Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS
3
Maceration, Percolation and Infusion
Techniques for the Extraction of
Medicinal and Aromatic Plants
Abstract
J. Singh
Techniques of maceration, percolation and infusion have been traditionally used for
making galenicals and tinctures from medicinal and aromatic plants (MAPs). This article
describes the underlying principals and mechanisms of these extraction techniques,
and discusses the various modifi cations made for the small- and large-scale
extraction of MAPs, the factors affecting the extraction process, and the quality of the
extracts produced.
3.1 Introduction
Before the nineteenth century, there was no real progress in
methods of extraction of plant materials for industrial use. Nonetheless, the
various classes of preparations involving simple expression and extraction
techniques were in vogue for a long time for the preparation of medicines
used in traditional medicine and in complimentary and alternative medicine,
practiced throughout the world. The techniques available were limited to expression,
aqueous extraction and evaporation; later on, the use of extraction
processes was extended by using alcohol as a solvent. Such techniques
were highly successful in the phytochemical fi eld and, consequently, single
pure molecules were isolated for industrial and medicinal uses. After the
nineteenth century, rapid progress was made in extraction processes which
led to the isolation and characterization of many groups of plant metabolites
of therapeutic importance, including both single chemical constituents
as well as standardized extracts of crude drugs. In manufacturing various
classes of medicinal plant preparations, such as decoctions, infusions, fl uid
extracts, tinctures, semisolid extracts (pilular) and powdered extracts, popularly
known as galenicals, both simple traditional methods and advanced
technologies are used, conforming to the offi cial procedures and specifi cations
as laid down in various pharmacopoeias and codices of the world.
Maceration, percolation and infusion are the general techniques
used for the extraction of medicinal plants and are mostly applied
for galenical preparations. The sole purpose of such basic extraction procedures
is to obtain the therapeutically desirable portion and eliminate the
inert material by treatment with a selective solvent known as menstruum.
These techniques also play a decisive role in the qualitative and quantitative
evaluation of the extracts. The standardized extracts thus obtained are
further processed for inclusion in other solid and semisolid herbal dosage
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