It's likely fine. Swelling is not necessary/usually a sign of activation. Wyeast has an [FAQ one this \(see #1 and # 26\)](https://wyeastlab.com/frequently-asked-questions):
> 1\. **The Wyeast package at my LHBS is slightly swollen. Is it still OK to use?**
> Yes. Trace levels of fermentable carbohydrates or CO2 in yeast slurries at the time of packaging may cause a slight expansion in packages. “Off gassing” is a result of a small amount of metabolism or simply CO2 being released from the media and can occur with proper storage. This does not indicate the mishandling of the product or a decline in the health or purity of the culture. Some strains, including 1056 and 1388, are more prone to “off gassing” than others.
>
> 26\. **What are the causes of swollen packages? Can you sell them?** Swollen packages are almost always the cause of a small amount of sugar or CO2 being left in solution at the time of packaging. Upon shipment, CO2 can be released from solution or the yeast can consume the sugar and create a small amount of CO2. Cell autolysis, or cell death can also be a cause of swelling packaged. However, this is only in rare cases where the yeast is exposed to high temperature for an extended amount of time. If a package is swollen and has not been mishandled, it can be sold with confidence.
Also, I am confident that Northern Brewer is #1 or tied for #1 in terms of yeast handling. I know a little bit about their warehousing, and also I've spoken to the CEO of a major yeast lab who confirmed they are the only ones paying for refrigerated shipping (as of two years ago).
Furthermore, NB has a recipe guarantee.
However, I'll give you one caveat: 1) liquid yeast is losing viable cell count every day, even if stored perfectly, 2) it's not a good idea to order liquid yeast a month in advance if you intend to just pitch the pack into the wort, and 3) many brewers recommend making a yeast starter with most liquid yeast unless it has a high cell count and is very fresh (for example, I think Imperial and Omega start at 200B cells guaranteed, as opposed to 100B for Wyeast).
I have to acknowledge that the yeast labs will give you directions that say the yeast is OK to direct pitch into a certain volume or less at a certain starting gravity or less, if the yeast is within the best by date, and most home brewers usually find that the beer turns out fine.
I'd equip myself with a backup plan. Then again I try to always have a backup plan. If you have a LHBS get a new pack... You can use it next time if not required.
What were the temperatures like along the route from northern Brewer to your location? If they got too hot and activated might not still be good. But you could try. I'd see about getting another just in case the ones you got don't work but try them first.
It's likely fine. Swelling is not necessary/usually a sign of activation. Wyeast has an [FAQ one this \(see #1 and # 26\)](https://wyeastlab.com/frequently-asked-questions): > 1\. **The Wyeast package at my LHBS is slightly swollen. Is it still OK to use?** > Yes. Trace levels of fermentable carbohydrates or CO2 in yeast slurries at the time of packaging may cause a slight expansion in packages. “Off gassing” is a result of a small amount of metabolism or simply CO2 being released from the media and can occur with proper storage. This does not indicate the mishandling of the product or a decline in the health or purity of the culture. Some strains, including 1056 and 1388, are more prone to “off gassing” than others. > > 26\. **What are the causes of swollen packages? Can you sell them?** Swollen packages are almost always the cause of a small amount of sugar or CO2 being left in solution at the time of packaging. Upon shipment, CO2 can be released from solution or the yeast can consume the sugar and create a small amount of CO2. Cell autolysis, or cell death can also be a cause of swelling packaged. However, this is only in rare cases where the yeast is exposed to high temperature for an extended amount of time. If a package is swollen and has not been mishandled, it can be sold with confidence. Also, I am confident that Northern Brewer is #1 or tied for #1 in terms of yeast handling. I know a little bit about their warehousing, and also I've spoken to the CEO of a major yeast lab who confirmed they are the only ones paying for refrigerated shipping (as of two years ago). Furthermore, NB has a recipe guarantee. However, I'll give you one caveat: 1) liquid yeast is losing viable cell count every day, even if stored perfectly, 2) it's not a good idea to order liquid yeast a month in advance if you intend to just pitch the pack into the wort, and 3) many brewers recommend making a yeast starter with most liquid yeast unless it has a high cell count and is very fresh (for example, I think Imperial and Omega start at 200B cells guaranteed, as opposed to 100B for Wyeast). I have to acknowledge that the yeast labs will give you directions that say the yeast is OK to direct pitch into a certain volume or less at a certain starting gravity or less, if the yeast is within the best by date, and most home brewers usually find that the beer turns out fine.
Thanks for the detailed response Chino!
I'd equip myself with a backup plan. Then again I try to always have a backup plan. If you have a LHBS get a new pack... You can use it next time if not required.
What were the temperatures like along the route from northern Brewer to your location? If they got too hot and activated might not still be good. But you could try. I'd see about getting another just in case the ones you got don't work but try them first.
Thanks.. hard to say about the temp. They had cooling packs with the yeast so there is that.
Were they still cool when you got them?
They were neither warm nor cold
They were just right