Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

8 MICRODISTILLATION,THERMOMICRODISTILLATION AND MOLECULAR DISTILLATION TECHNIQUES
recipe-based methods are time-tested but arguably not the most effi cient in
terms of yield, energy consumption per unit of product, etc. With the advent
of modern processing techniques, there is an urgent need to revisit the recipe-based
processing, understand the science underlying them and develop
modern, cost-effective processes. This article deals with some important
advances made in the extraction of MAPs and the post-extraction treatment
of the products and their byproducts.
8.2 Process Intensification
The modern chemical industry is undergoing drastic changes
driven mainly by economic considerations. There is an upsurge of interest
in clean, energy-effi cient and material-conserving processes. An entirely new
discipline, “process intensifi cation” (PI), has become the focus of a large
and sustained effort all over the world. Stankiewicz and Moulijn have given a
precise defi nition of PI as “Any chemical engineering development that leads
to a substantially smaller, cleaner and more energy effi cient technology”.
India has not been lagging behind in developing innovative PI concepts.
PI can be broadly divided into two categories, with specifi c
reference to processing of MAPs as per the defi nition of Stankiewicz and
Moulijn. These are processes that employ multifunctional equipment (MF)
and those that use process-intensifying equipment.
8.2.1 Multifunctional Equipment
This category of PI employs equipment that can perform multiple
functions simultaneously. Thus, earlier process plants that required a number
of different instruments devoted to individual tasks are being replaced by such
MF equipment. A brilliant example of the use of MF equipment is the conversion
of a slow and polluting process for the enzymatic hydrolysis of penicillin G
to 6-amino penicillanic acid (important intermediate for semisynthetic antibiotics)
into an intensified and sustainable process. Since MF equipment-based
plants are smaller and consume less energy, they have become popular for
globally competitive and sustainable processes.
8.2.2 Process-intensifying Equipment
This category of PI employs equipment that specifi cally focuses
on intensifying the rates of the various steps. In the case of MAP processing,
the main resistance in the overall extraction process is the diffusion of
the active molecules through the plant cell membrane to the surface before
extraction by the fl uid. Microwave-assisted extraction (MAE) is highly useful
in obtaining rapid and complete extraction without signifi cant damage
to the active molecules; this technique is discussed in some detail later.
Ultrasound-assisted extraction is also an alternative. However, considering
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