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Ochratoxin A (OTA), is one of the most commonly found mycotoxins in food. It is primarily produced by Aspergillus ochraceus and Penicillium verrucosum. OTA can causes serious damages to liver and kidney, increases the teratogenicity, and has been considered as a potential carcinogen (group 2 B). In this study, we demonstrated a new detection system for the detection of OTA using fluorescence biosensing according to an anti-OTA aptamer and fluorescence quencher using single-walled carbon nanohorns (SWCNHs). In the presence of OTA, the OTA-specific aptamer underwent the conformation change from a random coil to an antiparallel G-quadruplex. The latter one was resistant to being adsorbed onto SWCNHs, leading to the pertection of the fluorescence of SYBR Gold. As a result, the remained fluorescent intensities correlated with the concentrations of OTA. The detection limit of OTA was 2.3 ng/ml, meanwhile the linear detection range was 5–500 ng/ml, with a satisfactory linear correlation (R2 = 0.992) of the fluorescence intensity and the logarithm of OTA concentrations. The aptasensor was subjected to quantify the concentration of OTA in red wine samples. As a result, this label-free aptasensor was suitable for the test of OTA in food samples.

Information on the presence of ochratoxin A (OTA) in local Ethiopian coffee is scarce. Therefore, the objective of this study was to type the fungal and mycotoxin contamination levels in Ethiopian coffee consumed by the local community. Coffee samples were collected from six major coffee growing districts in Jimma zone of Oromiya regional state in Ethiopia. Total fungal incidence mounted up to 87% and Aspergillus (79%), Fusarium (8%) and Penicillium (5%) were the predominant toxigenic genera. OTA producing species A. westerdijkiae, Aspergillus ochraceus, and Aspergillus steynii were identified for the first time in Ethiopia and were shown to be the predominant species while aflatoxin (AF) producing Aspergillus species were scarce. Using an in vitro approach, the OTA production potential was assessed under standardized conditions. Based on this experiment, it was concluded that Aspergillus westerdijkiae isolates were clearly the most potent producers of OTA. The median OTA level in the locally sold Ethiopian coffee was 1.53 μg/kg. Notwithstanding this low median value, significant differences in fungal and toxin incidences were observed between the different coffee processing types, coffee sample types, and storage characteristics.

The inhibition effects of bacillomycin D on the growth of Aspergillus ochraceus and the production of ochratoxin A (OTA) in food samples were investigated. The mycelia growth and sporulation were completely inhibited by 30 μg/mL of bacillomycin D. Microscopic morphological changes such as the distortion of hyphae and the disruption of spores at 20 μg/mL of bacillomycin D were significantly observed. The use of bacillomycin D resulted in cell damage, nucleic acids and proteins divulge, and more production of reactive oxygen species (ROS), and all these factors actively contributed to the promotion of apoptosis of A. ochraceus . In addition, 90 μg/g of bacillomycin D completely inhibited the growth of A. ochraceus and the production of OTA in food samples. Our results suggested that bacillomycin D showed a significant antifungal activity against A. ochraceus that could be used as a potential natural antimicrobial to control food contamination and ensure food safety.

The major objective of this study was to determine the antifungal, anti-toxicogenic and anti-sporulation effect of selected essential oils in the control growth of Aspergillus spp. by contact vapour method in in vitro and in situ condition. In continue, the effect of the essential oils treatment on the sensory profile of the bread was evaluated. In this study, ten essential oils (EOs), namely: thyme, clove, laveder, cumin, oregano, cinnamon, basil, rosemary, sage and lemongrass were tested against four strains of Aspergillus [Aspergillus flavus (SLO-B-201), Aspergillus parasiticus (SLO-B-219), Aspergillus ochraceus (SLO-B-245) and Aspergillus westerdijkiae (SLO-B-249)] isolated from bread samples. The Aspergillus strains were tested for potential production of mycotoxins by thin layer chromatography (TLC). The chemical composition of all tested EOs was identified by GC-MS and by gas chromatography with flame ionization detector (GC-FID). The antifungal activity, the minimum inhibitory doses (MIDs), anti-toxicogenic and antisporulation effect of the selected EOs were investigated by gas diffusion method in both, in vitro and in situ analyses. The results indicated that the thyme, clove, oregano, cinnamon and lemongrass were highly effective against tested toxigenic Aspergillus species in vapour phase. A treated bread sample with EOs does not have negative effect on the sensory properties of the breads, with exception of oregano and lemongrass. In this context, application EOs in vapour phase seems to be an effective, sustainable and safe method and promising alternative to the use of chemical inhibitors for bread preservation.

