Effect of water activity, temperature and incubation time on growth and ochratoxin A production by Aspergillus niger and Aspergillus carbonarius on maize kernels

The aim of this study was to determine the effects of water activity (a_w) (0.92-0.98), temperature (5-45 °C) and incubation time (5-60 days) on growth and ochratoxin A (OTA) production by Aspergillus niger and Aspergillus carbonarius on maize kernels using a simple method. Colony diameters of both strains at 0.92 a_w were significantly lower than those at 0.96 and 0.98 a_w levels. The optimum growth temperature range for A. niger was 25-40 °C and for A. carbonarius 20-35 °C. A. niger produced OTA from 15 to 40 °C, and the highest OTA level was recorded at 15 °C. The concentration of OTA produced at 0.92 a_w was significantly lower than those at 0.96 and 0.98 a_w. A. carbonarius produced OTA from 15 to 35 °C and the maximum concentration was achieved at 15 °C, although not differing statistically from the concentration detected at 20 °C. At 0.98 a_w the OTA concentration was significantly higher than at 0.96 and 0.92 a_w. Our results show that maize supports both growth and OTA production by A. niger and A. carbonarius. The studied strains were able to produce OTA in maize kernels from the fifth day of incubation over a wide range of temperatures and water availabilities. Although the limit of quantification of our method was higher than that required for the analysis of OTA in food commodities, it has proved to be a useful and rapid way to detect OTA production by fungi inoculated onto natural substrates, in a similar way as for pure culture. Both species could be a source of OTA in this cereal in temperate and tropical zones of the world.     

Is intraspecific variability of growth and mycotoxin production dependent on environmental conditions? A study with Aspergillus carbonarius isolates

The aim of this study was to assess the impact of suboptimal environmental conditions on the intraspecific variability of A. carbonarius growth and OTA production using thirty isolates of A. carbonarius.Three a_w/temperature conditions were tested, one optimal (0.98a_w/25 °C) and two suboptimal: 0.90a_w/25 °C and 0.98a_w/37 °C as suboptimal water activity and temperature, respectively, which might take place through over ripening and dehydration of grapes. For each condition, 12 Petri dishes were inoculated, and colony growth and OTA production were measured over time.ANOVA revealed significant differences among μ and λ within the 30 assayed isolates. Coefficients of variation (CV%) revealed a wider dispersion of growth rates at 0.90a_w/25 °C compared to 0.98a_w/25 °C, and a more than 4-fold higher CV at 0.98a_w/37 °C compared to 0.98a_w/25 °C. However, dispersion of lag phases was similar at 0.98a_w/25 °C and 0.90a_w/25 °C and wider at 0.98a_w/37 °C.There were significant differences (p < 0.05) among OTA levels (ng/mm²) for the different conditions, values being lower under marginal conditions, and particularly at 0.98a_w/37 °C. Coefficients of variation (CV%) revealed a wider dispersion of OTA production at 0.90a_w/25 °C compared to 0.98a_w/25 °C, while CV at 0.98a_w/37 °C was similar to that at 0.98a_w/25 °C.In order to address the strain variability in growth initiation and prove the well-established notion of reducing OTA in foods by preventing fungal growth, a greater number of strains should be included when developing models for conditions that are suboptimal both for a_w for OTA production and temperature levels for growth.     

Impact of non-selective fungicides on the growth and production of ochratoxin A by Aspergillus ochraceus and A. carbonarius in barley-based medium

The aim of this study was to assess the influence of the non-selective fungicides mancozeb, copper oxychloride, and sulfur on the growth and capability for producing ochratoxin A (OTA) of ochratoxigenic isolates of Aspergillus carbonarius and A. ochraceus in barley-based medium. Lag phases and growth rates were determined for each fungicide at different doses, at 15°C and 25°C and at 0.97?a_w . Mancozeb at 40?mg?l^?1 inhibited fungal growth and provided lag phases >24 days at 10–20?mg?l^?1 and 15°C. OTA was observed only at 25°C and doses <10?mg?l^?1. At 15°C, copper oxychloride proved inhibitory at 800?mg?l^?1, while at 25°C growth was not delayed and only high doses decreased OTA levels. Sulfur was inhibitory or provided large lag phases at 5–8?g?l^?1 (at 15°C) while at 25°C growth took place even at 8?g?l^?1, although OTA levels were low or undetectable. The antifungal activity decreased in the order mancozeb?>?copper oxychloride?>?sulfur, and was lower at 25°C than at 15°C. OTA accumulation was affected by the type of fungicide, dose, temperature and time. The efficacy of these fungicides on the growth of A. carbonarius and A. ochraceus and OTA production in barley-based medium is assessed for the first time.     

