a Oniris , UMR CNRS 6144 GEPEA , Nantes , France.
b University of Natural Resources and Life Sciences , Vienna , Austria.
J Microencapsul. 2019 Jan;36(1):72-82. doi: 10.1080/02652048.2019.1599456. Epub 2019 Apr 9.
Microparticles made from hydrogenated sunflower oil without essential oil and with different essential oil concentrations (75-300 g/kg; g of essential oil per kg of microparticles) were stored for 1 or 2 months at 25 or 37 °C. Before and after storage the essential oil concentration, flowability, optical appearance, melting behaviour and crystalline structure of the microparticles were investigated. Essential oil recovery, melting behaviour and crystalline structure were identical for the essential oil containing microparticles and were not affected during storage. The surface structure of the microparticles varied with their essential oil concentration. While the particles containing 75 g/kg essential oil were covered by erect fat crystals, those with 225 g/kg and higher were mostly smooth with some round shaped dumps. However, the surface of all essential oil containing microparticle batches had reached their final stage after production already and did not change during storage. Microparticles without essential oil presented two melting peaks; all microparticle batches with essential oil had one peak. Peaks in the X-ray scattering powder diffraction signal of the essential oil-free microparticles after production can be associated with the α-form of the hydrogenated vegetable oil. During storage, a conversion of the α-form to the stable β-form was observed. Microscopy showed that these microparticles also developed strong fat crystals throughout storage. The triglycerides in microparticles with essential oil seem to directly take on the stable β-form. The formation of robust microparticle agglomerates during storage was prevalently observed for the fat crystal forming product batches, meaning the products without or with low essential oil concentration.
由氢化葵花籽油制成的微粒子，不含精油且精油浓度不同（75-300g/kg；每公斤微粒子中的精油克数），在 25 或 37°C 下储存 1 或 2 个月。在储存前后，研究了微粒子的精油浓度、流动性、光学外观、熔融行为和晶体结构。含精油的微粒子的精油回收、熔融行为和晶体结构相同，在储存过程中不受影响。微粒子的表面结构随其精油浓度而变化。虽然含有 75g/kg 精油的粒子被直立的脂肪晶体覆盖，但含有 225g/kg 及更高浓度精油的粒子则大多光滑，有些呈圆形凹陷。然而，所有含精油的微粒子批次的表面在生产后已经达到最终阶段，在储存过程中不会发生变化。不含精油的微粒子呈现两个熔融峰；所有含精油的微粒子批次都有一个峰。生产后无精油微粒子的 X 射线散射粉末衍射信号中的峰可以与氢化植物油的α形式相关联。在储存过程中，观察到α形式向稳定的β形式转化。显微镜显示，这些微粒子在整个储存过程中也形成了强烈的脂肪晶体。含精油的微粒子中的甘油三酯似乎直接采用稳定的β形式。在储存过程中，形成坚固的微粒子团聚体主要观察到在形成脂肪晶体的产品批次中，这意味着不含精油或精油浓度低的产品。
