Look into any spice cabinet and you’re sure to find ingredients long past their expiration dates (bay leaves from the Civil War era, anyone?). Many brewers find themselves faced with the same problem of leftovers. If you buy in bulk to save money, you’re guaranteed to have some things sit around for a while. But even if you purchase ingredients on a batch-by-batch basis, you can end up with leftovers because not every recipe calls for a whole number of two-ounce hops packages.
You can keep this under control if you know two things: how best to store each type of ingredient and how long each is likely to last.
Breaking It Down by Ingredient
There’s a common set of reasons why things go stale: heat, moisture, and oxidation. Sometimes light can also create chemical and physical changes that hurt the flavor and viability of your brewing ingredients. So the simplest storage advice is to avoid all of those conditions as much as possible. But each ingredient has its own sensitivities and shelf life, so let’s look at them a little closer.
Malt and Malt Extract
Malt and malt extract are prone to oxidation and temperature-related damage, so they’re best stored in a cool, dry place, and in airtight containers if possible. In practice, I keep dried malt extract in an airtight jar in my freezer, but everything else is sealed in plastic bins and kept in a corner of my brew room.
Packaged malt extract will keep for up to 2 years, but bulk purchases that have been exposed to air are best used within 2–3 months. Pre-ground malt will last about 2 months as well. Unmilled grain is a little more complicated. Light-colored diastatic malts such as 2-row or Pilsner malt will stay fresh for 6–12 months, while specialty grains will last for 12–18 months. More heavily kilned malts, such as roasted barley or chocolate malt, can last even longer.
Old malt extract can break down chemically and sometimes pick up mold. Either of these things will affect the flavor of your beer. Old grain can have similar problems, along with enzyme breakdown, which means your mash efficiency can suffer, too.
Hops
Hops are even more sensitive to environmental factors. Their alpha acids, which contribute bitterness to our beer, break down over time even under the best of storage conditions. The form factor can make a difference by reducing surface area, with hops plugs being more stable than leaf hops, for instance. Furthermore, different strains exhibit different levels of fragility, which makes it even harder to create a blanket rule. Regardless of that, the best way to store hops is in your freezer, vacuum-sealed in oxygen-resistant plastic, or in an airtight jar that has been purged with CO2.
Unopened packages will last longest, with hops pellets holding up for up to 3 years, whole flower hops lasting 1–2 years, and plugs good for up to 2 years. On the other hand, those leftovers from a previous batch require more effort than just folding over the bag. Store them in an airtight container in the freezer and they’ll last about half as long as intact packages.
Old, stale hops can have a cheese-like aroma that is fairly undesirable, but you can identify that with a quick sniff before you use them. The bigger challenge is the hidden decay of alpha acids, which will reduce the bitterness without any obvious cue. Brewing software and online sites offer calculators to determine the impact of age, which can help you adjust. You might also consider using your older hops more for aroma and flavoring.
Yeast
As a living thing, yeast is most susceptible to the ravages of time and temperature. Fortunately, packaged yeast is easy to store properly—the refrigerator will protect the yeast and keep the cells dormant. Under these conditions, liquid yeast is generally fresh for something on the order of 6 months, although at the far side of that time, it’s a good idea to make a starter in advance of brew day. Dry yeast is even more stable, lasting up to a couple of years. All the major vendors include expiration dates on the package, so let that be your guide.
The obvious risk of using old yeast is that you’re pitching a smaller quantity of healthy, active cells, so there may be a longer lag before fermentation kicks in. Yeast health in general, though, can affect how well the yeast cells do their job. If your yeast is stressed, you’re more likely to end up with off-flavors.
Other Ingredients
As long as they’re stored in a cool dry place, most additives, such as Irish moss or gypsum, will last indefinitely. Yeast nutrient is often labeled as good for a year, but even that should be fine for quite a bit longer. Moisture is the primary issue. A humid climate makes it easier for these items to absorb water, which will make them clump and perhaps even break down.
Cleaning House
Follow the above guidelines, but pay attention to your senses. Crunch a kernel of grain, sniff the hops, and see how your yeast starter gets going—if anything seems off, go ahead and toss it. I also recommend using an inventory tool (even if it’s only an Excel spreadsheet) to track what you have on hand, so you can be sure to use ingredients before they go bad.