Ochratoxins in Wines: A Review of Their Occurrence in the Last Decade, Toxicity, and Exposure Risk in Humans

Comprehensive Review of Aflatoxin and Ochratoxin A Dynamics: Emergence, Toxicological Impact, and Advanced Control Strategies

Filamentous fungi exhibit remarkable adaptability to diverse substrates and can synthesize a plethora of secondary metabolites. These metabolites, produced in response to environmental stimuli, not only confer selective advantages but also encompass potentially deleterious mycotoxins. Mycotoxins, exemplified by those originating from Alternaria, Aspergillus, Penicillium, and Fusarium species, represent challenging hazards to both human and animal health, thus warranting stringent regulatory control. Despite regulatory frameworks, mycotoxin contamination remains a pressing global challenge, particularly within cereal-based matrices and their derived by-products, integral components of animal diets. Strategies aimed at mitigating mycotoxin contamination encompass multifaceted approaches, including biological control modalities, detoxification procedures, and innovative interventions like essential oils. However, hurdles persist, underscoring the imperative for innovative interventions. This review elucidated the prevalence, health ramifications, regulatory paradigms, and evolving preventive strategies about two prominent mycotoxins, aflatoxins and ochratoxin A. Furthermore, it explored the emergence of new fungal species, and biocontrol methods using lactic acid bacteria and essential mustard oil, emphasizing their efficacy in mitigating fungal spoilage and mycotoxin production. Through an integrative examination of these facets, this review endeavored to furnish a comprehensive understanding of the multifaceted challenges posed by mycotoxin contamination and the emergent strategies poised to ameliorate its impact on food and feed safety.

Biocontrol of Occurrence Ochratoxin A in Wine: A Review

Viticulture has been an important economic sector for centuries. In recent decades, global wine production has fluctuated between 250 and almost 300 million hectoliters, and in 2022, the value of wine exports reached EUR 37.6 billion. Climate change and the associated higher temperatures could favor the occurrence of ochratoxin A (OTA) in wine. OTA is a mycotoxin produced by some species of the genera Aspergillus and Penicillium and has nephrotoxic, immunotoxic, teratogenic, hepatotoxic, and carcinogenic effects on animals and humans. The presence of this toxin in wine is related to the type of wine-red wines are more frequently contaminated with OTA-and the geographical location of the vineyard. In Europe, the lower the latitude, the greater the risk of OTA contamination in wine. However, climate change could increase the risk of OTA contamination in wine in other regions. Due to their toxic effects, the development of effective and environmentally friendly methods to prevent, decontaminate, and degrade OTA is essential. This review summarises the available research on biological aspects of OTA prevention, removal, and degradation.

Comprehensive Insights into Ochratoxin A: Occurrence, Analysis, and Control Strategies

Ochratoxin A (OTA) is a toxic mycotoxin produced by some mold species from genera Penicillium and Aspergillus. OTA has been detected in cereals, cereal-derived products, dried fruits, wine, grape juice, beer, tea, coffee, cocoa, nuts, spices, licorice, processed meat, cheese, and other foods. OTA can induce a wide range of health effects attributable to its toxicological properties, including teratogenicity, immunotoxicity, carcinogenicity, genotoxicity, neurotoxicity, and hepatotoxicity. OTA is not only toxic to humans but also harmful to livestock like cows, goats, and poultry. This is why the European Union and various countries regulate the maximum permitted levels of OTA in foods. This review intends to summarize all the main aspects concerning OTA, starting from the chemical structure and fungi that produce it, its presence in food, its toxicity, and methods of analysis, as well as control strategies, including both fungal development and methods of inactivation of the molecule. Finally, the review provides some ideas for future approaches aimed at reducing the OTA levels in foods.

A Predictive Assessment of Ochratoxin A's Effects on Oxidative Stress Parameters and the Fermentation Ability of Yeasts Using Neural Networks

The aim of this paper was to examine the effect of different OTA concentrations on the parameters of oxidative stress (glutathione (GSH) and malondialdehyde (MDA) concentrations) and glucose utilization in ethanol production by wine yeasts. In addition to the above, artificial neural networks (ANN) were used to predict the effects of different OTA concentrations on the fermentation ability of yeasts and oxidative stress parameters. The obtained results indicate a negative influence of OTA (4 µg mL-1) on ethanol production after 12 h. For example, K. marxianus produced 1.320 mg mL-1 of ethanol, while in the control sample 1.603 µg mL-1 of ethanol was detected. However, after 24 h, OTA had no negative effect on ethanol production, since it was higher (7.490 and 3.845 mg mL-1) in comparison to control samples. Even low concentrations of OTA affect GSH concentrations, with the highest being detected after 12 and 24 h (up to 16.54 µM), while MDA concentrations are affected by higher OTA concentrations, with the highest being detected at 24 h (1.19 µM). The obtained results with the use of ANNs showed their potential for quantification purposes based on experimental data, while the results of ANN prediction models have shown to be useful for predictions of what outcomes different concentrations of OTA that were not part of experiment will have on the fermentation capacity and oxidative stress parameters of yeasts.

