Abstract
Local heating has been widely recognised as a primary factor contributing to probiotic inactivation during powder compaction, a critical stage in the tabletting process. However, despite the importance of compression speed in tablet manufacturing, its impact on the thermomechanical behaviour of probiotic formulations remains inadequately understood. In this study, the survival rates of Bifidobacteria at various compression speeds were evaluated using the finite element (FE) method that considers the thermal tolerance of this probiotic. In particular, the effects of compression speed and die wall friction on frictional heat generation rate during tabletting were quantitatively analysed for the first time. The results demonstrate that Bifidobacteria survival rate decreases with increasing compression speed, primarily due to the rise in frictional heat generation rate. Furthermore, it was found that reducing the friction coefficient between the powder and die wall can effectively reduce frictional heat generation rate, and this effect becomes more significant at high compression speeds. Therefore, die wall lubrication can reduce frictional heating during compaction, mitigating thermal degradation and improving probiotic viability in large-scale tablet production. Based on these findings, compression speed can be strategically optimised to minimise thermal degradation, providing a robust solution for enhancing probiotic viability in industrial tabletting processes.