|Case Studies of Neem Processing Projects Assisted by GTZ in Kenya, Dominican Republic, Thailand and Nicaragua (GTZ, 2000, 152 p.)|
|2. Survey of neem-processing methods|
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