Thermal behavior and hydration properties of yeast proteins from Saccharomyces cerevisiae and Kluyveromyces fragilis

High pressure homogenization of yeast cells followed by incubation at 50 de grees C for the dissociation of ribonucleic acid-protein complexes resulted in a high denaturation degree of isolated proteins. Proteins in intact cel ls exhibited an ample endothermic peak with peak temperatures (T-P) at 66.6 6 and 63.67 degrees C for S. cevevisiae and K. fragilis, respectively. No d ifferences were found with respect to the associated enthalpy changes for b oth studied species. The isolation of proteins from its biomass shifts T-P to values around 50 degrees C. Impurities such as nucleic acid, polysacchar ides and other intracellular components seem to play a protective role upon denaturation. Isolated proteins showed solubilities lower than 40% but exh ibited water retention properties and wettability from 3.5 to 7.0 mi of wat er/g of protein. (C) 2000 Elsevier Science Ltd. All rights reserved.