Ultrasound and shear stress effects of lipid crystallization in nano-sized particles

用微束x射线衍射研究了一个粒子的结晶过程。三叶草苷作为油包水（O/W）乳状液的油相。制备了以下粒径：100海里;500 nm， 1微米，30微米和50微米，在100 W， 20 kHz的条件下加入超声辐照。照射时间为2秒。观察结果如下：(i)超声（US）照射：在室温下，有US的样品结晶速度比没有US的样品快。(2)结晶速率的尺寸效应：对于1、30、50微米大小的微米级颗粒，US对结晶有促进作用，而对于100、500微米大小的纳米级颗粒，US对多晶型结晶的出现没有明显的影响。(3)US辐照对结晶形貌的影响：US促进的结晶始终是稳定的多晶型、β型。这一结果与块状脂肪（iv）脂肪晶体的结果吻合较好……更多的化晶机制：在球晶中观察到晶体从中心到边缘的生长。我们认为具有随机取向的多晶/中晶被驯服在球晶的中心。晶体沿脂肪加链填充方向生长。由于薄层晶体之间的几何选择，层状平面沿径向由中心位置向外方向定向。这些晶体生长在棕榈油和1,3-二棕榈酰-2-油基-sn-甘油（POP）的球晶中可见。由于在不同的脂肪分子之间观察到相同的形态，这种机制在脂肪球晶中被普遍接受。(5)关于油滴结晶的剪切效应，由于我们无法购买剪应力机，没有做过实验。买这台机器的钱太少了。但是，我们正在努力生产这台机器，它将在今年秋天完成。我们将尝试测量剪切应力对油滴结晶的影响

Microbeam X-ray diffraction study of crystallization in one particle has been done. Trilaurin was used as oil phase of oil-in-water (O/W) emulsion. The fallowing particle sizes was prepared; 100 nm; 500 nm, 1 micro-meter, 30 micrometer and 50 micrometer The ultrasound irradiation was added in the condition of 100 W, 20 kHz. The irradiation time was 2 sec. The following results were observed;(i) Ultrasound (US) irradiation: Crystallization of the sample with US was faster than that without US at room temperature.(ii) The size effect of the rate of crystallization: As for micro-meter sized particles, 1, 30 and 50 micrometer, crystallization is promoted by US, while no remarkable effect was observed with nano-meter sized particles, such as 100 and 500 mar-meter diameter(iii) US irradiation effect for the appearance of polymorphic crystallization: Crystallization promoted by US was always stable polymorph, beta form. This result is quite good agreement with that of bulk fat(iv) Fat crystal … More lization mechanism: Crystal growth from center to edge was observed in spherulite. We think that poly/mid with random orientations tamed at the center of spherulite. Than, crystal growth proceeded along the direction of fatty add chain packing. As a result of geometrical selection among thin layer crystals, lamellar planes were directed along the radial direction from the center position to outer position. These crystal growth have been seen in the spherulites of palm oil and 1,3-dipalmitoyl-2-oleoyl-sn-glycerol, POP. Because the same morphology was observed between different fat molecules, this mechanism wane generality accepted in the spherulite of fat.(v) As for the shear effect for the crystallization of oil droplets, no experiment has been done because we cannot purchase the shear stress machine. It is too small money to buy the machine. However, new we are trying to produce the machine and it will be completed in this autumn. We will try measure the shear stress effect for crystallization in oil droplet Less