Impact of Fungi Co-occurrence on Mycotoxin Contamination in Maize During the Growing Season

Maize is a possible host of many fungi, some of them able to produce different mycotoxins. Few studies exist on co-occurring fungi and resulting multi-mycotoxin contamination in field; for this reason, in field trials were conducted in two consecutive years to verify fungal incidence and mycotoxin production in the case of the co-occurrence of the three main mycotoxigenic fungi of maize in Italy: Aspergillus flavus, Fusarium verticillioides, and Fusarium graminearum able to produce, respectively, aflatoxin B1 (AFB1), fumonisins (FBs), and deoxynivalenol (DON). Artificial inoculation was done after silk emergence of maize and samples were collected with a 2 week schedule up to harvest time (four samplings). Fungal interaction resulted as playing a role for both fungal incidence and mycotoxins production, as did weather conditions too. Main interactions were noted between A. flavus and F. verticillioides, and between F. verticillioides and F. graminearum. In particular, as a result of fungal co-occurrence, AFB1 resulted stimulated by F. graminearum presence while no effects were noted in FBs and DON in case of F. verticillioides-F. graminearum co-occurrence. Interestingly, the co-presence of A. flavus significantly reduced both FB and DON production.

Mycotoxins and Related Fungi in Italian Paddy Rice During the Growing Season and Storage

Mycotoxigenic fungi and relative mycotoxins contamination were monitored in Italian paddy rice samples both in field during the growing season and the first five months of storage. Three experimental fields, nine rice varieties and three sowing densities were considered; then, different lots of paddy rice were stored in warehouses at different temperature regimes. Fusarium spp. and Aspergillus spp. were found to be the fungi most likely to produce mycotoxins throughout the growing season. In particular, A. flavus and A. niger were found only rarely both in field and in post-harvest, while A. versicolor was always present although in low concentrations. Penicillium spp. strains were isolated sporadically and were found to be irrelevant in Italian rice fungal contamination. Sterigmatocystin (STC) was the main mycotoxin found in Italian rice, while aflatoxin (AFB₁), deoxynivalenol (DON) and ochratoxin A (OTA) were rarely detected. Contamination generally increased from post-flowering to ripening; considering rice varieties, significant differences (p ≤ 0.01) were found in fungal contamination and STC production; no differences were observed between sowing densities. During storage, an increase in STC content was observed in higher temperature regimes, while all the other considered mycotoxins remained unchanged. These results indicated that contamination by STC, an emerging mycotoxin not legislatively regulated by the European Union, can be relevant in rice.

Fate of mycotoxins and related fungi in the anaerobic digestion process

In this study, the possibility to manage maize contaminated with aflatoxins and fumonisins for the production of biogas was considered. This is a priority in the climate change scenario that is expected to increase the occurrence of aflatoxins in maize. The results clearly underline how the anaerobic digestion process used in biogas plants is able to reduce aflatoxin contamination, mainly when highly contaminated maize is used for feeding the biodigestors without affecting the efficiency of methane production. In particular, the higher aflatoxin contamination is, the higher is mycotoxin reduction during biodigestion, with reductions up to 95% in digestate. The co-occurring mycotoxins, fumonisins, were also reduced by around 15%. The vitality of mycotoxin producing fungi was also significantly reduced. Biogas production is therefore suggested as a good alternative use for uncompliant maize.

Mitigation measures for acrylamide reduction in dough-based potato snacks during their expansion by frying

Acrylamide (AA) can occur in fried and baked food products which contain reducing sugars and free asparagine. Recently, the European Commission established mitigation measures and benchmark levels for the reduction of AA in food. The content of reducing sugars in raw materials and the temperature and time of the expansion process by frying were considered in this study of the preparation of dough-based potato snacks, mainly destined for children. Final moisture and bulk density were also evaluated. An increase from 0.15 to 1.0% in reducing sugar content, due to the addition of micro-ingredients in the dough, caused a remarkable AA increase of five- to six-fold. During frying at temperatures between 175 and 195°C, AA was produced after only a few seconds; the AA content was affected more by process time than by temperature. The best temperature/time conditions for expansion by frying were 185°C for 8 s.

Modeling Growth and Toxin Production of Toxigenic Fungi Signaled in Cheese under Different Temperature and Water Activity Regimes

The aim of this study was to investigate in vitro and model the effect of temperature (T) and water activity (aw) conditions on growth and toxin production by some toxigenic fungi signaled in cheese. Aspergillus versicolor, Penicillium camemberti, P. citrinum, P. crustosum, P. nalgiovense, P. nordicum, P. roqueforti, P. verrucosum were considered they were grown under different T (0-40 °C) and aw (0.78-0.99) regimes. The highest relative growth occurred around 25 °C; all the fungi were very susceptible to aw and 0.99 was optimal for almost all species (except for A. versicolor, awopt = 0.96). The highest toxin production occurred between 15 and 25 °C and 0.96-0.99 aw. Therefore, during grana cheese ripening, managed between 15 and 22 °C, ochratoxin A (OTA), penitrem A (PA), roquefortine-C (ROQ-C) and mycophenolic acid (MPA) are apparently at the highest production risk. Bete and logistic function described fungal growth under different T and aw regimes well, respectively. Bete function described also STC, PA, ROQ-C and OTA production as well as function of T. These models would be very useful as starting point to develop a mechanistic model to predict fungal growth and toxin production during cheese ripening and to help advising the most proper setting of environmental factors to minimize the contamination risk.

