Aflatoxin Formation Research Articles

Inhibitory effects of essential oils on the growth of grain storage molds and the formation of aflatoxin in stored organic corn grains

AbstractBackgroundMold contamination in post‐harvest grain storage degrades grain quality and produces mycotoxins, causing economic losses and health issues. This study evaluated the inhibitory effects of six essential oils (cinnamon, clove, eugenol, orange terpenes, oregano, and thyme oil) on total and specific mold genera growth using potato dextrose agar (PDA) and selective media plates, respectively, at different concentrations of EOs (0–0.8 mg/mL). The antifungal index (AI) of each treatment were measured after 7 days incubation at 22°C. The fungicidal activity of EOs in stored organic corn grains was tested using a simulated fumigation method, and the aflatoxin contents in the corn grains were determined biweekly for 6 weeks.ResultsResults indicate that the tested EOs, except orange terpenes, significantly inhibited mold growth. Overall, eugenol demonstrated the highest effectiveness against total mold growth with cinnamon oil following closely behind. The cinnamon oil also consistently showed highest AI and lowest IC50 (0.065 mg/mL) against the growth of Aspergillus and Penicillium followed by clove oil with IC50 being 0.12 mg/mL. The Fusarium spp. was more sensitive to EOs, particularly cinnamon oil (IC50 = 0.006 mg/mL), and eugenol and oregano oil (IC50 = 0.01 mg/mL). In the simulated fumigation tests, cinnamon, oregano, and thyme oils at 0.05 mL/25 g corn significantly inhibited the mold growth and aflatoxin production at water activity 0.85, and temperature 25 and 35°C over a period of 42 days storage.ConclusionThe EOs tested in this study except orange terpenes can potentially serve as alternatives to toxic synthetic fungicides/fumigants for organic corn grain protection during storage.

Efficacy of atoxigenic Aspergillus flavus from southern China as biocontrol agents against aflatoxin contamination in corn and peanuts

Aspergillus flavus is a ubiquitous facultative pathogen that routinely infects important crops leading to formation of aflatoxins during crop development and after harvest. Corn and peanuts in warm and/or drought-prone regions are highly susceptible to aflatoxin contamination. Controlling aflatoxin using atoxigenic A. flavus is a widely adopted strategy. However, no A. flavus genotypes are currently approved for use in China. The current study aimed to select atoxigenic A. flavus endemic to Guangxi Zhuang Autonomous Region with potential as active ingredients of aflatoxin biocontrol products. A total of 204 A. flavus isolates from corn, peanuts, and field soil were evaluated for ability to produce the targeted mycotoxins. Overall, 57.3% could not produce aflatoxins while 17.15% were incapable of producing both aflatoxins and CPA. Atoxigenic germplasm endemic to Guangxi was highly diverse, yielding 8 different gene deletion patterns in the aflatoxin and CPA biosynthesis gene clusters ranging from no deletion to deletion of both clusters. Inoculation of corn and peanuts with both an aflatoxin producer and selected atoxigenic genotypes showed significant reduction (74 to 99%) in aflatoxin B1 (AFB1) formation compared with inoculation with the aflatoxin producer alone. Atoxigenic genotypes also efficiently degraded AFB1 (61%). Furthermore, atoxigenic isolates were also highly efficient at reducing aflatoxin concentrations even when present at lower concentrations than aflatoxin producers. The use of multiple atoxigenics was not always as effective as the use of a single atoxigenic. Effective atoxigenic genotypes of A. flavus with known mechanisms of atoxigenicity are demonstrated to be endemic to Southern China. These A. flavus may be utilized as active ingredients of biocontrol products without concern for detrimental impacts that may result from introduction of exotic fungi. Field efficacy trials in the agroecosystems of Southern China are needed to determine the extent to which such products may allow the production of safer food and feed.

Molecular docking analysis of Omt-A protein model from Aspergillus flavus with synthetic compounds.

