Implications of Green Solvents on Delignification and Saccharification of Neem Oil Seed Cake for Sustainable Biorefinery Applications

Neem (Azadirachta indica) oilseed cake (NOC) is a derivative of neem oil production considered to be lignocellulosic (lignin 6.20 ± 0.90%, w/w; hemicellulose 18.90 ± 0.11%, w/w; cellulose 24.90 ± 0.08%, w/w) biomass, which could be used as a substrate for value-added chemicals production. This study attempts to fractionate lignin, hemicellulose, and cellulose of NOC through an organosolv pretreatment under optimized conditions for enhanced deep eutectic solvent (DES) saccharification. Optimization has been performed through one variable at a time (OVAT) for the parameters including treatment time, solid-to-liquid (S/L) ratio, and temperature for delignification of NOC. The resultant delignification was found to be 70.23 ± 1.09%, w/w, under optimum conditions of S/L ratio (1:14) at 60 °C for 90 min of treatment. Therefore, the treated solid residue obtained following organosolv pretreatment was subjected to saccharification using deep eutectic solvent (DES). The conversion of NOC-derived fermentable sugars to fuels and chemicals could be an efficient approach towards biorefinery.