Abstract
The organic fraction soluble in different organic solvents with increasing polarity was studied during the composting process, following its transformation from raw material until the stable final product with the aim to establish new quality indices of compost maturity. All apolar fractions during the composting process had a reduction higher than 50%. Part of the compounds have been utilized by the microflora as energetic material and to perform the biotransformations, and part has been transformed in molecule like the humic molecules. However, in our conditions a relevant part (36%) of apolar material is recovered at the end of the biotransformation. The spectroscopic analysis indicates in the final product an increase of lipidic compounds, as esters or acids as well as hydrocarbons with longer linear aliphatic chain.