Aflatoxin is a potent mycotoxin of Aspergillus flavus that has been classified as a Group I carcinogen. O-methyltransferase A (Omt-A) is a critical enzyme in the formation of aflatoxin. It catalyzes the methylation of norsalic acid to form the highly toxic intermediate averantin. The ligand-protein interaction of Omt-A was performed with piperlonguminin and blasticidins. The maximum affinity of -10.6 was found for the 5ICC_A piperlonguminine at site1 (X,Y,Z: -15.282, 21.785, 5.672). Compounds such as Blasticidin S, Neoeriocitrin, Blasticidin S - hydrochloric acid, 6,6''-Bigenkwanin, Pipernomaline, and Eriodictyol were found to have binding features to protein residues, as shown by computational interaction at the molecular level.

Potensi Bubuk Cengkeh dalam Menekan Perkembangan Jamur pada Benih Kacang Tanah Secara In-Vitro

This study aims to find the type of clove leaf powder and dosage that is effective for suppressing the development of the fungusAspergillus sp. on peanuts. This study used powdered clove leaves of tuni, raja, and forest obtained from Waai Village, Salahutu District. A completely random design was used in this study, with 12 treatment combinations and 3 replications. The results showed that the development of fungiAspergillus flavus inhibited at a dose of 1 g/100 mL PDA as evidenced by an inhibition of 91% by tuni clove leaf powder as well as being able to suppress aflatoxin production from the fungus. These results were statistically shown in the following parameters, namely: colony diameter, inhibition, and the formation of aflatoxin in the treatment.

Streptomyces tetracycline’s computational behavior against polyketide synthase of aflatoxigenic fungi

produces a variety of bioactive compounds that prevent fungal growth, including aflatoxins. Aflatoxigenic fungi ( and ) are being researched concerning spp. and can prevent the spread of aflatoxins-producing fungi. Aflatoxin-degrading enzymes, which can convert poisonous aflatoxins into less dangerous compounds, are also produced by spp. The processes through which these microorganisms can be used to reduce aflatoxins in food and agricultural systems are still the subject of active research. To evaluate the novelty of tetracycline against the biosynthesis of aflatoxin in aflatoxigenic fungi via computational approach. In this study, we performed molecular docking of polyketide synthase (Pks-A), an enzyme that initiates aflatoxin biosynthesis using tetracycline, using the online SeamDock server. Our results showed that tetracycline had a strong affinity for Pks-A in the binding pocket. The binding energy of tetracycline was -12.7 kcal/mol, indicating a strong binding affinity between the two molecules. Furthermore, the binding site was located in the active site, which is a conserved region in Pks-A and is essential for catalysing the formation of aflatoxin. The results of our docking study suggest that tetracycline may be an effective inhibitor of aflatoxin biosynthesis.

Biosynthesis and characterization of chitosan nanoparticles, determination of its antifungal and antiaflatoxigenic against Aspergillus flavus isolates

Aflatoxin is a mycotoxin generated mostly by the fungus Aspergillus flavus, which may be found in food and feed. It is a carcinogenic poison for both humans and animals. The goal of this investigation was to see if toxicogenic A. flavus strains might be found on nuts in the Kurdistan Region. A total of Fifty nut samples. The colony color of A. flavus and texture were used to identify macromorphological qualities, whereas the spore color, size, structure, conidiophore structure, and vesicle shape were used to assess micromorphological properties. Direct imaging of the UV fluorescence of A. flavus colonies on coconut agar media (CAM) was used to detect aflatoxin formation. Natural compounds, such as chitosan, have been suggested as a way to prevent fungal infection because of their extensive and well-known antibacterial action against a variety of microorganisms. The goal of this entry was to morphologically characterize and determine aflatoxigenic A. flavus isolates, characterize nanoparticles using UV–visible, X-ray diffraction (XRD), Energy-dispersive X-ray (EDX), and scanning electron microscope (SEM) analyses, and determine the formulations' in vitro antifungal activity on the treated fungus. Individual concentrations were created by altering the percentages of ingredients such chitosan solution, chitosan nanoparticles, glycerol, and canola oil. The final concentrations of chitosan solution and chitosan nanoparticles were 20% and 2% respectively. Chitosan nanoparticles completely inhibit the growth of A. flavus at 2%.

