Drying techniques of probiotic bacteria as an important step towards the development of novel pharmabiotics

Abstract

The increasing knowledge about the human microbiome leads to the awareness of how important probiotics can be for our health. Although further substantiation is required, it appears that several pathologies could be treated or prevented by the administration of pharmaceutical formulations containing such live health-beneficial bacteria. These pharmabiotics need to provide their effects until the end of shelf life, which can be optimally achieved by drying them before further formulation. However, drying processes, including spray-, freeze-, vacuum- and fluidized bed drying, induce stress on probiotics, thus decreasing their viability. Several protection strategies can be envisaged to enhance their viability, including addition of protective agents, controlling the process parameters and prestressing the probiotics prior to drying. Moreover, probiotic viability needs to be maintained during long-term storage. Overall, lower storage temperature and low moisture content result in good survival rates. Attention should also be given to the rehydration conditions of the dried probiotics, as this can exert an important effect on their revival. By describing not only the characteristics, but also the viability results obtained by the most relevant drying techniques in the probiotic industry, we hope to facilitate the deliberate choice of drying process and protection strategy for specific probiotic and pharmabiotic applications.

Effect of cryopreservation and lyophilization on viability and growth of strict anaerobic human gut microbes

“…Mechanical stress due to intra-and extracellular ice crystal formation and increased osmotic pressure caused by solutes in the remaining unfrozen fraction can potentially lead to the disruption of bacterial membranes and ultimately to lethal damage (Malik, 1991;Meryman, 2007). During lyophilization, the removal of water by sublimation further increases osmotic pressure and can cause severe damage to membranes and surface proteins (Broeckx et al, 2016). However, despite lower viable cell counts in the lyophilized cultures without protectant, viability was maintained during storage at 4°C while viability of the corresponding cryopreserved cultures declined at À80°C, especially for the freezing-sensitive B. obeum, R. intestinalis and E. hallii.…”

Functional Dehydrated Foods for Health Preservation

“…Changes may occur in cellular structures (cell membranes) constituting probiotics cells, and in key properties responsible for the product functionality (cell membrane permeability, mechanical strength of the cell membrane assembly, etc.) [58,67,68]. Moreover, drying might cause changes in the chemical structures responsible for the biological value of various bioactive components (protein, fat) [67].…”

“…[58,67,68]. Moreover, drying might cause changes in the chemical structures responsible for the biological value of various bioactive components (protein, fat) [67]. Besides, drying with hot air can induce reactions, mainly of oxidation, which decrease the functional value of nutritive compounds (vitamin, antioxidant).…”

Combining Prebiotic and Mixture of Freeze Dried Probiotics to Develop Synbiotics that Induce Apoptosis in Human Colon Tumor Cells

“…While they are well-known in the food industry, the enthusiasm in probiotics has spiked latelyto the pharmaceutical industry, the administration of pharmaceutical formulations containing such viable health promoting bacteria, these pharmabiotics need to provide their benificial effects until the end of shelf life (Broeckx et al, 2016).…”