Influence of water activity and temperature on conidial germination and mycelial growth of ochratoxigenic isolates of Aspergillus ochraceus on grape juice synthetic medium. Predictive models

The first stages in the development of Aspergillus ochraceus, an ochratoxin A‐producing fungus that infects grapes and may grow on them, have been studied on a synthetic nutrient medium similar to grape in composition. Spore germination and mycelial growth have been tested over a water activity (a_w) and temperature range which could approximate to the real conditions of fungal development on grapes. Optimal germination and growth were observed at 30 °C for all three isolates tested. Maximal germination rates were detected at 0.96–0.99 a_w at 20 °C, while at 10 and 30 °C the germination rates were significantly higher at 0.99 a_w. Although this abiotic factor (a_w) had no significant influence on mycelial growth, growth rates obtained at 0.98 a_w were slight higher than those at other a_w levels. Predictive models for the lag phase before spore germination as a function of water activity and temperature have been obtained by polynomial multiple linear regression, and the resulting response surface models have been plotted. Copyright © 2005 Society of Chemical Industry     

Modeling the effect of natamycin,pine-resin and environmental factors on the growth and OTA production by Aspergillus carbonarius using response surface methodology

The effect of two antifungal compounds (natamycin, pine-resin), temperature and water activity, on the growth rate, lag phase duration and Ochratoxin A (OTA) production by three Aspergillus carbonarius isolates (Ac-28, Ac-29, and Ac-33), was studied by means of Response Surface Methodology (RSM) based on a Central Composite Design (CCD). Two different experimental designs were performed as a function of temperature (16.6–33.4 °C), water activity (0.90–0.97 a_w), natamycin (0–1000 ng ml^− 1) or pine-resin (0–2.61%, w/v) on a Synthetic Grape-juice Medium (SGM). OTA production was analyzed after 5, 10 and 15 days of incubation. A second-order polynomial model was fitted to each response parameter to assess the growth and OTA potential of all fungal isolates. Results showed that natamycin, a_w and temperature had significant effects on the lag phase duration of all isolates, as well as on OTA accumulation after 10 days of incubation for Ac-29 and 15 days for Ac-28 and Ac-33 isolates. The same results were obtained for OTA production after treatment with pine-resin. However, fungal growth rates were not statistically significant in both experiments, with the exception of Ac-29 and Ac-33 after treatment with pine-resin. Overall, high natamycin concentrations (800 and 1000 ng ml^− 1) delayed fungal growth depending on the environmental factors assayed. Moreover, treatment with pine-resin at 16.6 °C/0.94 a_w/1.1% w/v, as well as at 25 °C/0.90 a_w/1.1% w/v, completely inhibited fungal growth up to 15 days of incubation.     

Mould contamination and the influence of water activity and temperature on mycotoxin production by two aspergilli in melon seed

Both the moisture levels and the incidence of mould contamination recorded for shelled water melon seed samples (22) obtained from 9 markets were generally higher as those recorded for the unshelled seed samples. 16 fungi, mostly toxigenic, were isolated from the surface-disinfected mouldy seeds. Of these isolates, 7, 3 and 2 species belonged to Aspergillus, Penicillum and Fusarium genera, respectively, while Botryodiplodia, Rhizopus, Sclerotium and Syncephalastrum had one respresentative each. Production of aflatoxins (B₁, B₂) by 5 toxigenic strains of Aspergillus flavus and of ochratoxin A by 4 toxigenic strains of A. ochraceus in melon seed at varying water activity (a_w) and temperature levels were investigated. Of the a_w levels (0.65, 0.70, 0.80, 0.90 and 0.98) provided, toxins were detected only at and above 0.80 with the peak production recorded at either 0.90 or 0.98 a_w level. Whereas aflatoxins were produced and detected under all the test temperatures (15, 20, 25, 30, 35, and 40 °C), the elaboration of ochratoxin A was detected only as from 25 to 40 °C. Optimum temperature for toxin production by all the strains of the two fungi used was 30 °C.     