Fe3O4/ZIFs-based magnetic solid-phase extraction for the effective extraction of two precursors with diverse structures in aflatoxin B1 biosynthetic pathway

The aflatoxin B1 (AFB1) early warning technique based on precursors is an effective strategy for the prevention of AFB1 contamination risk. The determination of precursors is imperative to ensure the efficiency of the early warning technique. Herein, a controllable magnetic adsorbent Fe3O4/ZIFs was first introduced for the effective extraction and determination of averantin (AVN) and sterigmatocystin (ST) precursors in cereal by combining magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC). Benefiting from the abundant adsorption sites and multifunctional groups matching the analytes, Fe3O4/ZIFs effectively and simultaneously extracted AVN and ST with great differences in polarity and structure via multiple interactions. AVN was extracted by Fe3O4/ZIFs mainly through π–π and hydrophobic interactions, while ST was extracted predominantly by electrostatic interactions and surface complexation. The limits of detection were 0.08 μg kg−1 (AVN) and 0.36 μg kg−1 (ST). The developed method exhibited satisfactory spiked recoveries (79.1%–105.4%) in the determination of AVN and ST in rice. This work provides a novel analytical strategy for further studying AFB1 early warning technique and the formation and transformation of aflatoxins.

The Effect of Different Packaging Materials on Geometric, Color Properties and Aflatoxin Formation of Stored Hazelnut

Bu çalışma jüt ve naylon ambalajların, depolama süresince Tombul ve Kara fındık çeşitlerinin meyve - iç boyutları ve renk özellikleri ile aflatoksin düzeylerine etkisini belirlemek amacıyla yürütülmüştür. Bu amaçla bir yıl süreyle depolanan fındıkların meyve ve içlerinin boyutları, ağırlıkları, randımanı, kabuk kalınlığı, göbek boşluğu, sağlam ve kusurlu iç oranı, beyazlama oranı ile diğer bazı kalite özellikleri incelenmiştir. Natürel ve kavrulmuş fındıkların L, a, b, kroma ve hue değerleri belirlenerek renk skalası elde edilmiştir. Ayrıca depolama süresince örneklerdeki aflatoksin oluşumu takip edilmiştir. Çalışma sonuçlarına göre ambalaj farkının meyve ve iç boyutları üzerinde önemli bir etki oluşturmadığı ancak naylon ambalajın sağlam iç oranının düşürdüğü, kusurlu iç ve beyazlama oranını arttırdığı gözlenmiştir. Naylon ambalajın parlaklığı ve renk doygunluğunu arttırdığı görülse de farklılık duyusal olarak net anlaşılamamaktadır. Depolama süresinin meyve ve iç boyutlarını genellikle etkilemediği ancak sağlam iç oranını düşürdüğü, kusurlu iç oranı ve beyazlama oranını arttırdığı ayrıca renk değerlerini duyusal olarak fark edecek düzeyde etkilemediği gözlenmiştir. Depolama süresince hiçbir örnekte aflatoksin oluşumuna rastlanmamıştır.

