Is candelilla wax a poly-functional material? Its use in the development of structured W/O emulsions

Abstract: Candelilla wax (CW) is an efficient gelator of vegetable oils with n-alkanes (≈67%) and terpenoid alcohols (≈23%) as major components. We investigated the development of water-in-oil emulsions (W/O) at different water to safflower oil (W:O) ratios (40:60, 50:50, 60:40), using CW (0.75%, 1.5%, 2.25%, 3%) as the only functional agent. After full solubilization of the CW in the oil (90°C for 30 min), the solution was cooled and after achieving 25°C the corresponding water amount was added while stirring for 60 s with an ultra-turrax type homogenizer. The W/O emulsions were evaluated during 20 days of storage at 25°C for water droplet size distribution (WDSD), microstructure, emulsion stability through DSC freeze/thaw cycles, and rheological measurements. The microscopic and X-ray analysis showed that, at all CW concentrations and W:O ratios used, the terpenoid alcohols stabilized the water-oil interface while n-alkanes formed an oleogel in the oil phase developing a structured W/O emulsion (Fig. 1). All the structured W/O emulsions showed frequency independent rheological behavior and were stable during the 20 days of storage (25°C). Independent of the W:O ratio, as the CW concentration increased the WDSD decreased and the emulsion elasticity (G’) increased. However, the emulsions developed at 2.25% and 3% CW showed lower % recovery after applying a strain, particularly at the 50:50 and 60:40 W:O ratios. In contrast, the W/O emulsions developed with 1.5% CW using 40:60 and 50:50 W:O ratios showed similar rheological behavior that commercial mayonnaise, showing excellent % recovery ( > 80%) (Fig. 2), and were stable to freeze-thaw-cycles even after 20 days of storage (25°C). These results showed that CW is a poly-functional material able to develop structured W/O emulsions, useful for the formulation of trans-free, low-fat stable edible spreads.