Dear Mr. Wizard,

I have been brewing for a little over a year and usually buy my ingredients by the batch, meaning I only buy what I’m going to brew for every batch I make. I have been thinking about buying ingredients in greater quantity and storing them. I know that hop pellets don’t age as fast as whole hops, but can or should you freeze hop pellets to extend their life? If you can or should, how long would they keep?

Sean Faires
Springfield, Illinois

Mr. Wizard replies:

This is a good question with a very straightforward answer — storing hops at freezer temperatures does extend their life and will not damage the hops. How can I be so definitive, one may ask? Because when hop processors store hops, they store them at temperatures ranging from 20–30° F and keep them in this temperature range until they are sold. If the hop variety has good storage properties, and if it is packaged properly, hops will remain fresh for two to three years. Most pellets are vacuum packed to minimize oxygen in the package. This is key since oxygen is the primary concern during hop storage. The other two concerns are time and temperature. Storage time can be maximized whenever exposure to oxygen and temperature are minimized.

There are a few points I want to make about this question. For starters, hops are not frozen during cold storage because hop pellets and compressed cones have very little moisture. The small quantity of water in processed hops is called bound water and does not freeze or crystallize like free water. (Free water is removed from the hops when they are kiln dried.) This is an important distinction because freezer burn occurs when frozen free water sublimes — changes state from solid to gas without passing through the aqueous state. Freezer burn is a real problem when foods containing free water are stored in freezers. Freezer burn can be minimized by using wrappings with excellent barrier properties and by eliminating gas spaces between the wrapping and the food. This can be a real challenge, but we don’t have to worry about this issue with hops.

The other point is that commercial freezers are much different than the types most of us have at home. The main difference is that they don’t have a refrigerator full of smelly food sharing the same air. If hops are not stored in an air-tight container — something that does not allow gas migration, like glass or a foil bag — the hops can pick up flavors from other items stored in your refrigerator or freezer. If you happen to have one of those vacuum sealers laying around, you could split up your hops into small bags of some convenient weight — one-ounce packs, for example— vacuum seal the bags, and then place them in a big glass jar with a metal lid. The jar will prevent any stink from touching the hop bags and the vacuum-packed hops would have little oxygen to damage them.

If you don’t have a vacuum sealer you can get handy foil bags from coffee shops that are fitted with a zipper lock and check valve. Just fill it up with your hops, zip the bag closed and squeeze the air out through the check valve. I am sure that if you found a coffee shop with this type of bag, they would sell the bags to you for a reasonable price.

I would err on the safe side and put this bag into a jar just in case some particularly persistent molecules are emanating from the freshly-sliced onion stored in the neighboring refrigerator. If the hops remain sealed in their original package, they can just be stored in the fridge or freezer. The bag should keep oxygen and odors out.

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