European survey on sterigmatocystin in cereals, cereals-based products, beer and nuts

Based on the EFSA proposal ‘Survey on sterigmatocystin in food’ (GP/EFSA/CONTAM/2013/02), this study provides a survey on the occurrence of this mycotoxin. A total of 1,259 samples of cereal grains (429), cereal products (713), beer (53) and nuts (64) were analysed for the presence of sterigmatocystin (STC). Samples were mainly collected at processing plants, storage facilities, wholesale and retail between August 2013 and November 2014, in nine European countries, mostly Greece, Italy, the Netherlands and the United Kingdom. The products originated from 27 European countries and 18 other countries. All samples were analysed by methods based on liquid chromatography coupled with tandem mass spectrometry. The limit of quantification (LOQ) was 0.5 µg/kg and the limit of detection (LOD) was in the range 0.05-0.15 µg/kg (0.005-0.01 µg/l for beer). Overall, STC was identified in 10% of the samples; it was not detected in either beer or nut samples. More than 50% of the contaminated samples contained levels between LOD and LOQ; in the other cases, levels were between 0.5-6 µg/kg with one exception (33 µg/kg in oats). In cereal grains, rice and oats seemed the cereals most prone to STC contamination (100% unprocessed rice, 22% oats grains); however the number of rice samples was limited (n=28) and the samples were collected almost exclusively in Italy and Greece. In cereal products, levels were lower than in cereal grains. The highest incidence was in processed rice (21%) and breakfast cereals (19%), while for the other cereal products this was between 5-7%. In the contaminated cereal products, rice and oats were often present as ingredients.

New assessment based on the use of principal factor analysis to investigate corn silage quality from nutritional traits, fermentation end products and mycotoxins

BACKGROUND

A survey on 68 dairy farms was carried out to evaluate the ensiling procedures adopted to store corn silage. Samples from core, lateral and apical zones of the feed-out face of silos were analysed. A principal factor analysis (PFA) was carried out on the entire database (196 silage samples and 36 variables) and 11 principal factor components (PCs) were retained and interpreted.

RESULTS

Ensiling procedures influenced the area exposed to risk of air penetration. Cores had higher dry matter, starch and lactic acid content or lower pH, fibre, propionate and butyrate concentrations than peripheral samples (P < 0.05). The highest (P < 0.05) mycophenolic acid and roquefortina C concentrations were detected in lateral samples. Chemical and digestibility variables loaded on two PCs; four PCs were characterized by end-products associated with clostridia, heterolactic, homolactic and aerobic fermentations; two PCs were associated with mycotoxins, whereas three PCs explained ensiling procedures.

CONCLUSION

The main quality traits of corn silages differed throughout the entire silo face. Minimization of the area exposed to risk of air penetration represents the best strategy to preserve the nutritional value and safety of corn silages. PFA allowed a clusterization of original variables into 11 PCs, appearing able to discriminate well and poorly preserved corn silages.

Review on Mycotoxin Issues in Ruminants: Occurrence in Forages, Effects of Mycotoxin Ingestion on Health Status and Animal Performance and Practical Strategies to Counteract Their Negative Effects

Ruminant diets include cereals, protein feeds, their by-products as well as hay and grass, grass/legume, whole-crop maize, small grain or sorghum silages. Furthermore, ruminants are annually or seasonally fed with grazed forage in many parts of the World. All these forages could be contaminated by several exometabolites of mycotoxigenic fungi that increase and diversify the risk of mycotoxin exposure in ruminants compared to swine and poultry that have less varied diets. Evidence suggests the greatest exposure for ruminants to some regulated mycotoxins (aflatoxins, trichothecenes, ochratoxin A, fumonisins and zearalenone) and to many other secondary metabolites produced by different species of Alternaria spp. (e.g., AAL toxins, alternariols, tenuazonic acid or 4Z-infectopyrone), Aspergillus flavus (e.g., kojic acid, cyclopiazonic acid or β-nitropropionic acid), Aspergillus fuminatus (e.g., gliotoxin, agroclavine, festuclavines or fumagillin), Penicillium roqueforti and P. paneum (e.g., mycophenolic acid, roquefortines, PR toxin or marcfortines) or Monascus ruber (citrinin and monacolins) could be mainly related to forage contamination. This review includes the knowledge of mycotoxin occurrence reported in the last 15 years, with special emphasis on mycotoxins detected in forages, and animal toxicological issues due to their ingestion. Strategies for preventing the problem of mycotoxin feed contamination under farm conditions are discussed.

