Preparation and Evaluation of Edible Microcapsules for Thermal Energy Storage

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 μ m 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.