(introduction...)
Neem seeds are a valuable raw material. They contain not only
insecticidal and fungicidal ingredients, but also up to 48% oil. Even the
extracted neem cake can be used as fertiliser and might have effects on soil
pests. There are various technologies available to extract the active
ingredients of neem. Which technique should be used depends mainly on the
quality required (content of Als) for the final product.
The costs of the extraction plants vary accordingly: the higher
the level of azadirachtin required, the more expensive are the plants.
Considering the solubility of the leading component azadirachtin, it is clear
that only polar solvents should be used for extraction. Still, the cold pressed
neem oil could contain up to 0.6% azadirachtin A.
Water and alcohol are the best solvents. Often methanol is the
preferred alcohol because of the availability and price.
Four different types of technologies are available, the types
first described being the most commonly used ones:
A) EXTRACTION with alcohol (also called one-step
extraction)
B) AZADIRACHTIN-ENRICHED EXTRACTS (also called two-step
extraction)
C) EXTRACTION USING CENTRIFUGES
D) EXTRACTION WITH
SUPRACRITICAL
CO2
