Study On The Properties Of Rhizoma Alismatis Starch And Its Octenyl Succinic Anhydride Modified Starch

Rhizoma Alismatis, the tubers of Alisma orientalis (Sam.) Juzep., was a rich resource in starch.Rhizoma Alismatis was mainly used in clinic and health food.It has not been researched about Rhizoma Alismatis starch until now. This experiment studied on extraction, properties of Rhizoma Alismatis starch as well as the properties of Octenyl Succinic Anhydride modified Rhizoma Alismatis starch.in order to promote the Rhizoma Alismatis comprehensive utilization.First, this experiment optimized several essential steps of Wet Milling Processing to extract Rhizoma Alismatis starch, which affected Rhizoma Alismatis starch quality.It showed that the most output and the least protein content of starch were extracted by steeping in 0.02mol/L saturated limewater (pH=10), milling degree with 15μm and wiping off protein under alkali condition.Secondly, Rhizoma Alismatis starch granules were observed by scanning electron microscopy(SEM), Optical Microscope, and determined the solubility, swelling capacity, RVA viscosity profiles ,the paste properties of Rhizoma Alismatis starch. The results showed that: (1) Rhizoma Alismatis starch granules were mainly ellipse or rotundity, smooth surface, single or plural grain and its diameter range was 2.50～13.75μm.(2) Rhizoma Alismatis starch had typical Second Expansion Process ,so it belonged to the restrictive type (3) From RVA viscosity profiles, the gelatinization temperature of Rhizoma Alismatis starch was higher than potato starch, lower than corn starch, peak viscosity,break down were higher than corn starch, lower than potato starch,pasting time was same as corn starch;gelatinization temperature raised and peak viscosity reduced under acidic condition; gelatinization temperature and peak viscosity both recuced under alkali condition; gelatinization temperature raised, peak viscosity and final viscosity increased with sucrose and NaCl.(4) The paste of Rhizoma Alismatis starch was short paste, Non-Newtonian Flows. The transparency of Rhizoma Alismatis starch paste was lower than corn and potato;the retrogradation and the freeze-thaw were between potato and corn;the retrogradation and freeze-thaw became better with sucrose and citric acid, but it was opposite with NaCl.Finally, Octenyl Succinic Anhydride modified Rhizoma Alismatis starch (Rhizoma Alismatis OSA-Starch) granules were observed by Optical Microscope.The reaction efficiency, swelling capacity, RVA viscosity profiles, and the paste properties which including transparency, freeze-thaw, retrogradation, emulsification and theological properties were determined. The results showed that: (1) the OSA-statch granules surface had minor corrosion; the enzymolysised OSA-starch granule surface appeared remarkable corrosion. (2)The degree of the substitute and reaction efficiency of Rhizoma Alisrnatis OSA-starch was higher than the potato and corn under the same reaction conditions. (3) From RVA viscosity profiles of Rhizoma Alismatis OSA-starch, the gelatinization temperature lowered, the peak viscosity increased with the degree of substitute increased.(4)while the degree of substitute increased, the swelling capacity was gradually increased, the transparency and retrogradation got better, and the freeze-thaw deteriorated.The transparency increased under sucrose condition; the retrogradation lowered by adding a small amount of sucrose, but it gradually changed for the better along with the increased addition. The transparency lowered under citric acid condition; the retrogradation became worse by adding a small amount of sucrose, but the paste was very stable, even there was no retrogradation when up to a certain amount. Add salt would reduce the transparency of the paste, and aggravate the retrogradation of the paste. (5) Rhizoma Alisrnatis OSA -starch paste belonged to Non-Newtonian Flows and its consistency coefficient (k), viscosity behavior index (n) increased with the increased degree of substitute.(6) The emulsification of Rhizoma Alismatis OSA-starch changed like parabola with the increased degree of substitute; the emulsification was better while the OSA-starch content was 1.2% and the homogenization time was 1 min. (7) When the Dextrose Equivalent (DE%)increased, the gelatinization temperature oftbe RVA viscosity profiles of enzymolysised Rhizoma Alismatis OSA -starch raised first, then decreased gradually, peak viscosity and break down minished.