Occurrence of Ochratoxin A in Chinese wines: influence of local meteorological parameters

Occurrence and impact of carbendazim and hymexazol residues on yeast growth and ochratoxin A contamination during wine production

BACKGROUND

Grapes are highly vulnerable to infection by carbon black aspergilli, which produce ochratoxin A (OTA), a mycotoxin. Carbendazim and hymexazol are widely applied to control grape diseases. Howerver, fungicides, toxigenic fungi, and OTA can be transferred from grapes to wine causing potential safety issues. The impact of these residues on fungal populations and OTA during vinification are currently unclear. Here we investigated the effects of carbendazim and hymexazol on the viability of Aspergillus carbonarius and OTA contamination during an indoor wine-processing experiment.

RESULTS

The population size of A. carbonarius substantially increased at 24 h followed by a significantly decreased at 72 h after destemming and crushing. However, carbendazim and hymexazol notably inhibited the growth of A. carbonarius in must samples. In addition, yeast growth was substantially deleyed by carbendazim, hymexazol, and OTA during the first 3 days in compared with the control. Carbendazim, hymexazol, and OTA residues declined over time, and the processing factors (PFs) for carbendazim and hymexazol throughout vinification were 0.164, 0.074, and 0.185-0.476, respectively. Carbendazim and hymexazol each reduced OTA concentrations. However, there was no significant difference after 48 h. Addition of carbendazim or hymexazol significantly reduced the level of A. carbonarius but had no significant effect on the final concentration of OTA in mature wine.

CONCLUSION

The wine-making process can reduce the residues of OTA, carbendazim, and hymexazol in grapes, but it is recommended that grapes chosen to make wine should be free of A. carbonarius contamination. © 2023 Society of Chemical Industry.

Fluorescent Sensor Based on Magnetic Separation and Strand Displacement Amplification for the Sensitive Detection of Ochratoxin A

Ochratoxin A (OTA) is a common mycotoxin, and it is a significant threat to human health throughout the food chain. In this study, a sensitive and specific fluorescent sensor based on magnetic separation technology combined with chain displacement amplification was developed for fast and easy detection of OTA in food. The designed strand displacement amplification can improve the sensitivity for the detection, and the magnetic nanomaterials can provide a large surface area, thus enhancing the capture efficiency of the target from the sample. Based on those designs, the experimental results showed that the proposed method displayed excellent performance. The linearity range was 0.5-128.0 ng/mL. The detection limit was 0.125 ng/mL; the relative standard deviations were 3.92-7.71%. Additionally, the developed method was satisfactorily applied to determine OTA in wheat, corn, and red wine samples at three spiked levels (1.0, 8.0, and 64.0 ng/mL). The recoveries ranged from 85.45 to 107.8% for wheat flour, 101.34 to 108.35% for corn flour, and 91.15 to 93.80% for red wine, respectively. Compared with high-performance liquid chromatography, the proposed method showed a lower limit of detection and equal recovery. Hence, the designed method is a potential and good detecting tool for OTA residue analysis in complex matrix samples.

Contamination, Detection and Control of Mycotoxins in Fruits and Vegetables

Mycotoxins are secondary metabolites produced by pathogenic fungi that colonize fruits and vegetables either during harvesting or during storage. Mycotoxin contamination in fruits and vegetables has been a major problem worldwide, which poses a serious threat to human and animal health through the food chain. This review systematically describes the major mycotoxigenic fungi and the produced mycotoxins in fruits and vegetables, analyzes recent mycotoxin detection technologies including chromatography coupled with detector (i.e., mass, ultraviolet, fluorescence, etc.) technology, electrochemical biosensors technology and immunological techniques, as well as summarizes the degradation and detoxification technologies of mycotoxins in fruits and vegetables, including physical, chemical and biological methods. The future prospect is also proposed to provide an overview and suggestions for future mycotoxin research directions.

