The effect of industrial potato processing on the concentrations of glycoalkaloids and nitrates in potato granules

The aim of this study was to determine the effects of the different stages of industrial processing of potatoes, on the content of glycoalkaloids (chaconine and solanine) and nitrates in the raw material, intermediates, finished granules and waste products.The material used for the study included samples of raw tubers, semi-finished products and finished products taken directly from 8 points in the technological line for the production of potato granules, and 3 points from the waste product line. The samples were collected three times within two years of research (in 2009 and 2010) from the following places: 1/unpeeled potato, 2/potato after peeling, 3/potato after blanching, 4/potato after cooling, 5/steamed potato, 6/pneumatically dried potato, 7/product after fluidization drying, 8/granulated product, and waste products: 9/peels, 10/waste after air drying and 11/after fluidization drying.In the raw material, intermediates, finished granules and waste products, the concentrations of glycoalkaloids (α-chaconine and α-solanine) were determined using an HPLC method, and nitrates were determined colorimetrically using an RQflex analyser.It was found that the industrial processes of potato granules significantly decreased the concentration of glycoalkaloids (chaconine and solanine) and nitrates in intermediates and finished products when compared to raw material. The highest decrease in glycoalkaloids was caused by peeling (50%) and blanching (63%). The concentration of nitrates decreased the most after thermal processes - after blanching a decrease of 20% and after air drying - by 50%. The dehydrated potato granules contained on average 14% of the initial quantity of glycoalkaloids and 48% of nitrates. High content of toxic compounds was found in potato peels but dry wastes after pneumatic drying or after fluidization contained proportionally low contents of those compounds.

► The industrial processes potato granules decreased the content of TGA and nitrates. ► The highest decrease in glycoalkaloids was stated after peeling and blanching. ► The highest decrease in nitrates was stated after blanching and air drying. ► The potato granules contained 14% of the initial quantity of glycoalkaloids. ► The finish products contained 48% of the initial quantity of nitrates.