Ochratoxin A in dried vine fruits from Chinese markets

A total of 56 dried vine fruits, including 31 sultanas and 25 currants, were selected from Chinese markets in 2012. All samples were analysed for Ochratoxin A (OTA) using solid-phase extraction and high-performance liquid chromatography (HPLC) with fluorescence detection. It turned out that 58.9% of the samples were positive and the OTA amount ranged from <0.07 to 12.83 μg/kg, with a mean level of 0.99 μg/kg. Only one sample exceeded the European Union (EU) maximum level of 10 μg/kg. Meanwhile, it was shown that OTA contamination increased among north-western, northern and southern China, which showed OTA means of 0.08, 0.99 and 2.01 μg/kg, respectively. Moreover, in samples of products sold in sealed plastic bags, i.e. consumer-size packages (n = 19, mean = 0.30 μg/kg) less OTA was detected when compared with sampled bulk packages (n = 37, mean = 1.67 μg/kg). In addition, sultanas (mean = 0.92 μg/kg) had less OTA contamination than currants (mean = 1.22 μg/kg).     

Aspergillus carbonarius as the main source of ochratoxin A contamination in dried vine fruits from the Spanish market

Ochratoxin A (OTA) can occur in a wide range of foods, but unexpectedly high concentrations have been detected in dried vine fruits of various origins. The European Union has recently established a maximum OTA limit of 10 microg/kg for these foodstuffs. In order to determine the likely origin of OTA, a mycological study of 50 dried fruit samples (currants, raisins, and sultanas) representative of the Spanish market was conducted. Fungal contamination was detected in 49 of 50 (98%) samples. Black aspergilli were isolated from all of the positive samples. Aspergillus niger var. niger was isolated from 98% of the samples, and Aspergillus carbonarius was found in 58% of the samples. One hundred sixty-eight A. niger var. niger isolates and 91 A. carbonarius isolates were screened for their ability to produce OTA. Eighty-eight (96.7%) A. carbonarius isolates and one (0.6%) A. niger var. niger isolate were found to be OTA producers. Black aspergilli were the dominant fungi. Among black aspergilli, A. carbonarius has shown a consistent ability to produce OTA and is the most probable source of this mycotoxin in these substrates.     

Mycotoxins in botanicals and dried fruits: A review

Botanicals are used in many countries for medicinal and general health-promoting purposes. Numerous natural occurrences of mycotoxins in botanicals and dried fruits have been reported. Aflatoxins or ochratoxin A (OTA) have been found in botanicals such as ginseng, ginger, liquorice, turmeric, and kava-kava in the USA, Spain, Argentina, India, and some other countries, while fumonisins have been found in medicinal wild plants in South Africa and in herbal tea and medicinal plants in Turkey. Zearalenone was identified in ginseng root. Dried fruits can be contaminated with aflatoxins, OTA, kojic acid, and, occasionally, with patulin or zearalenone. One main area of concern is aflatoxins in dried figs; bright greenish yellow fluorescence under ultraviolet light is associated with aflatoxin contamination. OTA in dried vine fruits (raisins, sultanas, and currants) is another concern. There are also reports of aflatoxins in raisins and OTA in dried figs, apricots, dried plums (prunes), dates, and quince. Maximum permitted levels in the European Union include 4 µg kg^-1 for total aflatoxins in dried fruit intended for direct consumption and 10 µg kg^-1 for OTA in dried vine fruit. This review discusses the occurrence of mycotoxins in botanicals and dried fruits and analytical issues such as sampling, sample preparation, and methods for analysis. Fungal contamination of these products, the influence of sorting, storage, and processing, and prevention are also considered.     

Occurrence of ochratoxin A in Italian wines.