TINGKAT PERTUMBUHAN ASPERGILLUS FLAVUS SP DAN PEMBENTUKAN AFLATOKSIN PADA BERBAGAI METODE PENYIMPANAN DENGAN KADAR AIR BIJI JAGUNG PAKAN

The objectives of this study are 1) To determine the best storage method for maize forgrowth Aspergillus Flavus sp and aflatoxin formation, 2) To determine the best water content regulation during storage of maize which can suppressgrowth Aspergillus Flavus sp and aflatoxin formation. This research consisted of two stages, namely corn sampling and main research. In the main research, analysis of moisture content with different storage methods, growth analysis of Aspergillus Flavus sp and levels of aflatoxin using the ELISA method was carried out. The statistical analysis method used was a completely randomized design with two factors. From the results of the Water Content analysis, the highest increase in water content for all treatments was seen in the storage treatment using HDPE plastic at 30% moisture content, namely the initial water content of 30 increased to 35.55%, with an increase of 5.55%. Whereas the lowest increase in water content for all treatments was seen in the storage treatment with spread at 15% moisture content, namely with an initial water content of 15% to 15.64% with an increase of 0.64%. Theincrease in the growth of Aspergillus flavus sp highestfor all treatments was seen in the storage treatment by packaging using HDPE plastic at 30% moisture content, namely thegrowth rate Aspergillus flavus sp initialof 1.97 x 103 increased to 88.93 x103, while the increase in the growth of Aspergillus flavus sp. The lowest for all treatments was seen in the storage treatment with spread at 15% moisture content, namely the growth of Aspergillus flavus sp early 1.54 x 103 to 33.34x103. The highest aflatoxin test was at the water content level of 30% with the storage method packed using HDPE plastic, while the lowest aflatoxin test result was at the 15% moisture level with the storage method spread out

Antifungal and Antiaflatoxigenic Activities of Different Plant Extracts against Aspergillus flavus

In the current study, four organic solvents, including ethanol, methanol, acetone, and diethyl ether, were used to extract turmeric, wheat bran, and taro peel. The efficiency of three different concentrations of each solvent was assessed for their antifungal and anti-mycotoxin production against Aspergillus flavus. The results indicated that 75% ethanolic and 25% methanolic extracts of taro peels and turmeric were active against fungus growth, which showed the smallest fungal dry weight ratios of 1.61 and 2.82, respectively. Furthermore, the 25% ethanolic extract of turmeric showed the best result (90.78%) in inhibiting aflatoxin B1 production. After 30 days of grain storage, aflatoxin B1 (AFB1) production was effectively inhibited, and the average inhibition ratio ranged between 4.46% and 69.01%. Simultaneously, the Topsin fungicide resulted in an inhibition ratio of 143.92%. Taro extract (25% acetone) produced the highest total phenolic content (61.28 mg GAE/g dry extract wt.) and showed an antioxidant capacity of 7.45 μg/mL, followed by turmeric 25% ethanol (49.82 mg GAE/g), which revealed the highest antioxidant capacity (74.16 μg/mL). RT-qPCR analysis indicated that the expression of aflD, aflP, and aflQ (structural genes) and aflR and aflS (regulatory genes) was down-regulated significantly compared to both untreated and Topsin-treated maize grains. Finally, the results showed that all three plant extracts could be used as promising source materials for potential products to control aflatoxin formation, thus creating a safer method for grain storage in the environment than the currently used protective method.

Regulator of G Protein Signaling Contributes to the Development and Aflatoxin Biosynthesis in Aspergillus flavus through the Regulation of Gα Activity.