Plant extracts as biocontrol agents against Aspergillus carbonarius growth and ochratoxin A production in grapes

Aspergillus carbonarius (Bainier) Thom. is an important pathogen and ochratoxin A (OTA) producer in grapes that can be controlled by adopting sustainable approaches. Here we evaluate the application of natural plant extracts as an alternative to synthetic fungicides to reduce OTA contamination and to prevent infection of grapes by two isolates of A. carbonarius. In a preliminary screening, natural extracts of chestnut flower, cistus, eucalyptus, fennel, and orange peel were evaluated for their antifungal and anti-mycotoxigenic efficiency in a grape-based medium at concentrations of 10 and 20 mg/mL. Cistus and orange peel extracts demonstrated the best antifungal activity at both concentrations. Although the eucalyptus extract demonstrated no significant effect on Aspergillus vegetative growth, it significantly reduced OTA by up to 85.75 % at 10 mg/mL compared to the control. Chestnut flower, cistus, eucalyptus, and orange peel extracts were then tested at the lowest concentration (10 mg/mL) for their antifungal activity in artificially inoculated grape berries. The cistus and orange peel extracts demonstrated the greatest antifungal activity and significantly reduced mold symptoms in grapes. Moreover, all tested natural extracts were able to reduce OTA content in grape berries (17.7 ± 8.3 % - 82.3 ± 3.85 % inhibition), although not always significantly. Eucalyptus extract was particularly efficient, inhibiting OTA production by both strains of A. carbonarius by up to >80 % with no effects on fungal growth. The use of natural eucalyptus extract represents a feasible strategy to reduce OTA formation without disrupting fungal growth, apparently maintaining the natural microbial balance, while cistus and orange peel extracts appear promising as inhibitors of A. carbonarius mycelial growth. Our findings suggest that plant extracts may be useful sources of bioactive chemicals for preventing A. carbonarius contamination and OTA production. Nonetheless, it will be necessary to evaluate their effect on the organoleptic properties of the grapes.

Climate Change-A Global Threat Resulting in Increasing Mycotoxin Occurrence

During the last decade, scientists have given increasingly frequent warnings about global warming, linking it to mycotoxin-producing moulds in various geographical regions across the world. In the future, more pronounced climate change could alter host resilience and host-pathogen interaction and have a significant impact on the development of toxicogenic moulds and the production of their secondary metabolites, known as mycotoxins. The current climate attracts attention and calls for novel diagnostic tools and notions about the biological features of agricultural cultivars and toxicogenic moulds. Since European climate environments offer steadily rising opportunities for Aspergillus flavus growth, an increased risk of cereal contamination with highly toxic aflatoxins shall be witnessed in the future. On top of that, the profile (representation) of certain mycotoxigenic Fusarium species is changing ever more substantially, while the rise in frequency of Fusarium graminearum contamination, as a species which is able to produce several toxic mycotoxins, seen in northern and central Europe, is becoming a major concern. In the following paper, a high-quality approach to a preventative strategy is tailored to put a stop to the toxicogenic mould- and mycotoxin-induced contamination of foods and feeds in the foreseeable future.

A Bacillus-based biofungicide agent prevents ochratoxins occurrence in grapes and impacts the volatile profile throughout the Chardonnay winemaking stages

Bacillus-based biocontrol agents have emerged as a strategy to eliminate or reduce the use of synthetic fungicides that are detrimental to health and the environment. In vineyards, a special concern arises from the control of Aspergillus carbonarius, a fungus known for its potential to produce ochratoxins. Ochratoxin A (OTA) is the most toxic form among ochratoxins and its maximum limit in wine has been established in Europe and Brazil as 2 μg/kg. Wine quality, especially the volatile profile, may be influenced by the antifungal strategies, since fungicide residues are transferred from grapes to must during winemaking. The objective of this study was to evaluate, for the first time, the impact of a biocontrol strategy containing Bacillus velezensis P1 on the volatile profile and occurrence of ochratoxins when grapes infected with A. carbonarius were used in winemaking. The evaluation of ochratoxins was carried out by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToF-MS), and volatile compounds were analyzed using comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry (GC × GC/qMS). Six ochratoxins were identified in must prepared with Chardonnay grapes inoculated with A. carbonarius (ochratoxin α, ochratoxin β, ochratoxin α methyl-ester, ochratoxin α amide, N-formyl-ochratoxin α amide and OTA). Although winemaking causes a decrease in the levels of all forms of ochratoxins, the co-occurrence of these mycotoxins was verified in wine made with grapes containing A. carbonarius. B. velezensis P1 prevented the occurrence of ochratoxins in must, ensuring the safety of wines. Regarding the volatile profile, a predominant presence of terpenic compounds was verified in samples treated with B. velezensis when compared with those not treated with the biocontrol strategy, whereas the presence of A. carbonarius resulted in a higher concentration of volatile compounds with an odor described as fatty/waxy, possibly compromising wine quality. Therefore, B. velezensis P1 is a new biofungicide possibility to produce ochratoxin-free grapes and high-quality wines.