To estimate the dietary intake of ochratoxin A (OTA), information on the fate during wheat processing is needed. The wheat contaminated with OTA at both levels (93.22 and 248.93 μg/kg) was artificially inoculated by Aspergillus ochraceus . Concentrations of OTA were 1.43–1.66 times higher in bran than whole wheat and 1.27–1.50 times higher in shorts than bran. A concentration reduction of 43.29–55.16% for OTA in flour was observed, with the final concentrations of 41.80 and 138.33 μg/kg in flour respectively. Whereas, OTA was not transferred or decomposed during milling, as the total amount of OTA in all milling fractions didn't decreased. The further losses of OTA were various depending on different processes. The concentration of OTA increased by 11–16% when the flour was processed into Chinese steamed bread (CBS), with the OTA concentrations of 49.2 and 161.35 μg/kg in CBS. It revealed fermentation and steaming increased the OTA levels in CBS. The loss of OTA was small in the Chinese fried bread sticks (CFBS) (38.84 and 129.02 μg/kg), being of 6.73–9.63%. A higher reduction of 23.27–23.92% for OTA was detected in the noodles processing, with the final concentration of 32.98 and 108.24 μg/kg in noodles respectively. The result revealed that the temperature, pH values and strains involved the processes exerted different effects. High temperature (180 °C) and alkaline condition (pH > 7) facilitated to the removal of OTA, while fermentation (with dry yeast) increased the OTA levels in products.

Aspergillus carbonarius (AC) and Aspergillus ochraceus (AO) are the major ochratoxin A (OTA)-producing fungi isolated from grapes. Seventy-three yeast strains from 10 species were tested for their capabilities in inhibiting the growth and OTA production by AC and AO in agar medium and grape berries using a co-culture method for in vitro and in vivo experiments, respectively. Results showed that five yeast strains, namely, Candida zemplinina M3, Saccharomyces cerevisiae M114 and C297, Pichia kluyveri M117, and Metschnikowia aff. fructicola M179, significantly inhibited AC and AO in agar medium and grape berries. OTA production in grape berries also significantly decreased. The inhibition efficacy varied with the yeast used. Comparatively, M114 showed the highest reduction of decay incidence of 80% and 40% caused by AC and AO, respectively. The spore germination of AC was inhibited when co-cultured with M114 in liquid cultivation but not when co-cultured in yeast-free supernatant. However, the yeast-free supernatant obtained from 3 d of co-culture of AC and M114 inhibited the germination of fungal spores. The population of M114 in grape berries inoculated with AC was higher than that of the control, particularly at 72 h (28.35 times higher). The volatile compounds produced by M114 had no effect on AC growth. In summary, five strains of yeast that can inhibit growth and OTA production by AC and AO were obtained. Results demonstrated the intrinsic mechanism of the inhibition effect, which was possibly attributed to the competition for space and nutrients of fungi and yeasts or the production of antifungal metabolite(s) by yeast in the co-culture.

Spices can be heavily contaminated with Penicillium verrucosum and Aspergillus ochraceus, which develop during cultivation and after harvest if relative humidity is not controlled during storage. The present study was undertaken with the aim to provide an analytical method to detect OTA in spices commercialized in China, specifically to develop a simple and rapid method for the determination of Ochratoxin A content in spices via immunoaffinity column and high performance liquid chromatography with fluorescence detection (HPLC-FLD). The recovery (75.0–102.0%) and repeatability (RSD

Ochratoxin A (OTA) is a type of mycotoxin mainly produced by fungus belonging to the genus Aspergillus and Penicillium and plays a critical role in food safety since it causes serious health problem. Biological control by using microorganisms is considered a promising approach for detoxification of this mycotoxin. In order to find bacteria with efficient OTA elimination capability, one bacteria strain JSW-B1 with OTA removal ability was isolated from soil samples and was identified as Bacillus megaterium based on morphological and 16S rRNA analysis. After incubation of isolate JSW-B1 in liquid culture medium containing 2.5 μg/mL OTA for 72 h, the OTA removal percentage was 80.3%. No degradation products of OTA could be detected by liquid chromatography. About 62.6% OTA could be removed by the viable cell fraction after incubation for 72 h compared to 13.7% by cell-free supernatant. Meanwhile, heat treatment significantly enhanced OTA removing capability of the cells, suggesting that the OTA removal activity of the isolate JSW-B1 was mainly attributed to the adsorption by bacterial cells. In addition, the antifungal experiments revealed that isolate JSW-B1 was able to suppress the mycelial growth of Aspergillus ochraceus on solid medium with an inhibition ratio of 41.9% and reduce the fungal incidence on maize corns with a reduction ratio of 15%. Taken together, our results indicated that B. megaterium JSW-B1 could be considered as potential biological agent to control toxigenic fungal growth and mycotoxin contamination in agricultural products.

