Effect of Low-molecular Additives on Precipitation of Potato Fruit Juice Proteins under Different Temperature Regimes

The effects of two mineral and two organic acids, four organic solvents (methanol, ethanol, 2-propano and acetone) and three inorganic metal salts in combination with temperature regimes 0 and 22C on the yield and resolubility of potato tuber proteins were studied. Using acids, the yield of precipitated protein ranged from 22.3% (citric acid, 0C) to 54.5% (acetic acid, 22C) of total protein; however, the resolubility was generally very low. The precipitation with organic solvents resulted in significantly higher yield as well as resolubility (P < 0.05) when precipitated at low temperatures. The yield ranged from 23.4% (ethanol, 22C) to 64.5% (2-propanol, 0C) of total protein. The use of the salts resulted in precipitates with high resolubility regardless of the temperature regimes. The yield of precipitated protein ranged from 25.8% (ZnCl2, 0C) to 86.4% (FeCl3, 0C) of total protein. PRACTICAL APPLICATIONS The work studied the possibility of isolation of native potato proteins from potato fruit juice (PFJ) resulting from starch manufacturing process. Ethanol and FeCl3 were evaluated as the most promising precipitators for the recovery of potato tuber proteins from PFJ. However, ethanol usage for industrial isolation of potato proteins is strongly limited by the temperature regime in contrast to FeCl3, which could be used in a much wider range of temperature regimes without significant difference in protein yield and resolubility. 1 Corresponding author. TEL: +420387772441; FAX: +420387772431; EMAIL: vhermanova@