Chemical Profile and Bioactivity of Essential Oil Fractions as a Function of Distillation Time

A number of medicinal and aromatic plants contain essential oils; some are grown on large areas as high-value crops for commercial production of essential oils. Plant-derived essential oils are natural products with diverse applications in various industries such as in food and bevernes, perfumery and cosmetics, in pharmaceutical products, in aromatherapy, and also as eco-friendly pesticides. The aroma, composition, and the bioactivity of the essential oils within single plant species may vary significantly, due to genetic and environmental factors, but may also depends on postharvest management and extraction procedure. The end users demand consistency in supply and quality. The specific chemical profile and aroma of the essential oil forms the basis for its utilization and price on the international markets. For most of the commercially grown essential oil crops, the conditions for essential oil extractions that would guarantee consistency of quality but also economics have been researched and identified. Steam and hydrodistillation have been traditionally used as economical and simple methods for extraction of the essential oil from a number of aromatic plants. Still there is no agreement in the literature regarding the optimal distillation time. Our research in the last five years have demonstrated that by varying the steam or hydro-distillation time, one could obtain oils with defined specific composition, opening the possibilities to produce unique essential oils from the same batch of biomass or seed. Furthermore, by manipulating the extraction time and conditions, one can obtain oils or oil fractions with differential bioactivity. The resulting products (essential oil fractions) could have diverse industrial, medical, or environmental applications. These findings could be used by industry to develop new products, to reduce energy inputs and oil losses, and speed up oil extraction. Our results clearly demonstrated that the conditions for oil extractions must be reported when the essential oil content and composition of a specific plant has been reported. This will facilitate comparisons of oil yield and composition. Herewith, we summarize the recent research on how steam or hydrodistillation time and conditions alters essential oil yield and composition from some of the most widely grown and utilized essential oil crops.