Preservation of Mimosa tenuiflora Antiaflatoxigenic Activity Using Microencapsulation by Spray-Drying.

Mimosa tenuiflora aqueous extract (MAE) is rich in phenolic compounds. Among them, condensed tannins have been demonstrated to exhibit a strong antioxidant and antiaflatoxin B1 activities in Aspergillus flavus. Since antioxidant capacity can change with time due to environmental interactions, this study aimed to evaluate the ability of encapsulation by spray-drying of Mimosa tenuiflora aqueous extract to preserve their biological activities through storage. A dry formulation may also facilitate transportation and uses. For that, three different wall materials were used and compared for their efficiency. Total phenolic content, antioxidant activity, antifungal and antiaflatoxin activities were measured after the production of the microparticles and after one year of storage at room temperature. These results confirmed that encapsulation by spray-drying using polysaccharide wall materials is able to preserve antiaflatoxin activity of Mimosa tenuiflora extract better than freezing.

Mimosa tenuiflora Aqueous Extract: Role of Condensed Tannins in Anti-Aflatoxin B1 Activity in Aspergillus flavus.

Aflatoxin B1 (AFB1) is a potent carcinogenic mycotoxin that contaminates numerous crops pre- and post-harvest. To protect foods and feeds from such toxins without resorting to pesticides, the use of plant extracts has been increasingly studied. The most interesting candidate plants are those with strong antioxidative activity because oxidation reactions may interfere with AFB1 production. The present study investigates how an aqueous extract of Mimosa tenuiflora bark affects both the growth of Aspergillus flavus and AFB1 production. The results reveal a dose-dependent inhibition of toxin synthesis with no impact on fungal growth. AFB1 inhibition is related to a down-modulation of the cluster genes of the biosynthetic pathway and especially to the two internal regulators aflR and aflS. Its strong anti-oxidative activity also allows the aqueous extract to modulate the expression of genes involved in fungal oxidative-stress response, such as msnA, mtfA, atfA, or sod1. Finally, a bio-guided fractionation of the aqueous extract demonstrates that condensed tannins play a major role in the anti-aflatoxin activity of Mimosa tenuiflora bark.

Impact of encapsulated orange essential oil with ß-cyclodextrin on technological, digestibility, sensory properties of wheat cakes as well as Aspergillus flavus spoilage.

BACKGROUND: The majority of studies with essential oils in foods focus mainly on improving the shelf life of products; however, the present study goes further and demonstrates not only the effect of essential oil on conservation properties, but also the effect of free and encapsulated orange essential oil (OEO) on the technological, sensorial and digestibility properties of bakery products. RESULTS: OEO was encapsulated into ß-cyclodextrin (ß-CD) by inclusion complex formation (ß-CD/OEO 97.4% of encapsulation efficiency). OEO demonstrated in vitro antifungal activity against Aspergillus flavus (inhibition zone of 11.33 mm on mycelial growth). In situ antifungal activity against A. flavus confirmed that free OEO can effectively delay the fungal growth, unlike encapsulated OEO. Regarding texture profile and starch digestibility: cake with ß-CD/OEO showed lower hardness (31.64 N) and lower starch digestibility (69.10%) than cake with free OEO (44.30 N; 82.10%, respectively) and the addition of OEO (both free and encapsulated) decreased the adhesiveness of the cakes. Cake with free OEO showed a higher intensity of orange aroma, being preferred by 60% of panelists, whereas cake with ß-CD/OEO presented a very slight orange taste and aroma. CONCLUSION: The encapsulation of OEO into ß-CD improved the crumb texture of cakes and promoted a lower starch digestibility in the cakes. On the other hand, the encapsulation process was not effective under the conditions tested (OEO concentration and baking temperatures), compromising the action of the OEO as a natural flavoring and preservative agent. © 2021 Society of Chemical Industry.

High voltage atmospheric cold plasma treatment inactivates Aspergillus flavus spores and deoxynivalenol toxin.

