He Chuqi, Wang Haodong, Yang Yucheng, Huang Yayan, Zhang Xueqin, Arowo Moses, Ye Jing, Zhang Na, Xiao Meitian
College of Chemical Engineering, Huaqiao University, Xiamen 361021, China.
Xiamen Engineering and Technological Research Center for Comprehensive Utilization of Marine Biological Resources, Xiamen 361021, China.
Pharmaceutics. 2021 Mar 5;13(3):335. doi: 10.3390/pharmaceutics13030335.
The drying process is a significant step in the manufacturing process of enteric hard capsules, which affects the physical and chemical properties of the capsules. Thus, the drying characteristics of plant-based enteric hard capsules were investigated at a constant air velocity of 2 m/s in a bench scale hot-air dryer under a temperature range of 25 to 45 °C and relative humidity of 40 to 80%. Results indicate that the drying process of the capsules mainly occur in a falling-rate period, implying that moisture transfer in the capsules is governed by internal moisture diffusion rate. High temperature and low relative humidity reduce drying time but increase the drying rate of the capsules. Investigation results of the mechanical properties and storage stability of the capsules, however, reveal that a fast drying rate leads to plant-based enteric hard capsules of low quality. Scanning electron microscopy further demonstrates that more layered cracks appear in capsules produced under a faster drying rate. The Page model yielded the best fit for describing thin-layer drying of the capsules based on the coefficient of determination and reduced chi-square. Moreover, it was established that the effective moisture diffusivity of the capsules increases with an increase in drying temperature or reduction in relative humidity.
干燥过程是肠溶硬胶囊制造过程中的一个重要步骤，它会影响胶囊的物理和化学性质。因此，在台式热风干燥机中，在2 m/s的恒定风速下，于25至45 °C的温度范围和40至80%的相对湿度条件下，对植物基肠溶硬胶囊的干燥特性进行了研究。结果表明，胶囊的干燥过程主要发生在降速阶段，这意味着胶囊内的水分传递受内部水分扩散速率控制。高温和低相对湿度可缩短干燥时间，但会提高胶囊的干燥速率。然而，对胶囊机械性能和储存稳定性的研究结果表明，快速干燥速率会导致植物基肠溶硬胶囊质量较低。扫描电子显微镜进一步表明，在较快干燥速率下生产的胶囊中会出现更多的层状裂纹。基于决定系数和约化卡方，Page模型最适合描述胶囊的薄层干燥。此外，还确定了胶囊的有效水分扩散率随干燥温度的升高或相对湿度的降低而增加。
