Preparation and Evaluation of Edible Microcapsules for Thermal Energy Storage

Abstract

Edible thermal-energy-storage (TES) microcapsule was prepared through the formation of complex coacervate. Coconut oil was selected for the core material with its freezing point of ca. 3.3℃ based on the differential scanning calorimetry analysis. The microcapsule containing coconut oil was prepared using a rotor-stator homogenizer through complex coacervation by mixing the oil with gelatin and gum arabic at various oil contents. The microcapsule showed the maximum diameter of 20 μm and higher freezing point (ca. 11℃) than the pure oil. It would be due to the effect of wall material. Because the sticky property of the microcapsule with higher oil contents hindered well-handling, the highest oil content in the microcapsule was practically 67%. The TES capacity of the microcapsule was evaluated using a pseudo food model. The capacity was much higher when the oil content was higher. In addition, microcapsule itself also played a role as a thermal insulator due to the low heat conductivity. When the ambient air temperature changed between -7.2 to 39℃, the microcapsule containing 67% oil exhibited its TES capacity, and the temperature of the pseudo food ranged between 3.6 to 29℃. Although the temperature range was relatively wider, this result indicates the development of the edible TES microcapsule.