Fungal contamination is a concern for the food industry. Fungal spores resist food sterilization treatments and produce mycotoxins that are toxic for animals and humans. Technologies that deactivate spores and toxins without impacting food quality are desirable. This study demonstrates the efficiency of a high voltage atmospheric cold plasma (HVACP) technology using air to generate reactive oxygen (ROS) and nitrogen (RNS) species for the degradation of Aspergillus flavus cultures and the deoxynivalenol (DON) mycotoxin. Optical emission and absorption spectroscopy demonstrate ionization of hydroxyl groups, atomic oxygen and nitrogen, and confirm production of ROS and RNS, e.g. O3, NO2, NO3, N2O4, and N2O5. Fungal cultures show a depletion in pigmentation and an ~50% spore inactivation after 1-min treatments. Treated spores show surface ablation and membrane degradation by scanning electron microscopy. Twenty-minute direct HVACP treatments of 100 µg of DON in one mL aqueous suspensions resulted in a greater than 99% reduction in DON structure and rescued over 80% of Caco-2 cell viability; however, the same treatment on 100 µg of powdered DON toxin only showed a 33% reduction in DON and only rescued 15% of cell viability. In summary, HVACP air treatment can inactivate both fungal spores and toxins in minutes.

Effect of different carbon sources on the growth and enzyme production of a toxigenic and a non-toxigenic strain of Aspergillus flavus.

Two strains of A. flavus one toxigenic (CECT 2687) and the other non-toxigenic (NRRL 6541) were studied for their genomic potential, growth capacity, and the production of enzymes on simple sugars, polysaccharides, and complex substrates under solid-state fermentation (SSF). According to the genome analysis, this fungus has many genes to degrade different types of polysaccharides and therefore it would be able to grow on different substrates. Both strains grow in all the carbon sources, but visibly CECT2687 grows slower than NRRL6541. However, we propose the growth index (GI) to establish a dry weight-diameter relationship as a more reliable measure that truly shows the growth preferences of the fungus. Considering this, the NRRL6541 shows less growth in 11 of the 16 evaluated carbon sources than CECT2687. Complex substrates were the best carbon source for the growth of both strains. Corncob (CC) induced the production of xylanases, pectinases, and almost all the accessory enzymes evaluated (except for α-xylosidase) this could make it an agricultural waste of interest to produce hemicellulolytic enzymes. Both strains produce a great variety of xylanases and pectinases (pathogenicity factors) making A. flavus a good potential candidate for the degradation of polysaccharides with a high content of xylan and pectin.

Modelling the effect of temperature and water activity on the growth rate of Aspergillus flavus and aflatoxin production in peanut meal extract agar.

Aspergillus flavus is the predominant species that produce aflatoxins in stored peanuts under favourable conditions. This study aimed to describe the growth and aflatoxin production by two A. flavus strains isolated from imported raw peanuts and to model the effects of temperature and aw on their colony growth rate as a function of temperature and aw in Peanut Meal Extract Agar (PMEA). A full factorial design with seven aw levels (0.85-0.98 aw) and five temperature levels (20-40 °C) was used to investigate the growth and aflatoxin production. Colony diameter was measured daily for 28 days while AFB1 and total aflatoxin were determined on day 3, 7, 14, and 21. The maximum colony growth rate, µmax (mm/day) was estimated by using the primary model of Baranyi, and the µmax was then fitted to the secondary model; second-order polynomial and linear Arrhenius-Davey to describe the colony growth rate as a function of temperature and aw. The results indicated that both strains failed to grow at temperature of 20 °C with aw <0.94 and aw of 0.85 for all temperatures except 30 °C. The highest growth rate was observed at 30 °C, with 0.98 aw for both strains. The analysis of variance showed a significant effect of strain, temperature, and aw on the fungal growth and aflatoxin production (p < 0.05). Furthermore, both secondary models were in good agreement with the observed µmax. However, the polynomial model was found to be a better predictor of the experimental data. A similar pattern was observed in aflatoxin production but in a narrower range of temperature (25-35 °C) and aw (0.92-0.98 aw). The highest production of aflatoxins was observed on day 21 at 30 °C with the aw level of 0.98 for both strains. Overall, the current findings may help in improving the mycotoxin management and intervention strategies in peanuts, especially during storage.

Aspergillus flavus as a Model System to Test the Biological Activity of Botanicals: An Example on Citrullus colocynthis L. Schrad. Organic Extracts.