Fumonisin B1, zearalenone and deoxynivalenol production by Fusarium moniliforme,F proliferatum and F graminearum in mixed cultures on irradiated maize kernels

The impact on fungal growth and mycotoxin formation of interactions between fumonisin‐producing isolates of Fusarium moniliforme and F proliferatum and a zearalenone (ZEA)‐ and deoxynivalenol (DON)‐producing isolate of F graminearum inoculated together on irradiated maize at 15 and 25 °C and at 0.98, 0.95 and 0.93 a_w was studied. The presence of F graminearum decreased the fungal populations (CFU g⁻¹ grain) of F moniliforme and F proliferatum under almost all conditions tested. In the presence of F moniliforme, CFUs of F graminearum increased significantly at 25 °C, especially at 0.93 and 0.95 a_w, while the presence of F proliferatum caused them to increase at 15 °C. The presence of F graminearum always inhibited FB₁ production, except at 25 °C and 0.98 a_w where it increased. However, the observed differences were not statistically significant. There was no effect of fungal interaction on ZEA production by F graminearum; however, when paired with F moniliforme and F proliferatum, DON production by F graminearum was significantly stimulated, especially at 0.98 a_w. © 2000 Society of Chemical Industry     

Comparative study of toxigenic potential of Aspergillus flavus and Aspergillus niger isolated from Barley as affected by temperature,water activity and carbon source

The objective of the present work was to evaluate the ability of two mycotoxigenic species Aspergillus flavus and Aspergillus niger, isolated from barley, to produce aflatoxin B1 (AFB1) and ochratoxin A (OTA), respectively, as affected by nutritional and environmental factors. Six carbon sources (D-fructose, D-glucose, D-galactose, lactose, sucrose and starch) and different water activities (0.90, 0.95 and 0.98), temperature (20 and 28 °C) and incubation time (5 and 10 days) were tested. The results showed that optimal conditions for growth on Barley Meal Extract Agar (BMEA) medium were 28 °C and 0.95 a_w for A. niger strain and 28 °C and 0.98 a_w for A. flavus strain. Optimal conditions for OTA and AFB1 production were largely different for the two tested strains. A. niger had an optimal OTA production at 0.98 a_w and 20 °C after 10 days of incubation while A. flavus had an optimal AFB1 production at 0.95–0.98 a_w and 28 °C after 5 days of incubation. These results indicates that A. flavus has a higher optimum temperature for mycotoxin synthesis than A. niger and takes greater advantage of drier conditions for maximum AFB1 production. In the current study, both OTA and AFB1 production of A. niger and A. flavus were highly influenced by carbon sources. The sugar that provided the highest toxin levels in the cultures of the two species was sucrose with the lowest levels given by starch. OTA production by A. niger was also highly induced by fructose as carbon sources, while, AFB1 production by A. flavus was favored by glucose. Globally, our results showed, significantly different optimal conditions for production of AFB1 and OTA, respectively, by A. flavus and A. niger.     

Dynamics of phytosterol degradation in a bulk of rapeseed stored under different temperature and humidity conditions

Improper rapeseed preservation and storage after harvest may contribute to a reduction of phytosterol contents in the seeds. The aim of the study was to investigate the dynamics of phytosterol degradation in bulks of rapeseed stored under various temperature and water activity conditions. In the experiments a hazardous level of fungal infestation was considered to reflect the population of fungi colonizing seeds during vegetation and harvest at adverse weather conditions. Changes in phytosterol contents intensified with the increase in storage temperature and water activity in seeds. The temperature in the range of 12–24 °C and water activity in seeds a_w = 0.75–0.76 significantly limited phytosterol degradation (6.5% and 8% after 48 and 72 days of storage), whereas in seeds with a_w = 0.90 stored at 30 °C major phytosterol losses were observed (61% after 48 days of storage). Among the identified phytosterols the pattern of changes in campesterol content was similar to that for β-sitosterol, whereas brassicasterol degradation proceeded similarly as the reduction in avenasterol and stigmasterol levels. The degradation of stigmasterol, brassicasterol and avenasterol was more rapid than that of campesterol and β-sitosterol. Correlation analysis showed that acid value and seed germination may be used as predictive factors for phytosterol degradation. The correlation between the fungal population and phytosterol concentration was found only in seed samples, in which a substantial mould activity was observed (a_w ≥ 0.80 at t = 24-30 °C and a_w ≥ 0.86 at t = 12-18 °C). The results provide useful quality control points, which may be used to improve the existing postharvest management systems of rapeseed preservation and storage.     

