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A combination of steam explosion (SE) and alkaline peroxide (AP) used to pretreat bamboo was investigated. Steam explosion at 224 °C for 4 min was applied to bamboo, and the pretreated bamboo was delignified by alkaline peroxide. Enzymatic hydrolysis was compared in the pretreated samples. Steam pretreatment led to remarkable hemicellulose solubilization (63.2%). Lignin solubilization (93.1%) was achieved by alkaline peroxide treatment of steam-pretreated bamboo at 80 °C for 1 h in 0.88% (v/v) H2O2, whereas only 33.4% of lignin was solubilized when using raw bamboo. Pretreatment methods resulted in a low degree of polymerization and increased hydrolysis of cellulose. A maximum glucose yield of 90.5% was achieved with a combined steam explosion and alkaline peroxide pretreatment. The surface structure of treated bamboo and the adsorption of enzyme on the substrate were characterized by X-ray photoelectron spectroscopy. Delignification decreased enzyme adsorption and increased enzymatic conversion. SEM analyses indicated that SE-AP pretreatment disrupted lignin networks and exposed crystalline cellulose in bamboo more effectively than SE or AP pretreatment alone. [ABSTRACT FROM AUTHOR]

Abstract: The steam pre-treatment with low severity preserves valuable biomass components, and further delignification with alkaline peroxide could improve hydrolysis. A combination of low severity steam pretreatment and alkaline peroxide post-treatment of Lespedeza stalks was investigated. The post-treatment of steam-pretreated Lespedeza stalks with alkaline peroxide significantly increased the cellulose content and changed the structure of the cellulose-rich fractions. A glucose yield of 503.5mgg−1 raw material from enzyme hydrolysis was obtained when the steam-pretreated material (184°C for 4min) was post-treated with 2% hydrogen peroxide at 60°C for 24h with a substrate concentration of 3.3%. Its hydrolysis yield is 88.8%, which is higher than that of samples processed by steam pretreatment alone (63.7%). The samples obtained by post-treatment with alkaline peroxide were found to have a smoother surface and looser structure in scanning electron microscopy images. The isolated lignin preparations had a yield range from 10.9 to 14.7 (% dry matter). The lignin was characterized by thermogravimetric analysis/differential thermal analysis, Fourier transform infrared spectroscopy, and gel permeation chromatography. Alkaline peroxide treatment increased the thermal stability of lignin, and decreased the amounts of all functional groups. Depolymerization and repolymerization occurred during the alkaline peroxide treatment. [Copyright &y& Elsevier]

Abstract: The enzymatic hydrolysis of sugarcane bagasse was investigated by treating a peroxide–alkaline bagasse with a pineapple stem juice, xylanase and cellulase. Pre-treatment procedures of sugarcane bagasse with alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 24 factorial designs, with pre-treatment time, temperature, magnesium sulfate and hydrogen peroxide concentration as factors. The responses evaluated were the yield of cellobiose and glucose released from pretreated bagasse after enzymatic hydrolysis. The results show that the highest enzymatic conversion was obtained for bagasse using 2% hydrogen peroxide at 60°C for 16h in the presence of 0.5% magnesium sulfate. Bagasse (5%) was treated with pineapple stem extract, which contains mixtures of protease and esterase, in combination with xylanase and cellulase. It was observed that the amount of glucose and cellobiose released from bagasse increased with the mixture of enzymes. It is believed that the enzymes present in pineapple extracts are capable of hydrolyze specific linkages that would facilitate the action of digesting plant cell walls enzymes. This increases the amount of glucose and other hexoses that are released during the enzymatic treatment and also reduces the amount of cellulase necessary in a typical hydrolysis. [ABSTRACT FROM AUTHOR]

Abstract: A two-stage pretreatment method was proposed and tested for deconstruction of recalcitrant Miscanthus. During a 1st pretreatment at 50°C, 1.0–4.0% alkaline peroxide solutions were used to partially remove hemicellulose and lignin. The remaining solids were subjected to a 2nd pretreatment at 121°C with electrolyzed water. Using 15 filter paper units of cellulase per gram cellulose, a digestibility of 95% was achieved by the two-stage method, which was higher than 81% obtained from a 1% H2SO4 pretreatment (200°C, 8min). A mass balance for the two-stage process showed that 63% hemicellulose and 64% lignin were removed from the Miscanthus samples after the 1st pretreatment. The Scanning Electron Microscopy images and Fourier Transform Infrared Spectroscopy spectra revealed that after the 1st pretreatment, crystalline cellulose fibers were partially exposed and the linkages between residual lignin and hemicellulose disappeared. After the 2nd pretreatment, cellulose fibers were completely exposed even with cracks developed. [Copyright &y& Elsevier]