Growth and toxin production of phomopsin A and ochratoxin A forming fungi under different storage conditions in a pea (Pisum sativum) model system.

Phomopsins are mycotoxins mainly infesting lupines, with phomopsin A (PHOA) being the main mycotoxin. PHOA is produced by Diaporthe toxica, formerly assigned as toxigenic Phomopsis leptostromiformis, causing infections in lupine plants and harvested seeds. However, Diaporthe species may also grow on other grain legumes, similar to Aspergillus westerdijkiae as an especially potent ochratoxin A (OTA) producer. Formation of PHOA and OTA was investigated on whole field peas as model system to assess fungal growth and toxin production at adverse storage conditions. Field pea samples were inoculated with the two fungal strains at two water activity (aw) values of 0.94 and 0.98 and three different levels of 30, 50, and 80% relative air humidity.After 14 days at an aw value of 0.98, the fungi produced 4.49 to 34.3 mg/kg PHOA and 1.44 to 3.35 g/kg OTA, respectively. Strains of D. toxica also tested showed higher PHOA concentrations of 28.3 to 32.4 mg/kg.D. toxica strains did not grow or produce PHOA at an aw values of 0.94, while A. westerdijkiae still showed growth and OTA production.Elevated water activity has a major impact both on OTA and, even more pronouncedly, on PHOA formation and thus, proper drying and storage of lupins as well as other grain legumes is crucial for product safety.

Impact of experimental thermal processing of artificially contaminated pea products on ochratoxin A and phomopsin A.

Fungi of Aspergillus and Penicillium genus can infect peas (Pisum sativum), leading to a contamination with the nephrotoxic and carcinogenic ochratoxin A (OTA). Under unfavourable conditions, a fungus primarily found on lupines, Diapothe toxica, may also grow on peas and produce the hepatotoxic phomopsin A (PHOA). To study the effect of processing on OTA and PHOA content, two model products-wheat/rye-mixed bread with pea flour addition and pea pasta-were manufactured at small-business scale from artificially contaminated pea flour. The decrease of OTA and PHOA contents were monitored along the production process as indicators for toxin transformation. Pea bread dough was subjected to proofing for 30-40 min at 32 °C and baked at 250 °C to 230 °C for 40 min. OTA content (LODs < 0.1 µg/kg) showed a reduction in the bread crust (initially 17.0 µg/kg) to 88% and no reduction in the crumb (110%). For PHOA (LODs < 3.6 µg/kg), a decrease to approximately 21% occurred in the bread crust (initially 12.5 µg/kg), whilst for crumb, a less intense decrease to 91% was found. Pea pasta prepared with two toxin levels was extruded at room temperature, dried and cooked for 8 min in boiling water. In pea pasta, OTA was reduced from 29.8 to 13.9 µg/kg by 22% each after cooking, whilst 15% and 10% of the initial toxin amounts were found in the cooking water, respectively. For PHOA, 60% and 78% of initially 14.3 µg/kg and 7.21 µg/kg remained in the cooked pasta. As only the decrease of the initial content was measured and no specific degradation products could be detected, further research is needed to characterise potential transformation products. Heat treatment reduces the initial PHOA content stronger than the OTA content during pasta cooking and bread making. However, significant amounts of both toxins would remain in the final products.

Uptake and molecular impact of aluminum-containing nanomaterials on human intestinal caco-2 cells.

Aluminum (Al) is one of the most common elements in the earth crust and increasingly used in food, consumer products and packaging. Its hazard potential for humans is still not completely understood. Besides the metallic form, Al also exists as mineral, including the insoluble oxide, and in soluble ionic forms. Representatives of these three species, namely a metallic and an oxidic species of Al-containing nanoparticles and soluble aluminum chloride, were applied to human intestinal cell lines as models for the intestinal barrier. We characterized physicochemical particle parameters, protein corona composition, ion release and cellular uptake. Different in vitro assays were performed to determine potential effects and molecular modes of action related to the individual chemical species. For a deeper insight into signaling processes, microarray transcriptome analyses followed by bioinformatic data analysis were employed. The particulate Al species showed different solubility in biological media. Metallic Al nanoparticles released more ions than Al2O3 nanoparticles, while AlCl3 showed a mixture of dissolved and agglomerated particulate entities in biological media. The protein corona composition differed between both nanoparticle species. Cellular uptake, investigated in transwell experiments, occurred predominantly in particulate form, whereas ionic Al was not taken up by intestinal cell lines. Transcellular transport was not observed. None of the Al species showed cytotoxic effects up to 200 µg Al/mL. The transcriptome analysis indicated mainly effects on oxidative stress pathways, xenobiotic metabolism and metal homeostasis. We have shown for the first time that intestinal cellular uptake of Al occurs preferably in the particle form, while toxicological effects appear to be ion-related.