Chemical hazards in grapes and wine, climate change and challenges to face

Climate change has an impact on the chemical risks associated to wine consumption related with grape development and microbial contamination. We can classify chemical hazards in wine into two groups: those present in grapes due to agricultural practices, environmental contamination or fungal growth and those coming from fermentation and the winemaking process. The first group includes mycotoxins, whilst the second encompasses ethyl carbamate, biogenic amines, sulfur dioxide and proteins used as technological ingredients such as fining material. Usually the effective control of chemical hazards is achieved by assuring that they either are minimized or absent in the final product since their removal is somewhat difficult and sometimes it may affect sensory properties, which is a major issue in wine. Interestingly, it is possible to give recommendations to avoid excess of these compounds, but more research is needed to face future challenges related to climate change and consumer demands.

Kresoxim-methyl and famoxadone as activators of toxigenic potential of Aspergillus carbonarius

Ochratoxin A (OTA) is a secondary metabolite produced by filamentous fungi species belonging to the genera Penicillium and Aspergillus. The contamination of grapes by ochratoxigenic species occurs worldwide in regions of tropical and temperate climates. Better control of fungal growth is achieved through good cultural practice and proper selection of fungicides. Kresoxim-methyl and famoxadone are the most common fungicides used in vineyards. This study aimed at analysing the OTA production and toxigenic potential of Aspergillus carbonarius under fungicide treatment with famoxadone and kresoxim-methyl. The growth rate of A. carbonarius was evaluated by measuring the glucosamine content and the diameter of the fungal colonies. OTA production was quantified by HPLC analysis. The treatment with fungicides, kresoxim-methyl and famoxadone, significantly reduced the fungal growth, by 76% and 60%, respectively. However, the mycotoxin production was greater in the fungicide-treated groups than the control group, showing that even though the fungicides were effective in controlling fungal growth, they were ineffective against mycotoxin production.

Ochratoxin A in the Portuguese Wine Market, Occurrence and Risk Assessment

Ochratoxin A (OTA) is mainly found in cereals and cereal-based foodstuffs, but also in wine. Being one of the most consumed alcoholic drinks in Portugal and one of the main sources of human exposure to OTA, wine monitoring and exposure studies are essential. The analytical methodology consisted of the direct injection of the filtered samples into the liquid chromatograph, equipped with fluorescent detection (LC-FLD). Linearity was adequate, both in mobile phase and in matrix-matched solutions, with R² values higher than 0.997. The limits of detection were 0.08 and 0.39 µg/L for white and red wine, respectively and recoveries were above 91.9%. One hundred wine samples acquired on the Portuguese market were investigated. In 5 samples the OTA was detected, with the red wine presenting higher frequency of contamination. Regarding the risk to human health it was observed that the estimated weekly intake (EWI) is considerably lower than the established tolerable weekly intake (TWI).

High-performance liquid chromatography-tandem mass spectrometry method for simultaneous detection of ochratoxin A and relative metabolites in Aspergillus species and dried vine fruits

A simple, sensitive and reliable quantification and identification method was developed for simultaneous analysis of ochratoxin A (OTA) and its related metabolites ochratoxin alpha (OTα), ochratoxin B (OTB) and mellein. The method was assessed by spiking analytes into blank culture media and dried vine fruits. Performance was tested in terms of accuracy, selectivity and repeatability. The method involves an ultrasonic extraction step for culture samples using methanol aqueous solution (7:3, v/v); the mycotoxin is quantified by high-performance liquid chromatography coupled with electrospray ionisation and triple quadrupole mass spectrometry (LC-ESI-MS/MS). The recoveries were 74.5-108.8%, with relative standard deviations (RSDs) of 0.4-8.4% for fungal culture. The limits of detection (LODs) were in the range of 0.03-0.87 μg l(-)(1), and the limits of quantification (LOQs) ranged from 0.07 to 2.90 μg l(-)(1). In addition, the extraction solutions and clean-up columns were optimised specifically for dried vine fruit samples to improve the performance of the method. Methanol-1% sodium bicarbonate extraction solution (6:4, v/v) was determined to be the most efficient. Solid-phase extraction (SPE) was performed as a clean-up step prior to HPLC-MS/MS analysis to reduce matrix effects. Recoveries ranged from 80.1% to 110.8%. RSDs ranged from 0.1% to 3.6%. LODs and LOQs ranged from 0.06 to 0.40 μg kg(-)(1) and from 0.19 to 1.20 μg kg(-)(1), respectively. The analytical method was established and used to identify and quantify OTA and related compounds from Aspergillus carbonarius and Aspergillus ochraceus in cultures and dried vine fruits. The results showed that A. carbonarius produced OTα, OTB and OTA, whereas A. ochraceus produced OTB, OTA and mellein after 7 days of cultivation. Of 30 commercial samples analysed, 10 were contaminated with ochratoxins; OTB, OTα and mellein were also detected in different samples.

