Encapsulation of tea tree oil by amorphous beta-cyclodextrin powder

An innovative method to encapsulate tea tree oil (TTO) by direct complexation with solid amorphous beta-cyclodextrin (beta-CD) was investigated. A beta-CD to TTO ratio of 90.5:9.5 (104.9 mg TTO/g beta-CD) was used in all complexation methods. The encapsulation was performed by direct mixing, and direct mixing was followed by the addition of water (13-17% moisture content, MC) or absolute ethanol (1:1, 1:2, 1:3 and 1:4 TTO:ethanol). The direct mixing method complexed the lowest amount of TTO (60.77 mg TTO/g beta-CD). Powder recrystallized using 17% MC included 99.63 mg of TTO/g beta-CD. The addition of ethanol at 1:2 and 1:3 TTO:ethanol ratios resulted in the inclusion of 94.3 and 98.45 mg of TTO/g beta-CD respectively, which was similar to that of TTO encapsulated in the conventional paste method (95.56 mg TTO/g beta-CD), suggesting an effective solid encapsulation method. The XRD and DSC results indicated that the amorphous TTO-beta-CD complex was crystallized by the addition of water and ethanol. (C) 2016 Elsevier Ltd. All rights reserved.