Rheological Properties of Fermentation Fluids

In many cases, a fermentation process must be a high solids process in order to be economic. Substrate, microbes, or product, or all three together may be considered as solids. In general, fermentation broths of mold and streptomyces exhibit non-Newtonian behavior, either Bingham 

Deindoerfer (1960) and Richards (1961) have published excellent reviews on this subject, and presented an appraisal of the use of these properties in engineering and analytical correlations employed in fermentation practice. Although there are some cases where the operation and scale-up of these mycelial fermentations have been accomplished successfully using either the power input per unit volume or the overall oxygen transfer coefficient of Newtonian fluids as a basis, this does not preclude further study of the scale-up of non-Newtonian fermentation broths. On the contrary, much more information about properties such as oxygen transfer in bubble aeration, and mixing time in non-Newtonian fermentation fluids is needed to provide a better understanding of the operation and scale-up of fermentation processes. 

---

However, it is clear that attempts to correlate antibiotic production with the effect of temperature changes during fermentation should be carried out with an understanding of the correlation between the rheological properties of fermentation fluids and mass transfer, nutrient requirements, and the rate of production at each stage of fermentation. 

---