New Applications and Methods Utilizing Radio-Frequency Impedance Measurements for Improving Yeast Management
Author: Publication date: 01/01/70
Radio-frequency (RF) impedance or capacitance measurements are used in many of the larger automated breweries for measuring viable yeast cell concentration. This paper reports the latest applications for this technique in the yeast pitching and yeast recovery lines and new on-line methods for monitoring live yeast cell concentrations during fermentation. The new methods include a range of probes that can be inserted into either a production propagator under highly aerated conditions
or a production fermenter or it can be submerged into a vessel to monitor the yeast-concentration profile in real time. The paper also describes how the RF impedance measurement can be combined with a bulk fluorescence measurement to measure both live and dead yeast cell counts.
The application of a novel biomass sensor to the control of yeast pitching rate
Author: Boulton C. A., Maryan P.S. and Loveridge D. Publication date: 01/01/70
Accurate methods of pitching rate is essential for consistent fermentation performance. traditional methods, typically dispensing a metered volume of yeast slurry of pre determined suspended solids are unreliable and difficult to automate. methods based in-line optical measurements are inherently inaccurate since viable and dead cells are not distinguished.
These problems are overcome by a novel biomass sensor which measures the dielectrical permittivity of yeast suspensions at radio-frequencies. The probe is responsive to viable cells only, over an extended range and is unaffected by gas bubbles and trub.
the application of the device to in-line automatic pitching rate control is described