Heterotrimeric G-proteins play crucial roles in growth, asexual development, and pathogenicity of fungi. The regulator of G-protein signaling (RGS) proteins function as negative regulators of the G proteins to control the activities of GTPase in Gα subunits. In this study, we functionally characterized the six RGS proteins (i.e., RgsA, RgsB, RgsC, RgsD, RgsE, and FlbA) in the pathogenic fungus Aspergillus flavus. All the aforementioned RGS proteins were also found to be functionally different in conidiation, aflatoxin (AF) biosynthesis, and pathogenicity in A. flavus. Apart from FlbA, all other RGS proteins play a negative role in regulating both the synthesis of cyclic AMP (cAMP) and the activation of protein kinase A (PKA). Additionally, we also found that although RgsA and RgsE play a negative role in regulating the FadA-cAMP/PKA pathway, they function distinctly in aflatoxin biosynthesis. Similarly, RgsC is important for aflatoxin biosynthesis by negatively regulating the GanA-cAMP/PKA pathway. PkaA, which is the cAMP-dependent protein kinase catalytic subunit, also showed crucial influences on A. flavus phenotypes. Overall, our results demonstrated that RGS proteins play multiple roles in the development, pathogenicity, and AF biosynthesis in A. flavus through the regulation of Gα subunits and cAMP-PKA signals. IMPORTANCE RGS proteins, as crucial regulators of the G protein signaling pathway, are widely distributed in fungi, while little is known about their roles in Aspergillus flavus development and aflatoxin. In this study, we identified six RGS proteins in A. flavus and revealed that these proteins have important functions in the regulation of conidia, sclerotia, and aflatoxin formation. Our findings provide evidence that the RGS proteins function upstream of cAMP-PKA signaling by interacting with the Gα subunits (GanA and FadA). This study provides valuable information for controlling the contamination of A. flavus and mycotoxins produced by this fungus in pre- and postharvest of agricultural crops.

Formation of B- and M-group aflatoxins and precursors by Aspergillus flavus on maize and its implication for food safety

Aflatoxins count to the most toxic known mycotoxins and are a threat to food safety especially in regions with a warm and humid climate. Contaminated food reaches consumers globally due to international trade, leading to stringent regulatory limits of aflatoxins in food. While the formation of aflatoxin (AF) B1 by the filamentous fungus Aspergillus flavus is well investigated, less is known about the formation kinetics of its precursors and further aflatoxins. In this study, autoclaved maize kernels were inoculated with A. flavus and incubated at 25 °C for up to 10 days. Aflatoxins and precursors were analyzed by a validated UHPLC-MS method. Additional to AFB1 and AFB2, AFM1 and AFM2 were detected, confirming the ability of the formation of M-group aflatoxins on cereals by A. flavus. The measured relative levels of AFB2, AFM1, and AFM2 on maize compared to the level of AFB1 (mean of days 5, 7, and 10 of incubation) were 3.3%, 1.5%, and 0.2%, respectively. The occurrence and kinetics of the measured aflatoxins and their precursors sterigmatocystin, O-methylsterigmatocystin, 11-hydroxy-O-methylsterigmatocystin, aspertoxin, and 11-hydroxyaspertoxin (group 1) as well as of dihydrosterigmatocystin and dihydro-O-methylsterigmatocystin (group 2) supported the so far postulated biosynthetic pathway. Remarkable high levels of O-methylsterigmatocystin and aspertoxin (17.4% and 4.9% compared to AFB1) were found, raising the question about the toxicological relevance of these intermediates. In conclusion, based on the study results, the monitoring of O-methylsterigmatocystin and aspertoxin as well as M-group aflatoxins in food is recommended.

Potential of Trichoderma spp. for Biocontrol of Aflatoxin-Producing Aspergillus flavus.

The inhibitory action of 20 antagonistic Trichoderma isolates against the aflatoxigenic isolate A. flavus ITEM 9 (Af-9) and their efficacy in reducing aflatoxin formation in vitro were examined. Production of metabolites with inhibitory effect by the Trichoderma isolates was also investigated. Antagonistic effect against Af-9 was assessed by inhibition of radial growth of the colonies and by fungal interactions in dual confrontation tests. A total of 8 out of 20 isolates resulted in a significant growth inhibition of 3-day-old cultures of Af-9, ranging from 13% to 65%. A total of 14 isolates reduced significantly the aflatoxin B1 (AfB1) content of 15-day-old Af-9 cultures; 4 were ineffective, and 2 increased AfB1. Reduction of AfB1 content was up to 84.9% and 71.1% in 7- and 15-day-old cultures, respectively. Since the inhibition of Af-9 growth by metabolites of Trichoderma was not necessarily associated with inhibition of AfB1 production and vice versa, we investigated the mechanism of reduction of AfB1 content at the molecular level by examining two strains: one (T60) that reduced both growth and mycotoxin content; and the other (T44) that reduced mycotoxin content but not Af-9 growth. The expression analyses for the two regulatory genes aflR and aflS, and the structural genes aflA, aflD, aflO and aflQ of the aflatoxin biosynthesis cluster indicated that neither strain was able to downregulate the aflatoxin synthesis, leading to the conclusion that the AfB1 content reduction by these Trichoderma strains was based on other mechanisms, such as enzyme degradation or complexation. Although further studies are envisaged to identify the metabolites involved in the biocontrol of A. flavus and prevention of aflatoxin accumulation, as well as for assessment of the efficacy under controlled and field conditions, Trichoderma spp. qualify as promising agents and possible alternative options to other biocontrol agents already in use.

