GLYCOALKALOIDS IN POTATO TUBERS: THE EFFECT OF PEELING AND COOKING IN SALTED WATER

The important glycoalkaloids in potatoes are alpha-solanine and alpha-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. alpha-Solanine and alpha-chaconine appear to have two main toxic actions, one on cell membranes and another one on acetylcholinesterase. Symptoms of alpha-solanine/alpha-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 alpha-solanine and alpha-chaconine in peeled potato skin, raw potato pulp and cooked peeled potato tubers. The limit of quantification (LOQ) for alpha-solanine and alpha-chaconine was found to be 5.0 mg kg(-1) for each glycoalkaloid. In this study the factors of potential loss of alpha-solanine and alpha-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.