Citrullus colocynthis L. Schrader is an annual plant belonging to the Cucurbitaceae family, widely distributed in the desert areas of the Mediterranean basin. Many pharmacological properties (anti-inflammatory, anti-diabetic, analgesic, anti-epileptic) are ascribed to different organs of this plant; extracts and derivatives of C. colocynthis are used in folk Berber medicine for the treatment of numerous diseases-such as rheumatism arthritis, hypertension bronchitis, mastitis, and even cancer. Clinical studies aimed at confirming the chemical and biological bases of pharmacological activity assigned to many plant/herb extracts used in folk medicine often rely on results obtained from laboratory preliminary tests. We investigated the biological activity of some C. colocynthis stem, leaf, and root extracts on the mycotoxigenic and phytopathogenic fungus Aspergillus flavus, testing a possible correlation between the inhibitory effect on aflatoxin biosynthesis, the phytochemical composition of extracts, and their in vitro antioxidant capacities.

Bioactive coatings from nano-biopolymers/plant extract composites for complete protection from mycotoxigenic fungi in dates.

BACKGROUND: Contamination of date fruit with mycotoxigenic fungi is a hazardous threat. The present study investigated the effectiveness of natural derivatives for controlling this. Chitosan (Cts) was produced from Aspergillus niger mycelia and characterized and then nanochitosan (NCt) particles were synthesized from fungal Cts. Edible-coating films were formulated based on Cts, NCt, pomegranate peel extract (PPE) and their composites and these were evaluated as antifungal materials against mycotoxigenic fungi, Aspergillus flavus, Aspergillus ochraceus and Fusarium moniliforme. RESULTS: The Cts produced had 88.7% deacetylation, a molecular weight of 24.5 kDa and 98% solubility in diluted acetic acid, whereas the particle diameters of synthesized NCts ranged from 35 to 65 nm. The inhibition zone assay emphasized the antifungal effectiveness of the entire coating films. The most effective agent for preparing edible film was the blend of NCt + PPE followed by Cts + PPE based films. The practical application of antifungal films for date decontamination with respect to mycotoxigenic fungi demonstrates that the films were very effective for controlling the entire fungal strain and preventing growth on the fruits. CONCLUSION: The NCt + PPE and Cts + PPE based films were found to be the most effective because they could completely eliminate the growth of any fungal spore on date fruit after 48 h from the coating experiment. © 2019 Society of Chemical Industry.

Antioxidant and antimicrobial markers by UPLC®-ESI-Q-TOF-MSE of a new multilayer active packaging based on Arctostaphylos uva-ursi.

49 different non-volatile compounds were determined in Spanish Arctostaphylos uva-ursi leaves using UPLC®-ESI-Q-TOF with MSE technology. Both positive and negative electrospray ionization were applied. MarkerLynx® was proposed as a powerful tool to distinguish samples from eight wild populations of Spain by determining their non-volatile markers. Development of HRMS methods let to analysis of metabolites in plants. Antioxidant and antimicrobial capacities of different extracts were evaluated. Plant extract with the strongest antioxidant and simultaneous good antimicrobial capacity (Lierta) was chosen and incorporated in a multilayer packaging. Then, antioxidant capacity of the new packaging was evaluated and the efficient free radical scavenging properties were demonstrated.

Preservation of red pepper flakes using microwave-combined cold plasma treatment.

BACKGROUND: Red pepper flakes are often contaminated with various microorganisms; however, any technologies aiming to decontaminate the flakes should also maintain their quality properties. This study investigated the effect of microwave-combined cold plasma treatment (MCPT) at different microwave power densities on microbial inactivation and preservation of red pepper flakes. Red pepper flake samples inoculated with spores of Bacillus cereus or Aspergillus flavus and without inoculation were subjected to MCPT at 900 W for 20 min at either low microwave power density (LMCPT, 0.17 W m-2 ) or high microwave power density (HMCPT, 0.25 W m-2 ). RESULTS: The numbers of B. cereus and A. flavus spores on red pepper flakes after LMCPT and HMCPT were initially reduced by 0.7 ± 0.1 and 1.4 ± 0.3 log spores cm-2 and by 1.5 ± 0.3 and 1.5 ± 0.2 log spores cm-2 respectively and remained constant for 150 days at 25 °C. Immediately after HMCPT, the concentrations of capsaicin and ascorbic acid in the flakes were significantly lower than in untreated samples; however, no difference in concentration was detected during storage. Neither LMCPT nor HMCPT affected the antioxidant activity or color of the flakes during storage. LMCPT also did not affect the sensory properties and the concentrations of capsaicin and dihydrocapsaicin of the flakes, indicating its suitability in preserving their quality properties. CONCLUSION: MCPT may provide an effective non-thermal treatment for food preservation which can improve the microbial safety and stability of red pepper flakes while maintaining intact their qualitative properties. © 2018 Society of Chemical Industry.

