Controlled Depolymerization Of Chitosan By Enzymolysis And Derivatized To Nitrite-free Curing Color Agent For Meat

In order to obtain nitrite-free glycosylated hemoglobin pigments of high stability, strongcoloring and good solubility, the study controllably degrades CTS to COS by Homogeneousliquid chelation reaction and enzymatic hydrolysis. Then, prepare nitrite-free curing pigmentsfor meat by glycosylation between the COS and Hemoglobin-His coordination polymer.Meantime, research the application of new pigments in Cantonese sausage, which providedthe theory basis to applicate in the meat products and other food. Major researches are asfollows:1. Metal-coordination controlled degradation of chitosan by enzymatic hydrolysisPrepare CTS-Cu(II) chelate by homogeneous liquid chitosan chelation reaction, usingUV-visible spectroscopy to confirm the formation of chelate. The chelate characteristic peakis at234nm. Then, Optimize degradation conditions of cellulase on CTS-Cu(II) chelate,combined with ultrafiltration and spectrophotometry to compare degradation results. Resultsindicate that the chitosan degradation rate is proportional to the chelation rate of theCTS-Cu(II) chelate. When the CTS-Cu(II) chelate was degraded at a chelation rate of100%,most molecular weights of the products are under3kDa, and the yield is79.58%.2. Glycosylation of Hb-COS and preparing nitrite-free curing agentCOS was chosen to modify Hemoglobin with the reaction of glycosylation grafting, anduse Box-Benhnken model to optimize the reaction conditions. Results show that thesignificant of various factors affecting the glycosylation reaction is pH> temperature> time,and significant levels are0.1%,1%and5%respectively. Analyzing by response surface, theoptimum reaction condition to obtain stable glycosylation product is: time15.5min,temperature60.5℃, pH4.27. In security ligand screening experiments, first select differenttypes of ligands to coordinate with hemoglobin. Second, make glycosylation reaction betweenhemoglobin and oligochitosan. Results show that, the thermal stability of the product COS ofthe His ligand is close to the Sodium Nitrite, and far above coordination products withthiamine hydrochloride and Nicotinamide, which shows that His is the best substitute ofnitrite among Niacin, Nicotinamide and organic amine.3. Structure and property characterization of Hb-COS glycosylation modified product The structure of Hb-COS glycosylation modified product was characterized by UV、SDS-PAGE、FTIR and so on. Results of the UV show that coordination reaction andglycosylation reaction are two independent processes. SDS-PAGE shows that Hb combinewith COS producing large molecular weight products, and meanwhile, depolymerizing tosome small molecular weight compounds. Glycosylated hemoglobin’s infrared spectrumshows absorption characteristics of the polysaccharide, which further demonstratesglycosylated hemoglobin is a covalent bonding product.Properties, including photostability, thermostability, emulsifying property, emulsionstability, colourity and solubility are determined. Results show that, all the properties ofhemoglobin had been improved after glycosylation reaction. When contrast the glycosylationproduct between CTS and COS, we can found that the colourity and solubility ofCOS-glycosylation product are better than CTS, but because of CTS’s larger viscosity,CTS-glycosylation product’s emulsion stability is better than COS.4. Research of the nitrite-free curing agent application to cantonese sausageUse colorimeter L*a*b*measurement system to do colorimetric analysis of thesausage samples of different amount of new pigments, and chromaticity values are used todetermine the optimum amount of new pigments in Cantonese sausage. Results show that, theoptimal quantity of the nitrite-free pigments is0.2g/100g. Then, based on the nationalstandard, determine textures, acid value and basic composition of Cantonese sausages addingsodium nitrite and nitrite-free curing agent respectively. Results show that there is nosignificant difference in textures and basic ingredients between them. Dynamic measurementresults of acid value show that Cantonese sausage of nitrite-free curing agent is slightly higherthan the control group (sodium nitrite). However, among the experimental period of40days,acid values were less than4mg/g, conformed to the national standard.