Abstract: Objective: To optimize the acid hydrolysis of konjac glucomannan (KGM) for preparing konjac oligo-glucomannan with low intrinsic viscosity by response surface methodology. Methods: Based on one-factor-at-a-time experiments, a three-variable, three-level Box-Behnken experimental design was applied to establish a quadratic polynomial model for the intrinsic viscosity of konjac oligo-glucomannan (KOGM) as a function of hydrolysis time, temperature and HCl-to-ethanol ratio. The results of response surface analysis indicated that the optimal hydrolysis condition were hydrolysis time of 50 min, HCl-to-ethanol ratio of 3.8% and hydrolysis temperature of 82 ℃. The experimental intrinsic viscosity of KOGM obtained under these conditions was 55.613 cm3/g, which was consistent with the theoretical value. The experimental data could be well fitted with the regression model established. Conclusion: The model is reliable and can be used in practice.

Key words: response surface methodology, konjac glucomannan, acid hydrolysis, intrinsic viscosity