Isothermal crystallization of hydrogenated sunflower oil:: I -: Nucleation
Isothermal crystallization of hydrogenated sunflower oil:: I -: Nucleation
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DOI：
10.1007/s11746-998-0172-y
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发表时间：
1998-10-01
影响因子：
2
通讯作者：
Añón, MC
中科院分区：
文献类型：
--
作者：
Herrera, ML;Falabella, C;Añón, MC
利用偏光显微镜和激光成核装置研究了向日葵籽油在两种不同氢化条件下的成核动力学。当使用激光时，观察到的诱导时间短于通过显微镜测量的诱导时间。激光法被认为是更灵敏和准确的。两种不同的结晶行为被发现取决于样品的化学组成。具有高含量的反式三油酸甘油酯的样品在接近熔点的温度下以β形式结晶。它们根据结晶温度表现出β '和β形式，就像天然半固体脂肪如棕榈油一样。具有高含量的混合油酸和反油酸三酰基甘油的样品即使在接近熔点的温度下也以β '形式结晶，并且它们在本研究中使用的条件下不显示β形式。两种氢化条件下氢化向日葵籽油的成核活化自由能均较低。结果表明，向日葵籽油的成核过程是一个Cast过程，且成核初期需要较低的过冷度。这些结果对于工艺设计也很重要，特别是对于在生产线末端脂肪应完全结晶的工艺。
Nucleation kinetics of sunflower seed oil, which was hydrogenated under two different conditions, was studied by means of a polarized light microscope and an optical setup with a laser as the light source. When the laser was used, observed induction times were shorter than the ones measured by the microscope. The laser method was found to be more sensitive and accurate. Two different crystallization behaviors were found depending on the chemical composition of the samples. Samples with high content of trielaidin crystallized in the beta form at temperatures close to the melting points. They exhibited both beta' and beta forms depending on crystallization temperature, as happens in natural semisolid fats such as palm oil. Samples with high content of mixed oleic and elaidic triacylglycerols crystallized in the beta' form even at temperatures close to the melting points and they did not show beta form under the conditions used in this study. Activation free energies of nucleation for hydrogenated sunflower seed oil were low for the two hydrogenation conditions. It can be concluded that nucleation of sunflower seed oil is a Cast process and initially needs low supercooling. These results are also important from a practical point of view for processing design, especially in regards to processes in which fats should be completely crystallized by the end of the production line.