Fungal and mycotoxin problems in grape juice and wine industries

Dynamic Succession of Natural Microbes during the Ecolly Grape Growth under Extremely Simplified Eco-Cultivation

The composition and continuous succession of natural microbial communities during grape growth play important roles in grape health and flavor quality as well as in characterizing the regional wine terroir. This study explored the diversity and dynamics of fruit epidermal microbes at each growth and developmental stage of Ecolly grapes under an extremely simplified eco-cultivation model, analyzed microbial interactions and associations of weather parameters to specific communities, and emphasized metabolic functional characteristics of microecology. The results indicated that the natural microbial community changed significantly during the grape growth phase. The dominant fungal genera mainly included Gibberella, Alternaria, Filobasidium, Naganishia, Ascochyta, Apiotrichum, Comoclathris, and Aureobasidium, and the dominant bacterial genera mainly contained Sediminibacterium, Ralstonia, Pantoea, Bradyrhizobium, Brevundimonas, Mesorhizobium, Planococcus, and Planomicrobium. In summary, filamentous fungi gradually shifted to basidiomycetous yeasts along with fruit ripening, with a decline in the number of Gram-negative bacteria and a relative increase in Gram-positive bacteria. The community assembly process reflects the fact that microbial ecology may be influenced by a variety of factors, but the fungal community was more stable, and the bacterial community fluctuated more from year to year, which may reflect their response to weather conditions over the years. Overall, our study helps to comprehensively profile the ecological characteristics of the grape microbial system, highlights the natural ecological viticulture concept, and promotes the sustainable development of the grape and wine industry.

Carvacrol nanocapsules as a new antifungal strategy: Characterization and evaluation against fungi important for grape quality and to control the synthesis of ochratoxins

Fungi are a problem for viticulture as they can lead to deterioration of grapes and mycotoxins production. Despite the widespread use of synthetic fungicides to control fungi, their impact on the agricultural ecosystem and human health demand safer and eco-friendly alternatives. This study aimed to produce, characterize and assess the antifungal activity of carvacrol loaded in nanocapsules of Eudragit® and chia mucilage as strategy for controlling Botrytis cinerea, Aspergillus flavus, Aspergillus carbonarius, and Aspergillus niger. Eudragit® and chia mucilage were suitable wall materials, as both favored the encapsulation of carvacrol into nanometric diameter particles. Fourier Transform Infrared Spectroscopy (FTIR) analysis suggested a successful incorporation of carvacrol into both nanocapsules, which was confirmed by presenting a good encapsulation efficiency and loading capacity. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analyses revealed adequate thermal resistance. All fungi were sensible to carvacrol treatments and B. cinerea was the most sensitive compared to the Aspergillus species. Lower concentrations of encapsulated carvacrol than the unencapsulated form were required to inhibit fungi in the in vitro and grape assays. Additionally, lower levels of carvacrol (unencapsulated or encapsulated) were used to inhibit fungal growth and ochratoxin synthesis on undamaged grapes in comparison to those superficially damaged, highlighting the importance of management practices designed to preserve berry integrity during cultivation, storage or commercialization. When sublethal doses of carvacrol were used, the growth of A. niger and A. carbonarius was suppressed by at least 45 %, and ochratoxins were not found. The nanoencapsulation of carvacrol using Eudragit® and chia mucilage has proven to be an alternative to mitigate the problems with fungi and mycotoxins faced by the grape and wine sector.

Genomic analysis reveals genes that encode the synthesis of volatile compounds by a Bacillus velezensis-based biofungicide used in the treatment of grapes to control Aspergillus carbonarius

