PRESS RELEASE

Wellpark Brewery assess the benefits accrued from  installing a Multi-channel Yeast Monitor in their new  yeast room

The Wellpark Brewery (Interbrew,UK) has been able to assess the benefits  accrued from installing a multi-channel Yeast Monitor in their new yeast room.   They also looked at the long term drift of the instrument and the need or frequency for re-calibration over a 2 year period.

The Yeast Monitor Model 320 was installed in the summer of 2000.  The system was multi-channel  using the Fast Scan Multiplexer 638 with one probe installed in yeast pitching main and a second probe in the cropping main.  The Yeast Monitor was calibrated to deal with up to 5 different yeast strains.  Calibration of the concentration of yeast slurry was against a haemocytometer with correction for dead cells using methylene blue.

For the probe installed in the yeast pitching main, the real time concentration of live yeast was used for pitching rate control.  The probe readings were checked after 12 and 24 months against both a pre-calibrated Lab Yeast Analyser and a hamocytometer and were found to be +6%  and -2.8% against the standard offline readings. Before installation of the Yeast Monitor 75% of fermentations were within the standard cycle time but this figure improved to 90% after the Yeast Monitor was installed. 

The second probe in the yeast cropping main was set up so that only yeast above  8 x 108 viable cells/ml was diverted to the yeast storage tanks. The remainder of  the yeast was discarded.  Yeast concentrations as high as 2 x 109 viable cells/ml  were cropped.  This process of cropping the "cream of the yeast" ensured that  the  poor quality yeast at the beginning  and end of the cropping process was not  selected for repitching.  The probe was also able to identify the interface between the yeast and beer and prevented any dilution of beer into the yeast storage  vessel. The Yeast Monitor is particularly effective in this application when dealing  with yeasts that are poorly flocculent and the yeast /beer interface can be difficult  to assess by conventional methods.   After the Yeast Monitor was installed, the  brewery found that the yeast viability had increased from a low of 80% to 88%. The cropping probe was checked for long term drift after 1 and 2 years and like  the pitching probe, was found to be within 10% of the off-line measurements.

Back