Optimising the autohydrolysis of bagasse to extract D-xylose

This paper reports on the experimental investigation of the autohydrolysis of bagasse and determination of the conditions for optimum yield of D-xylose using an experimental design model. The process variables investigated were temperature, time at temperature, feed type (bagasse or bagacillo) and liquid-to-solid ratio. The optimum conditions show an inverse time temperature relationship and the optimal D-xylose production for bagasse autohydrolysis lies in a range of conditions that varies approximately from 12 minutes at 205°C to 2 minutes at 225 °C. No optimalliquid-tosolid ratio was determined and all tests indicate that the higher the liquid ratio, the higher the possible D-xylose yields. The highest yield achieved at 5 minutes at 217°C and 30: 1 liquid-to-solid ratio was 73 mg xylose per gram of dry bagasse feed. This is approximately 27% of the potential D-xylose yield. From the initial experimental design screening tests, little difference was observed between bagasse and bagacillo feeds in the extraction, although bagacillo has a slightly higher potential D-xylose yield. The optimum D-xylose yield in the autohydrolysis of bagasse occurred at a pH of 3.4.