جستجوی مقالات مرتبط با کلیدواژه « aspergillus flavus » در نشریات گروه « باغبانی »

This study explores the antifungal efficacy of oregano and cumin essential oils against Aspergillus flavus in almonds. Our findings revealed that oregano oil at a concentration of 150 µg l-1 was significantly more effective in inhibiting Aspergillus flavus growth than cumin oil at 300 µg l-1. After a 10-day incubation period, almonds treated with oregano oil exhibited an average fungal infection rate of just 5%, compared to 58% for cumin oil-treated almonds, and a high 95% in untreated control samples. This indicates a remarkable 94% reduction in Aspergillus flavus growth for oregano oil-treated almonds in comparison to the control group. In contrast, cumin oil showed a 39% decrease in fungal contamination relative to the control, demonstrating its lesser but notable antifungal potential. The study also found that almonds with dry peel had lower mold contamination rates than those with green peel when treated with these essential oils, highlighting the protective role of the hardened endocarp. Thirteen panellists rated almond qualities using a 9-point scale. Cumin oil treated almonds had higher aroma and flavor ratings than oregano oil and control almonds. Cumin offered a spicy aroma and harmonious flavor, while oregano had a medicinal aroma and bitter taste. Cumin effectively inhibited fungal growth and maintained almond quality. Sensory analysis showed a consumer preference for the aroma and taste of cumin oil-treated almonds, despite the lower antifungal efficacy. Overall, this research underscores the potential of oregano and cumin essential oils as sustainable alternatives to synthetic preservatives in controlling Aspergillus flavus infection in almonds post-harvest.

Samples were collected from different regions of two provinces, Markazi and Semnan, their contamination by Aspergillus flavus was examined. The results of A. flavus colony counts in different samples of almond showed that among 20 experimented samples, 11 samples were contaminated by fungus; therefore, 8 cultivars of almond, Shahroud 6, Shahroud 21, Shahroud 12, Shahroud 8, Shahroud 17, Rabie, Mengha, and Sangi Shireen, were collected in order to evaluate their sensitivity to fungal colonization and the sporulation rate of fungus on them. The results of statistical analysis showed that on the third, fifth, and seventh days, Shahroud 12 was the least resistant cultivar [average pollution (99.5%)], whereas Shahroud 6 was the most resistant [average contamination (7.36%)] at a level of 5 % for growth of A. flavus after 7 days. Experiments related to the testa of almond show that the testa can be a barrier against penetration of fungus into the inner part of the almond, decreaseing fungal growth, and thus reducing the weight of mycelium and sporulation in almonds.

In order to study the contamination of Aspergillus flavus and aflatoxin production in pistachio cultivars in the Semnan province, eight cultivars of pistachio were collected from major pistachio growing areas. Using the serial dilution method, ground pistachio kernels were inoculated on plates containing AFPA medium and incubated at 28° C. This experiment was performed using three replications in a completely randomized design. After three to seven days, the number of A. flavus colonies were identified and enumerated. Also, aflatoxin B1, B2, G1 and G2 contents of the samples were analyzed by HPLC method. On the other hand, the effect of two chemical fungicidesas a control method on the growth of Aspergillus flavus and aflatoxin production in pre-harvest pistachio cultivars was assessed under in vivo conditions. For this purpose, an orchard that was under cultivation by the most contaminated cultivar was selected, and a completely randomized design was carried out in the field. Two fungicides (tebuconazole 25% and mancozeb 80%) were applied at an application rate of 1 and 2 L or Kg ha-1, respectively. Aflatoxin B1 and B2 contents of the samples were analyzed using the HPLC method. The obtained results showed that there was a significant difference in A. flavus colonies number in different pistachio cultivars. Among these cultivars, Owhadi had the highest amount of contamination, and Akbari had the lowest contamination. The results showed that the contents of aflatoxin B1 and B2 were observed in Owhadi cultivar. , Tebuconazole 25% and mancozeb 80% reduced A. flavus growth compared to the control. However, this reduction was not significant. The obtained results of aflatoxin analysis showed that these two fungicides reduced the amount of aflatoxins B1 and B2 in pistachio cultivar, though there was not a significant reduction.It was concluded that the use of chemical fungicides were ineffective in preventing A. flavus growth and aflatoxin production in pistachio cultivars under in vivo conditions.

One hundred-thirty soil isolates of A. flavus were collected from commercial pistachio orchards in two main production regions including Rafsanjan (Kerman Province, south-eastern of Iran) and Damghan (Semnan Province, central north of Iran) and assayed for vegetative compatibility groups (VCGs). The sixteen and twenty VCGs were identified for 41 and 37 nit-mutant producing isolates of A. flavus. The variability in morphology was found among A. flavus isolates from different VCGs, but no variability among isolates from the same VCG. VCG diversity for A. flavus isolates from Damghan and Rafsanjan was 54 and 39%, respectively. The high VCG members in small size-isolates of A. flavus from Damghan indicated high genetic variability in fungal population. Because of the small number of sclerotium-producing isolates of A. flavus, we did not determine the relationships between sclerotium production with VCG in two pistachio production regions. This study was the first to determine the strain and VCG diversity of soil isolates of A. flavus from pistachio orchards in Iran.