Gaseous ozone to improve quality of corn as feedstuff

In the long term, fungi attacks will cause a decrease in the quality of corn during storage. In this case, Aspergillus flavus and Aspergillus parasiticus have become a serious concern related to food safety because of their ability to produce aflatoxins which are toxic to humans and animals. Nowadays, feed industries use fungicides to control fungal infections before the storage period due to their affordability, but the chemical residues are detrimental to our health. Therefore, an alternative method was needed to prevent and control fungi and aflatoxin formation in corn. One of the potential methods to apply is the gaseous ozonization. This research was conducted to investigate the potential of ozone in preventing fungal attacks and aflatoxin formation in corn, assuring that the corn quality can be maintained during the storage period. The objective of this study was to determine the effect of ozone on maintaining the quality of corn during storage, especially to reduce fungi colonies and aflatoxin formation. The experimental design used in this study was a completely randomized design with two treatment factors, namely temperature (20, 30, and 40°C) and exposure time (30 and 60 minutes). Corn quality parameters observed include moisture content, total fungal, moldy kernels, damaged kernels, and aflatoxin (AFB1, AFB2, AFG1, AFG2) contamination. The results showed that ozone treatment had an effect on reducing total fungal and aflatoxin contamination in corn, however, it had no effect on the moisture content, moldy kernels, and damaged kernels of corn. The optimum effect was obtained when the ozonization was conducted at a temperature of 20°C for 60 minutes exposure time, which results in the highest reduction in total fungal and total aflatoxin contamination of 36.77% and 92.45% respectively.

Licorice, Doum, and Banana Peel Extracts Inhibit Aspergillus flavus Growth and Suppress Metabolic Pathway of Aflatoxin B1 Production

Three different concentrations of four (ethanol, acetone, methanol, and diethyl ether) extracts of licorice, doum, and banana peel were evaluated for antifungal and antimycotoxigenic efficiency against a maize aflatoxigenic fungus, Aspergillus flavus. Among them, the licorice diethyl ether 75% extract was intensely active, showing the best wet and dry weight inhibition and exhibiting the highest efficacy ratio (91%). Regarding aflatoxin B1 (AFB1) production, all the plant extracts tested were effective against AFB1 production after one month of maize storage, with average efficacy ratios ranging from 74.1% to 97.5%. At the same time, Thiram fungicide exhibited an efficacy ratio of 20.14%. The relative expression levels of three structural genes (aflD, aflP, and aflQ) and two regulatory genes (aflR and aflS) were significantly downregulated when compared to untreated maize grains or Thiram-treated maize grains. The doum diethyl ether 75% peel extract showed the highest total phenolic content (60.48 mg GAE/g dry extract wt.) and antioxidant activity (84.71 μg/mL). GC–MS analysis revealed that dimethoxycinnamic acid, aspartic acid, valproic acid, and linoleic acid might imbue the extracts with antioxidant capacities in relation to fungal growth and aflatoxin biosynthesis. Finally, the results suggest that the three plant extracts can be considered a promising source for developing potentially effective and environmentally safer alternative ways to control aflatoxin formation, thus creating a potentially protective method for grain storage.

