Monitoring by GC-MS the alterations of free and esterified lipids during the stabilization process of fresh organic matter

Abstract

For good management of the composting process it is essential to dispose of criteria to follow the progressive changes with time of chemical parameters in order to set the optimun composting endpoint. On the other hand, monitoring of changes in compost composition during the stabilization process is of key importance in assuring the quality of the final product for its agricultutal use. Among the well specified standards for compost the organic matter stability assume a particularly important role. To this stability made a decisive contribution the quantitative and qualitative characteristics of the lipidic fraction. In this work we have monitorized by GC-MS the chemical changes that undergoes the lipids isolated from city refuse wastes at discrete intervals in the course of the composting process. Three different lipidic fraction were studied: i) from free monomers, ii) from sterified monomers, and from high molecular weight lipidic macromolecules, the two later obtained after saponification of the extract and the non extractable residue. Some significative alterations were detected, such as the increase in the concentration of low molecular weight alkanoic acids among the free lipids. Likewise, clear differences were found among the lipidic components released after transesterification treatment of compost samples at different degree of maturation with F3B-methanol.