Green synthesis of Stereospermum suaveolens capped silver and gold nanoparticles and assessment of their innate antioxidant, antimicrobial and antiproliferative activities.

Plant-extract mediated nanoparticles synthesis is a viable alternative to chemical reduction techniques. Here, we report the microwave-assisted rapid synthesis of silver and gold nanoparticles by the phytoreducer Stereospermum suaveolens for the first time. The formation of the nascent silver and gold nanoparticles is confirmed by their intense surface plasmon resonance peaks at 431 and 585 nm in UV-visible spectroscopy. The poly phenolic and alcoholic functional groups present in the aqueous root bark extract that performed the bioreduction processes have been detected using Fourier transform infrared spectroscopy. Powder X-ray diffraction and selected area electron diffraction patterns settled face centered cubic crystal structures to both silver and gold nanoparticles with a preferred orientation towards the (111) plane. Transmission electron microscopic analysis proved more or less spherical geometry of the silver and gold nanoparticles with average diameter of 49.77 ± 11.64 and 27.19 ± 5.96 nm, respectively. The nanoparticles showed excellent free-radical scavenging activity than the root bark extract Stereospermum suaveolens and the IC50 values obtained were 108.36 ± 1.62, 45.59 ± 0.18, 34.53 ± 0.31 µg/mL, respectively, for the extract, gold and silver nanoparticles. The metal nanoparticles have accomplished good antimicrobial properties towards bacterial and fungal pathogens and were demonstrated herein. The antiproliferative effects of the synthesized silver and gold nanoparticles on human lung adenocarcinoma cells A549 were studied using the MTT assay and the obtained IC50 values 33.81 ± 0.72 and 52.97 ± 0.73 µg/mL lies in the clinical range.

Impact of infrared treatment on quality and fungal decontamination of mung bean (Vigna radiata L.) inoculated with Aspergillus spp.

BACKGROUND: Mung bean is a rich source of protein, carbohydrates and fiber content. It also exhibits a high level of antioxidant activity due to the presence of phenolic compounds. Aspergillus flavus and A. niger are the two major fungal strains associated with stored mung bean that lead to post-harvest losses of grains and also cause serious health risks to human beings. Thus there is a need to explore an economical decontamination method that can be used without affecting the biochemical parameters of grains. RESULTS: It was observed that infrared (IR) treatment of mung bean surface up to 70 °C for 5 min at an intensity of 0.299 kW m-2 led to complete visible inhibition of fungal growth. Scanning electron microscopy revealed that surface irregularities and physical disruption of spores coat are the major reasons behind the inactivation of IR-treated fungal spores. It was also reported that IR treatment up to 70 °C for 5 min does not cause any negative impact on the biochemical and physical properties of mung bean. CONCLUSION: From the results of the present study, it was concluded that IR treatment at 70 °C for 5 min using an IR source having an intensity of 0.299 kW m-2 can be successfully used as a method of fungal decontamination. The fungal spore population was reduced (approximately 5.3 log10 CFU g-1 reductions) without significantly altering the biochemical and physical properties of grains. © 2017 Society of Chemical Industry.

Antiaflatoxigenic and Antimicrobial Activities of Schiff Bases of 2-Hydroxy-4-methoxybenzaldehyde, Cinnamaldehyde, and Similar Aldehydes.

2-Hydroxy-4-methoxybenzaldehyde (HMBA) is a nontoxic phenolic flavor from dietary source Decalipus hamiltonii and Hemidesmus indicus. HMBA is an excellent antimicrobial agent with additional antiaflatoxigenic potency. On the other hand, cinnamaldehyde from cinnamon is a widely employed flavor with significant antiaflatoxigenic activity. We have attempted the enhancement of antiaflatoxigenic and antimicrobial properties of HMBA, cinnamaldehyde, and similar molecules via Schiff base formation accomplished from condensation reaction with amino sugar (d-glucamine). HMBA derived Schiff bases exhibited commendable antiaflatoxigenic activity at the concentration 0.1 mg/mL resulting in 9.6 ± 1.9% growth of Aspergillus flavus and subsequent 91.4 ± 3.9% reduction of aflatoxin B1 with respect to control.

