Center of Engineering, ZIW/TVT, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany.
Chem Phys Lipids. 2010 May;163(4-5):390-6. doi: 10.1016/j.chemphyslip.2010.03.005. Epub 2010 Mar 25.
The effect of lauric acid and low-HLB sucrose esters (L-195, S170) on the isothermal crystallization of coconut oil was investigated by differential scanning calorimetry. The fundamental crystallization parameters, such as induction time of nucleation and crystallization rate, were obtained by using the Gompertz equation. The Gibb's free energy of nucleation was calculated via the Fisher-Turnbull equation based on the equilibrium melting temperature. All additives, investigated in this work, proved to have an inhibition effect on nucleation and crystallization kinetics of coconut oil. Our results revealed that the inhibition effect is related to the dissimilarity of the molecular characteristics between coconut oil and the additives. The equilibrium melting temperature (T(m) degrees ) of the coconut oil-additive mixtures estimated by the Hoffman-Weeks method was decreased with the addition of lauric acid and increased by using sucrose esters as additives. Micrographs showing simultaneous crystallization of coconut oil and lauric acid indicated that strong molecular interaction led to the increase in lamellar thickness resulting in the T(m) degrees depression of coconut oil. The addition of L-195 modified the crystal morphology of coconut oil into large, dense, non-porous crystals without altering the polymorphic occurrence of coconut oil. The enhancement in lamellar thickness and crystal perfection supported the T(m) degrees elevation of coconut oil.
通过差示扫描量热法研究了月桂酸和低 HLB 蔗糖酯（L-195、S170）对椰子油等温结晶的影响。通过使用 Gompertz 方程获得了基本结晶参数，如成核诱导时间和结晶速率。根据平衡熔融温度，通过 Fisher-Turnbull 方程计算了成核的吉布斯自由能。在这项工作中研究的所有添加剂都被证明对椰子油的成核和结晶动力学具有抑制作用。我们的结果表明，抑制作用与椰子油和添加剂之间分子特性的差异有关。通过 Hoffman-Weeks 方法估算的椰子油-添加剂混合物的平衡熔融温度（T（m）°）随月桂酸的添加而降低，而用蔗糖酯作为添加剂则增加。显示椰子油和月桂酸同时结晶的显微照片表明，强烈的分子相互作用导致了片层厚度的增加，从而导致椰子油的 T（m）°降低。L-195 的添加将椰子油的晶体形态改造成大而密集、无孔的晶体，而不改变椰子油的多晶型发生。片层厚度的增加和晶体完整性的提高支持了椰子油的 T（m）°升高。
