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

Abstract

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.

Physical Properties of Beeswax, Sunflower Wax, and Candelilla Wax Mixtures and Oleogels

“…BW and CLW crystallization and melting profiles (Fig. A and S1A) were similar to previous reports (Blake et al, ; Doan et al, , ; Jana and Martini, ; Serrato‐Palacios et al, ; Toro‐Vazquez et al, ). The exothermic and endothermic peaks of the two waxes overlapped significantly.…”

“…The high melting waxes formed monotectic systems with BEW, but interestingly there was a synergistic interaction at various ratios of the wax mixtures that resulted in stronger solid properties and firmness compared to oleogels made from either wax alone. Similar studies with mixtures of pure wax components such as HC with FFA (Serrato‐Palacios et al, ) or stearic acid with stearyl alcohol (Gandolfo et al, ; Schaink et al, ) also indicate that mixing often results in changes in crystal size and microstructure, which in turn affects the rheological and melting properties. Thus, further characterization of mixed wax systems is necessary to understand how the oleogel properties can be tailored.…”

“…CLW melting T on was 54.4 °C, and it had two overlapping endotherms as well as a shoulder peak. According to Serrato‐Palacios et al, , who conducted a detailed analysis of the phase behavior of two major components of CLW, hentriacontane (C31 HC), and mellissic acid (C30), the DSC melting and crystallization profile of CLW is governed by the alkanes, mainly hentriacontane (C31). The low‐temperature endotherm peak (marked with an arrow at 59.8 °C in Fig.…”

“…Pseudophase diagrams (Craven and Lencki, ; Jana and Martini, ; Serrato‐Palacios et al, ; Tavernier et al, ) were drawn for the DSC endotherms by plotting a line through the lowest endothermic peak T on to represent the solidus line, below which everything is solid, and through the T p of the highest melting peak to represent the liquidus line, above which everything is liquid. These diagrams are considered pseudophase diagrams because the two waxes are not made up of pure components but are rather mixtures of wax components.…”

Stearic Acid Modified Stearyl Alcohol Oleogel: Analysis of the Thermal, Mechanical and Drug Release Properties

“…The dispersed phase, which is usually a solid component, forms an interconnected network structure. The liquid phase is immobilized within the network formed by the dispersed phase [3]. The process of immobilization of the liquid phase is also regarded as structuring of the liquid [4].…”