Fruit-Based Fermented Beverages: Contamination Sources and Emerging Technologies Applied to Assure Their Safety

The food and beverage market has become broader due to globalization and consumer claims. Under the umbrella of consumer demands, legislation, nutritional status, and sustainability, the importance of food and beverage safety must be decisive. A significant sector of food production is related to ensuring fruit and vegetable conservation and utilization through fermentation. In this respect, in this review, we critically analyzed the scientific literature regarding the presence of chemical, microbiological and physical hazards in fruit-based fermented beverages. Furthermore, the potential formation of toxic compounds during processing is also discussed. In managing the risks, biological, physical, and chemical techniques can reduce or eliminate any contaminant from fruit-based fermented beverages. Some of these techniques belong to the technological flow of obtaining the beverages (i.e., mycotoxins bound by microorganisms used in fermentation) or are explicitly applied for a specific risk reduction (i.e., mycotoxin oxidation by ozone). Providing manufacturers with information on potential hazards that could jeopardize the safety of fermented fruit-based drinks and strategies to lower or eliminate these hazards is of paramount importance.

From Grapes to Wine: Impact of the Vinification Process on Ochratoxin A Contamination

Ochratoxin A (OTA) is one of the major mycotoxins, classified as "potentially carcinogenic to humans" (Group 2B) by the International Agency for Research on Cancer (IARC), and wine is one of its main sources of intake in human consumption. The main producer of this toxin is Aspergillus carbonarius, a fungus that contaminates grapes early in the growing season. The vinification process, as a whole, reduces the toxin content in wine compared to the grapes; however, not all vinification steps contribute equally to this reduction. During the maceration phase in red wines, toxin concentrations generally tend to increase. Based on previous studies, this review provides an overview of how each step of the vinification process influences the final OTA contamination in wine. Moreover, certain physical, chemical, and microbiological post-harvest strategies are useful in reducing OTA levels in wine. Among these, the use of fining agents, such as gelatin, egg albumin, and bentonite, must be considered. Therefore, this review describes the fate of OTA during the winemaking process, including quantitative data when available, and highlights actions able to reduce the final OTA level in wine.

One-step immunoassay based on switching peptides for analyzing ochratoxin A in wines

A one-step immunoassay is presented for the detection of ochratoxin A (OTA) using an antibody complex with switching peptides. Because the switching peptides (fluorescence-labeled) were able to bind the frame region of antibodies (IgGs), they were dissociated from antibodies immediately when target analytes were bound to the binding pockets of antibodies. From the fluorescence signal measurements of switching peptides, a quantitative analysis of target analytes, via a one-step immunoassay without any washing steps, could be performed. As the first step, the binding constant (KD) of OTA to the antibodies was estimated under the continuous flow conditions of a surface plasmon resonance biosensor. Then, the optimal switching peptide, among four types of switching peptides, and the reaction condition for complex formation with the switching peptide were determined for the one-step immunoassay for OTA analysis. Additionally, the selectivity test of one-step immunoassay for OTA was carried out in comparison with phenylalanine and zearalenone. For the application to the one-step immunoassay to detect OTA in wines, two types of sample pre-treatment methods were compared: (1) a liquid extraction was carried out using chloroform as a solvent with subsequent resuspension in phosphate-buffered saline (total analysis time < 1 h); (2) direct dilution of the wine sample (total analysis time < 0.5 h). Finally, the direct dilution method was found to be effective for the one-step immunoassay based on the switching peptide assay for OTA in wines with a markedly improved total analysis time (< 0.5 h). Additionally, the assay results were compared with commercial lateral flow immunoassay.

