The Fresh Loaf

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Yeast Test

JerrytheK's picture

Yeast Test

The last few batches of yeasted dough I mixed made OK but not great bread. I thought that the initial proof was a bit weak.

So I decided to test the yeast I've been using.

I buy a 1# (454 g) bag of fas-instant yeast from either Costco or Amazon. I prefer Costco, as it's less expensive, but they don't always carry it.

I put part of the yeast into a snap top plastic container, and then vacu seal the rest and freeze it.

I used the test method from red star yeast.

The test using the in the snap-top-box yeast was not bad, but about 10 - 15% less of a rise in the measuring cup than the protocol said should be the result.

I then tested the yeast I had saved, sealed and frozen. That exceeded the test protocol by about 10 - 15%.

So the yeast had definitely degraded sitting in a cabinet.

Tossed the in-the-cabinet yeast and replaced it with that I had stored.

idaveindy's picture

How long had the yeast been sitting in the cabinet from the time the package was opened?

And, was it past the expire date?  And if not, how much longer until  the expire date?

BrianShaw's picture

I store mine in a tight sealing glass jar in the freezer. When using, I dip out of the frozen jar and sprinkle into the dough or proofing water. It’s well past the “use by” date and still quite vibrant. Periodically I test it to verify. 

JerrytheK's picture

The yeast had a production date of 01 19.

I bought/opened it on 10 July 19.

So it's only been sitting in the cabinet since that date, or about three months!

Its expiry date is 01 21.

The cabinet/kitchen probably reached the mid to hi 70s during the summer.

I'll probably take the advice and move it to the freezer, rather than letting it sit in the cabinet at room temperature.