Study on the effects of several operational variables on the enzymatic batch saccharification of orange solid waste

In this work, batch enzyme-aided extraction and enzymatic saccharification of blade-milled orange waste was studied. The operation variables for this process were thoroughly analysed. It was determined that batch runs with initial pH values of 5.0 and 5.2 controlled during the first hour, 50 degrees C and 300-500 r.p.m. agitation resulted in the best yields, with a limited total and partial first-order enzyme deactivation (for cellulases and poly-galacturonidase, respectively). Orange peel waste (OPW) at 6.7% w/w dry solid, 0.22 filter paper units (FPU)/g DS and proportional activities of other enzymes led to over 40 g/L free monosaccharides and global yields to glucose over 80%. When using 10.1% w/w DS in these conditions, glucose yield was 63%, with total monosaccharide concentration on top of 50 g/L. Similar concentrations were obtained by additional partial drying of OPW to 60% humidity at DS/L ratios near 7.5% (glucose yield > 80%).