Research On The Carboxymethyl Cellulose Grafted Azo Pigment:Preparation And Anti-reduction Property

In recent years,the food safety issues have become increasingly prominent,and the safety of synthetic pigments have been questioned.Synthetic pigments are widely used in food,cosmetics,etc.However,a large number of studies have shown that the synthetic azo dyes in human body are easy to degrade to aromatic amines,endangering people's health seriously.Natural pigments have poor stability and high production cost,therefore,we should enhance anti-reduction property of modified azo dyes which provide people with a more secure edible pigment is imminent.Sodium carboxymethyl cellulose(CMC)is a kind of water soluble polymer derivative containing-OH and-COOH.It is non-toxic,good biocompatible,most importantly,sodium carboxymethyl cellulose is difficult to be degraded and absorbed due to its large molecular weight,so it is selected as the carrier of edible azo dye.This paper design the following two routes to modify the azo pigment:1 Sodium carboxymethyl cellulose is oxidized to dialdehyde cellulose,which react with lysine to synthesize Schiff base(DCMC-Lys),by Ca and Zn ions respectively,to synthesize DCMC-Lys-Ca-azo pigment and DCMC-Lys-Zn-azo pigment.We select sunset yellow,lemon yellow,carmine,amaranth azo pigment,though two path,to synthesize eight kinds of polymer pigments.The content of calcium and zinc in the polymer pigment are measured by ICP.And IR,SEM,~1H NMR are used to characterize the structure,the results show that the sodium carboxymethyl cellulose is grafted with azo pigment.NADH is used to reduce the polymeric pigment in the citric acid buffer,and the reduction rate is determined by UV.The results show that the modification can improve the ability of anti-reduction property.2 Mannich reactions of dialdehyde cellulose,azo pigment and amine(morpholine,carboxymethyl chitosan)are carried out in aqueous solution.Four kinds of CMC grafted azo dyes are prepared by one pot method,and the products are characterized by IR and ~1H NMR.The results show that CMC is grafted with azo pigment.NADH is used to reduce the pigment in the citric acid buffer,and the reduction rate is determined by UV.The results show that the modification can improve the ability of anti-reduction property.