Purchase And Storage Of Yeast

It’s happened a few times perhaps – you’ve got your juice ready to inoculate with yeast. You open the package of yeast and sprinkle it in a starter mixture, wait ten minutes and stir, and nothing happens. No foaming. Your yeast are not viable. How come? The most likely reason is how the yeast was stored.

Although yeast are ubiquitous, they can also be fragile wee things. These single celled microrganisms are a powerhouse of activity when they are viable, but under conditions they cannot tolerate, they can bring about disappointment. Storage in conditions too warm will be especially harmful and dry yeast exposed to humidity cannot be expected to be viable when you want to use them to make your wine.

As well, yeast have a shelf life beyond which they cannot be guaranteed by the manufacturer or lab from where they came. Because packages of yeast are so inexpensive, it’s probably not worthwhile to stock up on them. You only need to purchase what you know you will be using over the next six to 12 months and be sure to keep what you are not using at very cool temperatures. Stored in the refrigerator, yeast will remain viable for longer than the guaranteed shelf life. Stored at the bottom of a large chest freezer, I’ve had yeast do fine more than two years after purchase.

One of the biggest problems for the home winemaker is obtaining some yeast strains in small enough quantities. Some yeast strains are only available in large size packages because commercial wineries are their primary users and the large package sizes are meant to innoculate large batches of juice. If you want to try such yeasts, you have a few possibilities:

1. You can order a package and share with other winemakers that wish to use the same strain.
2. You can order a package yourself, and try to store it such that it be as ideal as possible. This will probably require the ability to vacuum seal the remaining yeast once you have opened the original package.
3. Become friends with a professional winemaker that uses that strain of yeast and see if you can trade a bottle of your own wine or something else for some.
4. Locate a retailer that buys the yeast in bulk and repackages it in vacuum sealed water resistant packaging.

Another problem with with yeast strain availability is that more often than not, the local wine supply shop will not stock quantities of yeast that they cannot sell within the shelf life period of the yeast. For a retailer to purchase the 5 gram packets of yeast, they will in all liklihood be required to purchase a box of 25 or more 5 gram packets of the same yeast strain in order to get the wholesale pricing. For some, they would never sell that much yeast of that strain and therefore lose money. In this case, you may be stuck trying to locate a retailer that is willing to ship you yeast they have in stock. Be sure to check around for the store’s reputation in providing fresh yeast on a mail order basis. And with that in mind, you may want to consider ordering yeast that will be shipped to you during the cooler months of the year.

In summary:

• If you can, purchase your yeast at a date close to when you will be using it.
• Look after your yeast by storing in very dry and cool conditions. For short to medium term storage, use the fridge.
• If you must store your yeast for some reason for longer than 12 months, try the freezer. But you will definitely want to proof it before you use it to make wine.
• Buy yeast from sources that go through it quickly to assure the longest shelf life possible.