As an expert sommelier and brewer, I can confidently say that dry yeast does have an expiration date, although it has a much longer shelf life compared to fresh yeast. Dry yeast, particularly active dry yeast, can remain active for about two years when left unopened. This is quite remarkable and makes it a popular choice for bakers and brewers alike.
However, it is important to note that the shelf life of dry yeast can vary depending on how it is stored. Storing dry yeast in the refrigerator or freezer can help extend its life even further. The cold temperatures slow down the yeast's activity and can preserve its viability for a longer period of time. Personally, I prefer to store my yeast in the refrigerator, as it provides a good balance between temperature control and convenience.
I have had experiences with using dry yeast that has been stored for over a year, and it has still produced excellent results. The yeast was still active and capable of fermenting the sugars in my dough or wort, resulting in delicious bread or beer. However, it is worth mentioning that as yeast ages, its activity may decrease slightly, and you may need to use a bit more yeast or give it a bit more time to ferment properly.
To ensure the best results, it is always a good idea to check the expiration date on the packaging of your dry yeast before using it. If it is past the expiration date, it is best to get a fresh batch to guarantee optimal fermentation. Additionally, it is important to store the dry yeast in airtight containers to prevent moisture and air from affecting its viability.
Dry yeast does have an expiration date, but its shelf life is much longer compared to fresh yeast. When stored properly in the refrigerator or freezer, dry yeast can remain active for up to two years or even longer. However, it is always a good idea to check the expiration date and store the yeast in airtight containers to ensure the best results.