Extractives: Easily negligible chemical compounds from detoxification

When talking about detoxification of biomass hydrolyzate, almost all the research and studies focus on these compounds such acetic acid, sugar degraded products (furfural, HMF etc). However, small amount of extractives exist in the hydrolyzate, which is often ignored. Actually, some of these extractives, naturally exist in biomass for coloration and as insectcides, which are also toxic to miroorganisms. For example, stilbenes are generally very toxic! So, it is not enough to remove just furfural and acetic acid.

Typical extractives in tree:

- Resin acids (no or little in hardwood)
- Fatty acids
- Monoterpenes (turpentine)
- Phenolics (Gallic acid, vanillin, Stilbenes, Flavonoids, Lignans)

- Others (Alkanes, Proteins, Monosaccharides and derivatives)

Extractive components are “small” molecules that can be extracted with a solvent from wood, bark, or foliage.
-Generally, extractives are present in small amounts.
-Extractives vary tremendously within species, between species, and within trees.
-There are thousands of different extractives present in wood.