Method for preparing crosslinking-oxidization jointly modified starch

Abstract

The invention discloses a method for preparing crosslinking-oxidization jointly modified starch, which comprises the following steps: (1) adding water into rice starch to prepare starch milk, adding 0.01 to 0.03 percent of NaCl into the starch milk and uniformly mixing the starch milk and the NaCl; (2) adjusting the pH value of the mixture to 9.0 to 11.0, adding epoxy chloropropane in an amount which is 0.1 to 0.9 percent of the weight of the rich starch for performing reaction at 20 to 50 DEG C for 2 to 5 hours, adjusting the pH value of the mixture obtained after reaction to 6.0 to 7.0 to obtain crosslinked rice starch; (3), adjusting the reaction temperature to 30 to 50 DEG C and adjusting the pH value of the crosslinked rice starch to 8 to 10; and (4) adding sodium hypochlorite solution of which the mass concentration of active chlorine is 7 to 10 percent in an amount which is 40 to 50 percent of the weight of the rice starch for performing further reaction for 20 to 40 minutes, removing excessive chlorine in the reactants by using solution of sodium bisulfate, adjusting the pH value of the resulting product to 6.0 to 6.5, filtering the resulting product, washing the resulting product and drying the resulting product. The crosslinking-oxidization jointly modified rice starch has a viscosity of more than or equal to 1,800cP, a shearing stress at 30 DEG C of up to 1,200dy / cm2, high swelling performance, high transparency and stability.

Description

technical field [0001] The invention relates to a preparation method of compound modified starch, in particular to a preparation method of cross-linked oxidized rice starch which has both the performance of oxidized starch and the performance of cross-linked starch by using rice as a raw material. Background technique [0002] The main component of rice is starch (accounting for more than 80%). Restricted by raw materials, cost and people's consumption level, rice starch and its derivatives started relatively late and developed slowly, accounting for a very small proportion in the industry of starch and its derivatives. [0003] Some characteristics of rice starch itself (such as low viscosity, easy retrogradation, etc.) limit its application range. The introduction of functional groups into starch through chemical or physical denaturation to change its physical and chemical properties is beneficial to expand the application range of starch. Modified starch can be widely us...

AI Technical Summary

Problems solved by technology

However, the single modified starch itself still has some disadvantages, such as low viscosity of oxidized starch, not resistant to shearing, and poor swelling and low transparency of cross-linked starch.