Identification of the Anti-Aflatoxinogenic Activity of Micromeria graeca and Elucidation of Its Molecular Mechanism in Aspergillus flavus.

Of all the food-contaminating mycotoxins, aflatoxins, and most notably aflatoxin B1 (AFB1), are found to be the most toxic and economically costly. Green farming is striving to replace fungicides and develop natural preventive strategies to minimize crop contamination by these toxic fungal metabolites. In this study, we demonstrated that an aqueous extract of the medicinal plant Micromeria graeca-known as hyssop-completely inhibits aflatoxin production by Aspergillus flavus without reducing fungal growth. The molecular inhibitory mechanism was explored by analyzing the expression of 61 genes, including 27 aflatoxin biosynthesis cluster genes and 34 secondary metabolism regulatory genes. This analysis revealed a three-fold down-regulation of aflR and aflS encoding the two internal cluster co-activators, resulting in a drastic repression of all aflatoxin biosynthesis genes. Hyssop also targeted fifteen regulatory genes, including veA and mtfA, two major global-regulating transcription factors. The effect of this extract is also linked to a transcriptomic variation of several genes required for the response to oxidative stress such as msnA, srrA, catA, cat2, sod1, mnsod, and stuA. In conclusion, hyssop inhibits AFB1 synthesis at the transcriptomic level. This aqueous extract is a promising natural-based solution to control AFB1 contamination.

Time-course of germination, initiation of mycelium proliferation and probability of visible growth and detectable AFB1 production of an isolate of Aspergillus flavus on pistachio extract agar.

The aim of this work was to assess the temporal relationship among quantified germination, mycelial growth and aflatoxin B1 (AFB1) production from colonies coming from single spores, in order to find the best way to predict as accurately as possible the presence of AFB1 at the early stages of contamination. Germination, mycelial growth, probability of growth and probability of AFB1 production of an isolate of Aspergillus flavus were determined at 25 °C and two water activities (0.85 and 0.87) on 3% Pistachio Extract Agar (PEA). The percentage of germinated spores versus time was fitted to the modified Gompertz equation for the estimation of the germination parameters (geometrical germination time and germination rate). The radial growth curve for each colony was fitted to a linear model for the estimation of the apparent lag time for growth and the growth rate, and besides the time to visible growth was estimated. Binary data obtained from growth and AFB1 studies were modeled using logistic regression analysis. Both water activities led to a similar fungal growth and AFB1 production. In this study, given the suboptimal set conditions, it has been observed that germination is a stage far from the AFB1 production process. Once the probability of growth started to increase it took 6 days to produce AFB1, and when probability of growth was 100%, only a 40-57% probability of detection of AFB1 production was predicted. Moreover, colony sizes with a radius of 1-2 mm could be a helpful indicator of the possible AFB1 contamination in the commodity. Despite growth models may overestimate the presence of AFB1, their use would be a helpful tool for producers and manufacturers; from our data 5% probability of AFB1 production (initiation of production) would occur when a minimum of 60% probability of growth is observed. Legal restrictions are quite severe for these toxins, thus their control from the early stages of contamination throughout the food chain is of paramount importance.

Single vs multiple-spore inoculum effect on growth kinetic parameters and modeled probabilities of growth and aflatoxin B1 production of Aspergillus flavus on pistachio extract agar.

The objective of the present study was to assess the differences in modeled growth/AFB1 production probability and kinetic growth parameters for Aspergillus flavus inoculated as single spores or in a concentrated inoculation point (~500 spores). The experiment was carried out at 25°C and at two water activities (0.85 and 0.87) on pistachio extract agar (3%). Binary data obtained from growth and AFB1 studies were modeled using linear logistic regression analysis. The radial growth curve for each colony was fitted to a linear model for the estimation of the lag phase for growth and the mycelial growth rate. In general, radial growth rate and lag phase for growth were not normally distributed and both of them were affected by the inoculation type, with the lag phase for growth being more affected. Changing from the multiple spore to the single spore inoculation led to a delay of approximately 3-5days on the lag phase and higher growth rates for the multiple spore experiment were found. The same trend was observed on the probability models, with lower predicted probabilities when colonies came up from single spores, for both growth and AFB1 production probabilities. Comparing both types of models, it was concluded that a clear overestimation of the lag phase for growth occurred using the linear model, but only in the multiple spore experiment. Multiple spore inoculum gave very similar estimated time to reach some set probabilities (t10, t50 and t100) for growth or AFB1 production due to the abruptness of the logistic curve developed. The observed differences suggest that inoculum concentration greatly affects the outcome of the predictive models, the estimated times to growth/AFB1 production being much earlier for the concentrated inoculum than for a single spore colony (up to 9days). Thus the number of spores used to generate data in predictive mycology experiments should be carefully controlled in order to predict as accurately as possible the fungal behavior in a foodstuff.

