Abstract:

This study aimed to reduce the water absorption rate of konjac glucomannan by removing its acetyl group in
order to promote its application in flour-based products. Factors influencing deacetylation efficiency, including ethanol
concentration, NaOH concentration, temperature and time, were investigated in this study. Meanwhile, the removal
efficiency of acetyl group was evaluated by Fourier transform infrared spectroscopy (FT-IR) analysis and water absorption
rate. The optimum reaction parameters for deacetylation were determined as 40%, 0.12 mol/L, 60 ℃ and 12 min for ethanol
concentration, NaOH concentration, reaction temperature and time, respectively. Under these conditions, the acetyl group
in konjac glucomannan was completely removed and water absorption rate of deacetyled konjac glucomannan decreased to
9.32% of that of the original sample. In summary, the acetyl group in konjac glucomannan could be effectively removed by
using ethanol-alkali method. Deacetylation could reduce the water absorption rate of konjac glucomannan and increase its
proportion in flour, thus improving flour farinograph quality.

Key words: konjac glucomannan, water absorption rate, acetyl group, farinograms