Fungal control strategies based on the use of Bacillus have emerged in agriculture as eco-friendly alternatives to replace/reduce the use of synthetic pesticides. Bacillus sp. P1 was reported as a new promising strain for control of Aspergillus carbonarius, a known producer of ochratoxin A, categorized as possible human carcinogen with high nephrotoxic potential. Grape quality can be influenced by vineyard management practices, including the use of fungal control agents. The aim of this study was to evaluate, for the first time, the quality parameters of Chardonnay grapes exposed to an antifungal Bacillus-based strategy for control of A. carbonarius, supporting findings by genomic investigations. Furthermore, genomic tools were used to confirm that the strain P1 belongs to the non-pathogenic species Bacillus velezensis and also to certify its biosafety. The genome of B. velezensis P1 harbors genes that are putatively involved in the production of volatiles and hydrolytic enzymes, which are responsible for releasing the free form of aroma compounds. In addition to promote biocontrol of phytopathogenic fungi and ochratoxins, the treatment with B. velezensis P1 did not change the texture (hardness and firmness), color and pH of the grapes. Heat map and hierarchical clustering analysis (HCA) of volatiles evaluated by GC/MS revealed that Bacillus-treated grapes showed higher levels of compounds with a pleasant odor descriptions such as 3-hydroxy-2-butanone, 2,3-butanediol, 3-methyl-1-butanol, 3,4-dihydro-β-ionone, β-ionone, dihydroactinidiolide, linalool oxide, and β-terpineol. The results of this study indicate that B. velezensis P1 presents desirable properties to be used as a biocontrol agent.

Mycobiota in Slovak wine grapes: A case study from the small Carpathians wine region

The microbiological characteristics of the grapes are made up of a wide variety of microorganisms, including filamentous fungi. Their presence in grapes is traditionally associated with deterioration in quality. The health of the grapes is very important for obtaining quality wine. The objective of this study was to investigate the diversity of mycobiota on the surface and inside of different grapevine varieties at harvest time in the temperate climate of Slovakia and to identify potentially pathogenic isolates of Aspergillus and Penicillium producing selected mycotoxins. During the 2021 grape harvest, grapes were collected from the Small Carpathians wine region. Eleven grape samples were analyzed by the plating method and plating method with surface disinfection. Emphasis was placed on Aspergillus and Penicillium species because of their importance in mycotoxin production. Of the 605 fungal strains detected, 11 genera were identified in the exogenous mycobiota. The most common and abundant genera were Alternaria and Botrytis. In the genus Aspergillus, A. section Nigri is the most abundant, while in the genus Penicillium, P. raistrickii reached the highest frequency and abundance. Of the 379 strains detected and identified from the endogenous mycobiota, the most common genera were again Alternaria and Botrytis and the most abundant genus was Botrytis. Penicillium species were detected in 17% of all fungi found, with P. raistrickii dominating. The A. section Nigri reached only 4% of the relative density of all isolates. Potentially toxigenic Aspergillus and Penicillium species were tested for toxinogenity by thin layer chromatography. The most important mycotoxin-producing species found were A. section Nigri but without ochratoxin A production.

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.

Elicitation of Fruit Fungi Infection and Its Protective Response to Improve the Postharvest Quality of Fruits

Fruit diseases brought on by fungus infestation leads to postharvest losses of fresh fruit. Approximately 30% of harvested fruits do not reach consumers’ plates due to postharvest losses. Fungal pathogens play a substantial part in those losses, as they cause the majority of fruit rots and consumer complaints. Understanding fungal pathogenic processes and control measures is crucial for developing disease prevention and treatment strategies. In this review, we covered the presented pathogen entry, environmental conditions for pathogenesis, fruit’s response to pathogen attack, molecular mechanisms by which fungi infect fruits in the postharvest phase, production of mycotoxin, virulence factors, fungal genes involved in pathogenesis, and recent strategies for protecting fruit from fungal attack. Then, in order to investigate new avenues for ensuring fruit production, existing fungal management strategies were then assessed based on their mechanisms for altering the infection process. The goal of this review is to bridge the knowledge gap between the mechanisms of fungal disease progression and numerous disease control strategies being developed for fruit farming.

Fast and Accurate Determination of Minute Ochratoxin A Levels in Cereal Flours and Wine with the Label-Free White Light Reflectance Spectroscopy Biosensing Platform

Ochratoxin A (OTA) is one of the most toxic naturally encountered contaminants and is found in a variety of foods and beverages, including cereals and wine. Driven by the strict regulations regarding the maximum allowable OTA concentration in foodstuff and the necessity for on-site determination, the development of fast and sensitive methods for the OTA determination in cereal flours and wine samples, based on white light reflectance spectroscopy, is presented. The method relied on appropriately engineered silicon chips, on top of which an OTA-protein conjugate was immobilized. A polyclonal antibody against OTA was then employed to detect the analyte in the framework of a competitive immunoassay; followed by the subsequent addition of a biotinylated secondary antibody and streptavidin for signal enhancement. A small size instrument performed all assay steps automatically and the bioreactions were monitored in real time as the software converted the spectral shifts into effective biomolecular adlayer thickness increase. The assay developed had a detection limit of 0.03 ng/mL and a working range up to 200 ng/mL. The assay lasted 25 min (less than 1h, including calibrators/antibody pre-incubation) and was accomplished following a simple sample preparation protocol. The method was applied to corn and wheat flour samples and white and red wines with recovery values ranging from 87.2 to 111%. The simplicity of the overall assay protocol and convenient instrumentation demonstrates the potential of the immunosensor developed for OTA detection at the point of need.