A total of 96 red wines and 15 white dessert wines produced mostly in the years 1995-97 in 19 Italian regions were analysed for ochratoxin A (OTA). The amount of OTA ranged from < 1 to 3856 ng/l the median (mean) was found to be 90 (419) ng/l for the red wines and 8 (736) ng/l for the white dessert wines. Our survey shows that the geographic region of origin has a strong influence on OTA contamination, both for red and for dessert wines: in fact, wines produced in southern Italy were markedly more contaminated. The overall median (mean) OTA concentration in the red wines produced in the four Italian areas (northwest, northeast, centre and south) was 2 (11), 90 (81), 134 (295) and 1264 (1233) ng/l. The same trend was observed for the white dessert wines: OTA concentrations of over 1000 ng/l were found in four out of five samples from southern Italy (1185, 2454, 3477, 3856 ng/l), while central and northern samples showed very low contamination. The contribution of wine to mean daily OTA intake can be considered negligible in the case of people drinking wine manufactured in northern and central Italy; this is not true if a medium drinker constantly consumes red wine produced in southern Italy in this case wine alone could supply the diet with an amount of OTA equal to or even above the tolerable daily intake of 5 ng/kg body weight recommended by the Scientific Committee on Food of the European Commission.     

Raisins and Currants as Conventional Nutraceuticals in Italian Market: Natural Occurrence of Ochratoxin A

The healthy consumers make a strong pressure to natural products that can prevent the chronic diseases and improve the general health status, and therefore an important aspect that have to be considered is the safe level of the nutraceuticals. This study reports the occurrence of Ochratoxin A (OTA) and associated fungal contamination in 35 samples of dried vine fruits imported in the European community potentially used for the development of new nutraceutical supplements. High pressure liquid chromatography analysis identified 18 samples as contaminated by OTA with an average level of 2.6 μg/kg. OTA was measured in 4 samples of currants (mean value of 6.6 μg/kg) and 13 samples of raisins (mean value of 1.4 μg/kg). In one sample of currants and one of raisins from Turkey OTA exceeded the limits set by European Commission of 10 μg/kg, being contaminated with 12.61 and 15.99 μg/kg, respectively. All the positive samples were confirmed by Orbitrap Q Exactive through their molecular weight and the corresponding fragmentation. The worldwide consumption of dried vine fruits contributed to OTA exposure in several group of consumers. In particular, considering the potential nutraceutical approach, this consumption may be represent a severe risk for healthy consumers that consider these products like healthy and salutistic for their contents in antioxidants, flavonoids, and polyphenols. Data reported in this study confirmed the need to regularly monitor mycotoxin levels in these food products and optimize the process of fruits drying in order to reduce the development of toxigenic molds.     

Ochratoxin A in dried vine fruit: method development and survey

A method is described for the determination of concentrations of the mycotoxin ochratoxin A in dried vine fruits (currants, raisins and sultanas) using acidic methanolic extraction,immunoaffinity chromatography clean-up and HPLC determination. The limit of detection was estimated as 0.2mug/kg, and recoveries of 63-77% were achieved at 5mug/kg. HPLC-mass spectrometric confirmation of the identity of ochratoxin was obtained. Ochratoxin A and aflatoxins were determined in 60 samples of retail dried vine fruits purchased in the United Kingdom. Ochratoxin A was found in excess of 0.2mug/kg in 19 of 20 currant, 17 of 20 sultana and 17 of 20 raisin samples examined, an overall incidence of 88% . The maximum level found was 53.6mug/kg. No aflatoxin was found in any sample analysed, using a method with a detection limit of 0.2mug/kg for each of aflatoxin B1, B2, G1 and G2.     

European research on ochratoxin A in grapes and wine

European wine production represents about 70% of world production and thus is an important export commodity. Ochratoxin A (OTA) was first detected as a wine contaminant in 1996 and the role of Aspergillus section Nigri and A. carbonarius in OTA production discovered in Europe in 1999. Subsequently Europe-wide surveys have shown that A. carbonarius is predominantly responsible for OTA contamination of grapes, wine and vine fruits. Analyses of wine samples throughout Europe have shown that there is a gradient in OTA concentration with a decrease from red, to rose and to white wines. The latitude of production is an important factor in determining risk from OTA contamination. Some geographic regions in Southern Europe are more prone to contamination with the toxigenic species and OTA. Ochratoxin A has also been found in much higher concentrations (max. 53 mug/kg) in dried vine fruit than in wine suggesting that A. carbonarius can dominate the drying vine fruit ecosystem. There is a significant lack of knowledge in Europe on conducive climatic conditions preharvest and their relationship with levels of risk from OTA contamination in grapes and their fate in wine production. This needs to be integrated with cultivation system to maximise the prevention of OTA entering this food chain.     

