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  • Author or Editor: V. Ostry x
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The important glycoalkaloids in potatoes are α-solanine and α-chaconine. Their natural function is probably to serve as stress metabolites or phytoalexins for the protection of the potato when attacked by insects, fungi, etc. They contribute flavour to potatoes but at higher concentrations cause bitterness and are toxic to humans. α-Solanine and α-chaconine appear to have two main toxic actions, one on cell membranes and another one on acetylcholinesterase. Symptoms of α-solanine/α-chaconine poisoning involve an acute gastrointestinal upset with diarrhea, vomiting and severe abdominal pain. An instrumental high-performance thin-layer chromatography (HPTLC) method was applied for the quantification of α-solanine and α-chaconine in peeled potato skin, raw potato pulp and cooked peeled potato tubers. The limit of quantification (LOQ) for α-solanine and α-chaconine was found to be 5.0 mg kg −1 for each glycoalkaloid. In this study the factors of potential loss of α-solanine and α-chaconine in potato tubers during peeling (factor=0.8) and cooking into edible stage in salted water (factor=0.8) were examined. The combined loss factor of peeling and cooking for sum of both glycoalkaloids in potato tubers was 0.64. These factors were practically used for the probabilistic exposure assessment of the intake of potato glycoalkaloids in the Czech Republic.

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Genetically modified (GM) plants are obtained by adding to them one or more foreign genes that encode new properties, such as tolerance to herbicides, resistance to insects and the ability to produce new substances. The aim of this study was the detection and identification of GM foodstuffs. Six different types of samples (soybeans, soya products, tomatoes, maize flour, rice and papaya) were collected at 12 places in the Czech Republic during the years 2002–2007. It represents a total of 1225 samples of foodstuffs.Samples were investigated for the presence of material derived from the following genetically modified organisms (GMOs) which are approved for food use in the European Union (EU): Roundup Ready soybean (RRS) and maize lines Bt176, Bt11, T25, GA21, MON810, DAS1507 and some non-approved in the EU: maize lines Bt10 and starlink, rice, tomatoes and papaya. Polymerase chain reaction (PCR)-based methods and enzyme-linked immunosorbent assay (ELISA) were used for the detection of GM foods.RRS was detected in 14 (4.9%) samples of soybean out of 288 and in 88 (30.5%) soya products out of 288 samples. The amount of RRS in positive samples was determined by quantitative PCR. The content was in the range of 0.01–75.3% RRS. GM maize was detected in 5 (1.7%) of 288 samples. Maize lines MON810, Bt176 and StarLink were detected in the maize samples. GM rice was detected in 2 (1.9%) samples out of 102. All investigated tomatoes and papaya samples were negative for detection of GM.

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The presence of genetically modified organisms (GMOs) was analysed in food samples from the Czech food markets. Four different types of food samples (soya beans, soya bean products, maize flour, and rice) were collected at twelve places in four terms in the years 2008–2013. It represents a total 1152 food samples. Soya and maize were chosen, because these are the major transgenic crops grown worldwide. Increased cultivation of GM rice in China, India, Indonesia, and the Philippines has been observed. Polymerase chain reaction-based methods were applied to detect GMOs. GMOs were detected in 107 samples (9.3%). The results show that in food from the Czech food market GMOs mainly in maize flour and rice were found. GM maize was detected in 63 (21.9%) maize flour samples. Maize lines MON810, NK603, and Bt176 were detected in 14 (22%), 9 (14%), and 1 (1.6%) maize flour samples, respectively. Unauthorised GM rice was detected in 39 (13.5%) rice samples. Unauthorised rice Bt63 was detected in one sample of rice. Roundup Ready soya was detected in 4 (1.4%) soya bean samples and in 1 (0.35%) soya product sample. These results were compared with results of the world´s studies.

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Authors: J. Varga, Z. Koncz, S. Kocsubé, T. Mátrai, J. Téren, V. Ostry, J. Skarkova, J. Ruprich, A. Kubatova and Z. Kozakiewicz

Ochratoxin A is a mycotoxin produced by Aspergillus and Penicillium species. This mycotoxin is a common contaminant of various foods including cereal products, spices, dried vine fruits, coffee, cocoa, beer and wine. Apart from cereal products, beer and wine contribute significantly to ochratoxin exposure of humans. In the Mediterranean region of Europe, the black Aspergillus species are the sources of ochratoxin contamination of grape products. In this study, we examined the source of ochratoxin contamination of grapes in Hungary and the Czech Republic. The mycobiota of grape berries from 25 Hungarian and Czech vineyards was examined. Potential ochratoxin producing fungi were only identified in grapes from Southern Hungary. Among the 16 black Aspergillus strains isolated, 12 belong to the A. niger species, and 10 produced small amounts (1.5–10 μg kg −1 ) of ochratoxin A in a liquid medium. We could also identify an A. tubingensis isolate which produced 3.5 μg kg −1 ochratoxin A in a liquid medium at pH 6.0. However, the amount of ochratoxin A produced was very low even in a medium which is favourable for mycotoxin production, and ochratoxin A was not detected in any of the grape juice, must and wine samples examined, indicating the absence of health hazard to costumers. Other potentially toxigenic fungi including Aspergillus flavus, Penicillium expansum and Alternaria species were also isolated. Further studies are in progress to evaluate the importance of these fungi in food safety.

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