Development of Preparation Method for Microencapsulating Uycalyptus Oil Containing Fine Aqueous Droplets by Use of Interfacial Condensation Reaction between Hydroxy Propyl Methyl Cellulose and Tannic Acid

Abstract

It was tried to develop the preparation method for microencapsulating the uycalyptus oil containing fine aqueous droplets by using the interfacial condensation reaction between hydroxyl propyl methyl cellulose and tannic acid. Uycalyptus oil containing fine aqueous droplets was dispersed in the continuous water phase to form the (W/O)/W emulsion. Tannic acid and hydroxyl propyl methyl cellulose were dissolved in the inner aqueous droplets and in the outer continuous water phase, respectively. Tannic acid transferred through the oil phase from the inner water droplets to the interface between the oil phase and the continuous water phase and then, reacted with hydroxyl propyl methyl cellulose. In the experiment, the concentrations of hydroxyl propyl methyl cellulose and tannic acid were mainly changed stepwise. The uycalyptus oil containing the fine water droplets could be microencapsulated satisfactorily. It was found that the microcapsules were composed of the gelated hydroxyl propyl methyl cellulose film as the shell, the fine aqueous droplets as the first core and the oil droplet as the second core.

Preparation of Microcapsules Containing Triple Core Materials with Interfacial Condensation Reaction

“…In order to confirm whether the microcapsules could be prepared or not according to the microencapsulation mechanism presented in the previous study [7], first, the stability of (W/O)/W emulsion before and after the microencapsulation process without addition of calcium chloride powder was investigated by visual confirmation. Figure 2 shows the photographs of the (W/O)/W emulsion without and with the microencapsulation process.…”

“…The microcapsules were prepared by modification of the reported methods [7]. Figure 1 shows the flow sheet for preparing the microcapsules containing the triple core materials together with the schematic diagrams of mi- croencapsulation process.…”

“…From Figure 2 and Figure 3, it was found that tannic acid (TA) transferred from the inner water droplets to the interface through α-tocopherol (α-oil) and reacted with hydroxyl propyl methyl cellulose (HPMC) and the inner aqueous droplets could be microencapsulated well as well as the eucalyptus oil [7]. Figure 4 shows the dependences of mechanical strength (S t ) and mean diameters (d p ) of microcapsules on the HPMC concentration (C HPMC ).…”

“…Authors have developed the preparation method for microencapsulating the eucalyptus oil with the interfacial condensation reaction between hydroxyl propyl methyl cellulose and tannic acid and established the optimum preparation conditions [7]. In the microencapsulation mechanism, authors describe the importance of tannic acid to transfer from the inner water droplets to the interface through the eucalyptus oil phase and subsequent reaction with hydroxyl propyl methyl cellulose.…”