Occurrence of ochratoxin A in wine and ochratoxigenic mycoflora in grapes and dried vine fruits in South America

Grape and wine production in South America represents about 6.6% and 10% respectively of the world grape and wine production. The available information on the ochratoxigenic mycoflora and ochratoxin A (OTA) presence in wine grapes, wines, grape juices and dried vine fruits is limited. Surveys have been carried out in Argentina and Brazil which showed that Aspergillus niger aggregate are predominant in the Argentinean varieties while from the Brazilian varieties the species A. niger, Aspergillus ochraceus and Aspergillus carbonarius were isolated. A mycobiota survey from wine grapes in Argentina showed that while Alternaria alternata was predominant, Aspergillus section Nigri species were isolated from 60% of samples. About 41% of black Aspergilli isolates produced OTA with levels ranging from 2 to 24.5 ng mL(-1). In another study, about 83% of A. carbonarius isolates from dried vine fruits produced OTA, with levels ranging from 2 to 5200 ng mL(-1). A survey of grape juices and wines of Brazilian, Argentinean and Chilean origin were found to contain very low levels of OTA. Studies are in progress in Latin America on the ecophysiology of ochratoxigenic fungi and OTA occurrence to reduce the impact of this toxin in the food chain.     

Ochratoxin A in sultanas from Turkey I: Survey of unprocessed sultanas from vineyards and packing-houses.

A method for the determination of ochratoxin A (OTA) in sultanas from Turkey using extraction with a sodium bicarbonate solution (2% NaHCO3) followed by immunoaffinity clean-up and liquid chromatography with fluorescence detection was used to assess the frequency of occurrence and level of OTA. In-house validation was carried out with spiked samples at levels of 0.15, 1.5, 5.0 and 10 microg kg-1 and average recoveries were 91, 93, 87 and 89%, respectively. The limits of detection and limit of quantification in Turkish sultanas were 0.026 and 0.09 microg kg-1, respectively. A survey for the presence of OTA was carried out on 264 unprocessed sultana samples during the production seasons between 1998 and 2000 collected annually from vineyards and from packing-houses. The analyses of unprocessed sultanas showed that 32.2% of the total number of samples contained no detectable OTA, whereas 9.8% of sultana samples had OTA concentrations above 10 microg kg-1, and the remaining 58% had levels within the range 0.026-10 microg kg-1. There were big differences in median concentrations between years. Considering the year of production, it appears that sultanas produced in 1998 and 2000 showed the lowest incidence of OTA contamination (median<0.02 microg kg-1), whereas 2002 showed the highest incidence (median=4.3 microg kg-1). The overall mean OTA concentration was calculated as 3.4 microg kg-1, and the overall median as 0.9 microg kg-1. Among the samples analysed, the highest detected level of OTA was 54 microg kg-1.     

Contribution to the study of ochratoxin A in Spanish wines.

With the aim of assessing ochratoxin A (OTA) contamination in wines from a Spanish northern region and the influence of harvest conditions, the following samples were analysed: 40 wines (28 red and 12 white) obtained from grapes cultivated in three different places of the northern Spanish region of Navarra, but in different years, 20 samples in 1997 and 20 in 1998. Wine samples were provided by a viticultural experimental station with very consistent and controlled cultural and enological practices. A high-performance liquid chromatography (HPLC) method with fluorescence detection and immunoaffinity columns was employed (LOD = 0.05 ng ml(-1); method recovery = 101%). Eighty five per cent of the samples from 1997 showed OTA levels >0.05 ng ml(-1) (range 0.056-0.316 ng ml(-1)) and 15% of the samples from 1998 showed OTA levels above the LOD (range 0.074-0.193 ng ml(-1)). Averages detected in 1997 positive samples were 0.185 ng OTA ml(-1) wine (SD = 0.023) in white wine samples (n = 6) and 0.160 ng ml(-1) (SD = 0.119) in the red wine samples (n = 11). These differences between contamination by OTA in the samples from the two different years were attributed to the different quality of the grapes, due to the bad climate in 1997. The possibility of the loss of the mycotoxin was excluded by the analysis of OTA in contaminated wine during 12 months. This study showed that OTA is stable in wine for at least 1 year.     

