Cocoa butter was fractionated in temperature gradient from acetonic 15.20 and 25 % (w/v) solutions. The fractions of sn-l-palmito-2-oleo-3-stearine (palmitooleostearine, POS), which predominate in this fat (34 - 36 %) were separated between 0 and 25°C and were purified through repeated refractionation when there were obtained the a, ß and ß’ polymorphic forms. By emulsification in model water systems with emulsifying agent and colloid of protection for voiumic fractions between 0.05 and 0.4 there was established that the interfacial surface (IS) determined by turbidimetry decrease from ß through ß’ to a in all cases. Because IS is correlated with the emulsifying activity index (EAI) there was admitted that the microcrystalline structure of each polymorphic form can be found in the interfacial orientation degree of the triacylglycerides (TAG). The significative growth of EAI from a to ß coincides with the growth of the thermodynamic stability of those polymorphic forms.
