Preparation And Investigation Of High Absorption Property Cross-linking Non-crystalline Porous Starch

Starch and modified starch have increasingly being used in the food, pharmaceutical, paper making, textile, chemical industry, environmental protection industry. Limited to the polycrystal system of starch, the modified efficiency is low. The non-crystalline process destroy the crystal area in raw starch. The internal original ordered arrangement in starch is disturbed. The modified chemical reagent can react with starch much more easily. The industrialization of non-crystalline starch has a wide development prospect.The non-crystalline modified porous corn starch with high adsorption performance was prepared through non-crystallization, esterification and enzymolysis process. The kinetics of raw starch and non-crystalline starch was studied through wet-crosslinking process. The effection of non-crystalline process on subsequent reation rate was investigated.The results showed that when reaction temperature was50℃, crosslinking agent dosage was5%, reaction time was2h, the settlement area of product was0.45mL, and the crosslinking degree was greatly improved. The conditions of dry esterification were as follows:the starch concentration was30%, esterification agent dosage was10%, urea dosage was5%, esterification temperature was150℃, reaction pH was5.0, reaction time was2h. Compared with raw corn starch, the degree of substitution of non-crystalline corn starch was greatly improved. After the non-crystallization and esterification process, the solubility of starch declined slightly, the specific volume increased, the particle was not broken, and the paticle size increased. The crystal area was destroyed with a certain degree decline of crystallinity.The non-crystalline modified porous corn starch was prepared through enzymolysis based on non-crystalline esterified corn starch. The results of single element and orthogonal experiments showed the best hydrolysis conditions were:15%starch concentration,2.0%enzyme dosage, reaction temperature45℃, pH4.4, reaction time12h.Under these conditions, the water adsorption was178%and the oil adsorption was134%. The water and oil adsorption of the product were more than twice as much as the raw com starch was. Compared with ordinary corn porous starch, the water absorption was increased by31%and the oil absorption increased by28%. Compared with raw com starch, the solubility, specific volume, bet surface area and paticle size of the product increased. There were many pores in different sizes on the paticle surface and extended to the interior paticle. The crystallinity degree almost unchanged after enzymolysis process.The wet process kinetics of cross-linking reaction were studied based on raw com starch, non-crystalline com starch, raw cassava starch and non-crystalline cassava starch. The contrast results of kinetics data showed that non-crystalline process can effectively improve the reaction activity.