Glycoalkaloids in potato tubers: The effect of peeling and cooking in salted water

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

Mycobiota of grapes collected in Hungarian and Czech vineyards in 2004

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