Hot water pretreatment of lignocellulosic biomass: Modeling the effects of temperature, enzyme and biomass loadings on sugar yield

•Liquid hot water pretreatment tested on high-yielding tropical perennial C4 crops.•65% inhibitor-free glucose yield from solid fraction of Energycane.•73% inhibitor-free glucose yield from solid fraction of Napiergrass.•4.2 and 0.6 g L−1 HMF produced by Energycane and Napiergrass at 200 °C.•4.6 and 3.6 g L−1 Furfural produced by Energycane and Napiergrass at 200 °C. Experimental conditions of liquid hot water (LHW) pretreatment were tested for two dedicated energy crops, Napiergrass (Pennisetum purpureum) and Energycane (Saccharum officinarum × Saccharum robustum). Both crops showed differential resistance to temperature during pretreatment and differences in response to biomass and enzyme loadings during subsequent enzymatic hydrolysis. Sugar response surfaces, for both glucose release per g pretreated biomass and as percent yield of glucose present in the initial biomass, were estimated using a General Additive Model (GAM) in R to compare non-linear sugar release as temperature, and biomass and enzyme loadings were manipulated. Compared to Napiergrass, more structural glucose is estimated to be recovered from Energycane per g of pretreated biomass under relatively less harsh pretreatment conditions, however, Napiergrass had the highest measured glucose yield. Sugar degradation products (furfural and hydroxymethylfurfural), pH, and biomass recovery differed significantly between crops across pretreatment temperatures, which could adversely affect downstream biochemical processes.