I did some searching about using very old dry yeast, but most message threads I found said throw it out, and only a handful said to try it anyway. I stumbled upon a comment from Kevin Lane at Fermentis who said it only loses about 5% viability every year when refrigerated, and about 10% when stored at room temperature.
I had a sealed packet of Safale US-04 dated Nov 2015 that had been refrigerated for years. I brewed in Jan 2021. The yeast was rehydrated for 15 minutes in a cup of 80F water before pitching. Even though the packet said to just pitch it, I still prefer rehydrating. No yeast starter was used. Airlock was bubbling in less than 24 hours, made plenty of krausen, and fermented out. OG 1.045, FG 1.014, flavor came out fine.
Next I had a sealed packet of Windsor dated Nov 2016 that was also refrigerated. Brewed right after the last beer. Rehydrated before using. No starter. Airlock was bubbling in less than 24 hours and had significant krausen. I read this strain has low attenuation. OG 1.054, FG 1.022, so not the greatest, but the beer turned out fine. Something I wanted to note is the packet was rock hard so I thought the yeast was too. It must have been vacuum sealed because the yeast poured fine once opened.
Maybe this will help someone in the future. Instead of all the guessing, an answer from someone who has actually done it.
I had a sealed packet of Safale US-04 dated Nov 2015 that had been refrigerated for years. I brewed in Jan 2021. The yeast was rehydrated for 15 minutes in a cup of 80F water before pitching. Even though the packet said to just pitch it, I still prefer rehydrating. No yeast starter was used. Airlock was bubbling in less than 24 hours, made plenty of krausen, and fermented out. OG 1.045, FG 1.014, flavor came out fine.
Next I had a sealed packet of Windsor dated Nov 2016 that was also refrigerated. Brewed right after the last beer. Rehydrated before using. No starter. Airlock was bubbling in less than 24 hours and had significant krausen. I read this strain has low attenuation. OG 1.054, FG 1.022, so not the greatest, but the beer turned out fine. Something I wanted to note is the packet was rock hard so I thought the yeast was too. It must have been vacuum sealed because the yeast poured fine once opened.
Maybe this will help someone in the future. Instead of all the guessing, an answer from someone who has actually done it.
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