Study the effect of fruit cultivar (intact, early split, irregular crack) on (Akbari, Abbasali, Khanjari) cultivars in Damghan city to Aspergillus Flavus fungus and effect of harvest time in early split pistachio in 1389, sampling from orchards has been performed. Samples after grinding by dilute cultivating in a specific AFPA medium bottles in a completely randomized model were three times recultivated. Colonies of A. flavus after3 to 7 days, were isolated, identified and counted. The results of Duncan grouping were analyzed by SAS software. Results of that study of contamination of samples to A. Flavus fungal Showed The contamination of the samples to the fungus A Flavus differ from each other, there is less contamination in the Khanjari cultivar and more contamination in Akbari cultivar. With delay in the harvest time, percentage of intact fruits and without front skin cracking decrease. The lowest percentage of early split (0 first) was at first harvesting time (Shahrivar 10) in Akbari cultivar and the highest percentage of early split (Shahrivar 20) in the the second harvest time in the Akbari cultivar.

In order to evaluate pistachio contamination to Aspergillus flavus in Semnan province; samples of pistachio kernels were collected from the last processing pistachio stage in traditional and semi-mechanized processing plants in 2010. They were examined for the presence A. flavus fungi. The samples were cultured on AFPA media. All plate were incubated for 3 to 7 days. At the end of incubation period, the plate were evaluated and isolates of A. flavus were identified and relative density of them were recorded. The isolates of A. flavus were evaluated for their ability to produce aflatoxins, when grown on natural substrate (autoclaved rice flour). The aflatoxins were extracted with chloroform and analyzed by TLC and densitometer. The results indicated that population density of A. flavus is varied with the type of processing plants. Traditional processing plants have more population density of A. flavus than semi-mechanized processing plants. 55 isolates of A. flavus out of the 86 tested isolates (%63.95) were able to produce one or several types of aflatoxins, while 31 isolates (%36.04) were unable to produce any type of aflatoxin. Among evaluated isolates, %9.30 of isolates produced all types of the aflatoxins, %8.13 produced AfB1,Af 2 and AfG1, %34.88 of isolates produced AfB1 and AfB2 and %11.62 of isolates only produced AfB1. Among aflatoxigenic isolates, the strength of toxin production varied from weak to strong.

In order to study on some of pistachio cultivars’ contamination of Khorasan-e-Razavi province,eight cultivars of pistachio kernels were collected from the pistachio production areas of this province. Using serial dilution method, 10 grams of ground pistachio was moved to 90 ml water peptone and continuous dilutions 10-1, 10-2 were prepared. Then 0.1 ml from each dilution was inoculated in three replicates on plates containing AFPA medium and was placed inside an incubator at 28 ° C for 72 hours. The characteristic of this environment is the advent of green yellowish colonies by Aspergillus flavus and Parasiticus that is distinguishing criteria of mentioned fungi. Since it has capacity to stop interfering bacteria and fungi growth causes the emersion of distinct and discrete colonies that are easily seperable and countable from each other. After three days, the number of colonies of A.flavus was identified and calculated in samples. The results of this research indicated that there was a significant difference in colonies number of these fungi in different pistachio cultivars (At 5% level). Among these cultivars Akbari Namavar had the highest contamination and against, Fandoghi 1 had the lowest contamination.

Contamination of pistachio nuts by aflatoxigenic strains of Aspergillus species is the greatest constraint to production and export of pistachio nuts in Iran, the leading producer of pistachio nuts in the world. Kerman province is the main region in Iran where 85%, of pistachio nuts are produced. Determining the population density of Aspergillus spores in the orchards and terminals which are the main sources of contamination would provide information about critical control points throughout pistachio production process. Density fluctuations of airborne Aspergillus flavus and Aspergillus niger spores were investigated during 2000-2002. The monthly density fluctuations of Aspergillus spp. spores were determined by exposing open petri-dishes containing AFPA and Cz media for 15 minutes, between 11 and 13 hours at different localities in each orchard from spring to winter, and at pistachio nut processing terminals during harvesting time. The results showed that density fluctuations of A. flavus and A. niger rose from the beginning of spring reaching a peak in September. The population then gradually decreased and had little variation in relation to different periods and places. Population density of Aspergillus spores increased during processing stages (especially hulling and peeling) at different pistachio terminals. In most cases, there were positive correlations (r = 0.69 - 0.91) between environmental temperature and spore density. The peak of spore density coincided with pistachio nut maturation characterized by splitting and cracking.