FTIR-ATR infrared spectroscopy for the detection of ochratoxin A in dried vine fruit

A method of screening sultanas for ochratoxin A (OTA) contamination, using mid-infrared spectroscopy/Golden Gate single-reflection ATR (attenuated total reflection), is described. The main spectral characteristics of sultanas from different sources were identified in a preliminary acquisition and spectral analysis study. Principal component analysis (PCA) showed that samples of various origins had different spectral characteristics, especially in water content and the fingerprint region. A lack of reproducibility was observed in the spectra acquired on different days. However, spectral repeatability was greatly improved when water activity of the sample was set at 0.62. A calibration curve of OTA was constructed in the range 10-40 µg OTA kg^-1. Samples with OTA levels higher than 20 µg kg^-1 were separated from samples contaminated with a lower concentration (10 µg OTA kg^-1) and from uncontaminated samples. The reported methodology is a reliable and simple technique for screening dried vine fruit for OTA.     

OCHRATOXIN A, HYDROXYMETHYLFURFURAL AND VITAMIN C LEVELS OF SUN-DRIED GRAPES AND SULTANAS

Ochratoxin A (OTA), hydroxymethylfurfural (HMF) and l ‐ascorbic acid (vitamin C) levels were detected in sun‐dried sultanas and raisins (Vitis vinifera L. cv. Sultanina). Ochratoxins produced by Aspergillus ochraceus, Aspergillus spp., Penicillium viridicatum, Penicillium cyclopium and Rhizophus spp. The main toxin of this group is OTA. It is nephrotoxic and immunotoxic. HMF can occur during nonenzymatic browning reactions that take the form of condensation reactions between amino acids and reducing sugars. It is known as a mutagenic and carcinogenic compound. The sultanas and raisin research samples were sun dried in the field and stored over a long period in the plant. Toxicological quality patterns evaluated for OTA and HMF levels were also evaluated. These are very important compounds for food safety. They are important critical control quality criteria of sun‐dried grapes. Vitamin C was examined because of sensitivity against physical and chemical factors such as oxygen, light, thermal treatments, alkali treatment and heavy metals, as well as being important for food labeling. The mean values of OTA in sultanas and raisins were 4.64 and 2.98 µg/kg, respectively. It is determined that the studied samples could be evaluated for safety limit of OTA, which is suggested by the European Community as 10 µg/kg. The HMF values of the samples were 5.50 and 33.57 mg/kg, respectively. The raisins were sun dried. The two types of samples without any pretreatment had a long sun drying period, and they showed higher mean of HMF level with content is had showed higher mean HMF level sultanas. The HMF content is with a critical control point for human health. The mean vitamin C levels of sultanas and raisins were 3.67 and 5.15 mg/100 g, respectively. The mean vitamin C values of sultanas were lower than those of raisins. It was estimated that alkali treatment could cause the destruction of l ‐ascorbic acid. The vitamin C content of sun‐dried grapes does not contribute much to nutrition.     

The effect of dipping pretreatment on ochratoxin A accumulation in sultanas and currants

Food Science and Biotechnology - The dipping pretreatment on the occurrence of ochratoxin A (OTA) in sultanas and currants was investigated. Grape samples were divided into two groups before a...     

Effect of yearly conditions and management practices on ochratoxin A production in Sultana Seedless vineyards

Sun drying of seedless grapes (Vitis vinifera cv. Sultanina) is widely practised in the western Aegean Region providing Turkey with a significant share in the world trade of sultanas. Research was initiated in 1998 to determine the incidence of ochratoxin A (OTA), to identify the major factors resulting in contamination and to develop techniques to reduce or prevent contamination. This paper assesses OTA formation in five experimental vineyards located in Manisa province of Turkey between 1998 and 2003. The cultural practices recorded were tillage (type and timing), fertilisation, plant protection, irrigation, trellising, pruning, GA(3) application, harvest maturity and date, and drying practices (type of drying yard, dipping into alkaline solution, length of drying period). In the experimental vineyards, no OTA was found at veraison. OTA levels in grapes harvested at fresh maturity ranged between 相似文献   

