J Am Oil Chem Soc (2015) 92:533–540 DOI 10.1007/s11746-015-2623-6 1 3 ORIGINAL PAPER Phase Behavior and Structure of Systems Based on Mixtures of n‑Hentriacontane and Melissic Acid Lourdes Liliana Serrato‑Palacios 1 · Jorge F. Toro‑Vazquez 1 · Elena Dibildox‑Alvarado 1 · Antonio Aragón‑Piña 2 · Maria del Rosario Morales‑Armenta 1 · Vrani Ibarra‑Junquera 3 · Jaime David Pérez‑Martínez 1 Received: 14 October 2014 / Revised: 13 January 2015 / Accepted: 21 February 2015 / Published online: 13 March 2015 © AOCS 2015 Introduction Application of vegetable waxes to gel vegetable oil is currently being explored to reduce the intake of fats rich in saturated and trans fatty acids [1]. Among the studied waxes, candelilla wax (CW) at concentrations higher than 1 % (w/w) develops vegetable oil organogels with recog- nized oil retention and textural properties that can produce solid-like water in oil emulsions [2, 3]. Some functional properties can be modulated by the addition of saturated TAGs (i.e., tripalmitin), as well as the application of shear- ing during the gelation process [4]. According to previous reports, the main components of CW are n-alkanes, with n-hentriacontane (C31; 35.5 %) as the major constituent, triterpenic alcohols (24.8 %), fatty acids with an even num- ber of carbons (16.6 %, of which 7.8 % is melissic acid), fatty alcohols (3.61 %), and C39 to C64 esters (5.83 %) [3]. Despite the large number of components, CW phase behavior is attributed almost exclusively to the C31 phase transitions because both CW and C31 have an orthorhom- bic subcell packing at room temperature [4, 5]. Within this context, it has been hypothesized that some CW compo- nents are incorporated into the C31 crystal lattice and that others melt at temperatures close to the C31 melting point [3, 4]. Nonetheless, the type of solid phase structure (i.e., solid solution, compound, solid dispersion) of CW remains unknown. This information is fundamental to understand and tailor the functionality (e.g., melting profile, organo- gelling capacity, and rheological properties) of this natural wax. The phase behavior of long-chain n-alkanes and fatty acids has been extensively studied, but mixtures of these compounds are largely unexplored. To the best of our knowledge only Benziane et al. [6] have studied this type of mixture and observed a eutectic behavior of Abstract Candelilla wax (CW) organogelation is a prom- ising method for providing structure to solid-like fat-based foods, cosmetics, and drug delivery systems. The main com- ponent, 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 alco- hols. In this initial examination of the role of CW compo- nents 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. Crys- tal packing of the pure components and mixtures had an orthorhombic subcell, and the microstructures of the mix- tures were extremely different from that of the pure compo- nents. In solutions with less than 50 % C31, the order–disor- der 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. Keywords n-Hentriacontane · Melissic acid · Candelilla wax · Organogel * Jaime David Pérez-Martínez jdavidperez@uaslp.mx 1 Facultad de Ciencias Químicas, Centro de Investigación y Estudios de Posgrado, Universidad Autónoma de San Luis Potosí, Av. Dr. Manuel Nava 6, Zona Universitaria, 78210 San Luis Potosí, SLP, Mexico 2 Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí, 78210 San Luis Potosí, Mexico 3 Bioengineering Laboratory, Universidad de Colima, 28400 Coquimatlán, Colima, Mexico