Paola Battilani

Climate change and food safety: An emerging issue with special focus on Europe

According to general consensus, the global climate is changing, which may also affect agricultural and livestock production. The potential impact of climate change on food security is a widely debated and investigated issue. Nonetheless, the specific impact on safety of food and feed for consumers has remained a less studied topic. This review therefore identifies the various food safety issues that are likely to be affected by changes in climate, particularly in Europe. Amongst the issues identified are mycotoxins formed on plant products in the field or during storage; residues of pesticides in plant products affected by changes in pest pressure; trace elements and/or heavy metals in plant products depending on changes in their abundance and availability in soils; polycyclic aromatic hydrocarbons in foods following changes in long-range atmospheric transport and deposition into the environment; marine biotoxins in seafood following production of phycotoxins by harmful algal blooms; and the presence of pathogenic bacteria in foods following more frequent extreme weather conditions, such as flooding and heat waves. Research topics that are amenable to further research are highlighted.

Ochratoxin A Production and Amplified Fragment Length Polymorphism Analysis of Aspergillus carbonarius, Aspergillus tubingensis, and Aspergillus niger Strains Isolated from Grapes in Italy

ABSTRACT Ochratoxin A is a potent nephrotoxin and a possible human carcinogen that can contaminate various agricultural products, including grapes and wine. The capabilities of species other than Aspergillus carbonarius within Aspergillus section Nigri to produce ochratoxin A from grapes are uncertain, since strain identification is based primarily on morphological traits. We used amplified fragment length polymorphisms (AFLPs) and genomic DNA sequences (rRNA, calmodulin, and β-tubulin genes) to identify 77 black aspergilli isolated from grape berries collected in a 2-year survey in 16 vineyards throughout Italy. Four main clusters were distinguished, and they shared an AFLP similarity of <25%. Twenty-two of 23 strains of A. carbonarius produced ochratoxin A (6 to 7,500 μg/liter), 5 of 20 strains of A. tubingensis produced ochratoxin A (4 to 130 μg/liter), 3 of 15 strains of A. niger produced ochratoxin A (250 to 360 μg/liter), and none of the 19 strains of Aspergillus “uniseriate” produced ochratoxin A above the level of detection (4 μg/liter). These findings indicate that A. tubingensis is able to produce ochratoxin and that, together with A. carbonarius and A. niger, it may be responsible for the ochratoxin contamination of wine in Italy.

Ochratoxin A in grapes and wine

The mycotoxin ochratoxin A is a potent nephrotoxin and a possible human carcinogen. It occurs in a variety of plant products, including wine, grape juice and dried vine fruits. Several surveys have shown that the range of ochratoxin A contents detected in wine produced in Europe varied between 0.01 and 3.4μgl−1. Both incidence and concentration of the toxin were higher in wines from southern regions and increased in the order white < rosè < red. In Italy, field trials were conducted in 1999 and 2000 to study fungi associated with grapes and their ability to produce ochratoxin. Aspergillus and/or Penicillium strains were present on grapes, starting from setting in a few vineyards. The highest level of grape colonisation was found at early veraison in 1999 and at ripening in 2000. In both years, 95% of strains belonged to the genus Aspergillus. Aspergillus niger aggregate was dominant, with about 50% of the ochratoxin-positive strains identified as A carbonarius. Other authors have confirmed the relevance of these fungi and underlined the contribution of A. carbonarius to the ochratoxin contamination of wine. This species is very invasive and colonises and penetrates berries, even without skin damage. It emerges that temperature, rain and relative humidity are the main factors that influence ochratoxin production in grapes.

Epidemiology of toxin-producing fungi and ochratoxin A occurrence in grape

Fungi responsible for ochratoxin A (OTA) production have been studied especially on cereals, where Penicillium verrucosum and Aspergillus ochraceus are to be considered the main producers. Until 1998, these fungi were also believed to be responsible for the production of the toxin in grape, but OTA-producing A. carbonarius and A. niger were identified in dried vine fruits in 1999. Further studies pointed out that mycoflora potentially responsible for the presence of OTA in grapes are present in the field. Aspergilli are dominant to Penicillia, and among these Aspergilli section Nigri. A. carbonarius probably plays an important role because of the high percentage of positive strains and the amount of OTA produced. Aspergilli section Nigri are present on grape bunches early in the season and their frequency increases during later growth stages. At early veraison and ripening, the incidence of colonised berries is more related to the year than to the growth stage, but not to visible symptoms, since it is normal to isolate fungi from intact berries. Differences in ochratoxin content of berries have been detected between years, when the same vineyards, managed in the same way, showed high levels (1999) or the absence (2000) of the toxin. The results suggest that meteorological differences between years and grape-growing areas are responsible for differences in OTA levels, but the data are at present insufficient to draw firm conclusions.

Review of predictive models for Fusarium head blight and related mycotoxin contamination in wheat.

Mould growth and mycotoxin production are related to plant stress caused by environmental factors such as: extreme weather; insect damage; inadequate storage conditions and incorrect fertilization; these predispose plants to mycotoxin contamination in the field. Fusarium species infect wheat during the flowering period. In addition to losses of yield, these fungi can also synthesize toxic components (mycotoxins) in suitable environmental conditions, thus threatening animal and human health. Given the severe consequences and the fact that mycotoxins affect production throughout the world, the ability to predict Fusarium head blight (FHB) and deoxynivalenol (DON) and other mycotoxin contamination is important to reduce the year-to-year risk for producers. Owing to these dangerous consequences in Argentina, Belgium, Canada, Italy, the United States and in Europe, computer models, based on weather variables (temperature, rainfall and moisture level), have been developed to predict the occurrence of FHB and DON contamination in wheat.

