Dead Yeast Cells Aren’t Much Fun

Going nowhere fast.

Going nowhere fast.

Two things you may not know about me are: 1) I can be a penny-inching miser (comes from standing in food lines as a child) and 2) I grew up listening to the Dr. Demento Show (yes, I was a nerd).

So, when my son’s small batch of Aglianico was not showing any signs of fermentation (after he pitched the yeast), an old favorite started to play in my head.

I had some open packets of RC212 and D47 in my bins of winemaking supplies, so we decided to take a pinch of each, reactivate them and run the ferment with that mixture.

When there was no activity, I first checked the must temperature. When that was in an appropriate range, I ran a little experiment:

I mixed up some water, sugar, DAP and StartUp powder. I divided this into three glasses. In one, I attempted to reactivate the RC212, in another the D47. In my “control” glass I reactivated some Fleischmann’s baker’s yeasts from a freshly-opened packet.

Sure enough, after a few hours, the Fleischmann’s was bubbling vigorously, while the other two mixtures were perfectly still after a few hours.

I had opened these packets of RC212 and D47 last October/November and then sealed them in zip-lock bags. It turns out that this method is insufficient for preserving yeasts. As a matter of fact, although these are freeze-dried yeasts, cool(-ish), dark, dry storage conditions are not enough to maintain their viability once the packet is opened.

Oxygen is the greatest enemy of freeze-dried yeasts. When I ordered some yeasts from Napa Fermentation earlier this week, it was recommended that I store the left overs of the 500-gram brick I will be getting either in vacuum-sealed bags, or in zip-lock bags into which I should first inject inert gas, and then squeeze out any gas. Refrigeration is an obvious plus.

Lesson learned.

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About SUAMW

Father, husband, physician, amateur guitarist, wine lover, wine writer, wine grower and wine maker trying to do it all within eye shot of downtown Los Angeles. http://www.shutupandmakewine.com http://twitter.com/Dr_Arthur_P
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