Storing Malt Grains Before Brewing – How Long Is Too Long?


Unfortunately for most of us, homebrewing remains a hobby and life sometimes gets in the way of making a good beer from fresh ingredients. When our brewing plans get altered and postponed for several months, is it worth keeping the grain we’ve already bought or is it doomed to the compost heap? Well, that’s the purpose of this article.

So, how long can you store malted/unmalted and crushed/uncrushed grain for before it goes bad? When stored correctly, grains used in brewing have a storage life of 6 months to a year. Moisture & O2 exposure are the biggest risks. Chilling & freezing lead to the longest shelf-life and unmalted and unmilled grains generally also last longer. After 12 months, grains should be replaced if unused.

I’ve read and heard a lot of different answers both online and in the brewing community, but are any of these opinions based on hard evidence and what really affects the shelf-life of stored grains?

That’s what I wanted to find out. So, in this article, I’ve brought together all the evidence from my research and I think it’s the most useful insight into storing grains around!

Important terms and processes

So, before I delve into everything that my research revealed, let’s just clarify some key ideas that will be important to understand later. What exactly do we mean by ‘malted’ grain and what does crushing or milling grain does to its shelf-life?

The Malting Process

Most brewers, even hard-core all-grain brewers, will never actually malt their own grains. In most countries, malted-grains are easy to come by and they save you a lot of time but perhaps not money. However, for storage, there is a distinct difference in the chemical characteristics of unmalted and malted grains.

Grains are malted by steeping them in cold water for around 2 hours while ensuring that all the kernels are floating on the surface. The grain is then allowed to air dry for around 8 hours before the process is repeated with a fresh batch of water another 1 or two times.

By this time germination has begun and the grains are then lain out for 2-3 days in a moist environment at about 64°F/18°C to encourage more germination. After that, the malt is evenly dried out and the final stage is to remove the rootlets which have grown during germination.

This entire process is done to unlock the enzymes which are naturally present in grains and will help the brewer to convert starches into sugars. In this way, malted grains have been processed and so they will react differently to storage than unmalted grains.

The process of crushing/milling

In brewing crushing and milling mean the same thing, whereas for other industries milling really means making flour.

The idea behind crushing brewing grains is to open up the kernels and allow a better flow of water in and around them. This will help the brewer extract more sugar into the wort and so increase the efficiency of the mashing process.

Although beneficial for brewing, the crushed grains with their additional surface area are more susceptible to moisture and oxygen when being stored. So, again crushed and uncrushed grains will have different shelf-lives from each other.

However, in reality for our needs, we are unlikely to ever store grains for long enough that it will really affect the final beer. So, let’s not get too hung up on the difference here, although I will explore that difference a little later on.

How long does brewing grain last?

Most brewing ingredients, including yeast, last a considerably long time. It would be a very rare set of circumstances which would mean that you couldn’t brew with ingredients which you bought today before they went off.

However, grain doesn’t last as long as some people claim (I’ve read some crazy assertions on some forums) especially when they confuse agricultural-purposed grains with brewing-treated grains.

So, as a general rule, for both malted and unmalted grains try to use them within 3-6 months if they are being dry stored and 6-12 months if frozen. Refrigerated grains will last between 4 and 8 months if stored correctly.

Below is a quick guide for popular grains which have been crushed before storing:

Milled Grain
Unchilled
Chilled
Frozen
Barley
3 months
4 months
6 months
Rice
3 months
4 months
6 months
Corn
3 months
4 months
6 months
Oats
2 months
3 months
4 months
Wheat
3 months
4 months
6 months

Below is a guide to those same grains which have not been crushed before storing:

Unmilled Grain
Unchilled
Chilled
Frozen
Barley
6 months
9 months
12 months
Rice
6 months
9 months
12 months
Corn
6 months
9 months
12 months
Oats
4 months
6 months
8 months
Wheat
6 months
9 months
12 months

source

So, as you can see, as a general rule of thumb you can store your grain for anything from 6 months on a shelf to a full year in the freezer.

How do you store brewing grains?

If we assume that we are referring to the more widely used malted and crushed grains, there are two main dangers to watch out for: light, heat, moisture, and oxygen. Additional things to worry about are insects, small mammals.

Dry climates

If you are out in the desert or live somewhere where you’ve never even seen mold, then you don’t have to worry so much about moisture ruining your grain. Something as simple as a metal trash can in your cool garage with a decent seal could be ideal for storing your grain in the short term.

However, for longer storage projects, even in these climates you might want to freeze store those grains to get the longest lifespan you can for them.

Humid climates

Grains should always be stored in an airtight container whether you plan to keep them in the pantry, your refrigerator or even your freezer. A zip-lock bag is a good option if you can buy the large ones or some Tupperware containers with a good seal.

