Gel-chromatography fractionation and thermal characterization of rice starch affected by hydrothermal treatment
Gel-chromatography fractionation and thermal characterization of rice starch affected by hydrothermal treatment
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水热处理对大米淀粉的凝胶色谱分离和热表征
作者：
Shin Lu;Ching;C. Lii
以高直链淀粉TNS 19和糯质TCW 70两个水稻品种为材料，研究了水热处理后稻米淀粉的热行为和分子再分布。处理条件包括在40°C下浸泡2小时，并分别在0和18psi蒸汽压力下汽蒸10或20分钟。对于未处理的TNS 19和TCW 70，通过差示扫描量热法测量，分别在65和72°C下观察到较低温度的吸热。水热处理引起的转变，以较高的糊化温度和较低的转变焓变化。同时，仅TNS 19在115°C下观察到较高温度的吸热。支链淀粉的热降解明显导致大分子量的减少和小分子量的增加。将热湿处理的米粉与水混合并加热至糊化，然后在4或25°C下储存。储存过程中，转变焓随着转变峰温度的降低而增加。这些结果表明，老化的程度增加与存储时间为两个品种的水稻。在4°C储存时，从第7天起在蜡质TCW 70中观察到更高的转变焓，尽管在25°C储存时，在整个21天内没有观察到类似的变化。
Two rice cultivars, high amylose TNS 19 and waxy TCW 70, were selected for a study of thermal behavior and molecular redistribution of rice starch after hydrothermal treatments. The treatment conditions included soaking for 2 hr at 40°C and steaming for 10 or 20 min at 0 and 18 psi steam pressure, respectively. Lower temperature endotherms, measured by differential scanning calorimetry, were observed at 65 and 72°C for the untreated TNS 19 and TCW 70, respectively. The hydrothermal treatments caused a shift to higher gelatinization temperatures and lower transition enthalpy changes. Simultaneously, a higher temperature endotherm was observed at 115°C for TNS 19 only. The thermal degradation of amylopectin apparently resulted in a decreased amount of large molecules and an increased amount of smaller molecules. The heat-moisture-treated rice flour was mixed with water and heated to gelatinization and then stored at 4 or 25°C. The transition enthalpies increased with concomitant decreases of transition peak temperatures during storage. These results indicate that the extent of retrogradation increases with storage time for both rice cultivars. At 4°C storage, a higher transition enthalpy was observed in waxy TCW 70 from day 7, although at 25°C storage, no similar changes were observed throughout 21 days.
Kanno.t.；Azuma.Y.；Maekawa.M：酶。
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