Phase Behavior and Structure of Systems Based on Mixtures of n-Hentriacontane and Melissic Acid

Candelilla wax (CW) organogelation is a promising method for providing structure to solid-like fat-based foods, cosmetics, and drug delivery systems. The main component, n-hentriacontane (C31), defines, to a large extent, the thermal properties of CW. CW is a complex mixture of n-alkanes, fatty acids, triterpenic alcohols, and fatty alcohols. In this initial examination of the role of CW components on the phase behavior and structure, CW and binary mixtures of C31 and melissic acid (C30) were studied in bulk and in solutions of vegetable oil. Binary mixtures of C31 and C30 presented a predominantly monotectic phase behavior in which the melting temperature of C31 remained constant independently of the mixture composition. Crystal packing of the pure components and mixtures had an orthorhombic subcell, and the microstructures of the mixtures were extremely different from that of the pure components. In solutions with less than 50 % C31, the order-disorder transition observed in bulk C31 was absent. Organogels of C31, C30, or the mixture were softer than those of CW. The increased strength of CW organogels is associated with the relatively small crystal size of this system.