Background: For majority of Polish people potatoes are indispensable component of daily diet. Boiled or steamed potatoes are considered as food meeting the requirements of right nourishment. They are a source of nutrient components, however, potatoes may contain undesirable compounds.
Objective: The aim of this work was evaluation of dry matter and some nutritients (starch, vitamin C) and potentially toxic (nitrates (V), reducing sugars) constituents in edible potatoes purchased in a retail network in Szczecin in spring and autumn seasons.
Material and methods: The estimation included 25 samples of different potatoes cultivars. Studies were conducted in autumn (October 2008 and 2009) and in spring (March 2009 and 2010). In the samples the content of the following constituents was determined: dry matter (by drying to constant matter), starch (Evers's method), vitamin C (Tillmans's method), reducing sugars (Luff-Schoorl's method) and nitrates (V) (by method with the use of phenol-disulphanic acid).
Results: It was stated that there were significant differences between the samples regarding the content of the tested constituents. Concentration of dry matter and starch ranged 14.50-21.23% and 9.25-15.05%, respectively. In potato tubers, which were under the researches in autumn and spring, mean contents of these constituents were nearly the same. Mean concentrations of vitamin C were almost two times lower in potatoes bought in spring (8.47 and 7.77 mg x 100 g(-1)) than in autumn (15.61 and 14.80 mg x 100 g(-1)). The content of reducing sugars exceeded the recommended highest level (0.5%) in the majority of the tested samples. Accumulation of these constituents occurred especially in potatoes available in markets in spring (mean 1.69 and 1.25%). Only in a few samples the content of nitrates (V) was higher than 200 mg NO3-/kg f. m.
Conclusions: The majority of potatoes samples was characterized by a low content of dry matter (< 20%), very low (< 13%) or low (13.0-14.4%) content of starch and low concentration of nitrates (V). Potatoes available in markets in spring contained little vitamin C but a lot of reducing sugars. Due to the possibility of toxic acrylamide formation they should be fried occasionally.