Hongos productores de micotoxinas asociados a hierbas medicinales en la Ciudad de São Paulo, Brasil / Mould and mycotoxins associated in medicinal plants in São Paulo, Brazil

Antecedentes: la fitoterapia es una de las más antiguas prácticas utilizadas por la humanidad. Hasta mediados del siglo XIX, cuando se introdujeron los medicamentos, la formulación de estos generalmente era basada en plantas medicinales. Objetivos: Determinar la micobiota y los niveles de aflatoxinas originadas de Aspergillus sección Flavi aislados de las 50 muestras de medicamentos fitoterápicos comercializados actualmente en la ciudad de São Paulo, Brasil. Métodos: Cincuenta (50) muestras de medicamentos fitoterápicos en la forma de hojas (té-25) y cápsulas (25) fueron colectadas de agosto de 2000 a julio de 2001. Los hongos filamentosos aislados fueron identificados al nivel de género de acuerdo con las características morfológicas y criterios taxonómicos. El análisis de aflatoxinas fue realizada por cromatografía de capa fina (TLC). Resultados: El análisis microbiológico mostró que 41 (82 por ciento) de los medicamentos fitoterápicos presentaron un crecimiento fúngico sobre las 100 UFC/g. Un total de 106 especies de seis diferentes géneros fueron aislados (Aspergillus, Penicillium, Mucor, Rhizopus y Alternaria). El género Aspergillus fue el predominante (60.5 por ciento) seguido por Penicillium (20,0 por ciento). Aspergillus niger (30 por ciento) A. flavus (22 por ciento), A. fumigatus (6,5 por ciento) y A. parasiticus fueron las especies de Aspergillus identificadas. Se observó que 13 (56,5 por ciento), de los 23 A. flavus aislados y dos aislados de A. parasiticus produjeron aflatoxinas. Conclusiones: La contaminación observada en la mayoría de los productos y el alto nivel de cepas productoras de aflatoxinas justifica un análisis más cuidadoso de los medicamentos fitoterápicos comercializados y la aplicación de leyes más rigurosas son necesarias para garantizar la calidad de los productos.

Background: phytotherapy is one of the most ancient practices used by humanity. In Antiquity until the middle of the XIX century, when chemotherapeutic drugs were introduced, formulation of medicines was usually based on medicinal plants. Objective: To determine mycobiota and levels of Aspergillus section Flavi aflatoxins isolated from 50 samples of phytotherapeutic remedies currently commercialized in São Paulo, Brazil. Methods: Fifty (50) samples of phytotherapeutic remedies in the form of leaves (teas-25) and powders (capsules-25) were collected from August 2000 to July 2001. Filamentous fungi isolates were identified at the genera level in accordance with morphological characteristics and taxonomic criteria. Aflatoxins were performed by Thin-layer chromatography (TLC). Results: The microbiological analysis showed that 41 (82 percent) of phytotherapeutic remedies presented a fungal growth over 100 CFU/g. A total of 106 species of six different genera were isolated (Aspergillus, Penicillium, Mucor, Rhizopus and Alternaria). The genus Aspergillus was the predominant (60.5 percent) followed by Penicillium genus (20.0 percent). Aspergillus niger (30 percent) A. flavus (22 percent), A. fumigatus (6.5 percent) and A. parasiticus were the species of Aspergillus identified. It was observed that 13 (56.5 percent) of 23 A. flavus isolates and two A. parasiticus isolates produced aflatoxins. Conclusions: The contamination observed in most products and the high level of aflatoxigenic strains justify the concern regarding the execution of more careful analyzes of the commercialized phytotherapeutic remedies and the application of more rigorous laws that may warrant the quality of these products.

