INFLUENCE OF CULINARY PROCESING ON THE NITRATE LEVELS IN POTATOES

Cilj naše raziskave je bil statistično ovrednotiti učinke kuhinjskih procesnih tehnik na vsebnost nitratov v gomoljih krompirja (Solanum tuberosum L.) različnih sort, načinov pridelave in porekla. Praktični del raziskave se je izvajal v letih 2012–2013 na Univerzi v Mariboru, kjer so bili nitrati analizirani s HPLC-metodo, v magistrskem delu pa smo dobljene rezultate še statistično ovrednotili. Procesne tehnike, ki vključujejo kuhanje, so pokazale statistično pomembno zmanjšanje vsebnosti nitratov v krompirju kot tudi v kombinaciji z lupljenjem, medtem ko so procesne tehnike, ki vključujejo cvrenje, povzročile znatno povečanje vsebnosti nitratov v vseh vzorcih krompirja. Druge procesne tehnike, ki vključujejo obdelavo v mikrovalovni pečici, parjenje, blanširanje in pripravo pireja, niso povzročile statistično pomembnih razlik v vsebnosti nitratov. Sorte krompirja so se med seboj razlikovale že po začetni koncentraciji nitratov in tudi bistveno vplivale na končni izid glede vsebnosti nitratov po kulinarični obdelavi. Glede na način pridelave (konvencionalna, integrirana, ekološka) ni bilo opaziti statistično pomembnih vplivov na spremembe vsebnosti nitratov po obdelavi. Rezultati študije lahko pomagajo zakonodajalcem pri oceni tveganja glede vsebnosti nitratov, potrošnikom pa pri izbiri kulinarične obdelave, ki najbolj zniža vsebnost nitratov v hrani.The purpose of our research was to statistically evaluate the effects of culinary processing techniques on the nitrate levels in potatoes tubers (Solanum tuberosum L.) different varieties, production methods and origin. The practical part of the research was conducted in the years 2012–2013 at the University of Maribor, where nitrate concentrations were analyzed by HPLC. These results were statistically evaluated in the present MSc thesis. Culinary processing techniques, which include cooking, have resulted in a statistically significant decrease in potatoe nitrate content, the same was observed in combination with peeling. On the other hand, processing techniques that include frying have resulted in a significant increase in the nitrate content in all of the analyzed potatoe samples. Other processing techniques, which include microwave, blanching and puree have not shown a statistically significant difference relative to the raw sample levels. Potato variety had a significant effect on raw sample nitrate levels as well as changes upon processing. In contrast, agricultural production method (conventional, integrated, ecological) did not. To conclude, the results of our research may aid legislators in assessing the risk of nitrate in vegetables and moreover, they can be of help to consumers when deciding which cooking technique to choose in order to minimize nitrate intake by vegetables