Fumonisin contamination and fumonisin producing black Aspergilli in dried vine fruits of different origin

Aspergillus niger isolates are able to produce fumonisins in high quantities on agar media with a low water activity. Several agricultural products fit this criterion, including dried vine fruits, dates and figs. Data on the occurrence and role of this species in fumonisin contamination of agricultural products with high sugar content are needed to clarify the importance of A. niger in human health. The mycobiota and fumonisin contamination of various dried vine fruit samples collected from different countries were examined to clarify the role of black Aspergilli in fumonisin contamination of such products. All except two of the examined samples were contaminated with black Aspergilli. Species assignment of the isolates was carried out using sequence analysis of part of the calmodulin gene. The range of fumonisin isomers present in the raisin samples, and produced by A. niger isolates collected from dried vine fruits was also examined using reversed-phase high-performance liquid chromatography/electrospray ionization-ion trap mass spectrometry (RP-HPLC/ESI-ITMS). Among the 30 A. niger/A. awamori isolates identified, 20 were found to be able to produce fumonisins (average contamination: 5.16 mg/kg; range: 0.017-19.6 mg/kg). The average fumonisin content of the 7 dried vine fruit samples which were found to be contaminated by potential fumonisin producing black Aspergilli was 7.22 mg/kg (range: 4.55-35.49 mg/kg). The isolates produced several fumonisin isomers also present in the dried vine fruit samples, including fumonisins B_1-4, 3-epi-FB₃, 3-epi-FB₄, iso-FB₁, and two iso-FB_2,3 forms. Fumonisin B₁ was detected for the first time in A. niger cultures. Most of these isomers have previously only been identified in Fusarium species. Our data indicate that A. niger and A. awamori are responsible for fumonisin contamination of dried vine fruits worldwide. The observed levels of contamination are alarming and pose a new threat for food safety.     

Micronutrient mineral and folate content of Australian and imported dried fruit products

A selection of Australian and imported fresh and dried fruit products, including sultanas, Sunmuscats, Carina currants, Zante currants, apricots, and prunes, were analyzed for selected minerals (Ca, Mg, Na, S, B, Al, Fe, Mn, Cu, Zn, Mo, and Se), folate and vitamin C, and the capacity of dried fruits for dietary provision of these micronutrients evaluated. Micro-nutrients were concentrated by a factor of 3-5 in dried fruits compared with their fresh fruit counterparts and were consequently present in nutritionally significant levels, in contrast to fresh fruit. Australian dried sultanas, Carina currant, Zante currant, apricots, and prunes contained Cu, Fe, K, and Mn at levels of >20% of daily Required Dietary Intake (RDI, taken as the average for adult men and women as nominated by the Australian National Health and Medical Research Council) and Sunmuscats contained Cu, Fe, and K at >20% of RDI. All dried fruits studied contained boron in the range of 1.5 to 5.4 mg per 100 g; however, the RDI for boron has not been defined by the NHMRC at the present time. All sultanas and currants studied contained folate at levels of 10-20% of RDI per 100 g. Experimental drying methods significantly affected folate levels with higher folate content in non-ground versus ground-based drying methods. Of the micro-nutrients supplying >20% of RDI, folate represents a particular nutrient for which the mean daily intake of adult Australians is typically inadequate. This study shows that dried fruit consumption, in contrast with fresh fruit, can provide significant proportions of daily requirements of several micronutrients, particularly folate.     

Ochratoxin A in beverages from Morocco: a preliminary survey

In a preliminary study, samples of Moroccan wines (n = 30), beers (n = 5) and fruit juices (n = 14) were assayed for ochratoxin A (OTA) by HPLC with fluorimetric detection, followed by confirmation by cleavage of the OTA molecule using carboxypeptidase with HPLC-fluorimetric determination of ochratoxin alpha (OT alpha). All the wine samples were contaminated, and the overall median OTA concentration was 0.65 microg/l (range 0.028-3.24 microg/l). One of the 14 samples of fruit juices was contaminated with a concentration of 1.16 microg/l, whereas none of the five beer samples was contaminated. This is the first report on the occurrence of OTA in various beverages from Morocco.     

