Hidrólise enzimática do sorgo sacarino (Sorghum bicolor L. Moench) para produção de açúcares fermentescíveis.

Abstract

The lignocellulosic residues are the most abundant in the world and currently there is a worldwide concern in reuses them as raw material in the production of bioethanol, its being possible due to these waste materials are rich in cellulose. Cellulose is a long chain polymer composed of one monomer glucose, linked by a glycosidic bond β-1-4. Glucose can be converted into ethyl alcohol via fermentation, and this can be achieved by enzymatic hydrolysis of cellulose and via acid hydrolysis. The main goal of this work was to evaluate the potential use of sweet sorghum (Sorghum bicolor L. Moench) by enzymatic hydrolysis to produce fermentable sugars. The sorghum was characterized physico-chemically in nature and after completes the pretreatment steps by conventional methods and through techniques of DRX, MEV, TG, DSC, It was also held grain size analysis strength flexion assay and sugars quantification by CLAE method. The basic pretreatment steps ware performed and acid, which were conducted in a pressurized reactor, as carried out enzymatic hydrolysis in both cases it was used as an experimental planning tool, design 23, in which was evaluated time, temperature and NaOH and H2SO4 concentration, in the stages of pretreatment, and the effect of the enzyme load (FPU.g-1), the mass of sorghum / volume ratio extract (g.mL-1) and the rotation shaker for hydrolysis step. They were used in the enzymatic hydrolysis of commercial enzymes Celluclast 1.5L and Novozyme beta-glucosidase proenzyme, 3,00g substrate temperature of 55 °C and pH 4.8, The pretreatment steps concentrate alpha-cellulose, which increased from 32.75% to sorghum in nature to 66.15% in the basic pre-treated sorghum and 54.99% in the basic pretreated sorghum followed by pretreatment acid. The DRX analyzes confirmed changes in crystallinity and MEV analysis showed changes in the residue morphology. Through TG/DTG and DSC analysis was confirmed the hemicellulose and lignin degradation, when using pretreatments. Through the flexural strength assay was found that are changes in the mechanical properties of the in nature sorghum after pretreatment steps. Enzymatic hydrolysis was conducted on sweet sorghum in natura and pretreated with NaOH, obtained a glucose concentration of 16713.7 mg l-1 for sweet sorghum in nature and 31639.3 mg L-1 for the pre-treated pulp with NaOH, both in the hydrolysis time was 48 hours.