Triticum spelta straw hydrothermal pretreatment for the production of glucose syrups via enzymatic hydrolysis

The global climate changes related to the use fossil fuels and the oil price volatility have been feeding the interest for renewable feedstock such as the by-products of the agroindustry. This is a challenging scenario as the diversity of plant materials worldwide calls for customized pretreatment processes to achieve a significant cellulose enzymatic saccharification coupled to the preservation of the biomass cellulose content as well as to a low degradation of biomass sugars into inhibitory compounds that is a recurrent problem in biomass processing. This work reports a statistical experimental design for hydrothermal pretreatment of spelt straw (Triticum spelta) aiming to maximize the straw enzymatic conversion in glucose syrups while minimizing the formation of undesirable biomass derived inhibitors. In the best pretreatment conditions of 180 °C for 10 min it was observed a cellulose conversion yield of 52.16% that resulted in a glucose syrup with 56.33 g L−1 in a reaction mixture presenting 200 g L-1 of pretreated straw. The liquid current from the pretreatment, rich in hemicellulose derived sugars, presented 1.63 g L−1 acetic acid, 0.67 g L−1 furfural and 0.06 g L−1 HMF. The cellulose content of the pretreated straw and the corresponding glucose concentration in the hydrolysate were mathematically modeled with relative deviation smaller than 5 % as a function of pretreatment parameters temperature and pretreatment time.