Studies On The Extraction And Properties Of Taro Starch

Taro (Colocasia esculenta (L.) Schott) is an abundant yet underutilized resource compared with yam, sweet potato, and potato, which greatly limits its use. Therefore, a further recognition of its potential and exploitation is of great significance.The extraction of taro starch was studied. Single factorial experiments were performed to probe the effect of marinating temperature, marinating time, pH value and clearance of colloid grind on the extraction rates of taro starch. The optimum condition was obtained as follows: clearance of colloid grind at 5.0μm, pH value at10.0, marinating time at 70 min and marinating temperature at 20℃ .Under this condition, the extraction rates was 80.22% . During the process of extracting of taro starch.whiteness of taro starch was also studied. The optimum condition was obtained as follows: The addition of Na2SO3 at 0.01‰ and the addition of Vc at 0.02‰. Under this condition, the whiteness of taro starch was 91.8%.The physical and chemical properties of taro starch were systematically studied, including granule morphology, X-ray diffraction pattern, molecular distribution, gelatinization and paste viscosity. The concentration, pH and other ingredients added such as sugar showed different effects on the starch gelatinization and paste viscosity properties. Highly purified amylopectin and amylose from taro starch could be obtained by re-crystallization. Taro amylose and amylopectin exhibited blue values of 1.18 and 0.20 and λmax of I-KI blue color at 614nm and 587nm, respectively. Amylose content of taro starch was 14.7%. Results of gel permeation chromatography (GPC) showed that taro amylopectin molecular weight had a wide distribution in the GPC profile. For , the following sequence was observed: taro amylase> taro amylopectin. As regards to dispersion, taro amylopectin > taro amylose. For taro amylopectin, both the dispersion and the proportion of long-branch chains were greater than those of short-branch chains.The production technology of oxidized starch was then studied. Single factorial experiments were performed to probe the effect of the addition quantity of effective chlorine, reaction time, pH and temperature on the whiteness and carboxyl of the resulting oxidized taro starch. Orthogonal experiments were then carried to obtain the optimum oxidative condition : dropping rate at0.80mL/min, the addition of effective chlorine at 1.5%, pH value at 8.0,reaction temperature at 35℃ , reaction time at 2.0h. Under this condition, the whiteness and the carboxyl content of taro starch was 95.8% and 0.120%, respectively.The physicochemical characteristics and structures of oxidized taro starch was analyzed by Micro Visco-Amylo-Graph, DSC, IR and X-ray diffraction, using natural taro starch as the control . The pasting temperature of oxidized taro starch changed, compared with the control. Both experimental facts implied that new functional groups had been derived. The reaction mainly occurred in the amorphous region of the molecular structure.Application test of oxidized taro starch prepared by this experiment was carried out, which indicated that oxidized taro starch can be used to cosmetics.