Abstract: Response surface methodology was used to optimize the conditions for alkaline extraction of xylan from corncob with the aim of maximizing the yield of xylan. The effects of NaOH concentration, solid-to-liquid ratio, extraction time and temperature on the yield of xylan were studied in single factor experiments. Subsequently, a regression model for the yield of xylan was established using a central composite design involving the above four factors at five levels and based on the model, response surface analysis was carried out to find out the optimum levels of these four factors. The results indicated that the optimum extraction conditions were NaOH concentration of 25 g/100 mL, solid-to-liquid ratio of 1:25, temperature of 94 ℃ and extraction time of 3 h. Under such conditions, the experimental yield of xylan was 24.39%, which was basically consistent with the predicted one of 24.41% and increased by 19.85% than the maximum one of 20.35% obtained in single factor experiments.

Key words: response surface method, corncob, xylan, extraction process