Adjustment and quantification of UV-visible spectrophotometry analysis: an accurate and rapid method for estimating Cladosporium spp. spore concentration in a water suspension

Cladosporium spp. are among the most important plant pathogens, plant endophytes, insect parasites and human pathogens in nature. The aim of this study was to increase the speed and accuracy of Cladosporium spp. spore counting using UV-visible spectrophotometry based on the regression model in a water suspension. Spores of C. ramotenellum AM55, C. limoniforme Br15, C. tenuissimum K15 and C. cladosporioides Ld13 fungi were diluted in sterile distilled water several times. Spore concentration/ml (SC) was counted with a hemocytometer. The spectrophotometer visible light absorption (ABS) was measured under 14 wavelengths from 300 to 950 nm for each dilution. The results showed that the morphological variation of the spores greatly affect the determination of the suitable wavelength. 650, 750, 500 and 400 nm wavelengths had the highest coefficient of determination (R²) values respectively for C. ramotenellum AM55, C. limoniforme Br15, C. tenuissimum K15 and C. cladosporioides Ld13 on the linear regression model. R² values were 0.9874, 0.9647, 0.8856 and 0.9711 respectively, for the 650, 750, 500 and 400 nm wavelengths. The linear equation of SC = 10⁷ × ABS-133,040 with the highest R2 value of 0.9532 had the best fit under a combinatorial regression model where SC and ABS of all Cladosporium spp. were presented. The proposed linear regression models can be used under in vivo and in vitro conditions for medicine or plant pathology studies which certainly increase the accuracy and speed of the future experiments compared to the hemocytometer method.

Ozone in wineries and wine processing: A review of the benefits, application, and perspectives

Ozone (O₃ ) is an emerging eco-friendly technology that has been widely used in the beverage industry due to its broad spectrum of usages, such as fermentation, microbial inactivation, Clean-in-Place (CIP) systems, and postharvest treatment. Wine is among the most financially profitable sectors of the beverage industry. Ozone technology as an alternative approach to conventional methods to inhibit microbes in wine processing and wineries has attracted researchers' attention as this emerging technology will probably play important roles in wineries in the future. This review discusses the prospective applications of ozone in winemaking and wineries and elaborates on ozone's antimicrobial effects on the control of the broad spectrum of microorganisms during wine processing. Also, this paper provides discussions on its effects of O₃  on wine quality and the benefits this emerging technology can bring to wineries. Ozone treatments can improve yeast fermentation by impacting the yeast ecology of postharvested wine grapes, mainly by affecting apiculate yeasts and adjusting the population of undesirable yeasts, such as Brettanomyces spp., during the fermentation process. Furthermore, ozone treatment may enhance wine's anthocyanin concentration, physicochemical properties, color, pH, oxidative stability, and concentration of pleasant volatile compounds and esters. This article presents important information to have a better understanding of the impact of ozone treatment on different stages of wine preparation.

A Comprehensive Review on Grape Juice Beverage in Context to Its Processing and Composition with Future Perspectives to Maximize Its Value

Red and purple grape juices (GJs) have long been consumed worldwide for their unique taste and nutritive value. Moreover, grape is postulated to play an important role in the improvement of cardiovascular risk factors owing to its rich polyphenol content. Little is known regarding GJ’s holistic chemistry and functionality as compared to those of other fruit juices. This review aims to compile the state-of-the art chemistry of colored grape juices and in context to its analysis and nutritional values. Further, a review of potential contaminants to be introduced during manufacturing and other factors that influence juice quality and or health effects are presented to help maximize GJ’s quality. A comparison between analytical methods for juice QC establishment is presented employing hyphenated platforms versus direct spectroscopic techniques. The enrichment of the colored skin with a myriad of phenolics poses it as a functional beverage compared to that of skinless juice.

