| In this paper, octenyl succinic anhydride modified starch (OSA starch)was from differentcompany and the rice flour was extruded. The physicochemical properties, digestibilityproperties and enzymatic properties of the samples were studied. Also,the productiontechnology of extreme high maltose and high-protein rise flour producing by the extrudedrice flour was studied. The content and results of the research were as follows:1. The physicochemical properties of six different sources of OSA starch weredetermined. The result indicated that all the samples had good water solubility. The DE valuehad a big difference, some were less than5and the others were more than20. There weresome differences among the samples in pH value and conductivity. For example, the pH valueof sample5and6was lower than others which was4.10or so. However, the conductivity andash content of sample6was higher than others. As its viscosity was lower under the sameconcentration, it was suitable for preparation of high concentration solution. Besides, theemulsibility of it was good, which could decrease the surface tension of water. Sample5hadlow DE value but had similar characters with sample6.2. Heat resistance, acid fastness and the effect of sterilization of three samples withlower DE value were studied, results showed that: heat resistance and acid fastness of thesamples were good. When the pH was2, the samples started to change at70℃. With theincrease of the temperature, the change was more obvious. This change accorded with thepyrolysis kinetics. When the pH was3, the samples started to change until80℃and90℃.However, when the pH was4or5, they were stable. The effect of sterilization on the structureof the samples was relatively large especially in pH of2.The change was not obvious in pH of3to6.3. The digestion and enzymolysis properties of the OSA starch were studied bydetecting changes of reducing sugar, sugar composition and surface tension. The high DEvalue products were produced by low DE value in the method of enzymolysis. Resultsshowed that the best conditions were as follows: pH6.0, temperature50℃. The DE valuewould be higher than25both in the two sample1and2after1hour’s enzymatic hydrolysis with the amount of enzyme1DP°/g. The amount of enzyme could decrease with the increaseof enzymatic hydrolysis time. The DE value would be higher than25after2hour’s enzymatichydrolysis with the amount of enzyme0.44DP°/g. But the DE value of sample5could notreach the requirement no matter how to increase the amount of β-enzyme and the extension oftime unless adding some pullulanase. That was because the branched chains were closed tothe non-reducing end of the modified starch molecule and this structure impeded the action ofβ-enzyme. The NMR of sample5and its hydrolysates showed that the native starch of sample5contained branched chain, the branched chain and anhydrous glucose units of octenylsuccinic acid group were closed to the non-reducing end of the modified starch.4. The digestion and enzymolysis properties of the expanded rice flour were studied,fitting it’s digestion and Michaelis-Menten kinetics equation. The production of extreme highmaltose and high-protein rice flour from the expanded rice flour were carried out initialexperiments, through single factor and orthogonal experiment to optimize the enzymolysisprocess parameters, which were as follows: temperature55℃, pH5.5, the amount ofβ-amylase3.63DP°/g and the amount of pullulanase0.36ASPU/g, the proportion of the twoenzymes was4and enzymolysis time was23hours. In this condition, the high maltose liquidwith its DE value56.93and the high-protein rice flour which reached39.53%of the proteincontent were gotten... |
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