Changes in glycoalkaloid and nitrate content in potatoes during dehydrated dice processing.

摘要

The aim of this experiment was the determination of glycoalkaloid and nitrate content in potatoes during stages of processing into dry potato dice. Samples obtained from the tubers of three potato varieties were used: a very early Denar variety of Polish origin; Innovator, an early Dutch variety; and a Polish medium early Pasat variety. There were sampled three times from the factory store in 2009 and 2010. The potatoes were diced in laboratory conditions, by first peeling with a carborundum peeler, dicing into 10x10x10 mm pieces and rinsing with water at a temperature of 20 degrees C. In the next stages, the diced potatoes were blanched in water at a temperature of 75 degrees C for 5 min then dried in a laboratory drier for 1 h at 120 degrees C. After 1 h of drying, the temperature was lowered to 55-60 degrees C in order to obtain a defined final moisture content of 8-11%. In the raw material, intermediates and finished products, the concentrations of glycoalkaloids ( alpha -chaconine and alpha -solanine) were determined using an HPLC method, and nitrates were determined colorimetrically using an RQflex analyser. It was found that the processes used in dried potato dice production significantly decreased concentrations of glycoalkaloids ( alpha -chaconine and alpha -solanine) in intermediate and finished products when compared to raw material. The highest decrease in the quantity of glycoalkaloids occurred during peeling (33%) and after blanching (17%) of peeled potato. Nitrate content fell the most after cutting and rinsing with water (13%), and after blanching (23%). On average, dry potato dice contained 44% of the initial quantity of glycoalkaloids and 40% nitrate content in the final dried product.