Air-transport alters the composition of essential oils in aromatic plants

A previous study has shown that aromatic plant material transported on a truck could lose all the essential oil during a half hour drive [1]. In our collaborative work, plant material is often air-freighted between continents, and it is suspected that the quality of the material is altered due to the reduced pressure in the cargo hold of an aircraft.

Aerial parts of the aromatic plants Artemisia afra Jacq. ex Wild., Mentha longifolia (L.) Huds., Ocimum basilicum L. and Salvia africana L. were harvested in South Africa. Essential oils were prepared in South Africa from the fresh plant material and from material dried at 40€C for 2 days. The oils were sealed in ampules and sent by air-freight to Denmark, along with portions of the dried plant material. In Denmark, essential oils were distilled from the air-freighted material and all the oil samples analysed by GC-MS.

The most pronounced changes occurred in S. africana where 60–75% of the monoterpenes were lost from the air-freighted material. In comparison, the sesquiterpene content did not change much for S. africana. Overall, there seemed to be a quantitative loss of 10–25% of the monoterpenes in all the oils. Consequently, it is necessary to be careful about the interpretation of work, both chemical and biological, done on essential oils from aromatic plants that have not been processed locally before shipping.

Reference: 1. Webber, L.N. et al. (2000), S. Afr. J. Plant Soil 17: 10–14.