Rheological Behavior of Fermentation Fluids

Abstract

The rheology of fermentation broths is of great importance in biotechnology. The application of rheological models to such broths is described and the Power law appears to be of most practical use for non‐Newtonian broths. Rheometer types and their applications are described. The cone and plate rheometer is favored for exo‐biopolymer fermentations. For mycelial fermentations disk spindle systems are deservedly popular when consistency and ease of use are of most importance, for example in monitoring an established fermentation. Disk turbine rheometers are often used in research environments but it has been shown recently that the use of cup and bob devices may also be feasible. For mycelial fermentations some correlations between rheological and morphological parameters are presented and discussed. Morphology is usually characterized by image analysis but this could be replaced in commercial environments by light scattering measurements of particle sizes. Some effects of non‐Newtonian broth rheology on fermenter mixing performance are described, including possible cavern formation if broths have a yield stress, however small.