Before you seal the grains, however, you want to try and remove as much moisture from them as you can. We all know the trick about putting a phone we’ve dropped into water into a bag of rice before we turn it on. It’s to suck up all the moisture, right? Well, you might not want to brew with that rice down the road if it’s been sitting full of moisture!

If you can get access to an electric dehydrating machine, that would be best. Otherwise, you can just spread your grain over some paper towels for a couple of hours before sealing them into your airtight containers.

Another method is to use those food-safe moisture absorbers, just place a couple into each bag or container of grain and they should trap any excess liquid in the air.

Risk of insects and rodents

Freezing is an effective way to kill any insects which happen to have found a home in your malted grain. For most of us, this isn’t really going to be a problem, but there is nothing worse than finding something looking back at you when you are mashing your beer. Avoid it as much as you can by freezing grain even if you plan to refrigerate it or dry store it in the long term.

Mice and rats, somewhat unbelievable, find it easy to munch through most types of plastic. So, if you know that you have a rodent issue in your storage space, then consider using metal storage containers instead or by ringing your storage area with traps. Luckily, they find it harder to bite through the side of a fridge or freezer!

Can I really freeze malted grains?

Yes, you really can. There is no danger to the active ingredient in grains, enzymes, which we need for brewing. Unlike with yeast which is a living organism and can be adversely affected by the freezing process, enzymes aren’t so susceptible.

The main difference is that enzymes aren’t alive, and so they can’t be killed by the extreme cold. So, even though the grains have been malted to activate the enzymes we need later in mashing, freezing them will not influence this process in any way. So, if you have space in your freezer or even your Keezer, this is a really effective way to extend the storage life of your grain. (source)

Crushed or Uncrushed?

To be honest, for most people’s storage needs the difference in the shelf-life of crushed or uncrushed grains is negligible. The major issue is that crushed grains have an added risk of exposure to moisture and oxygen (which degrades all organic matter) if not stored correctly. The difference is going to be a couple of months and really, you won’t suddenly see an effect on mashing efficiency or taste.

This being said, if you are able to choose between crushing or not crushing your grain before having to store it for an extended period, then opt for uncrushed storage! It will just give you that extra element of safety in terms of its expiration date.

How do you store unmalted grains in bulk?

Let’s say that you’ve finally pulled the trigger and you are living a life-long dream of opening up your own microbrewery. Although most commercial and amateur brewery operations deal with malted grains, unmalted grains can be a steal in comparison

So, if you have to bulk store unmalted grains which are pretty much directly from the fields, there are some tricks you can use to make sure that you don’t end up with little beasties in your beer later on.

Always store in containers with fairly new containers so that you can ensure the seals are airtight and won’t let bugs in. As an extra precaution, you can fill up the container and then cover it with brown paper before placing about a quarter of a pound of dry ice.

By pressing down on the lid of the container, you’ll push out any excess air. Then when the dry ice has evapourated you can seal the lid properly. The CO2 will suffocate any little creepy crawlies that may be in the container.

Another way to make sure that nothing is in your grain and happily eating away at it is by freezing it. This is to kill bugs when you don’t have any dry ice handy. Place it in your freezer for a couple of days after the previous step and then remove it and store it at room temperature for up to 30 days, this will allow any insect eggs to hatch, then you refreeze the grain to kill those baby insects (How cruel of you!). In this way, you could store unmalted grains for more than a year in the freezer.

Brewing beer with old grain

Although I’ve spoken to many people who have, so they say, successfully brewed with grain which was more than a year old, I’d say avoid it as much as you can.

Taste isn’t really the issue but rather the efficiency you’d get of extracting enough fermentable sugars from the grain. It’s true that enzymes don’t die, but after a while, they just aren’t going to work as well as they do when newly activated through germination. So, if you have had that grain for more than a year, just swallow the cost and get something fresher. That’s my advice.

Storing other brewing ingredients

The other two most important ingredients in brewing which you may want to store are hops and yeast.

Hops are very similar to grains in terms of storage as they are also a plant-based ingredient. So, chilling hops can make it last several months and freezing it would extend its useful life by a further few months.

Yeast, on the other hand, is a living thing and needs to be treated in a slightly different way. Yeast, for brewing, comes in two main forms: as a liquid solution or in freeze-dried dry packets. Yeast can last for up to a year in its dry form but only a few months when in a liquid packet.

For more details on yeast storage, check out this article which I researched and wrote. Also, if you are having issues with your yeast and want to know if it has gone past its expiry date, check out this article.

Phil - BeerCreation

Hey, I'm Phil. I'm passionate about all things beer. I love making it, drinking it and best all, learning about it!

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