Pressure-temperature phase transition diagram for wheat starch
Pressure-temperature phase transition diagram for wheat starch
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DOI：
10.1021/jf000497w
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发表时间：
2001-02-01
影响因子：
6.1
通讯作者：
Gervais, P
中科院分区：
文献类型：
--
作者：
Douzals, JP;Perrier-Cornet, JM;Gervais, P
小麦淀粉悬浮液在水中（5%干物质）承受不同的压力（0.1- 600mpa）和温度（-20至96度）15分钟。通过显微测量颗粒的双折射损失来测量处理后的糊化率。该方法以前是用差示扫描量热法校准的。发现异胶化曲线与展开蛋白质的压力-温度（P-T）图非常相似。分析结果首先考虑了与dT/dP曲线位移相关的热力学方面。根据已经给出的蛋白质方程，小麦淀粉的P-T糊化图将显示不同种类的热贡献，表明吸热、热或放热融化反应。其次，作为一个实际的结果，这些先前的P-T区域对应于特定的糊化条件，由淀粉膨胀指数测量的水化评价证实了这一点。根据压力-温度条件，糊化会涉及水化。与在常压下的热处理相比，降低压力和温度导致完全糊化，水化较少。提出了一种基于能量法的水化模型。
Wheat starch suspensions in water (5% dry matter) were subjected to various pressures (0.1-600 MPa) and temperatures (-20 to 96 degreesC) for 15 min. The gelatinization rate was measured after treatment by using microscopic measurements of the loss of birefringence of the granules. This method was previously calibrated by differential scanning calorimetry. Curves of isogelatinization were found to be quite similar to a pressure-temperature (P-T) diagram of unfolding proteins. Results were first analyzed by considering the thermodynamic aspects related to the dT/dP curve shifts. On the basis of equations already shown for proteins, the P-T gelatinization diagram of wheat starch would shaw different kinds of thermal contributions, suggesting endothermic, athermic, or exothermic melting reactions. Second, as a practical consequence, these previous P-T areas corresponded to specific gelatinization conditions as confirmed by hydration evaluation measured by starch swelling index. Depending on the pressure-temperature conditions, gelatinization would involve hydration. Lowering the pressure and temperature resulted in a complete gelatinization with less hydration in comparison with a thermal treatment at atmospheric pressure. A hydration model based on an energetic approach was proposed.