Modeling Growth Rate and Assessing Aflatoxins Production by Aspergillus flavus as a Function of Water Activity and Temperature on Polished and Brown Rice

Abstract: The aim of this study was to model the radial growth rate and to assess aflatoxin production by Aspergillus flavus as a function of water activity (a_w 0.82 to 0.92) and temperature (12 to 42 °C) on polished and brown rice. The growth of the fungi, expressed as colony diameter (mm) was measured daily, and the aflatoxins were analyzed using HPLC with a fluorescence detector. The growth rates were estimated using the primary model of Baranyi, which describes the change in colony radius as a function of time. Total of 2 secondary models were used to describe the combined effects of a_w and temperature on the growth rates. The models were validated using independent experimental data. Linear Arrhenius–Davey model proved to be the best predictor of A. flavus growth rates on polished and brown rice followed by polynomial model. The estimated optimal growth temperature was around 30 °C. A. flavus growth and aflatoxins were not detected at 0.82 a_w on polished rice while growth and aflatoxins were detected at this a_w between 25 and 35 °C on brown rice. The highest amounts of toxins were formed at the highest a_w values (0.90 to 0.92) at a temperature of 20 °C after 21 d of incubation on both types of rice. Nevertheless, the consistencies of toxin production within a wider range of a_w values occurred between 25 to 30 °C. Brown rice seems to support A. flavus growth and aflatoxin production more than the polished rice. Practical Application: The developed models can be used to estimate to what extent the change in grain ecosystem conditions affect the storage stability and safety of grains without the need for running long‐standing storage study. By monitoring the intergranular relative humidity and temperature at different locations in the storage facility and inputting these data into the models, it is directly possible to assess either the conditions are conductive for the growth of A. flavus or aflatoxin production.     

Water Activity and Temperature Effects on Fungal Growth and Ochratoxin A Production by Ochratoxigenic Aspergillus carbonarius Isolated from Tunisian Grapes

ABSTRACT: This study investigated the effects of temperature (15 to 37 °C) and water activity (0.90 to 0.99) on the growth and production of ochratoxin A (OTA) by Aspergillus carbonarius cultured on synthetic nutrient medium (SNM) after 5 and 10 d of incubation. Total of 8 ochratoxigenic A. carbonarius, isolated from vineyards located in different regions of Tunisia, were used. Growth data were modeled by the flexible model of Baranyi and growth rates at each set of conditions were obtained. For both growth and OTA production, optimal water activity was 0.99; however, optimal temperature varied. The optimal temperature for growth was 30 °C. At 37 °C, the growth rate decreased significantly (P < 0.05). Maximum toxin production occurred at temperatures in the range of 15 to 25 °C with the optimum one depending on the isolate tested. Significant amounts of OTA were produced after only 5 d of incubation. Our results showed that A. carbonarius isolated from Tunisian grapes behave as those from European and Australian grapes, as reported in the literature, although some differences in trends for growth and OTA production were observed.     

Growth and Enterotoxin A Production by Staphylococcus aureus in Precooked Bacon in the Intermediate Moisture Range

Different water activities were obtained in precooked bacon by varying the frying time. Water activity (a_w) correlated best to the moisture, salt and protein content. When stored aerobically at 37°C, S. aureus A100 was capable of rapid growth in precooked bacon at a a_w of 0.84 or above, whereas at 20°C a a_w of 0.88 or higher was required. Under anaerobic storage at 37°C, growth was observed at a a_w of 0.90, and at 20°C slight growth was noted at a a_w of 0.91. The increase in the minimal a_w required for aerobic growth at the lower temperature was reflected in the differences between the isotherms obtained at 37°C and 20°C. The maximum populations achieved were higher for samples stored aerobically. Enterotoxin A (19–821 ng/g) was found in all aerobically stored samples where growth occurred. Enterotoxin A (38–109 ng/g) was also found in all anaerobically incubated samples where the population of S. aureus increased more than one logarithmic cycle.     