Graphical abstract

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.

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.

Data Analytics Determines Co-occurrence of Odorants in Raw Water and Evaluates Drinking Water Treatment Removal Strategies

A complex dataset with 140 sampling events was generated using triple quadrupole gas chromatography-mass spectrometer to track the occurrence of 95 odorants in raw and finished water from 98 drinking water treatment plants in 31 cities across China. Data analysis identified more than 70 odorants with concentrations ranging from not detected to thousands of ng/L. In raw water, Pearson correlation analysis determined that thioethers, non-oxygen benzene-containing compounds, and pyrazines were classes of chemicals that co-occurred, and geosmin and p(m)-cresol, as well as cyclohexanone and benzaldehyde, also co-occurred, indicating similar natural or industrial sources. Based on classification and regression tree analysis, total dissolved organic carbon and geographical location were identified as major factors affecting the occurrence of thioethers. Indoles, phenols, and thioethers were well-removed through conventional and advanced treatment processes, while some aldehydes could be generated. For other odorants, higher removal was achieved by ozonation-biological activated carbon (39.3%) compared to the conventional treatment process (14.5%). To our knowledge, this is the first study to systematically identify the major odorants in raw water and determine suitable treatment strategies to control their occurrence by applying data analytics and statistical methods to the complex dataset. These provide informative reference for odor control and water quality management in drinking water industry.

Aspergillus carbonarius-derived ochratoxins are inhibited by Amazonian Bacillus spp. used as a biocontrol agent in grapes

Bacillus spp. have been used as a biocontrol strategy to eliminate/reduce toxic fungicides in viticulture. Furthermore, the presence of fungi that are resistant to commonly used products is frequent, highlighting the need for new biocontrol strains. Aspergillus carbonarius can produce ochratoxins, including ochratoxin A (OTA), which has a regulatory maximum allowable limit for grape products. The purpose of this study was to assess the ability of four Amazonian strains of Bacillus (P1, P7, P11, and P45) to biocontrol A. carbonarius and various forms of ochratoxins in grapes. Berries treated with strain P1 presented no fungal colonies (100% reduction), while P7, P11 and P45 strains caused a reduction of 95, 95 and 61% on fungal counts, respectively. Six forms of ochratoxin were found in the grapes inoculated with A. carbonarius, including ochratoxin α, ochratoxin β, ochratoxin α methyl-ester, ochratoxin α amide, N-formyl-ochratoxin α amide, and OTA. Four of these ochratoxin forms (ochratoxin β, ochratoxin α methyl-ester, ochratoxin α amide, N-formyl-ochratoxin α amide) are reported for the first time in grapes. These ochratoxins were identified using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToF-MS). All Bacillus strains inhibited the synthesis of OTA, which is the most toxic form of ochratoxin. No ochratoxin form was found when P1 and P7 were used. Although some forms of ochratoxin were detected in grapes treated with Bacillus spp. P11 and P45, the levels decreased by 97%. To our knowledge, this is the first report on the inhibition of Aspergillus carbonarius-derived ochratoxin by Bacillus species. P1 strain, identified as Bacillus velezensis, was found to be the most promising for completely inhibiting fungal growth and production of all ochratoxins.

Diversity of Mycobiota in Spanish Grape Berries and Selection of Hanseniaspora uvarum U1 to Prevent Mycotoxin Contamination

The occurrence of mycotoxins on grapes poses a high risk for food safety; thus, it is necessary to implement effective prevention methods. In this work, a metagenomic approach revealed the presence of important mycotoxigenic fungi in grape berries, including Aspergillus flavus, Aspergillus niger aggregate species, or Aspergillus section Circumdati. However, A. carbonarius was not detected in any sample. One of the samples was not contaminated by any mycotoxigenic species, and, therefore, it was selected for the isolation of potential biocontrol agents. In this context, Hanseniaspora uvarum U1 was selected for biocontrol in vitro assays. The results showed that this yeast is able to reduce the growth rate of the main ochratoxigenic and aflatoxigenic Aspergillus spp. occurring on grapes. Moreover, H. uvarum U1 seems to be an effective detoxifying agent for aflatoxin B₁ and ochratoxin A, probably mediated by the mechanisms of adsorption to the cell wall and other active mechanisms. Therefore, H. uvarum U1 should be considered in an integrated approach to preventing AFB₁ and OTA in grapes due to its potential as a biocontrol and detoxifying agent.

