Modeling and measurement of yeast flocculation.

A sedimentation/light extinction technique has been developed to quantitatively measure the state of flocculation of a suspension of yeast cells. This experimental method is based upon sedimentation theory with a modified light extinction theory that accounts for the dependence of the extinction coefficient on the floc size distribution, and the loosely-branched fractal structure of yeast aggregates. As demonstrated by comparisons with direct microscopic observations, this technique is capable of accurately determining the steady-state of floc sizes as well as floc settling velocities of a variety of yeast cultures.