Regarding the microalgae C. sorokiniana and P. tricornutum, the results of the carbohydrate analysis are shown in Table 6, together with the corresponding results of N. gaditana, to allow for comparison. The total sugar contents of the fresh samples obtained by analytical acid hydrolysis were found to be 40.3% and 13.2%, and as a consequence of the acid catalysed steam explosion pretreatment, the sugar released by the microalgae reached values of 38.2% and 12.7%, for C. sorokiniana and P. tricornutum, respectively. This represents a sugar yield of 95% for C. sorokiniana and of 96% for P. tricornutum.