Ochratoxigenic moulds and effectiveness of grape field antifungals in a climatic change scenario

BACKGROUND: The presence of ochratoxin A (OTA) in grapes and grape derivatives has been reported mainly in the Mediterranean area. Consequently, great efforts are being made to prevent the growth of Aspergillus on grapes. However, the European Commission suggests that climate change may result in increased temperatures and longer drought periods in southern Europe. Therefore the aim of this study was to investigate how ochratoxigenic fungal growth and the efficiency of fungicides used at present might be affected by environmental conditions predicted with climate change. RESULTS: The effectiveness of grape field antifungals (Switch, Flint Max and Equisetum arvense extract) under two alternating temperature, photoperiod and relative humidity (RH) scenarios (current: 20/30 °C, 16 h light/8 h darkness, 80% RH; predicted: 25/37 °C, 16 h light/8 h darkness, 75% RH) on the growth and OTA production of two Aspergillus carbonarius isolates and one Aspergillus ochraceus isolate on grapes was investigated. CONCLUSION: Predicted conditions reduced A. carbonarius and limited A. ochraceus growth. Antifungals reduced fungal infection (by 40‐84%), although no correlation between climatic conditions and effectiveness of the antifungals was found. However, Switch always showed the greatest reduction and E. arvense (0.02 g mL^?1 extract) the least. Higher temperatures affected OTA production by the isolates in different ways. In general, Switch and Flint Max reduced OTA production, while E. arvense stimulated it. Copyright © 2011 Society of Chemical Industry     

Ecophysiology of Fusarium temperatum isolated from maize in Argentina

The effect of water activity (a_w = 0.95, 0.98 and 0.995), temperature (15, 25 and 30°C), incubation time (7, 14, 21 and 28 days), and their interactions on growth and moniliformin (MON), beauvericin (BEA), fusaproliferin (FUS) and fumonisin B₁ (FB₁) production by two strains of Fusarium temperatum isolated from Argentinean maize were determined in vitro on sterile layers of maize grains. The results showed that there was a wide range of conditions for growth and mycotoxins production by F. temperatum. Both strains were found to grow faster with increasing a_w and at 30°C. In relation to mycotoxin production, the two strains produced more FUS than the other mycotoxins regardless of a_w or temperature evaluated (maximum = 50 000 μg g^?1). For FUS, MON and BEA, the maximum levels were observed at 0.98 a_w and 30°C (50 000, 5000 and 2000 μg g^?1 respectively). The lowest levels for these three mycotoxins were detected at 15°C and 0.95 a_w (1700 and 100 μg g^?1 for FUS and MON respectively), and at 0.98 a_w (400 μg g^?1 for BEA). The maximum levels of FB₁ were produced at 15°C and 0.98 a_w (1000 μg g^?1). At all a_w and temperatures combinations evaluated there was an increase in toxin concentrations with time incubation. The maximum levels were detected at 21 days. Statistical analyses of a_w, temperature, incubation time, and the two- and three-way interactions between them showed significant effects on mycotoxins production by F. temperatum. For its versatility on growth and mycotoxin production, F. temperatum represents a toxicological risk for maize in the field and also during grain storage.     

Influence of Temperature, pH, Water Activity and Antifungal Agents on Growth of Aspergillus flavus and A. parasiticus

Effect of temperature, pH, water activity, and nine antifungal agents on growth of Aspergillus flavus and A. parasiticus was determined on Sabouraud-Dextrose Agar and on corn. Maximal growth of the two molds occurred at 33°C, the highest temperature used, pH of 5.0 and a_w of 0.99. At 15°C, growth was observed at a_w of 0.95 but not 0.90. Slight growth was observed at an a_w, of 0.85 at 27°C and 33°C. Nine antifungal agents (Botran, Orthocide, Poly-ram 80, Topsin-M, Thiram, Imazalil, sodium propionate, sodium sulfite and DDVP) were tested for inhibition of growth. Activity of the antifungals increased as the a_w was decreased. All antifungals showed inhibitory activity, but Imazalil and DDVP were the most effective agents at the lowest concentrations.     

