Humins are carbon-based macromolecular substances, that can be found in soil chemistry or as a by-product from saccharide-based biorefinery processes.
[2] Humins also produced during the dehydration of sugars, as occurs during the conversion of lignocellulosic biomass to smaller, higher value organic compounds such as 5-hydroxymethylfurfural (HMF).
[3] However, the structure is dependent on feedstock type (e.g. xylose or glucose) or concentration, reaction time, temperature, catalysts and many other parameters involved in the process.
[7] While there is no clear evidence to substantiate or exclude the mechanisms, general consensus is on a series of condensation reactions that reduce the efficiency of biomass conversion strategies.
Humins are not considered to be a dangerous substance according to officially recognized hazardous material classification systems based on physical-chemical properties such as flammability,[8] explosiveness, susceptibility to oxidation, corrosiveness or eco-toxicity.