How to collect yeast in micro breweries?
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Yeast Storage
Yeast should be used as soon as possible and not stored for long periods before re-use (longer than 2 weeks). Yeast should be maintained between 1-2°C n an oxygen free dark environment. Warmer temperatures and oxygen exposure will increase the rate of culture degradation. A slight amount of head pressure can be applied with CO2 to maintain a positive pressure environment. Excessive pressure can be detrimental to the culture.
Yeast Collection/Storage Vessels:
When choosing a yeast storage vessel, factors to consider include: ease and effectiveness of cleaning and sanitation, size/volume, ease of use, access for testing/stirring if necessary, ability to easily purge CO2. Extreme care must be taken when cleaning and sanitizing the storage vessel and all associated parts. Fittings should be disassembled and soaked before every use. Vessels should be purged with CO2 prior to collection to minimize exposure to oxygen. The vessel will need ¼ to 1/3 volume of headspace to allow for slurry expansion during storage and feeding. Vessels should be able to maintain storage temperatures of 34°to 36°F (1-2°C).
Cornelius Kegs / Beer Kegs
Adapted beer kegs or Cornelius kegs make simple and economical yeast collection and storage vessels. Tanks can be stored on ice in a walk-in cooler to maintain an optimal storage temperature of 34°F (1°C). Cornelius kegs can be filled and discharged through the “out” fittings, allowing for closed collection and re-pitching procedures. A closed harvest and re-pitching procedure will minimize the opportunity for air-born contamination and is recommended if the malt mill is in the same room as the brewery or the mash is a dusty procedure.
Cylidroconical Fermenter
Storage of yeast for more than 48 hours in a glycol cooled cylindroconical fermenter is not recommended. Yeast is an excellent insulator and will typically be several degrees warmer in the center of the slurry than at the outside edge. Higher flocculating strains tend to pack more densely in the cone and therefore be more prone to increased temperatures in the center of the slurry.
Yeast Brink
Usually exclusive to larger breweries, a glycol cooled, agitated yeast brink has many advantages over other collection vessels. The agitation of glycol cooled slurry offers precision temperature control. A yeast brink allows for easy yeast washing and QC sampling as well as propagation. A yeast brink can either be mounted on a scale or fitted with a flow meter for delivering accurate and consistent re-pitching volumes.
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