Does tablet shape and height influence survival of fluidized bed-granulated living microorganisms during compaction?

The provision of effective probiotic formulations requires gentle processing to maintain the viability of the probiotic microorganisms, which is essential for their health-promoting effects. The drying of microorganisms by fluidized bed spray granulation and subsequent processing of the granules into tablets has proven to be a promising process route in previous studies of the same authors. In these, the influence of various factors was considered using cylindrical tablets with a diameter of 11.28 mm and a mass of 450 mg. These flat tablets are unpleasant to ingest and other tablet geometries should be considered for administration of probiotics but to date, no studies exist on the influence of geometric factors of the tableting tool and of the tablets on the survival of microorganisms. To address this aspect, the survival of Saccharomyces cerevisiae during the production of flat, round tablets with different tablet masses and thus heights as well as differently shaped convex tablets is determined and related to the physical-mechanical tablet properties to derive process-structure-property relationships. It turned out that higher tablet heights were advantageous regarding microbial survival and mechanical strength which is attributed to a lower elastic recovery. However, the use of differently shaped tools had a smaller influence on microbiological and mechanical tablet properties since the global tablet porosity was hardly affected.