Effects of Nutrients in Substrates of Different Grains on Aflatoxin B1 Production by Aspergillus flavus.

The current study was to better understand the potential factors affecting aflatoxin B1 (AFB1) accumulation varies between different grains. The nutrient composition and contents of defatted substrates were determined; additionally, according to the nutrient content of the substrates, the effects of starch, soluble sugars, amino acids, and trace elements on AFB1 production and mycelial growth in Czapek-Dox medium were examined. These results verified that removal of lipids from ground substrates significantly reduced the substrate's potential for AFB1 production by Aspergillus flavus. Maltose, glucose, sucrose, arginine, glutamic acid, aspartic acid, and zinc significantly induced AFB1 production up to 1.7- to 26.6-fold. And stachyose more significantly promoted A. flavus growth than the other nutrients. Thus, this study demonstrated that, combined with the nutrients content of grains, in addition to lipids, sucrose, stachyose, glutamic acid, and zinc might play key roles in various grains that are differentially infected by A. flavus. Particularly, two new nutrients (arginine and stachyose) of the grains we found significantly stimulate AFB1 production and A. flavus growth, respectively. The results provide new concepts for antifungal methods to protect food and animal feed from AFB1 contamination.

Evidence for synergistic activity of plant-derived essential oils against fungal pathogens of food.

The antifungal activities of eight essential oils (EOs) namely basil, cinnamon, eucalyptus, mandarin, oregano, peppermint, tea tree and thyme were evaluated for their ability to inhibit growth of Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus and Penicillium chrysogenum. The antifungal activity of the EOs was assessed by the minimum inhibitory concentration (MIC) using 96-well microplate analysis. The interactions between different EO combinations were done by the checkerboard technique. The highest antifungal activity was exhibited by oregano and thyme which showed lower MIC values amongst all the tested fungi. The antifungal activity of the other EOs could be appropriately ranked in a descending sequence of cinnamon, peppermint, tea tree and basil. Eucalyptus and mandarin showed the least efficiency as they could not inhibit any of the fungal growth at 10,000 ppm. The interaction between these two EOs also showed no interaction on the tested species. A combined formulation of oregano and thyme resulted in a synergistic effect, showing enhanced efficiency against A. flavus and A. parasiticus and P. chrysogenum. Mixtures of peppermint and tea tree produced synergistic effect against A. niger. Application of a modified Gompertz model considering fungal growth parameters like maximum colony diameter, maximum growth rate and lag time periods, under the various EO treatment scenarios, showed that the model could adequately describe and predict the growth of the tested fungi under these conditions.

Efficiency of Artemisia nilagirica (Clarke) Pamp. essential oil as a mycotoxicant against postharvest mycobiota of table grapes.

BACKGROUND: In order to get a potent botanical fungicide for the management of fungal decay of table grapes, an experiment was conducted in which 20 essential oils of higher plants were screened at 0.33 µL mL(-1) against dominant fungi causing decay of table grapes, including Aspergillus flavus, A. niger and A. ochraceus. Furthermore, the minimum inhibitory/fungicidal concentration, fungitoxic spectrum and mycotoxin inhibition activity of the most potent oil were determined. The efficacy of the most potent oil in preservation of table grapes, along with organoleptic evaluation, was also carried out by storing 1 kg of grapes in the oil vapour. RESULTS: Artemisia nilagirica oil was found to be most toxic, exhibiting 100% mycelia inhibition of all test fungi. Moreover, 0.29 µL mL(-1) A. nilagirica oil was fungistatic and 0.58 µL mL(-1) was fungicidal for all tested species of Aspergillus. The oil exhibited a broad range of fungitoxicity against other grape berry-rotting fungi. Artemisia nilagirica oil completely suppressed the growth and mycotoxin (AFB1 and OTA) secretion of aflatoxigenic and ochratoxigenic strains of Aspergillus at 1.6 µL mL(-1) . During the in vivo experiment, fumigation of 1 kg of table grapes with 200 and 300 µL dosage of A. nilagirica oil enhanced the shelf life for up to 9 days. The oil did not show any phytotoxic effect. Besides, oil application did not substantively change the sensory properties of the fruits. CONCLUSION: Artemisia nilagirica oil can be used as an alternative botanical fungicide for the control of fruit-rotting fungi of stored grapes.