Comparison of ethanol production during batch and fed-batch simultaneous saccharification and fermentation (SSF) using non-washed solids as substrate. Ethanol concentration (circles) during batch SSF (dashed-dotted lines), fed-batch SSF with substrate and enzyme feed (dashed lines), fed-batch SSF with yeast and substrate feed (dotted lines) and fed-batch SSF with yeast, enzymes and substrate feed (solid lines). The graph represents the mean of two biological replicates. Error bars are omitted for the sake of clarity. The total water insoluble solids (WIS), enzyme loading and yeast loading were 20% (w/w), 7.5 filter paper units (FPU) g WIS-1 and 5 g L-1, respectively, in all the experiments.