Synthesis of humic-like substances under sterile and non-sterile conditions in presence of quartz and volcanic ash

This study reports on the formation of Maillard compounds (humic-like substances called "melanoidins") from D-glucose and L-tyrosine in the presence of volcanic ash and pure quartz. It was demonstrated that the synthesis occurred not only under non-sterile, but also under sterile conditions, and under moisture and temperature stress. The temperature remained for 30 days at 70degreesC for 63% of the time. The non-sterile environment with a contact time of at least 30 days was the most favorable condition for the synthesis. In sterile environment, only low molecular weight polymers were formed, while in non-sterile systems high molecular weight substances were synthesized. The presence and the nature of mineral substrates appeared important even if not essential for the formation of humic-like substances. in fact, these substances were also formed by the reaction of the precursors alone.