I've purchased a 500 gram quantity of BM-45 wine yeast. This is more than I will use for winemaking this season. Can this yeast be stored for future use? If so, what would be the best conditions?

-William Frazier

RESPONSE:

Active Dry Yeast, at <5% moisture, is originally packaged in an oxygen free atmosphere either via nitrogen flush or vacuum. Under these conditions they will loose about 20% activity / year when stored at 20C.(68F) and about 5% activity / year when stored at 4C.(40F). It is the presence of Oxygen and the pick up of small amounts of moisture that causes the yeast to deteriorate at a faster rate, once the package has been opened. If you can vacuum pack (kitchen vacuum package equipment) or store in an air tight container and refrigerate you may retain a substantial amount of the activity. It would be wise to increase the inoculum 50% to be on the safe side. It is always a gamble, depending on how much moisture the cells have picked up each time you open and close the package and return to the refrigerator.

Dr. Clayton Cone