Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

3 MACERATION, PERCOLATION AND INFUSION TECHNIQUES FOR THE EXTRACTION OF MEDICINAL AND AROMATIC PLANTS
3.6.3 Percolators
Different types of percolators are used for small- and largescale
extraction.
3.6.3.1 Small-scale or Laboratory-scale Extraction
The processes for the manufacture of concentrated preparations,
maceration and percolations, are involved in extraction followed by the evaporation
of solvents. The two operations are combined in a continuous extraction
process.
The general procedures and apparatus used for small- or laboratory-scale
extraction are described in the following paragraphs.
3.6.3.1.1 Soxhlet Apparatus
On the laboratory scale, the Soxhlet apparatus is used. It consists
of a fl ask, a Soxhlet extractor and a refl ux condenser. The raw material
is usually placed in a thimble made of fi lter paper and inserted into the wide
central tube of the extractor. Alternatively, the drug, after imbibition with menstruum,
may be packed in the extractor taking care that the bottom outlet
for the extract is not blocked. Solvent is placed in the fl ask and brought to
its boiling point. Its vapors pass through the larger right hand tube into the
upper part of the extractor and then to the condenser where they condense
and drop back onto the drug. During this period, the soluble constituents
are extracted. When the level of the extract reaches the top of the syphon
tube, the entire volume of extract syphons over into the fl ask. The process
is continued until the drug is completely extracted. The extract in the fl ask is
then processed. This procedure is thus a series of short macerations.
Figure 4: Soxhlet apparatus for hot extraction
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