Enzymatic modification of yeast protein isolates

Abstract

Yeast protein isolate with 85% of pure protein and 1.2% of nucleic acids in dry matter was isolated from Sacchuromyces cereuisiue by a procedure of two pre-treatment steps, acidic extraction and isoelectric precipitation. The application of this yeast protein isolate was limited by its functionality resulting from the partially extreme isolating conditions. An enzymatic partial hydrolysis with Thermitase to a degree of hydrolysis of 5% not only improved the solubility and foaming properties, but also the water binding capacity and the emulsifying properties. The hydrolysate was free of bitter taste and could be applied either in two fractions of different solubility after centrifugation or as a whole product in food systems to improve the physiological and functional quality. The yeast protein hydrolysate had the same or even better properties than conventional protein products.