New Crops News, Spring 1991, Vol. 1 No. 1
A pilot-scale transportable steam distillation unit was designed and constructed in 1990 for the extraction of essential oils. This new extractor consists of a 300 liter still plus a steam generator, cold-water condensors and oil seperatory flasks mounted on a trailor. The unit can be operated by a single individual and yield more than 100ml of peppermint and spearmint oil per distillation. The extracted oil matches that which is produced commercially. The availability of this unit now permits the procurement of oil samples for industrial evaluation from small experimental field plots. Prior to this only very large commercial units or our very small laboratory extractors were available, neither compatible with obtaining the necessary amount of essential oil for industrial screening of oil samples. Such an extractor is critical in the screening and evaluation of new essential oil plants.
Much research effort has been carried out to develop new chemotypes of basil for oil extraction. High oil yielding lines are available with high concentrations of methyl cinnamate, methyl chavicol, geraniol, and linalool and methyl chavicol. While greater work is needed in stand establishment and weed control, the procurement of larger quantities of oil from these chemotypes is needed by the industrial end users. The crop can be grown, harvested and processed by commercial mint farmers in the same manner that peppermint and spearmint is already produced. By using the same equipment and steam distillation units, farmers could soon grow additional essential oil crops which are harvested at before or after their mint crops, thus utilizing their expertise in oil crops and their processing equipment more fully. Results of this work has already attracted an oil marketing company to co-support future developmental work on some types of basil oil.
Efforts have focused in the develpment of Artemisia annua, also known as sweet annie. This plant, grown in Indiana in a very limited acreage as a dried aromatic plant, may become a very important medicinal plant as it contains a compound which has been shown to be very effective in combatting malaria. The very low yields of artemisinin is one of the major factors limiting commercial production and processing in this country. Several individual plants have been identified with significantly higher concentrations of this compound (>0.50% g/dry weight) compared to the reported concentrations of 0.01-0.30 %g/dry weight). No commercial varieties of this new crop now exist.
A germplasm collection was screened in 1989 to identify plants with the highest artemisinin content. Seeds from the highest yielding plants were sown in the greenhouse and transplanted into the field in 1990. Individual plants were sampled for artemisinin content, selfed and seed collected. Analysis is still in progress but five individual plants with artemisinin contents of >0.50%g/dry weight have been identified. Selfed seed was collected for further selection and breeding in 1991. A single high artemisinin yielding plant was placed in tissue culture for clonal propagation and field evaluation in 1991. Concurrent studies are in progress to determine the seasonal variation in artemisinin content which would identify the optimum time to harvest plants.
James E. Simon
Department of Horticulture