Determination of effective diffusion coefficients in calcium alginate gel plates with varying yeast cell content

• Effective diffusion coefficients (De) have been determined for lactose, glucose, galactose, and ethanol in calcium alginate gel with varying yeast cell concentration. The measurements have been performed in a diffusion cell, and the results evaluated with the quasisteady-state method. An ultrasonic meter was used for gel thickness determination with an accuracy of 1.5% and a new method for the reproducible preparation of gel plates was developed. It was found thatD e in pure alginate gel decreased to about 90% of the diffusivity in water and did not vary with alginate concentration.D e decreased considerably with increasing yeast cell concentration. For the solutes studied, the effective diffusion coefficient can be estimated according to the equationD e =D eo (1 - ϕ)/[1+(ϕ/2)], whereD eo is the effective diffusivity in pure gel and ϕ is the volume fraction of yeast cells.

Subject headings

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Publication and Content Type

art (subject category)

ref (subject category)