The incidence of ochratoxin A was studied in different coffee (Coffea arabica L.) samples. A higher incidence of filamentous fungi was observed in the coffee swept from ground and floating coffee samples. The species Aspergillus ochraceus, Aspergillus sulphureus and Aspergillus sclerotiorum were ochratoxin A producing. In 128 (44%) samples ochratoxin A was not detected; however, in 89 samples (31%), ochratoxin A was detected at 0.1–5.0 μg/Kg levels. Other 25% samples presented contamination above 5.0 μg/Kg. This study showed that the fractions coffee swept from ground and floating coffee represents a serious risk of ochratoxin A contamination.

The objectives of this study were: (a) to evaluate the potential of the ELISA method in the determination of the produced OTA by Aspergillus ochraceus and Aspergillus carbonarius in malt extract agar (MEA) at different pH (3.9, 5.1, 5.9, 6.8), water activity (aw) (0.87, 0.93, 0.99), and temperature (10, 15, 20, 25, 30, 40 °C) levels, providing a rapid screening for the optimum and marginal conditions of OTA production, (b) to comparatively evaluate the performance of ELISA and HPLC method, and (c) to evaluate the ability of A. ochraceus to produce OTA in rehydrated Corinth raisins during storage for 36 days. Two independent experiments were carried out to estimate OTA production on MEA and Corinth raisins. The produced OTA was evaluated qualitatively by the ELISA method and selected cases were verified by HPLC. The levels of OTA decreased with water activity, whereas pH seemed to have no specific effect. Furthermore, A. ochraceus produced maximum amounts of OTA on raisins at the 24th day of incubation, indicating that the endogenous microflora may restrictively affect OTA production. The knowledge of optimal and marginal levels of ecological factors in order to optimise post-harvest and storage of food products may significantly affect the production of OTA. Moreover, endogenous microflora of certain foodstuffs may cause OTA detoxification and consequently reduction of OTA levels; a fact that has to be taken into account in food commodities such as raisins, grapes, and wine.

The effect of alternating temperatures in the storage of coffee was studied. From the day and night values, two average temperatures (25 and 14 °C) were chosen. Such changes may occur, mainly during storage in farm barns and transport. The study was carried out under different conditions of equilibrium relative humidity (ERH): 80%, 87% and 95% for the production of ochratoxin A (OTA) by Aspergillus ochraceus in raw coffee. Temperatures were cycled at 12 h intervals. Coffee was also maintained at 25 °C under similar conditions, but without temperature cycling, at the same three values of relative humidity. Ochratoxin production was analysed after periods of 39 and 60 days after the coffee had reached the equilibrium relative humidity. The water activity and moisture content of coffee were checked and OTA production was quantified. There was little or no OTA production at 80% ERH; at 87% and 95% OTA production was high after different days of incubation. Under alternating temperatures OTA production was higher than at constant temperature, and alternating temperatures indirectly favoured OTA production due to condensation and a subsequent rapid increase in moisture content and water activity of the coffee beans.

Ochratoxin A (OTA) is a highly toxigenic mycotoxin commonly present in a number of diverse agroproducts. Aspergillus Section Circumdati includes some of the most important OTA-producing species: Aspergillus ochraceus, Aspergillus elegans and the recently described Aspergillus steynii and Aspergillus westerdijkiae. In this work, OTA production by several strains of these four species from diverse origins and food matrices was examined. Identification of all the strains was carried out by specific PCR assays. The strains were cultivated in CYA solid medium and OTA was measured by HLPC. This study demonstrated for the first time the high capacity of A. steynii strains to produce OTA at higher levels than A. westerdijkiae,A. ochraceus and A. elegans strains showed low levels or no production at all. In conclusion, the results of this study suggest that the occurrence of A. steynii and A. westerdijkiae might represent the major potential risk for OTA contamination due to their high production and the diversity of commodities that these species may contaminate.

Contamination of roasted coffee with ochratoxin A (OTA) is directly related to the processing quality throughout the coffee production chain, from the farming to the roasting processes. The aim of this study was to evaluate the effects of roasting and particle size on the residual concentration of ochratoxin A in roasted and ground coffee. Coffee beans were artificially contaminated with Aspergillus ochraceus . The beans were roasted to three levels (light, medium and dark) and ground into three types (fine, medium and coarse) after an incubation period. OTA quantification was performed using high-performance liquid chromatography. The combination of dark roast and coarse particle size had the lowest concentration of OTA, 3.06 μg/kg with a 97.17% reduction. The results of this study show that roasting and particle size, rather than roasting alone, are critical for the residual concentration of OTA in roasted and ground coffee beans.