Origin, Succession, and Control of Biotoxin in Wine

Wine is a worldwide alcoholic beverage with antioxidant active substances and complex flavors. Moderate drinking of wine has been proven to be beneficial to health. However, wine has some negative components, such as residual pesticides, heavy metals, and biotoxins. Of these, biotoxins from microorganisms were characterized as the most important toxins in wine. Wine fermentation mainly involves alcoholic fermentation, malolactic fermentation, and aging, which endue wine with complex flavors and even produce some undesirable metabolites. These metabolites cause potential safety risks that are not thoroughly understood. This review aimed to investigate the origin, evolution, and control technology of undesirable metabolites (e.g., ochratoxin A, ethyl carbamate, and biogenic amines) in wine. It also highlighted current wine industry practices of minimizing the number of biotoxins in wine.

Colonization of Aspergillus carbonarius and accumulation of ochratoxin A in Vitis vinifera, Vitis labrusca, and hybrid grapes - research on the most promising alternatives for organic viticulture

BACKGROUND

Aspergillus carbonarius has been identified as one of the main fungi that produce ochratoxin A (OTA) in grapes. This nephrotoxic mycotoxin has been legislated against in several countries and is a major concern for viticulture. Knowledge of resistance to, or susceptibility to, colonization by A. carbonarius may be useful in selecting the most promising cultivars for organic agriculture and could help in preventing fungal contamination in vineyards. This study aimed to evaluate the colonization potential and the capacity to produce OTA by A. carbonarius in Vitis vinifera, V. labrusca, and hybrid grapes. The correlation between OTA levels and grape berry characteristics was also analyzed.

RESULTS

The OTA content was only strongly correlated with the thickness and hardness of the grape skins. The correlation between OTA levels and these parameters was negative (grapes with the least thickness and hardness had the highest OTA levels). Vitis vinifera grapes were more susceptible to A. carbonarius than V. labrusca and hybrid grapes at both 25 and 4 °C. Chardonnay (V. vinifera) grapes showed the highest levels of OTA, followed by Merlot, Cabernet Sauvignon, Tannat, and Moscato Branco. Italia grapes were the exceptions among V. vinifera cultivars, since they showed similar thickness, hardness, and fungal resistance as the V. labrusca and hybrid grapes.

CONCLUSION

The highest resistance to A. carbonarius was observed in the following grapes: hybrids (BRS Lorena and BRS Violeta), V. labrusca (Isabel and Bordo), and V. vinifera (Italia). These cultivars can be prioritized in the implementation of organic viticulture. © 2020 Society of Chemical Industry.

Occurrence and impact of fungicides residues on fermentation during wine production- A review

Continuous fungicide spraying is required to eliminate fungal pathogens on grapes. However, this practice is associated with several risks, including contamination and environmental imbalance, as well as toxicity to operators and the induction of resistance in pathogens. In addition, a strong correlation has been reported between the presence of fungicides and the occurrence of issues during alcoholic fermentation, resulting in negative impacts on the sensory quality of the final products. Numerous studies have evaluated residue concentrations of phytosanitary products in grapes, juices, and wines, and a significant number of studies have assessed the impact of different agrochemicals on bioprocesses. However, a review compiling the key results of these studies is currently lacking. This review incorporates results obtained in the last decade from research on the presence of fungicide residues, including azoxystrobin, boscalid, captan, copper, fenhexamid, folpet, pyraclostrobin, pyrimethanil and tebuconazole, and their effects on fermentation kinetics. Practical solutions to mitigate these problems, both in vineyards and industry, are also presented and discussed. This review highlights the constant high fungicidal agent concentrations (greater than 1 or 2 mg L^-1) used throughout the winemaking process, with the impact of residues being of particular concern, especially with regard to their effect on yeast activity and the fermentation process. Thus, the adoption of methodologies that allow winemakers to control and trace these residues is an important step in avoiding or reducing fermentation problems throughout the winemaking process.[Figure: see text].

