Does active dry yeast really expire?

Michael Pilat
  • Does active dry yeast really expire? Michael Pilat

    I was cleaning out my spice cabinet and deep in the back I found two packages (e.g., six envelopes) of active dry Red Star yeast that expired in March 2009, 15 months ago as of writing this question.

    With the thought that dry yeast is basically freeze-dried and should have a decent shelf life, I proofed one envelope in warm water with some sugar to see if it really "expires". It foamed right up, so it seems like the answer is, at least for one year after the marked date, no.

    Although in this case, does "expired" really mean "less effective" or "will taste funny"?

  • Yeast expires because it's a micro-organism (a fungus, in fact) that eventually dies. Your foaming yeast is still alive and should be fine to use; the expiry date is a decent estimate of how long the yeast will last, but various conditions (where and how yeast is stored among others) affect how long it will live.

  • I've used yeast that was even older than yours and although the taste of the resulting bread was fine, and it foamed up properly when tested, I found I had to use about 50% more of it to get the same density of the bread. In the end, I threw it out because it was too much trouble to experiment with it every time.

  • Expired yeast will taste less, and rise less or not at all.

    I believe the expiration date is a conservative estimate for yeast stored sealed at room temperature to still rise reliably. If the storage environment is better and you're willing to test before every batch, and use more yeast if necessary, I don't see why you couldn't continue to use it.

  • I've sucessfully used dry active yeast that is over five years old, keep it in the frige. When it's really old, I put a skosh of sugar in the proofing cup, to give the old fellers a bit of a leg up, and just wait till it's really foaming, then use it like usual, don't increase the quantities. It's the same bugs, and it tastes the same.

  • Weel, I tried to make pretzels and it never rose. And i was using old yeast so yes it does expires

  • I just baked a loaf of rye bread with dry yeast that had an expiration date of 2004 and the loaf turned out beautifully! All I did was mix 1 pkg of yeast with 1/4 c warm water and 1 tsp sugar and let it sit for 5 min. This was advice I'd read on the Internet, and it has worked. I'm thrilled bcse I have about 12 pkgs of expired yeast in my refrigerator!So don't let those dates intimidate you! Oh! I also have to let my bread rise in an oven that I've turned on to 250 degrees for 1 minute bcse I don't have a pilot light in my oven.Even without the optimal conditions for baking yeast bread, it can be done!

  • I just used a package of yeast that expired in 2007 for a belgian waffle recipe. It's been sitting in the kitchen, unrefrigerated. No movement—the bugs are dead!

    Update—I hated to see the waffles go to waste, so I bought some more yeast. To whet the appetite of the yeast bugs, I gave them some sugar to feast on in addition to their milk meal. The Fleischmann's RapidRise yeast puffed right up, so much so that it even got pasty. 1⅓ hours later it had doubled in size. Guess we'll have waffles for dinner now!

  • Old Active Dry Yeast:

    Better with age: Prehistoric yeast key to Fossil Fuels Beer:

    The yeast was actually trapped in the gooey tree resin during the Eocene epoch, 20 million years after the last dinosaur perished. High temperatures and warm oceans created a balmy environment throughout the Earth, with palm trees growing in what’s now Alaska. And, fortuitously, the yeast is an ancient relative of today’s Saccharomyces, or brewer’s yeast.

    If yeast can survive 45 million years trapped in Burmese tree sap, a couple decades sealed in a foil envelope should be no sweat.

  • Bottom line - 13 year old yeast works, here is the whole story - I am about to use some Fleischman's active-dry yeast that expired in 1999 (pre-millennium). I am feeling lucky because today is Christmas eve day (2012). I am using it in a bread machine (normal 4 hour bake mode) I will write back in 4 hours to tell you the results. Per my wife's advice, I tested it by putting a pinch in a small amount of warm sugar water. It was for sure doing something after about 5 to 10 minutes, not what you would call a foam, but it was generating a lot of opaque small masses and smelled yeasty. I also put in 50% more yeast (in the machine's special yeast receptacle) as recommended by answer 11. To make it interesting, I am also using some equally old dry milk. The "better for bread" flour is probably only 4 years old. The butter is less than a week old, the salt was bought about 6 months ago, and the water is 13.75 +/- 0.11 billion years old (per Wikipedia). The bread machine is approximately 15 years old. I am 54 years old. Wish me luck....OK, I'm back and I'm happy to report that I got a yummy 3/4 size loaf (served with real butter) enough for the family along with some soup I made from last Thanksgiving's Turkey stock.

  • Yeast does expire . Yeast will last longer than the date printed on the packet if it is kept in the refrigerator . It will last longer in the freezer (for up to a year or even more).

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baking yeast
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