Enzyme-assisted extraction for the HPLC determination of aflatoxin M1 in cheese

The extraction of aflatoxin M1 (AFM1) from cheese is generally carried out using chlorinated organic solvents. In this study, two innovative methods were developed, based on an enzyme-assisted (EA) extraction using proteolytic enzymes (pepsin or pepsin-pancreatin). After purification through an immunoaffinity column, AFM1 is determined by HPLC-FLD. A comparison between the new EA methods and an established chloroform (CH) method was carried out on 24 cheese samples. The results showed that the extraction efficiency of the EA methods was independent of ripening time of cheese, whereas the CH method was not able to fully recover AFM1 from ripened cheeses. The simpler (pepsin) of the two methods has been adopted by our laboratory for routine analysis of AFM1 in cheese. In comparison with the CH method, the pepsin-HCl (P-HCl) method is simpler, avoiding solvent evaporation, dissolution and partition in a separating funnel; moreover, it gives higher recoveries, comparable LOD and LOQ and more accurate results.

Co-occurrence of type A and B trichothecenes and zearalenone in wheat grown in northern Italy over the years 2009-2011

The occurrence of the most widespread type A and B trichothecenes and of zearalenone was surveyed in soft and durum wheat produced in northern Italy. A total of 293 wheat fields, grown in the years 2009-2011, were surveyed; for each field, weather and cropping system data were collected. The results indicated a high deoxynivalenol incidence, with durum always more contaminated than soft wheat; in 2010, the percentage of durum wheat samples exceeding the European Commission legal limit was 39.6%. As regards type A trichothecenes, widespread contamination was observed in 2010. In soft wheat, an incidence of 70% and 85% was found for T-2 and HT-2 toxins, respectively; all the durum wheat samples were contaminated. The trichothecene contamination was affected by weather conditions; copious rainfall and high relative humidity (RH) during flowering occurred in 2010, when the highest contamination of both type A and B trichothecenes was found.

Mycotoxin levels in maize produced in northern Italy in 2008 as influenced by growing location and FAO class of hybrid

The occurrence of principal mycotoxins in maize produced in northern Italy in 2008 was surveyed. Some easily available information related to each sample, such as hybrid maturity class, maize growth location and mean daily meteorological data were considered in order to explain the observed wide variability in mycotoxin contamination. In addition, a previously developed simple predictive model for aflatoxin B1 contamination in maize was tested using the 2008 data. 197 samples were collected at harvest and meteorological data (mean daily temperature, daily rainfall) were collected from 40 weather stations located near the sampling regions during the period 1 June to 30 September 2008. The results indicated that aflatoxin contamination is of concern in a restricted geographic region (south-east Po Valley). In this region, about 75.0% of the maize samples showed aflatoxin levels higher than 0.5 μg/kg. After a slight modification, the predictive model could indicate a possible high contamination risk. Moreover, the study confirmed that maize harvested in northern Italy was contaminated with fumonisins; throughout the northern Italian plain contamination occurred at significant levels. On the other hand, contamination with trichothecenes and zearalenone was generally low. It has been observed that FAO class 300-400 maize hybrids can be more susceptible to aflatoxin contamination and less to Fusarium mycotoxins than later maturing hybrids.

Plasma ochratoxin A levels, food consumption, and risk biomarkers of a representative sample of men and women from the Molise region in Italy

BACKGROUND

Ochratoxin A (OTA) is a mycotoxin present in food that can be found in human blood, due to its long half-life. Plasma OTA detection represents a good parameter for evaluating the exposure at the population level.

PURPOSE

The relation between plasma OTA levels, dietary habits, and specific disease risk biomarkers (body mass index (BMI), C-reactive protein (CRP), and cardiovascular risk score) was investigated.

METHODS

The study involved 327 subjects (150 men and 177 women) aged between 38 and 48 years. Food consumption was evaluated by means of the EPIC questionnaire; plasma OTA was measured by HPLC; CRP was determined in fresh serum samples by a latex particle-enhanced immunoturbidimetric assay.

RESULTS

OTA was detected in 99.1% of plasma samples (LOD 25 ng/L); the mean ± SD value was 0.229 ± 0.238 ng/mL. However, only 5.2% of samples exceeded 500 ng/L, considered the threshold for a possible pathogenic activity. The estimated mean daily dietary intake of OTA resulted 0.452 ± 0.468 ng/kg body weight (bw)/day, markedly lower than the tolerable daily intake set by EFSA (17.1 ng/kg bw/day). Processed and mutton/lamb meat were found to contribute most to plasma OTA variance. Nevertheless, cereals, wine, beer, and jam/honey consumption correlated positively with OTA levels. Plasma OTA showed a significant positive association with CRP and cardiovascular risk score (β = 0.20 ± 0.08; P = 0.015 and β = 0.25 ± 0.08; P = 0.001, respectively); however, the association was present in men but not in women.

CONCLUSIONS

Even if the hypothesis of a possible hepatic toxicity of OTA in humans is yet to be verified, the positive association between plasma OTA and CRP may indicate a possible role of OTA in inflammation status and consequently in the genesis of cardiovascular diseases and cancer.