Protein recoveries from potato juice by ultrafiltration, polyelectrolyte-coagulation and cryoconcentration were compared. The best yield was obtained by ultrafiltration. Depending on the method of potato juice concentration, differences were observed in: foaming and emulsifying properties, wettability, swelling, and buffer capacity of preparations. The dried preparations contained a high level of proteolytic enzymes inhibitors and glucoalkaloids. Thermal inactivation of preparations before drying led to 43-48% destruction of protease inhibitors and 8 l-&9% glycoalkaloids. At the same time it was observed that thermal treatment led to distinct changes in the amino acid composition of the proteins and had an adverse effect on the properties of the dried preparations.