Penicillium populations in dry-cured ham manufacturing plants

Seven ham manufacturing plants were sampled for 1 year to assess the mycoflora present in the air and on hams, with special attention given to potential mycotoxin producers. Temperature and relative humidity were recorded in the ripening rooms. Maturing rooms held hams from 2 to 3 through 6 to 7 ripening months, and aging rooms held hams for the following 6 to 7 months, until the 14-month ripening point, when they were ready for the market. Mean temperatures and relative humidities registered during the study were 14.9 degrees C and 62.4%, respectively, in maturing rooms and 16.3 degrees C and 57.6% in aging rooms. Aspergilli and penicillia, potential mycotoxin producers, were isolated in all the plants from the air and the ham. Aspergilli represented 5% of the isolates, while penicillia were largely dominant, with Penicillium nalgiovense being the most represented species (around 60% of the penicillia), followed by Penicillium nordicum, with 10 and 26% of the penicillia isolated, respectively, from the air or the ham. Ochratoxin A production ability, checked in vitro at 250C, was observed in 50% of the P. nordicum isolates obtained both from the air and the ham. Air and ham surface contamination by penicillia was greater in the ripening rooms, where higher temperatures were registered. A certain correlation was also observed between air and ham surface contamination. On the basis of this study, P. nordicum, the ochratoxin A producer that is notable on proteinaceous substrates, is normally present in ham manufacturing plants in Italy, even though not a dominant species. Further studies are necessary to clarify and ensure if dry-curing conditions minimize the potential risk of ochratoxin A formation in the product.

Logistic regression modeling of cropping systems to predict fumonisin contamination in maize.

The aims of this research were to monitor the presence of fumonisins in maize crops in northern Italy over a 6 year period, to study the role of the cropping system on fumonisin levels, and to contribute to the development of a predictive system for fumonisin contamination. In the 6 year period from 2002 to 2007, 438 maize samples were collected in five regions, supported by agronomic data, and analyzed for fumonisin content. Fumonisin was detected in almost all of the grain samples, but 2007 was less and 2005 more contaminated compared to the other years. Preceding crop, maturity class of hybrids, nitrogen fertilization, sowing and harvest week, and grain moisture significantly affected the level of contamination. The logistic regression developed explained around 60% of variability with major roles for longitude, maturity class, and growing weeks. The function can be used to quantify the effect of these factors in a predictive system.

Aflatoxin B1 contamination in maize in Europe increases due to climate change.

Climate change has been reported as a driver for emerging food and feed safety issues worldwide and its expected impact on the presence of mycotoxins in food and feed is of great concern. Aflatoxins have the highest acute and chronic toxicity of all mycotoxins; hence, the maximal concentration in agricultural food and feed products and their commodities is regulated worldwide. The possible change in patterns of aflatoxin occurrence in crops due to climate change is a matter of concern that may require anticipatory actions. The aim of this study was to predict aflatoxin contamination in maize and wheat crops, within the next 100 years, under a +2 °C and +5 °C climate change scenario, applying a modelling approach. Europe was virtually covered by a net, 50 × 50 km grids, identifying 2254 meshes with a central point each. Climate data were generated for each point, linked to predictive models and predictions were run consequently. Aflatoxin B1 is predicted to become a food safety issue in maize in Europe, especially in the +2 °C scenario, the most probable scenario of climate change expected for the next years. These results represent a supporting tool to reinforce aflatoxin management and to prevent human and animal exposure.

Role of maize hybrids and their chemical composition in Fusarium infection and fumonisin production

This study was designed to investigate the role of hybrids in maize Fusarium section Liseola interaction and fumonisin production, with particular emphasis on the occurrence and accumulation of hidden fumonisins in maize (masking phenomenon). In this 2 year study, naturally infected field crops were chosen with 10 maize hybrids, six of them grown in both years. Maize samples collected in 2010 showed a higher incidence of fungal infection as well as higher fumonisin contamination than those obtained in 2009 but a very similar incidence of F. section Liseola. Fumonisin masking was confirmed in raw maize, with a lower amount of hidden forms as compared to free fumonisins detected in the year with higher contamination. The chemical composition of the different hybrids was determined and correlated with the contamination data: the results obtained highlight the main role of fatty acids, with a higher fumonisin contamination in hybrids showing a higher linoleic acid content and a higher masking action in hybrids with higher oleic to linoleic ratio. These results represent a good basis to explain maize hybrid susceptibility to F. section Liseola infection, fumonisin contamination, and masking not related to a specific commercial hybrid but extendable to all hybrids.

Biocontrol of Penicillium nordicum Growth and Ochratoxin A Production by Native Yeasts of Dry Cured Ham

Twelve yeast strains isolated from the surface of Italian typical dry-cured hams, belonging to D. hansenii, D. maramus, C. famata, C. zeylanoides and H. burtonii species, and previously selected for their ability to grow in dry-cured ham-like substrates, were screened for antagonistic activity against a toxigenic strain of P. nordicum and inhibition of ochratoxin A (OTA) biosynthesis. On average, yeast inhibitory activity was lowered by increasing fungal inoculum and enhanced by NaCl presence. In the assay conditions, H. burtonii and C. zeylanoides were the most effective, both in inhibiting P. nordicum growth and OTA production. D. hansenii was the species with the lowest inhibitory activity, especially in the absence of salt. OTA production dropped from the range < LOD − 5000 ppb in P. nordicum control plates to the range < LOD − 200 ppb in yeast-added plates. OTA production increased in the presence of NaCl in P. nordicum control plates, while salt enhanced inhibition against OTA production in yeast-added plates.