Xylose production from sugarcane bagasse by surface response methodology/ Producao de xilose a partir do bagaco de cana-de-acucar por metodologia de superficie de resposta

The aim of this study was to optimize the production of xylose from sugarcane bagasse. The hydrolysis process was carried out to evaluate the effect of temperature and sulphuric acid concentration on the xylose production at 18, 30, and 50 min of hydrolysis. A Central Composite Rotatable Design (CCRD) was used to study two process variables, temperature (111.5; 114.0; 120.0; 126.0 and 128.5°C) and sulphuric acid concentration (0.20; 0.70; 1.90; 3.10 and 3.60% v [v.sup.-1]). Sulphuric acid had a greater influence on the hydrolysis process than temperature. At concentrations of sulphuric acid higher than 3.10% (v v-1), raising temperature had little influence on the yield of xylose production. The best condition to obtain xylose (266.73 mg g-1 of dry bagasse) was at 18 min of reaction, at 126°C and 3.10% (v [v.sup.-1]) of sulphuric acid, representing 96.0% of the theoretical maximum. Key words: hemicellulose, hydrolysis, HPLC, aldopentose, renewable carbon source Propos-se neste trabalho, otimizar a producao de xilose a partir do bagaco de cana-de-acucar. O processo de hidrolise foi realizado para avaliar o efeito de temperatura e concentracao de acido sulfurico na producao de xilose, em 18, 30 e 50 min de hidrolise. Um planejamento completo com pontos centrais foi usado para se estudar duas variaveis do processo, temperatura (111,5; 114,0; 120,0; 126,0 e 128,5°C) e concentracao de acido sulfurico (0,20; 0,70; 1,90; 3,10 e 3,60% v [v.sup.-1]). O acido sulfurico teve maior influencia no processo de hidrolise do que a temperatura. Nas concentracoes de acido sulfurico acima de 3,10% (v [v.sup.-1]), o aumento da temperatura teve pouca influencia no rendimento da producao de xilose. A melhor condicao para obtencao da xilose (266,73 mg g-1 de bagaco seco) foi a 18 min de reacao, 126[grados]C e 3,10% (v [v.sup.-1]) de concentracao de acido sulfurico, representando 96,0% do maximo teorico. Palavras-chave: hemicelulose, hidrolise, HPLC, aldopentose, fonte renovavel de carbono