples was above the maximum acceptable level (100 ng/L) approved by National Institute of Standard, Iran. The amount of AFM1 in pasteurized milk was significantly lower than that in the raw milk. In order to confirm the results of ELISA, 24 samples of raw milk and 2 samples of pasteurized milk were also evaluated by HPLC, from which, four positive and five negative samples were finally confirmed. Although there was no significant correlation between the number of positive and negative samples in both methods, the concentration of AFM1 was significantly correlated. The sensitivity and the specificity of the ELISA test was respectively 100% and 25%. Since the concentration of aflatoxin was higher than the accepted level, a proper strategy of feeding management of the dairy farms in the province are suggested. In spite of the fact that ELISA is a suitable method for screening of AFM1, using a method with higher specificity is also recommended.

Nowadays consumers' interest in processed foods such as probiotic beverages is increasing. Therefore, the purpose of this study was to produce a beverage made from sour grape juice and sour lemon peel containing Bacillus coagulans. In this experimental study, grape juice and sour lemon peel were prepared. Treatments containing 12 (treatment 1) and 9 (treatment 2) percent grape juice plus 25% lemon peel sweat and 107 CFU/mL of Bacillus coagulans were prepared. The results showed that the acidity decreased during storage and the pH decreased. Brix and alcohol also had a steady trend. Phenolic compounds and antioxidant properties were higher in samples containing 12% grape juice than in samples containing 9% juice (p<0.05). During the storage period, the amount of phenolic compounds decreased. The antioxidant property also decreased with time, with the effect of treatment 1 from 153.4 to 97.72 mmol Fe+2/g and in treatment 2 from 123.35 to 80.52 mmol Fe+ 2/g. The results showed that after 90 days, the treated beverages were free of microbial contamination (coliforms, Escherichia coli, mold and yeast). Bacillus coagulans count was not less than 107 CFU/mL. Sensory results showed that the overall acceptance of treatment 1 was more than treatment 2 but there was no significant difference between the two groups. According to the results, our best treatment was 12% grape juice with 25% lemon sour skin and 107 CFU/mL Bacillus coagulans.

Aspergillus flavus is one of the hazardous fungi which appear in poor storage conditions. This mold produces dangerous toxins of aflatoxins in corn grains. Hence the investigation of reduction possibility of its growth and toxins is important. In this research the effects of calcium oxide (0, %0.5 and %1) and gamma ray (0, 5, 10, 15 and 20 KGy) on growth of Aspergillus flavus and levels of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1 and aflatoxin G2 (AFG2) were investigated. Analysis of variance showed significant effects of irradiation (P<0.0001), calcium oxide (P<0.001) and their interactions (P<0.0001). Aspergillus flavus and AFB1 and AFB2 toxins decreased with increasing irradiation. Further reduction of AFB1 and AFB2 toxins was observed during accompaniment of 0.5% calcium oxide with irradiation. However, simultaneous application of 1% calcium oxide with radiation prevented and reduced more Aspergillus flavus. AFG1 and AFG2 toxins were not detected in any of the samples. Consequently, with considering 10 KGy standard food irradiation limits, it is recommended that 0.5% calcium oxide concentration before storage and irradiation intensity of 10 KGy after storage were applied for corn grains to control mold growth and production of aflatoxin toxins.

Considering the importance of the edible oils in the diet and the increasing demand for row and unprocessed oils, in this research the chemical properties of oils obtained from the cold press and solvent extraction of three different varieties of sesame seed including fatty acids composition, chlorophyll, carotenoids, sterol, tocopherol and aflatoxin values were determined. The peroxide value of oils in two conditions of thermal accelerated and optical oxidation was also compared. The results indicated that the extraction efficiency was the highest by using solvent for extraction (58.13%) and oleic acid and linoleic acid are the predominant fatty acids in sesame. There was a significant difference in total sterol, chlorophyll and carotenoid contents of oils extracted by cold pressing, solvent extraction and refined oils (P <0.05). The highest and lowest levels of total tocopherol were related to solvent extracted and refined oils, which were equivalent to 759.18 and 437.4 mg/kg, respectively. The peroxide value increased in accelerated light and temperature conditions over time, and the effect of light on the increasing of the peroxide value was higher than the temperature. The amount of aflatoxin in the extracted oil samples was below the detection limit (ppb 0.01). The results showed that the oils produced by cold pressing methods contain more micronutrients and antioxidants than the refined oils but have shorter shelf lives in unfavorable conditions.

Due to the adverse effects of chemical preservatives and the negative attitude of consumers, the use of herbal essential oils as natural preservatives has attracted particular attention. In this regard, 11 cake samples containing 0 to 1000 mg/kg extracts of ginger, cinnamon and cardamom solely or in combination were prepared and compared during 3 storage time (production day (day 1), day 30 and day 60) with two control samples with (positive control) and without (negative control) potassium sorbate in terms of chemical, microbial and sensory properties. Results showed that in all samples pH decreased with time and acidic and peroxide values ​​increased (P< 0.05). Microbial examination of the samples showed the amount of mold and yeast increased during storage time (P< 0.05). In terms of sensory properties, all samples were highly scored on the first day of production, however the sensory scores decreased during storage period. According to the results, using an equal combination of cardamom, ginger and cinnamon extracts (sample 3 containing cardamom and cinnamon and sample 4 with equal content of three extracts) were able to increase the shelf life and maintain the sensory properties of the cakes without the use of chemical preservatives.

Natamycin is a preservative used to control molds and yeast in dough; however, the Food and Drug Administration prohibits the use of any preservative in the production of dough. Therefore, this study aimed to determine the microbial contamination and natamycin concentration in 60 samples of dough from 10 dairy plants in Ardabil Province. Microbial tests were performed to determine the populations of coliforms, molds and yeasts as well as to detect Staphylococcus aureus and Escherichia coli contamination. The results showed that the amount of natamycin in 73.33% of the samples was higher and 26.67% was determined lower than 10 ppm. In addition, the highest concentration of application was found among the samples obtained in the warm season. S. aureus and E. coli were not observed in any of the samples. On the other hand, 20% of the samples exceeded the standard limit for mold and yeast count; while 15% of the samples exceeded the standard for the coliforms. Considering the presence of microbial and natamycin contamination in some industrial dough samples and their unacceptable quality, measures must be taken to eliminate contaminants.