Abstract: The cellulase extraction process of Thladiantha dubia Bunge tuber starch was studied by single factor experiment and orthogonal optimization experiment. The physicochemical properties of Thladiantha dubia Bunge tuber starch were further studied with potato starch and corn starch as control samples. The results showed that the optimum technological condition for extracting starch from Thladiantha dubia Bunge tuber by cellulase was enzymatic hydrolysis temperature of 50 ℃, enzyme concentration of 0.5%, pH of 5.0 and enzymatic hydrolysis time of 3 h. Under these conditions, the starch recovery could reach 88.75%; the starch content, water content, protein content, fat content and ash content of crude starch were 79.2%, 13.0%, 0.11%, 0.10% and 0.65%, respectively; the starch particle size of Thladiantha dubia Bunge tuber showed a bimodal distribution, the diameter was concentrated at 2.00~50.00 μm, the average particle size was 35.25 μm, and the particle size was between corn starch and potato starch; the transparency of starch paste was moderate, higher than that of commercially available corn starch, lower than that of commercially available potato starch; the starch of Thladiantha dubia Bunge tuber has no significant difference in water precipitation rate with potato starch and corn starch; the freeze-thaw stability of starch paste of Thladiantha dubia Bunge tuber was similar to that of potato starch paste and corn starch paste;the initial swelling temperature and swelling characteristics were similar to those of corn starch.

Key words: Thladiantha dubia Bunge tuber, starch, extraction process, physical and chemical properties