I became fanatical about baking in 1998. I was buying flour in 50 lbs. sacks from the local bakery. I was making Pain sur Poolish three days a week.
Even though I used only a pinch at a time, I was consuming yeast like, err, Monistat. I needed to buy in bulk.
Cool bakers all over the planet rely on SAF brand yeast. It’s an “instant” yeast, which among other things means the yeast need not be hydrated in warm water prior to mixing — simply measure it dry and mix it into the flour. Also, the product is sold as a 500g vacuum-packed brick that made a really neat whooshing noise when the package is cut open.
The first place I ordered the yeast from told me it would be a year before they could ship it. A year! Their explanation: they catered to survivalists, and had a 14-month backorder due to the impending Y2K disaster. You remember Y2K — the world was supposed to end, causing a dramatic drop in the availability of leavened grain products. Apparently this vendor’s entire customer base had ordered lifetime supplies of yeast and dried beans and bottled water and so on.
Anyway, I found another place to purchase the yeast. I’ve been keeping it in the freezer, using a tiny bit at a time for focaccias and ciabattas and pizzas and the occasional sweet baguette. My 500g stash is down to about 150g — another year’s worth, for sure. I realized today that I’ve been using it for 65 months, a good four years past its official expiration.