Inhibition of A. carbonarius growth and reduction of ochratoxin A by bacteria and yeast composites of technological importance in culture media and beverages

Five composites of yeast and six of bacterial isolates from fermented products were studied, in order to assess their ability to inhibit Aspergillus carbonarius growth and reduce OTA concentration in culture media and beverages. The antagonistic effect of the above composites against A. carbonarius growth was studied in synthetic grape medium of pH 3.5 and a_w 0.98, 0.95, 0.92 after incubation at 25 °C. Different combinations of initial inocula of bacteria or yeast composites and fungi were used (10² cfu/mL vs 10⁵ spores/mL; 10⁵ cfu/mL vs 10² spores/mL; and 10⁵ cfu/mL vs 10⁵ spores/mL). Regarding the OTA reduction experiment, 10³ and 10⁷ cfu/mL of the bacteria and yeast composites were inoculated in liquid media of different pH (3.0, 4.0, 5.0, and 6.1 or 6.5) and initial OTA concentration (50 and 100 μg/L) and incubated at 30 °C. Moreover, grape juice, red wine, and beer were supplemented with 100 μg/L of OTA and inoculated with composites of 16 yeasts (16YM) and 29 bacterial (29BM) strains (10⁷ cfu/mL) to estimate the kinetics of OTA reduction at 25 °C for 5 days. Fungal inhibition and OTA reduction were calculated in comparison to control samples. None of the bacterial composites inhibited A. carbonarius growth. The high inoculum of yeast composites (10⁵ cfu/mL) showed more efficient fungal inhibition compared to cell density of 10² cfu/mL. All yeast composites showed higher OTA reduction (up to 65%) compared to bacteria (2-25%), at all studied assays. The maximum OTA reduction was obtained at pH 3.0 by almost all yeast composites. For all studied beverages the decrease in OTA concentration was higher by yeasts (16YM) compared to bacteria (29BM). The highest OTA reduction was observed in grape juice (ca 32%) followed by wine (ca 22%), and beer (ca 12%). The present findings may assist in the control of A. carbonarius growth and OTA production in fermented foodstuffs by the use of proper strains of technological importance.     

Interrelationship Between Water Activity, Temperature and 5.5 Percent Oxygen on Growth and Enterotoxin A Secretion by Staphylococcus aureus in Precooked Bacon

The limiting water activity (a_w) for the growth of S. aureus A-100 sealed in cans at an oxygen concentration of 5.5% was 0.87 at 37°C and 0.91% at 20°C, values intermediate to those obtained previously for aerobic and anaerobic storage. Maximum populations attained at 37°C and 20°C were equal and once achieved population levels declined more slowly at 20°C than at 37°C. Enterotoxin A production was detected for population levels exceeding 10⁶ CFU/g bacon and were 100 ng/g bacon at 37°C and 16 ng/g bacon at 20°C. It is suggested that while temperature and oxygen are important considerations, a_w, being the main parameter in controlling microbial growth, should be measured directly rather than depending on indirect measurements such as the moisture-salt ratio.     

Modeling of germination and growth of ochratoxigenic isolates of Aspergillus ochraceus as affected by water activity and temperature on a barley-based medium

Aspergillus ochraceus is an ochratoxin producing fungus that can be found on stored cereal grains such as barley. The objective of this study was to determine the effects of water activity (a_w, 0.75–0.99) and temperature (10–30°C) on germination and growth on barley extract agar medium (BMEA) of three isolates of Aspergillus ochraceus. The three isolates showed an optimal a_w for germination and growth of 0.99–0.95 at 20–30°C, with a marked increase of the lag phases and decrease of germination and growth rates at the marginal levels of a_w and temperature assayed. Minimum level of a_w for germination was 0.80 and 0.85 for growth. Data were then modeled by an MLR regression and response surface models were obtained. These models may allow a rough prediction of germination/growth as a function of the storage temperature and moisture content of barley grains.     

Ochratoxin A production by Aspergillus carbonarius on some grape varieties grown in Italy

Fungi responsible for the presence of Ochratoxin A (OTA) in grapes have been identified as belonging to the black aspergilli, Aspergillus section Nigri, among which Aspergillus carbonarius is the main producer. Despite the widespread occurrence of OTA in various types of wine, there is no specific information on the ability of black aspergilli to infect berries and to produce OTA in different grape varieties. The aim of this study was to investigate the susceptibility to A carbonarius of twelve grape varieties representative of a wide range of characteristics, including geographical distribution. In all the conditions of berry status (intact and damaged) and temperature (20 and 25 °C) tested, the incidence of colonised berries and their OTA contents were always low in ‘Bianco d'Alessano’, ‘Pampanuto’ and ‘Uva di Troia’. In contrast, ‘Cabernet Sauvignon’, ‘Trebbiano’ and ‘Verdeca’ showed high fungal incidence and OTA content. The information gathered is relevant for defining risk factors for OTA presence in grapes, even if these data need to be confirmed by observations in vineyards. Copyright © 2004 Society of Chemical Industry