Geraniol-rich essential oil from Monarda Fistulosa L.

The genus Monarda, named after a Spanish physician, Nicholas de Monardes, is widely distributed throughout North America, most of which is Monarda fistulosa L. var. menthifolia (Graham) Fern (Scora 1967). Marshall and Scora (1972) reported on new hybrids of Monarda fistulosa developed hy Marshall, which yielded up to 1.0% oil on a fresh weight basis, and contained up to 90% geraniol, previously unreported in Monarda.

Monarda hybrids from MarshaIl’s breeding program come in a wide range of colours, including white, pink, scarlet, and purple. His first interest in the Monarda group was as a perennial flower. However, several triploid hybrids from Marshall’s crosses produce high amounts of geraniol. One such hybrid, Morden No. 3, has particularly high levels of geraniol, somewhat in excess of 90%. This hybrid is a perennial, somewhat drought tolerant and winter hardy under the severe winter conditions in Manitoba. The plants grow 60 to 80 cm in height, depending on the soil moisture availability.

Quality Parameters

Oil samples were obtained by steam distillation of either the whole plant or individual plant parts. In 1975 and 1976, steam distillation was carried out in a 25-liter stainless steel still, using a boiler operating pressure of 5.6 kg/cm2. Distillation was carried out for approximately 2.5 hrs, after which time only negligible amounts of oil were left in the plant tissue. Since 1977 all steam distillation has been carried out using pilot scale equipment, approximately 0.1 of commercial size, with a capacity of 385 kg fresh weight of mechanically chopped plant material.

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