Influence of Light and Water Activity on Growth and Mycotoxin Formation of Selected Isolates of Aspergillus flavus and Aspergillus parasiticus.

Aspergillus flavus and A. parasiticus are the main causes of aflatoxin contamination in various foods, particularly grains, as they can thrive in environments with lower water activity and higher temperatures. The growth of Aspergillus and the formation of the mycotoxins aflatoxin and cyclopiazonic acid are strongly influenced by environmental stimuli and can be reduced by modulating parameters such as water activity, pH, temperature and light during the storage. This study has two objectives—on the one hand, to assess how global warming and an increase in exposure to sunlight affect growth and mycotoxin formation, and on the other hand, how the findings from these experiments can be used to reduce fungal growth and mycotoxin formation in stored foods. Using growth substrates with two different water activities (aw 0.95, aw 0.98), together with a light incubation device consisting of different chambers equipped with diodes emitting visible light of five different wavelengths (455 nm, 470 nm, 530 nm, 590 nm, 627 nm) plus white light, we analyzed the growth and mycotoxin formation of selected Aspergillus flavus and A. parasiticus isolates. It was shown that light with a wavelength of 455/470 nm alone, but especially in combination with a lower water activity of aw 0.95, leads to a significant reduction in growth and mycotoxin formation, which was accompanied by reduced transcriptional activity of the responsible mycotoxin biosynthetic genes. Therefore, these results can be used to significantly reduce the growth and the mycotoxin formation of the analyzed fungi during storage and to estimate the trend of fungal infestation by Aspergillus flavus and A. parasiticus in water activity- and light exposure-equivalent climate change scenarios. Mycotoxin-producing aspergilli can be effective and sustainably inhibited using a combination of short-wave light and lowered water activity in the substrate. A higher annual mean temperature accompanying climate change may lead to an increased spread of aflatoxin-producing fungi in areas that were previously too cold for them. On the other hand, there will be regions in the world where contamination with aflatoxin-producing fungi will be reduced due to increased drought and sun exposure.

Effect of storage temperature on fungal growth and aflatoxin formation in oils extracted from wild almond nuts

The current research was performed to assess the fungal contamination in oils extracted from wild almonds (Alok) during 60 days of storage. To assess the influence of storage temperature on fungal growth and aflatoxin production, three batches of wild almond nuts were kept at 25, 30, and 35°C for 60 days, and extracted oils from nuts were evaluated at six periods of intervals. Storage at 25°C enhanced the fungal growth more rapidly while compared with the other temperatures, mainly due to offering the optimum temperature for the fungal proliferation. The highest level of aflatoxin B1 was noted at storage at temperature 30°C despite lower fungal growth at this temperature while compared with 25°C, which can be correlated with the optimum temperature for aflatoxin B1 production by Aspergillus species. Therefore, the association between fungi and aflatoxin production was not linear, while various environmental parameters affect this correlation. Practical applications Food products contaminated by fungi may be the source of aflatoxins at various stages like harvest, storage, extraction, and process, which can cause some health issues besides enormous economic losses. In this regard, the main postharvest issue correlated with wild almond is fungal growth on the kernels of grain through storage, which can result in an additional reduction in the quality of extracted oil including nutrients and unacceptability by consumers.

Investıgatıon of Natural Mycoflora and Aflatoxin Formation in Hazelnuts and Products