Detection of ochratoxin A and cis- and trans-resveratrol in red wines and their musts from Calabria (Italy)

The natural occurrence of ochratoxin A (OTA) and cis- and trans-resveratrols in red wines has been widely reported. The aim of this work was to evaluate the ochratoxin A (OTA) and both cis- and trans-resveratrol content of red wine (from must to wine) in a pilot-scale vinification process in Calabria (Italy). Eleven samples were collected at different stages of vinification and analysis was carried out by HPLC. Wine from manufacturer 3 contained the highest amount of trans-resveratrol (3.41 mg l(-1)). This wine was characterized by an Aglianico-Magliocco grape variety. Interestingly, data regarding OTA showed that the value of this contaminant was low in all analyzed samples and, in each case, below the legal limit (2.0 mg l(-1) (ppb)). Overall, the results demonstrated the high quality of wines produced in Calabria.     

Effects of fungal interaction on ochratoxin A production by A. carbonarius at different temperatures and a(w)

Ochratoxin A is a well-known mycotoxin produced by species of the genera Penicillium and Aspergillus. OTA-producing species from A. section Nigri are considered the source of OTA detected in grapes, dried vine fruits and wines. Other fungi present in grapes during their maturation can grow and interact with OTA-producing Aspergillus species and affect OTA production. In this study seven fungi (Alternaria alternata, Cladosporium herbarum, Eurotium amstelodami, Trichoderma harzianum, Penicillium decumbens, P. janthinellum and Candida sp.) disolated from grapes and dried vine fruits were grown in SNM medium paired with OTA-positive A. carbonarius at two temperatures (20 and 30 degrees C) and at two water activities (0.92 and 0.97). OTA production was tested after 5, 7, 10, 14 and 18 days of incubation, at four distances (1, 2, 3 and 4 cm) from A. carbonarius inoculation point in the inter-colony axis. At 0.92 a(w) OTA production was almost negligible. At 0.97 a(w) and 30 degrees C OTA accumulation was reduced when A. carbonarius was grown in paired cultures, particularly with A. alternata, C. herbarum, P. decumbens and P. janthinellum. At 0.97 a(w) and 20 degrees C, there was no clear effect of the interacting species on OTA accumulation; in general E. amstelodami and Candida sp. seemed to stimulate OTA production, whereas T. harzianum and P. decumbens reduced it. Competing mycoflora acted as an additional control factor against OTA accumulation at 30 degrees C; but at 20 degrees C, where OTA production is optimal, this did not happen. Thus maintaining the temperature of grapes at or above 30 degrees C during dehydration may provide some control against OTA accumulation in grapes.     

Occurrence of ochratoxin A in wine and grape juice marketed in Rio de Janeiro, Brazil.

Ochratoxin A (OA) is receiving attention world-wide because of the hazard it poses to human health. The aim was to test the distribution of OA in grape juice, pulps of frozen grapes, and national and imported table wine obtained from markets in Rio de Janeiro, Brazil. Analytical methodology using immunoaffinity column for OA extraction and clean-up with a final separation on a reversed-phase (C(18)) column and fluorescence detection in high-performance liquid chromatography showed a detection limit of 21 ng l(-1). The mean recovery was 91% for red wines and 82% for white wines; while the mean recoveries for juices and pulps of frozen grapes were 91.6 and 88%, respectively. Of 64 samples of grape juice and frozen pulps, 25% were positive for OA, being the mean content of 37 ng l(-1) with a maximum concentration of 100 ng l(-1). In wines, the mean concentration detected in 80 samples analysed was 34.4 ng l(-1) with 28.75% of positive samples. Red wines showed the highest percentages and levels of contaminated samples: 38% and 37 ng l(-1), respectively. The white wine contained levels above 26 ng l(-1) in 17.75% of the analysed samples. The levels of contamination detected in red wine sold in Río de Janeiro were not enough to surpass the virtually safe dose established as 5 n g kg(-1) body weight of daily intake.