A method of egg yolk fractionation. Characterization of fractions

A simple method of egg yolk fractionation was carried out and three fractions (granules, lipidic paste and watery fraction) were obtained. The chemical and physical properties of each fraction were assessed in order to evaluate its potential new applications. Additionally, lyophilization was evaluated as a possible technique to increase product shelf life. From a structural point of view, granules stress resistance is higher than in the case of the lipidic paste. Cure test and differential scanning calorimetry analyses showed that granules proteins are more resistant to heat denaturation than lipidic paste proteins. However, heat denaturation resistance of granules proteins is affected by freeze-drying process. Granules colour is not affected by lyophilization, while lipidic paste colour suffers a slight modification. Granules and lipidic paste, both fresh and lyophilized, have high emulsifying properties at all pH studied. Particle size measurements and scanning electron microscopy showed an increase in particle size of lyophilized fractions. According to their composition, granules, lipidic paste and watery fraction seem to be suitable to be employed as potential ingredients in food, cosmetic and biotechnological uses, respectively.