Extraction of Rosemary by Superheated Water

TLDR

Superheated water extraction requires more water but offers competitive energy costs by avoiding vaporization and recycling most heat. Superheated water (125–175 °C) rapidly extracts oxygenated fragrance and flavor compounds from rosemary, yielding higher amounts than steam distillation, while monoterpenes are extracted slowly and only trace sesquiterpenes, waxes, and lipids are removed, demonstrating viability for high‑quality plant extracts. Keywords: Rosmarinus officinalis, superheated water, subcritical water, extraction, fragrance, flavor.

Abstract

Superheated water under pressure between 125 and 175 °C has been shown to rapidly extract the oxygenated fragrance and flavor compounds from Rosmarinus officinalis, while the monoterpenes are extracted slowly, and only very small amounts of the sesquiterpenes, waxes, and lipids are removed. The eventual yields of oxygenated compounds are higher than are obtained by steam distillation. Although larger amounts of water are needed for extraction by superheated water, the energy costs are competitive because it is not necessary to vaporize the water and most of the heat required can be recycled. The experiments conducted on a laboratory scale indicate that extraction by superheated water could be a viable process for the production of high quality plant extracts. Keywords: Rosmarinus officinalis; superheated water; subcritical water; extraction; fragrance; flavor