Role of partial dehydration in a naturally ventilated room on the mycobiota, ochratoxins, volatile profile and phenolic composition of Merlot grapes intended for wine production

Dehydration of grapes has been used in various regions of the world to produce special wines, aiming to add value to oenological products. Post-harvest dehydration in rooms may be carried out regardless of weather conditions, without the additional cost of a specific infrastructure, in addition to the benefits of protecting the grapes from damages and environmental pollution. The objective of this study was to verify, for the first time, the impact of the dehydration in a naturally ventilated room on the quality of Merlot grapes. Physicochemical characteristics, mycobiota, occurrence of mycotoxins, volatile profile and phenolic composition of grapes were monitored on 7th, 14th and 21st days of dehydration (weight loss of 10, 20 and 27%, respectively). A decrease in aw (6%), pH (4%), and berry hardness (58%), along with an increase in total soluble solid content (15%) were observed during dehydration. The presence of Pestalotiopsis clavispora, Neopestalotiopsis clavispora, Colletotrichum siamense and Alternaria porri was favored during the dehydration process, while a decrease in the occurrence of Aspergillus niger and Phanerochaete sp. was verified. A. niger isolates showed no potential to produce forms of ochratoxins. These toxins were also not found in the grape samples. Regarding the volatile profile, 1-hexanal, 2-hexenal, and 1-octanal gave rise to the corresponding alcohols during dehydration, such as 1-hexanol, 2-hexen-1-ol, and 1-octanol. Acids (hexanoic, decanoic, and 3-hexenoic) resulted in the respective ethyl esters (hexanoate, decanoate, and ethyl 3-hexenoate) during dehydration. Terpenes as limonene, myrcene, and geraniol decreased throughout dehydration, while their biotransformation products (α-terpineol, 6-methyl-5-hepten-2-one, and linalool, respectively) had an increase in concentration. The phenolic content oscillated during dehydration, with an emphasis on increased levels of four hydroxybenzoic acids (ethyl gallate, p-hydroxybenzoic acid, gallic acid-hexose, and gallic acid), two hydroxycinnamic acids (caffeic acid and caftaric acid), two flavonols (kaempeferol galactoside and quercetin) and two anthocyanins (peonidin 3-O-hexoside and delphinidin 3-O-hexoside). Grapes of satisfactory quality were produced by dehydration in a naturally ventilated room. Even small wine producers can be encouraged to implement this procedure for the diversification of oenological products, as it has no costs related to the implementation of chambers/tunnels.

Recent Advances in Mycotoxin Analysis and Detection of Mycotoxigenic Fungi in Grapes and Derived Products

Mycotoxins are secondary metabolites of filamentous fungi that can cause toxic effects in human and animal health. Most of the filamentous fungi that produce these mycotoxins belong to four genera, namely, Aspergillus, Penicillium, Fusarium, and Alternaria. Mycotoxigenic fungi, along with mycotoxins, create a constant and serious economic threat for agriculture in many terms, counting product losses due to crop contamination and food spoilage, as well malnutrition when considering nutritional quality degradation. Given the importance of robust and precise diagnostics of mycotoxins and the related producing fungi in the grape food chain, one of the most important agricultural sectors worldwide, the present review initially delivers a comprehensive presentation of mycotoxin reports on grape and derived products, including a wide range of commodities such as fresh grapes, raisins, wine, juices, and other processed products. Next, based on worldwide regulations’ requirements for mycotoxins, and referring to the relative literature, this work presents methodological approaches for mycotoxin determination, and stresses major methods for the detection of fungal species responsible for mycotoxin production. The principle of function and basic technical background on the available analytical and molecular biology techniques developed—including chromatography, mass spectrometry, immunochemical-based assays, biosensors, and molecular assays—is briefly given, and references for their application to grape and derived product testing are highlighted.

