This study examined the effect of natural deep eutectic solvent (NADES) concentration on the kinetics of glucomannan swelling and deacetylation during the purification process and the characteristics of purified porang glucomannan (PGM). NADES was prepared from betaine and 1,2-propanediol (BPG14) at concentrations ranging from 30 % to 100 % (WBPG14/Wtotal). The deacetylation degree, along with the structural, thermal, and rheological properties of PGM, as well as the rate of glucomannan swelling and deacetylation, were investigated. The results showed that higher water content in BPG14 increased the cooperative diffusion coefficient and changed the glucomannan swelling behavior from a diffusion to a relaxation mechanism. The purification of glucomannan reached equilibrium after 1 h, although the cleavage of acetyl groups continued to increase. The suggested BPG14 concentration was 70 % (WBPG14/Wtotal), resulting in the strongest gel, with a glucomannan content of 89.04 % and a decrease in acetyl content from 1.59 % to 1.44 % (w/w). © 2024