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°C for the dissociation of ribonucleic acid-protein complexes resulted in a high denaturation degree of isolated proteins. Proteins in intact cells exhibited an ample endothermic peak with peak temperatures (TP) at 66.66 and 63.67°C for S. cerevisiae and K. fragilis, respectively. No differences were found with respect to the associated enthalpy changes for both studied species. The isolation of proteins from its biomass shifts TP to values around 50°C. Impurities such as nucleic acid, polysaccharides and other intracellular components seem to play a protective role upon denaturation. Isolated proteins showed solubilities lower than 40% but exhibited water retention properties and wettability from 3.5 to 7.0 ml of water/g of protein.