Development of the basics for the production of defined amorphous - crystalline core-shell particles during convective drying

富含糖粉的干燥、处理和储存仍然是一项具有挑战性的任务。这是因为糖以不同的物理状态存在，即玻璃态、橡胶状和结晶态。物理状态对粉末的性质有很大的影响，例如对再水化行为和化学或生物稳定性的影响。特别是在相变过程中，粉末的性能可能会恶化，例如可能会发生颗粒结块。当糖在干燥过程中以受控的方式结晶时，粉末就会防止结块。然而，玻璃态下的复水性能和粉末稳定性(微生物生长、降解反应)较好。具有玻璃核心和结晶外壳的粒子将结合这两种物理状态的优点。然而，制造这种颗粒需要对工艺和产品有详细的了解。到目前为止，这种详细的知识仍然缺失。该项目旨在缩小这一差距。必须研究以下关系：1.确定玻璃化转变温度、粘点、结晶行为和糖组成之间的关系。研究干燥动力学和产品温度对糖混合物的结晶行为和物理状态的影响在本项目中，将研究糖混合物中的糖在对流干燥和定向再水化过程中如何与其物理状态相互作用和行为。该项目基于以下假设：应利用薄膜干燥、复水和储存来识别和研究糖类混合物干燥时的相关机理。除了干燥动力学，该项目还专注于所生产薄膜的稳定性和特性。应研究玻璃化转变如何影响储存过程中的稳定性(吸湿性、粘性、结晶度、分子流动性)。因此，应该更深入地了解混合糖在干燥和受控再水化过程中导致特定粉末特性的机制。

Drying, handling and storing of sugar-rich powders are still a challenging task. This is due to the fact that sugars exist in different physical states, namely the glassy, rubbery and crystalline state. The physical state has a significant impact on the powder properties, e.g. on the rehydration behavior and the chemical or biological stability. Especially during phase transitions, the powder properties can deteriorate, e.g. caking of particles can occur. When the sugars are crystallized in a controlled way during drying, caking of the powder is prevented. However, the rehydration properties and the powder stability (growing of microorganisms, degradation reactions) are better in the glassy state. Particles characterized by a glassy core and a crystalline shell would combine the advantages of both physical states. However, detailed knowledge of the process and the product is necessary to manufacture such particles. This detailed knowledge is missing up to now. This project aims at closing this gap. The following relationships must be examined:1. identifying the relationship between the glass transition temperature , the sticky point , the crystallization behavior and the composition of the sugar2. Investigation of the influence of the drying kinetics and the product temperature on the crystallization behavior and the physical state of the sugar mixturesIn this project, it shall be studied how sugars in sugar mixtures interact and behave with regard to their physical state during convective drying and targeted rehydration. The project is based on the following hypotheses:The mechanisms which are relevant when drying sugar mixtures shall be identified and studied using thin-film drying, rehydration and storing. Apart from drying kinetics, the project concentrates on the stability and characteristics of the produced films. It shall be studied how the glass transition influences the stability during storage (hygroscopicity, stickiness, crystalline fraction, molecular mobility). Thus, a deeper knowledge shall be gained of the mechanisms in sugar mixtures which lead to specific powder properties during drying and controlled rehydration.