Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS
8 Microdistillation,Thermomicrodistillation
and Molecular Distillation Techniques
Abstract
V. G. Pangarkar
Medicinal and aromatic plants (MAPs) have assumed considerable signifi cance in view
of their special attributes. There are many compounds of great therapeutic value which
can be obtained only from the plant kingdom. Most of the ingredients in such extracts
and oils are large bulky molecules highly sensitive to processing conditions. The processes
for such extractions have been mostly based on “recipes”. In the recent past,
signifi cant advances have been made in the unit operations which are part of the recipe-based
processes. It is imperative that these advances, which are essentially aimed
at achieving better yields at lower costs and are termed “process intensifi cation”, are
incorporated into the processing of MAPs. This paper introduces the theme of process
intensifi cation as applied to the processing of MAPs and presents an overview of
several new technologies which allow rapid, cost-effective extraction. The application of
such innovative technologies can yield signifi cant benefi ts in terms of the quality of the
product and its yield per unit weight of the plant material processed. Recovery of dissolved
essential oil components from steam distillation condensates is also addressed
and the two available techniques are discussed in detail.
8.1 Introduction
Phytochemicals derived from medicinal and aromatic plants
(MAPs) have been important to humans for centuries. Before the advent
of modern synthetic chemistry, many aroma and fl avor chemicals were derived
from sources of natural origin such as fl owers, roots and stems. The
contemporary system of allopathic medicine, which has gained tremendous
importance in the treatment of various diseases, is mainly based on active
pharmaceutical compounds made synthetically. However, in recent years increasing
attention has been paid to the traditional systems of treatments
followed in Asia and Africa. The variety of medicinal plants and their constituents
are being discovered only recently. There are many compounds of
great therapeutic value which can be obtained only from the plant kingdom.
Thus, vincristine, perhaps better known as the chemotherapy agent Oncovin,
is only synthesized in the periwinkle plant Catharanthus roseus, and the
sole source of the compound is this plant species. There are many other
compounds which are equally valuable in other sectors such as food fl avors,
fragrances and cosmetics.
The processing of MAPs for obtaining the required extracts and
oils has been based on traditionally established “recipes”. Most of the ingredients
in such extracts and oils are large bulky molecules highly sensitive
to processing conditions. Generally, relatively mild conditions are used
in such processes to protect the integrity of the valuable components. The
129