Department of Process and Life Science Engineering, Division of Food and Pharma Lund University, 221 00, Lund, Sweden.
LUNARC, Lund University, Box 118, 221 00, Lund, Sweden.
Pharm Res. 2024 Aug;41(8):1671-1682. doi: 10.1007/s11095-024-03751-w. Epub 2024 Jul 29.
This paper investigates the critical role of material thickness in freeze-dried pellets for enhancing the storage stability of encapsulated bacteria. Freeze dried material of varying thicknesses obtained from different annealing durations is quantified using Scanning Electron Microscopy (SEM) and X-ray microtomography (μCT), the material thickness is then correlated to the storage stability of the encapsulated cells.
A formulation comprising of sucrose, maltodextrin, and probiotic cells is quenched in liquid nitrogen to form pellets. The pellets undergo different durations of annealing before undergoing freeze-drying. The material thickness is quantified using SEM and μCT. Storage stability in both oxygen-rich and oxygen-poor environments is evaluated by measuring CFU counts and correlated with the pellet structure.
The varying annealing protocols produce a range of material thicknesses, with more extensive annealing resulting in thicker materials. Storage stability exhibits a positive correlation with material thickness, indicating improved stability with thicker materials. Non-annealed pellets exhibit structural irregularities and inconsistent storage stability, highlighting the impracticality of avoiding annealing in the freeze-drying process.
Extensive annealing not only enhances the storage stability of probiotic products but also provides greater control over the freeze-drying process, ensuring homogeneous and reproducible products. This study underscores the importance of material thickness in freeze-dried pellets for optimizing storage stability for probiotic formulations, and emphasize the necessity of annealing as a critical step in freeze-drying quenched pellets to achieve desired structural and stability outcomes.
本文研究了材料厚度在冻干微丸中对增强包埋细菌储存稳定性的关键作用。使用扫描电子显微镜（SEM）和 X 射线微断层扫描（μCT）对不同退火时间获得的不同厚度的冻干材料进行定量分析，然后将材料厚度与包埋细胞的储存稳定性相关联。
一种包含蔗糖、麦芽糊精和益生菌细胞的配方在液氮中淬火形成微丸。微丸在进行冻干之前经历不同时间的退火。使用 SEM 和 μCT 对材料厚度进行定量分析。在富氧和贫氧环境下评估储存稳定性，通过测量 CFU 计数并与颗粒结构相关联。
不同的退火方案产生了一系列的材料厚度，更广泛的退火导致更厚的材料。储存稳定性与材料厚度呈正相关，表明较厚的材料具有更好的稳定性。未经退火的微丸表现出结构不规则和储存稳定性不一致，突出了在冻干过程中避免退火的不切实际性。
广泛的退火不仅增强了益生菌产品的储存稳定性，还对冻干过程提供了更大的控制，确保了均匀和可重复的产品。本研究强调了材料厚度在冻干微丸中对优化益生菌配方储存稳定性的重要性，并强调了退火作为冻干淬火微丸的关键步骤的必要性，以实现所需的结构和稳定性结果。
