Optimum conditions for dilute acid hydrolysis of hemicellulose in dried distillers grains with solubles

Corn dried distillers grains (DDGS) had high hemicellulose contents and were suitable for conversion to pentose under dilute acid conditions. The effects of the hydrolysis conditions, including reaction temperature (110-130 degrees C). time (30-90 min), and acid concentration (2-4%, w/v), on profile and yield of mono-sugars were determined using response surface methodology. Three major sugars, namely xylose, arabinose, and glucose were generated during dilute acid hydrolysis. Reaction temperature, time, and acid concentration had significant effects on xylose and arabinose yields, while glucose yield was affected only by temperature and acid concentration. Lower reaction temperature and longer reaction time favorably affected xylose and arabinose yields. The optimum levels of the independent variables were 112 degrees C reaction temperature for 84.5 min and 3.1% (w/v) acid concentration. The corresponding predicted responses were xylose yield of 267.3 mg/g dry matter, arabinose yield of 121.2 mg/g dry matter, and glucose yield of 46.3 mg/g dry matter. The selected second-order models were deemed the best since the experimental values were close to the predicted values at the optimum conditions, and high correlation coefficients (R-2) were obtained for all models. (C) 2010 Elsevier B.V. All rights reserved.