Development of Candelilla Wax Oleogels as a Medium of Controlled Release of Phosphorus in an In Vitro Model

Candelilla wax (CW) oleogels were developed as an alternative bolus material for delivering phosphorus into the rumen of goats. The systems were studied at three CW concentrations (10%, 15% and 20%) in vegetable oil. Each oleogel was added with a specific amount of calcium orthophosphate as a phosphorus source. The thermomechanical properties of the oleogels were characterized by DSC and rheology, and the viability of phosphorus delivery was evaluated using a laboratory model in two mediums (one aqueous and another with ruminal fluid). The results showed that the oleogels had a higher melting point (~52.8 °C) than the temperature of the ruminal environment and greater G′ values (1.6 × 106 Pa in 20% CW oleogel with phosphorus). Such characteristics guaranteed the integrity of the materials during the process in the model systems studied. It was demonstrated that when using the 20% CW oleogel, the phosphorus was slowly released for 84 h, completing a maximum of 83.3–98% of the total amount of phosphorus added to the bolus (in the aqueous and ruminal fluid models, respectively). These results enable us to propose this material as a delivery system for phosphorus supplementation in goats. Its effectivity in goats will be evaluated in future in vivo investigations.