Recent research finding
No.17 Improvement of Stability of Tea Tree Oil Components by Using Cyclodextrins

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Introduction

Tea tree oil(TTO)is an essential oil obtained by steam distillation of the leaves of Melaleuca alternifolia, a plant native to Australia, and is reported to have antibacterial, antifungal, antiviral, anti-inflammatory and analgesic properties. Therefore, currently TTO is widely used as an ingredient in cosmetics and healthcare products. The main compounds of TTO are monoterpenes, terpene alcohols and sesquiterpenes, and the contents of some key ingredients like α-terpinene, p-Cymene, Terpinen-4-ol are defined by international standard ISO 4730 and the identical Australian standard AS 2782-1997 for guarantee of the quality.

However, some tea tree oil components are not stable enough against oxygen, heat or daylight. Here we report oxidation stability of α-Terpinene and Terpinen-4-ol, are typical components of TTO, included in α-, β- or γ-cyclodextrin(CD)by heat treatment at 100℃.

Experimental Methods

Flavor Component and Specification of Tea Tree Oil

Component Flavor content
in OILTEA-185* [%]
Specification [%]
(ISO/FDIS-4730 : 2004)
a-Pinene 2.4 1 - 6
Sabinene 0.2 Trace - 3.5
a-Terpinene 9.3 5 - 13
Limonene 1.1 0.5 - 1.5
p-Cymene 3.0 0.5 - 8
1, 8-Cineol 3.7 Trace - 15
g-Terpinene 20.8 10 - 28
Terpinolene 3.4 1.5 - 5
Terpinene-4-ol 42.1 30 - 48
a-Terpineol 2.8 1.5 - 8
Aromadendrene 1.1 Trace - 3
d-Cadinene 0.7 Trace - 3
Globulol 0.1 Trace - 1
Viridiflorol 0.2 Trace - 1
Ledene 0.6 Trace - 3

* The analytical values were determined by Bronson & Jacobs.

Heat Stability of Tea Tree oil at 50 and 100℃

Initial Flavor Content in Tea Tree Oil Complex Powder

Effect of Heat Treatment at 50℃ on Flavor Content in Tea Tree Oil complex powder

Effect of Heat Treatment at 100℃ on Flavor Content in Tea Tree Oil complex powder

Initial Flavor Content in α-Terpinene Complex Powder

Effect of Heat Treatment at 50℃ on Flavor Content in α-Terpinene Complex Powder

Effect of Heat Treatment at 100℃ on Flavor Content in α-Terpinene Complex Powder

Formation of inclusion complex of α-Terpinene in CD for α-Terpinene / p-Cymene binary system

Conclusion

CDs markedly increased the stability of α-terpinene for oxidation, and decreased the production of p-cymen in order of α-CD > β-CD > γ-CD.

It is suggested that TTO / α-CD complex could use as a stable and safe ingredient of cosmetics or healthcare products