Removal of Ochratoxin A from Grape Juice by Clarification: A Response Surface Methodology Study

This study achieved maximum removal of ochratoxin A (OTA) during the grape juice clarification process with minimal reduction in antioxidant compounds (phenolic acid, flavonoids, and antioxidant capacity by FRAP) by the RSM method. Independent variables included three types of clarifiers—gelatin, bentonite, and diatomite (diatomaceous earth)—at a concentration level of 0.25–0.75% and clarification time of 1–3 h. OTA was measured by high-performance liquid chromatography with fluorescence detection. Clarifying agent concentration and clarification time affected the reduction amount of OTA and antioxidant compounds in grape juice. There was a direct linear correlation between the reduction amounts of OTA and antioxidant compounds and capacity with the concentration of bentonite, gelatin, and diatomite, and the clarification time. The reduction amount of OTA and antioxidant capacity followed the linear mode. However, the decreased phenolic acid and flavonoid values followed the quadratic model. The study results showed that if the concentrations of bentonite, gelatin, and diatomite and clarification time were 0.45, 0.62, 0.25%, and 1 h, respectively, the maximum amount of OTA reduction (41.67%) occurred. Furthermore, the phenolic acid, flavonoid, and antioxidant activity decrease amounts were at their lowest levels, i.e., 23.86, 7.20, and 17.27%, respectively.

Removal of Ochratoxin A from Red Wine Using Alginate-PVA-L. plantarum (APLP) Complexes: A Preliminary Study

The presence of ochratoxin A (OTA) in wines is a problem mainly due to the health damage it can cause to frequent drinkers. A method for removing these toxic substances from wine is the use of lactic acid bacteria with mycotoxin-adsorption capacities; however, their use is limited since a matrix in which they can be immobilized, to remove them after use, is needed. In this study, L. plantarum (LP) was encapsulated in a polymeric matrix composed of polyvinyl alcohol (PVA) and alginate, forming alginate–PVA–LP (APLP) complexes. Then, these complexes were characterized, and assays of OTA and phenol removal from wines were performed. As a result, it was observed that the APLP complexes at a concentration of 0.5 g mL⁻¹ removed over 50% of the OTA without substantially affecting the concentration of total phenols. In addition, it was determined that the presence of L. plantarum directly affected the ability to adsorb OTA from wines and did not decrease the total phenols. In conclusion, an alginate–PVA matrix allows immobilizing LP, and the complexes formed are an alternative for removing ochratoxin from contaminated wines.

Electrostatic adsorption and removal mechanism of ochratoxin A in wine via a positively charged nano-MgO microporous ceramic membrane

Ochratoxin A (OTA) is a very important mycotoxin. However, there are few studies on the removal of OTA in wine because of the great influence on product quality and difficulty in practical application. A nano-MgO-modified diatomite ceramic membrane (MCM) with a high positive charge was prepared and applied to remove OTA in wine. The isotherm adsorption between the positively charged membrane and OTA was in accordance with the Langmuir model, with a maximum adsorption capacity of 806 ng/g at 25 °C. All of the changes in adsorption enthalpy (ΔH), adsorption free energy (ΔG) and adsorption entropy (ΔS) were negative, which indicated that the combination of nano-MgO MCM and OTA was a spontaneous exothermic and nonspecific physical adsorption process. The concentrations of OTA in adsorption-treated wines were lower than 2 μg/kg, and the removal rates exceeded 92%. After OTA removal, the composition of wines was preserved to some extent.

Bio-control on the contamination of Ochratoxin A in food: Current research and future prospects

Ochratoxin A (OTA) is a secondary metabolite of several fungi and widely exists in various species of foods. The establishment of effective methods for OTA reduction is a key measure to ensure food processing and human health. This article reviews the current research of OTA reduction by biological approaches, summarizes the characteristics and efficiency of them, and evaluates the transformation pathways and metabolites safety of each degradation technology. The shortcomings of various methods are pointed out and future prospects are also proposed. Biological methods are the most promising approaches for OTA control. The defect of them is the long processing time and the growth of microbial cells may affect the product quality. Therefore, the control of OTA contamination should be conducted according to the food processing and their product types. Besides, it is significant for the exploitation of new strains, enzyme and novel adsorbents.

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The application of physical and chemical methods has been restricted.

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Existing biological methods can effectively detoxify OTA.

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OTA reduction systems should be established for different food.

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The exploitation of novel equipment, enzyme and adsorbents is essential.

Microbiological Decontamination of Mycotoxins: Opportunities and Limitations

The contamination of food and feeds with mycotoxins poses a global health risk to humans and animals, with major economic consequences. Good agricultural and manufacturing practices can help control mycotoxin contamination. Since these actions are not always effective, several methods of decontamination have also been developed, including physical, chemical, and biological methods. Biological decontamination using microorganisms has revealed new opportunities. However, these biological methods require legal regulations and more research before they can be used in food production. Currently, only selected biological methods are acceptable for the decontamination of feed. This review discusses the literature on the use of microorganisms to remove mycotoxins and presents their possible mechanisms of action. Special attention is given to Saccharomyces cerevisiae yeast and lactic acid bacteria, and the use of yeast cell wall derivatives.