A few years back a homebrew shop was selling a variety of expired Wyeast smack packs dated 2016 and 2017. They were about a year old when I bought them. When I researched using old liquid yeast, many threads discussed 6 month old yeast as beyond ancient, and some went as far as 2 years, suggesting that was stone age. Most said don't use it and get fresh yeast. Some I read involved a recently expired smack pack being thrown out without even testing to see it was viable.
The pack I had was made in fall 2016 and used in early August 2021. Smacked it, took about 5 days to fully swell at room temperature. Because of its age, I stepped it up to increase viability and cell count. I made a starter, let it sit on the stir plate about 24 hours, the next day I made another starter, and added that to the existing starter, and let it stir for another 24 hours. I pitched it after about 48 hours.
Airlock was bubbling within 24 hours. I let the beer stay in the fermenter almost a month. Made a nice krausen ring. Beer turned out fine, about 5% ABV, and has plenty of flavor. No off flavors were detected.
Yeast remained refrigerated before using. And there you go. Smack pack from 2016 finally used 5 years later. It fermented fine with proper care and a starter.
For those wondering, it was 3726 and I brewed a saison.
The pack I had was made in fall 2016 and used in early August 2021. Smacked it, took about 5 days to fully swell at room temperature. Because of its age, I stepped it up to increase viability and cell count. I made a starter, let it sit on the stir plate about 24 hours, the next day I made another starter, and added that to the existing starter, and let it stir for another 24 hours. I pitched it after about 48 hours.
Airlock was bubbling within 24 hours. I let the beer stay in the fermenter almost a month. Made a nice krausen ring. Beer turned out fine, about 5% ABV, and has plenty of flavor. No off flavors were detected.
Yeast remained refrigerated before using. And there you go. Smack pack from 2016 finally used 5 years later. It fermented fine with proper care and a starter.
For those wondering, it was 3726 and I brewed a saison.