Double Modification Of Waxy Maize Starch And Its Application In Powder Oil Microcapsules

The dissertation mainly studies that the waxy corn starch as the raw material was prepared the double-modified starch of waxy maize by the processes of oxidation and esterification and got the technique, studied the structure and basic properties of the double-modified starch, and conducted the research to its application in the powder oil microcapsules. The main results are as follows:1. The preparation conditions of the double-modified starch of waxy maize.The oxidized starch was obtained from waxy corn starch by oxidation with hydrogen peroxide. In single factor experiments, the effects of the varieties of factors on the carboxyl content are studied, including pH value, reactive temperature, the quantity of hydrogen peroxide and reactive time. On this basis, determined the optimization technique through the orthogonal experiment:the pH value was 8.0, the reactive temperature was 50 "C, the quantity of hydrogen peroxide was 16.0mL and reactive time was 4.Oh, may make the carboxyl content of modified starch about 0.099%.The oxidized starch, which was the highest carboxyl content, was esterified by octenyl succinic anhydride. In single factor experiments, the effects of the varieties of factors on the degree of substitute (DS) are studied. On this basis, determined the optimization technique through the orthogonal experiment:the pH value was 8.5,the reactive temperature was 35℃,concentration of the oxidized starch was 40%and reactive time was 4.Oh, may make the DS of waxy maize oxidized starch esters about 0.021.2. Properties of the double-modified starch of waxy comChemical structure, properties of granules and paste of native starch, oxidized starch and oxidized starch esters were compared, the conclusions were as follows:Oxidized waxy corn starch, the new absorption peaks generated at 1750cm-1 by the carboxyl stretching vibration of C=O to determine the-COOH introduced into the. waxy com starch; further esterified waxy corn oxidized starch, the new absorption peaks generated at 1590cm-1 as the peaks of the carbonyl, which was identified that the carboxyl groups was successful introduced into waxy corn oxidized starch.Modification of waxy corn starch mainly occurs in the amorphous regions of the granules. The crystal structure of the granules remained the native starch. But the crystallinity decreased, which indicated that modification also occurs in the crystal regions.Compared with the native starch, the paste properties of the waxy maize oxidized starch esters changed greatly. Viscosity of the paste decreases, freeze-thaw stability increases, the retrogradation stability increases and the transparency has been greatly improved. With increasing of DS, the properties improve. The results show that the double-modified starch of waxy maize has the dual advantages of the Oxidized starch and esterified starch, which will adapt to the development of industry.3. The application of the double-modified starch of waxy maizeThe application of waxy maize oxidized starch esters as wall material in the powder oil microcapsules was researched, and it can be instead of the expensive sodium caseinate. In single factor experiments, it determined that the dosage of oxidized starch esters in the microcapsules powder:11%. In these dosages, the embedding rate improved and the surface oil decreases. By the evaluations of sensory and storage stability and SEM, the product prepared with the oxidized starch esters has similar properties to the sodium caseinate. So the double-modified starch of waxy maize has extensive application value.