In this study, natural mycoflora of 30 raw and 50 roasted hazelnut, 20 hazelnut paste and 50 inner membrane samples and their total aflatoxin contents were determined. In mycological isolations, 1.8-2.56% of Aspergillus flavus and 42.7-65.44% of A. niger were determined in the raw hazelnut samples. A. flavus (2.2-12.2%) and A. niger (33.3-74.5%) were also detected in roasted hazelnut, while the percentages of these microorganisms in hazelnut paste samples were 0-13.1% and 43.5-100.0%, respectively. The ratio of A. flavus and A. niger in inner membranes was found to be 2.6-16.2% and 44.6-89.4%, respectively. Aflatoxin analysis showed that the levels of aflatoxin were 2.11–10.03 ppb in raw hazelnut, 0.1–4.04 ppb in roasted hazelnut, 0.2-6.02 ppb in hazelnut paste samples and 0.7-38.2 ppb in inner membrane samples. While only one of the raw hazelnut, roasted hazelnut and hazelnut paste samples had toxin above the legal limit, 100% of the inner membrane samples showed different levels of aflatoxin contamination. Since there is no limitation in the Turkish Food Codex on hazelnut inner membrane, the amount of aflatoxin, which is higher than 10 ppb in 25 of the samples, was considered to be high contamination. Kruskal Wallis and Mann Whitney U analyses were used for statistical evaluation of the samples. There was a significant difference in aflatoxin formation and moisture content between the samples in different groups (p <0.05).

Practical analysis of aflatoxin M1 reduction in pasteurized Milk using low dose gamma irradiation.

Milk and dairy products can be exposed to potential dangers such as aflatoxin M1 (AFM1). Various factors affect the formation of aflatoxin, which can be due to environmental changes and the lack of suitable substrate for healthy livestock feeding. The goal of this study is to reduce the toxin in pasteurized milk to a level below the European Codex Alimentarius Commission standard. For this purpose, the proper structure of the radioactive granite stone was first designed as a low level gamma irradiation (LLGI) without contact with pasteurized milk, and and the pasteurized milk containing AFM1 that placed in this structure is measured and compared with the control sample values using Association of Official Analytical Chemists (AOAC) method. Then, the reduction of the resulting aflatoxin in the milk and the LLGI dose rate are obtained. The LLGI dose rate is calculated using the Monte Carlo N-Particle Transport Code (MCNP). For simulation, in addition to the spectrum of gamma radiation emitted by radioactive granites, weight percent of each composition of the pasteurized milk and its component elements are also calculated. The results showed a 51.5% reduction of aflatoxin in pasteurized milk after 4days and 99% reduction after 8days compared to the control sample. The LLGI dose rate in milk is 0.39mGy per day. According to the international atomic energy agency (IAEA) report and pervious results, this dose rate level does not significantly affect chemical and sensory quality of milk, but can extend the shelf-life and provide a safer milk. Therefore, the structure constructed using radioactive granite in this study can be considered as one of the suitable methods for reducing aflatoxin.

The anti-aflatoxigenic mechanism of cinnamaldehyde in Aspergillus flavus

Aflatoxin B1 (AFB1), the predominant and most carcinogenic naturally polyketide, is mainly produced by Aspergillus flavus and Aspergillus parasiticus. Cinnamaldehyde has been reported for inhibiting the growth and aflatoxin biosynthesis in A. flavus. But its molecular mechanism of action still remains largely ambiguous. Here, the anti-aflatoxigenic mechanism of cinnamaldehyde in A. flavus was investigated via a comparative transcriptomic analysis. The results indicated that twenty five of thirty genes in aflatoxin cluster showed down-regulation by cinnamaldehyde although the cluster regulators aflR and aflS were slightly up-regulated. This may be due to the up-regulation of the oxidative stress-related genes srrA, msnA and atfB being caused by the significant down-regulation of the diffusible factor FluG. Cinnamaldehyde also inhibited aflatoxin formation by perturbing GPCRs and oxylipins normal function, cell wall biosynthesis and redox equilibrium. In addition, accumulation of NADPH due to up-regulation of pentose phosphate pathway drove acetyl-CoA to lipids synthesis rather than polyketides. Both GO and KEGG analysis suggested that pyruvate and phenylalanine metabolism, post-transcriptional modification and key enzymes biosynthesis might be involved in the suppression of AFB1 production by cinnamaldehyde. This study served to decipher the anti-aflatoxigenic properties of cinnamaldehyde in A. flavus and provided powerful evidence for its use in practice.