Ochratoxin A in Chinese dried jujube: method development and survey

A method was developed for the determination of the mycotoxin ochratoxin A in dried jujube (Zizyphus jujuba Miller) using alkaline methanolic extraction, immunoaffinity column clean-up (IAC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination. The limit of detection (LOD) was 0.01 μg kg(-1) and limit of quantification (LOQ) was 0.03 μg kg(-1). The average recoveries were 82%, 98% and 115% at 5, 0.5 and 0.1 μg kg(-1) spiked levels with relative standard deviations (RSD) of 2.9%, 5.2% and 9.2% accordingly. The method showed good linearity for both solvent standard calibration and matrix-matched standard calibration with correlation coefficients of 0.9998 and 0.9997 respectively. The intra-day precision RSD was 3.3% and the inter-day precision RSD was 4.0%. In addition, there was almost no matrix interference in LC-MS/MS detection after the IAC clean-up process. The proposed analytical set-up was successfully used to test 20 samples that were collected from local markets and stores. The results showed that all the samples were positive and the amount of OTA ranged from < 0.01 to 0.18 μg kg(-1), with a mean level of 0.14 μg kg(-1). In spite of the high positive rate, samples with this level would not cause significant health effects after consumption.

Exposure assessment to ochratoxin A in Chinese wine

A rapid, sensitive, reproducible, and inexpensive method of high-performance liquid chromatography with fluorescence detection after an anion-exchange solid-phase extraction cleanup step for the analysis of ochratoxin A (OTA) in Chinese wine was developed. The average recovery rate and the average RSD of recovery were 97.47% and about 4%. The relative standard deviations of both the interday and intraday precision were 6.7 and 12.6%, respectively. The limits of detection and quantitation were determined to be 0.01 and 0.03 μg/L, respectively. A total of 223 samples from the major wine-producing areas of China were analyzed for OTA. OTA was detected at levels of 0.01-0.98 μg/L. The mean was 0.15 μg/L. Then, participants as representative inhabitants were invited to answer the designed questionnaire about the quantity and frequency of wine consumption. All data were simulated by the point evaluation for the risk assessment of OTA contamination from wine. Those results indicated that daily intake (DI) of OTA for the average adult consumer varies between 0.86 and 1.08 ng/kg bw per week, which was lower than all the reference standards. However, the DI value (4.38-5.54 ng/kg bw per week) in the high percentile (97.5) was slightly above 5% PTWI (100 ng kg(-1) week(-1)) of the JECFA. In conclusion, OTA exposure from Chinese wine has no risk of harm. This research will provide the scientific basis for determining the maximum limit of OTA content in Chinese wine.

Presence of ochratoxin A (OTA) mycotoxin in alcoholic drinks from southern European countries: wine and beer

The main filamentous fungi producers of mycotoxins are Aspergillus spp., Penicillium spp., and Fusarium spp. Their effect can provoke a broad range of toxic properties including carcinogenicity and neurotoxicity, as well as reproductive and developmental toxicities. Ochratoxin A (OTA) is produced by Aspergillus and Penicillium spp. The purpose of this review was to evaluate the risk assessment of OTA in alcoholic drinks (beer and wine) by compiling the results obtained from studies and reviews related to the presence of OTA in these two drinks from southern European countries in the period 2005-2013 and comparing those results with the legislation available in the European Union.