A process for preserving the initial fermentable potential of an organic substrate over time is presented. The method comprises a) determining the moisture content (HM) of the organic substrate, b) comparing the determined moisture content (HM) to a predefined moisture level (HD), c) storing only the organic substrate of which the moisture content (HM) determined in step a) corresponds to the predefined moisture content (HD), d) when a fermentable potential cannot be determined based on the moisture content (HM) alone during steps a) and c), taking measurements of the methanogenic potential of the biomass, e) comparing the measurements of the methanogenic potential of the biomass obtained during step c) to that of step a), and f) adapting the storage conditions to keep the moisture content (HM) of the organic substrate collected at a value that of the predefined moisture content (HD).
