Optimization of ethanol-based-organosolv pretreatment of date palm (Phoenix dactylifera L.) seeds for 2G-sugars recovery: response surface methodology (RSM)

Date palm seeds (DPS) represent an important source of lignocellulosic biomass. The DPS chemical composition is as follows: 27.002% of hemicellulose, 40.227% of cellulose and 31.74% of total lignins. The objective of this study is to convert DPS to second-generation sugars. The ethanol-based-organosolv pretreatment of DPS is investigated using the cubic central composite experimental design (CCD) by studying the effect of two quantitative factors, viz.: temperature (140 degrees C, 160 degrees C, 180 degrees C) and ethanol concentration (0%, 48%, and 96%). The DPS digestibility was monitored thanks to the determination of 13 responses dealing mainly with: the severity factor; the different percentages of: solubilization; hemicellulose and cellulose removals; lignins removals; the inhibitor compounds; the protein ratio and both percentages of C5 and C6 sugars with their corresponding polysaccharides. It was concluded that hydrothermal pretreatment at 166 degrees C is the optimal condition. The optimum solubilization, hemicelluloses removal and residual cellulose percentages were 26.500%, 47.590% and 43.250%, respectively.