POTATO PROTEIN CONCENTRATES: THE INFLUENCE OF VARIOUS METHODS OF RECOVERY UPON YIELD, COMPOSITIONAL AND FUNCTIONAL CHARACTERISTICS

Abstract

Potato processing effluents represent a potential source of valuable protein as well as a major waste disposal problem. Potato protein is commonly recovered by heat (in excess of 90°C) with pH adjustment between 3.5 and 5.5. The present study compared yield, and some compositional, and functional characteristics of potato protein concentrate (PPC) recovered with either HCl or FeCl₃ (pH 3.0, 20–22°C), or HCl/heat (pH 4.8, 98–99°C). Under pilot plant conditions, recoveries of 22.7, 36.7, and 37.5% of the crude protein (N × 6.25) were obtained with HCl, FeCl₃, and HCl/heat, respectively. Crude protein content of the PPC precipitated by HCl, FeCl₃, and HCl/heat were 65.6, 57.5, and 78.2% respectively. Ash and vitamin C values were higher in those PPC recovered at room temperature, with Fe content being highest in the PPC recovered with FeCl₃. The nitrogen solubility of the FeCl₃ precipitate, at pH 7.0, was 1.5 and more than 7 times that of the HCl, and HCl/heat precipitates, respectively. Whipping capacity of PPC was not influenced by precipitation method. The most favorable fat absorption and water absorption capacities were exhibited by the HCl and HCl/heat precipitates, respectively.