Surveillance of Patulin in Apple, Grapes, Juices and Value-Added Products for Sale in Pakistan

The prime objective of the current study was to investigate the occurrence of mycotoxin patulin (PAT) in apples, grapes and their value added products. PAT was determined by a validated method based on HPLC with UV detector. A total of 381 samples comprising apple and grape fruits (n = 133 each), apple-based products (n = 76, juice, puree, jam) and grape juice (n = 39) were analyzed. PAT was found in 58.9% samples of apple and apple-based products, with a mean of 49.8 µg/kg (maximum 396 µg/kg), while 27.3% samples contained PAT beyond the maximum regulatory limit of 50 µg/kg. The average levels of PAT contamination in apple-derived products was higher in apple juice concentrate, followed by apple puree, apple juice and apple jam. The incidence of PAT in table grapes was 65.1%, with a mean of 53.9 µg/kg (maximum 505 µg/kg), whereas 23.8% exceeded the maximum level. Among the fruit samples, there were differences in PAT contents due to apple variety (6 types) or grape variety (8 types), as well as for sampling location. Our investigations showed the wide PAT occurrence in fruits and derived value-added products affecting consumer product safety, so that the population is chronically exposed to this toxin.

Mycotoxins in Functional Beverages: A Review

Consumer dietary habits have drastically changed in recent decades and functional beverages now have a strong position in the market. The majority of these beverages are produced using simple processes that use raw products, such as cereals, legumes, fruits, and nuts, among others, and these are known to be frequently contaminated with mycotoxins. This review is focused on the occurrence of these toxic compounds in plant-based milks, fruit juices, and herbal teas. The fate of the toxins during processing is discussed to establish the potential risk posed by the consumption of these kind of beverages regarding mycotoxin uptake.

Antifungal efficacy of sanitizers and electrolyzed waters against toxigenic Aspergillus

The presence of mycotoxin-producing fungi in food production environments is a cause of concern since they can contaminate food products, synthesizing toxic compounds in later steps. To avoid this, an effective hygiene and sanitation process of the environment and equipment should be adopted, using sanitizing agents with adequate antifungal efficacy. This work evaluated the effectiveness of different chemical sanitizers: benzalkonium chloride (0.3%, 1.2%, 2%), biguanide (2%, 3.5%, 5%), iodine (0.2%, 0.6%, 1%), peracetic acid (0.3%, 0.6%, 1%), sodium hypochlorite (0.5%, 0.75%, 1%), besides a new non-polluting technology, the electrolyzed water, both the acid in the chlorine concentrations of 60, 85 and 121 ppm and the respective basic electrolyzed water formed against strains of toxigenic Aspergillus flavus, Aspergillus nomius, Aspergillus parasiticus, Aspergillus carbonarius, Aspergillus niger, Aspergillus ochraceus and Aspergillus westerdijkiae through the methodology recommended by the European Committee for Standardization. Benzalkonium chloride and iodine were the most effective sanitizers to eliminate Aspergillus from the Flavi and Nigri section. Peracetic acid showed the best elimination of the growth of Aspergillus from Circumdati section. Sodium hypochlorite, biguanide, and electrolyzed water agents were the least effective, reducing less than 3 log from initial control, not being the most suitable agents for the control of toxigenic fungi in food industries.

Ochratoxigenic fungi and Ochratoxin A determination in dried grapes marketed in Tunisia

Purpose

With the present work, we aimed to assess the occurrence of ochratoxigenic fungi and Ochratoxin A (OTA) in dried grapes from Tunisia.

Methods

Dried grapes samples (n = 90) were investigated for the presence of ochratoxigenic fungi, which were further characterized at the species level through amplification of the internal transcribed spacer (ITS) region and polymerase chain reaction (PCR) product sequencing. Fungal isolates were tested for their ochratoxigenic potential by high-performance liquid chromatography with fluorescence detection (HPLC-FLD), as well as dried grapes samples after an immunoaffinity column (IAC) clean-up procedure.

Results

Black Aspergilli isolates were the dominant genre among the filamentous fungi found in dried grapes samples and were the only OTA-producing fungi encountered. Aspergillus niger aggregate were the most frequently found isolates reaching 70%, 80%, and 85% in dried grapes samples from regions of Kelibia, Sfax, and Rafraf, respectively, while covered 100% of the relevant mycobiota found in imported samples. Aspergillus carbonarius isolates were found only in Sfax’s and Kelibia’s samples, while uniseriate Aspergilli were found between 7 and 20% in dried grapes from Kelibia, Sfax, and the imported samples. The in vitro OTA production test showed that 88.9% of OTA-producing isolates belonged to A. carbonarius with OTA levels varying from 0.06 to 1.32 μg/g of Czapek Yeast Agar (CYA). The remaining OTA-producing fungi (11.1 %) belonged to A. niger aggregate group having a maximum OTA potential of 2.88 μg/g CYA, and no uniseriate Aspergilli isolate was able to produce OTA. All dried grapes samples were free of OTA presence.

