| Starch is the richest regenerate resource from the biosynthesis in nature. Owing to its vast territory, China has extremely plentiful potato resources, however, most natural starch can't be fully utilized. In order to improve the added value of starch products, we could develop the modification technology of starch in accordance with its structure, physicochemical properties and the requirements for application. Among them, carboxymethyl starch (CMS), crosslinking starch (CS) and crosslinking-carboxymethyl starch (CCMS) have attracted many domestic and foreign researchers'attention due to their excellent performances and wide range of applications.Firstly, this paper fully investigated the main reaction factors effect on the degree of substitution(DS) and the performances of paste solution in the process of CMS synthesis from the view of molecular structure and properties. The results show that the transparency and viscosity of CMS paste solution is not only influenced by the degree of carboxymethylation, but also influenced by the etherification uniformity. In addition, the extent of starch molecular degradation and particle breakage plays an important role to the viscosity of the paste solution. Through the optimization of technological design, different CMS products were prepared, of which the DS is up to 0.8601, the transparency is up to 92.2% and the viscosity is up to 1562mPa.s. Compared with potato starch, the transparency and viscosity of those paste solution were respectively increased by 56.8% and 87.7%. After freeze-thawing 20 times or storing at room temperature for 30 days, the transparency difference of the CMS paste solution is respectively 3.7% and 5.8%; the viscosity difference of them is respectively 84mPa.s and 126mPa.s, which greatly improved the freeze-thaw resistance and the stability of storag e (ageing resistance) of natural starch.With the development of society, human needs are increasingly perfecting. Single modified starch can not meet the application requirements of all walks of life. Secondly, Using firstly crosslinking and then carboxymethylation technology, we prepare CCMS products with moderate-crosslinking potato starch(swelling degree is 16.44). And then the physical and chemical properties of CCMS were mainly investigated: In strong acidic conditions(pH=3), its paste solution transparency and viscosity just drop 6.1% and 112mPa.s. After potato starch,the CMS and CCMS paste solution were cooked for 15 minutes with boiling water bath, the viscosity of the first two samples paste solution were reduced by 398 mPa.s and 968mPa.s, but the CCMS paste solution viscosity had little change, only to fall 59mPa.s. The paste solution liquidity index (PVI) of CCMS, which was prepared with crosslinking starch (swelling degree is 16.44), can reach to above 0.9, its anti-shearing effect is greatly improved, and the "shear thinning" phenomenonexist existing in potato, CMS and CMC also be basically eliminated. In conclusion, CCMS has better dual compound performances than the natural starch, CS and CMS, which can further broaden the application of starch products.In order to understand the chemical structure and properties of starch and starch derivatives clearly and intuitively, this paper fully characterize the molecular structure, particle morphology, pasting properties and aggregation state of particles on each products by FTIR, SEM, DSC , XRD and other chemical characterization method. From the chemical point of view, this paper also verifies the relationship between structure and properties of products and the advantages of structure and properties of CCMS. The results mentioned above will provide theoretical guidance for developing more superior performance products even triple or multiple compound performances products.
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