Conclusion

According to the present study’s findings, no OTA contamination was recorded in the investigated samples from Tunisian market. Nevertheless, the presence of strong OTA producers A. carbonarius in samples originated from the two out of three studied Tunisian regions, as well the high incidences of Aspergillus niger aggregate group with an attested potential for OTA production in all samples, necessitates further research on Tunisian dried grapes. Additionally, a continuous analysis of staple food of the Mediterranean diet is imperative to insure the best quality for the consumers and prevent potential health problems.

Advances in Analysis and Detection of Major Mycotoxins in Foods

Mycotoxins are the most widely studied biological toxins, which contaminate foods at very low concentrations. This review describes the emerging extraction techniques and the current and alternatives analytical techniques and methods that have been used to successfully detect and identify important mycotoxins. Some of them have proven to be particularly effective in not only the detection of mycotoxins, but also in detecting mycotoxin-producing fungi. Chromatographic techniques such as high-performance liquid chromatography coupled with various detectors like fluorescence, diode array, UV, liquid chromatography coupled with mass spectrometry, and liquid chromatography-tandem mass spectrometry, have been powerful tools for analyzing and detecting major mycotoxins. Recent progress of the development of rapid immunoaffinity-based detection techniques such as immunoassays and biosensors, as well as emerging technologies like proteomic and genomic methods, molecular techniques, electronic nose, aggregation-induced emission dye, quantitative NMR and hyperspectral imaging for the detection of mycotoxins in foods, have also been presented.

Advances in Occurrence, Importance, and Mycotoxin Control Strategies: Prevention and Detoxification in Foods

Mycotoxins are toxic substances that can infect many foods with carcinogenic, genotoxic, teratogenic, nephrotoxic, and hepatotoxic effects. Mycotoxin contamination of foodstuffs causes diseases worldwide. The major classes of mycotoxins that are of the greatest agroeconomic importance are aflatoxins, ochratoxins, fumonisins, trichothecenes, emerging Fusarium mycotoxins, enniatins, ergot alkaloids, Alternaria toxins, and patulin. Thus, in order to mitigate mycotoxin contamination of foods, many control approaches are used. Prevention, detoxification, and decontamination of mycotoxins can contribute in this purpose in the pre-harvest and post-harvest stages. Therefore, the purpose of the review is to elaborate on the recent advances regarding the occurrence of main mycotoxins in many types of important agricultural products, as well as the methods of inactivation and detoxification of foods from mycotoxins in order to reduce or fully eliminate them.

Effect of Aspergillus carbonarius on ochratoxin a levels, volatile profile and antioxidant activity of the grapes and respective wines

Aspergillus carbonarius can produce a possibly carcinogenic mycotoxin named ochratoxin A (OTA). The metabolism of this fungus can also impact grape and wine quality as it influences the volatile and phenolic profiles, which are related to aroma and antioxidant activity, respectively. The objective of this study was to evaluate the effect of A. carbonarius on OTA levels and for the first time on volatile profile and antioxidant activity of grapes and their respective wines. Cabernet Sauvignon (CS, red) grapes presented higher susceptibility to A. carbonarius than Moscato Italico (MI, white) grapes and OTA levels in their respective musts were in accordance with this same trend. However, vinification of red grapes resulted in 67% reduction of OTA, while the reduction observed with white wines was 45%. The presence of acids (hexanoic, octanoic, nonanoic and decanoic, fatty odor) was found to be an indicative of the fungus incidence in grapes. These acids were precursors of esters that might impart negative aroma (methyl nonanoate and isoamyl octanoate, fatty odor) or provide desirable fruity characteristics (ethyl hexanoate, ethyl octanoate and methyl octanoate) for wine. In addition, terpenes were detected only in wines produced with grapes (CS and MI) inoculated with A. carbonarius. The presence of A. carbonarius increased the antioxidant activity of CS grapes. For MI grapes and both wines (CS and MI) no differences were verified in the antioxidant activity of the samples affected or not affected by this fungus. Although A. carbonarius occurrence has shown no influence on the antioxidant activity of wines, it produced OTA and has negatively influenced the wine odor profile, due to the production of some volatiles that impart a deleterious effect on wine aroma.