Grains must be milled before being used on a brew day, but this also puts them at risk of decay.
Every experienced homebrewer knows the importance of fresh grains as the grains that weren’t stored properly dramatically lose quality due to dangers such as oxidation and moisture exposure.
Milled grains should be used within a couple of months for maximum brewing results and should be stored in airtight containers outside of light, humidity, and rodents in cold places in the meantime. Comparatively Unmilled grains can last for up to 2 years when properly stored.
Thus it’s important to properly store your grains before use and if you happen to have leftovers for next time, it’s important to take care of them as well, so your future brew doesn’t suffer.
Understanding the storage life of grains
The storage life of grains can vary depending on several factors, including the type of grain, storage conditions, and whether the grain is whole or refined. Here are some general guidelines for common grains used in brewing:
- Malted Barley:
- Unmilled (Whole): Unmilled malted barley can be stored for up to 1 to 2 years or even longer when kept in a cool, dry, and dark place in airtight containers.
- Milled (Crushed): Milled malted barley should ideally be used within a few weeks to a couple of months for the best brewing results due to the risk of oxidation. Storing milled barley in airtight containers can help maintain freshness during this shorter timeframe.
- Wheat and Rye:
- Unmilled (Whole): Whole wheat or rye grains can also be stored for up to 2 years or more when stored properly in airtight containers in a cool, dry, and dark location.
- Milled (Crushed): Milled wheat and rye grains, like malted barley, are best used within a few weeks to a couple of months for optimal results. Storing them in airtight containers helps extend their freshness during this shorter storage period.
- Specialty Grains:
- Unmilled (Whole): Specialty grains, such as roasted barley or caramel malts, can be stored for up to a year or more when stored in airtight containers in a cool, dry, and dark place.
- Milled (Crushed): Specialty grains that are milled should also be used within a few weeks to a couple of months to maintain their freshness. Storing them in airtight containers is recommended.
As you can see, there are some differences in how long different grains remain fresh, but what they all have in common is that using them as soon as possible is the best practice.
Factors Affecting Storage Life
1. Oxygen exposure
It’s important to reduce the contact the milled grains make with oxygen as it is the reason number one for decay.
Oxidation is a nightmare in brewing and it can occur at almost every stage of brewing. Milled grains have fewer layers for protection as the husk no longer protects against environmental dangers such as oxygen. The result of an oxidized grain is that the grain loses the essence which results in mellowed flavors and aromas when used in brewing.
It’s a similar story as it’s with the hops, so it’s easy to spot the bad grain and hops even by smell. Good grains and hops will be full of powerful smell and when you taste they should have a strong concentrated and bitter taste.
For this reason, It would be ideal to create a vacuum using a vacuum sealer and plastic bags with an air-seal zipper.
As you can see in the photo, the first bag was filled with more oxygen and the seal was worse as I didn’t use a sealed zipper but a clothing clip, and the grains were stored with lots of air still in the bag. If I properly used the vacuum sealer I could have had a vacuum state and a perfect storage condition but I was a bit lazy as I planned to use the grain next week already.
2. Temperature and humidity
Room temperature is great for grain storing purposes as the grain isn’t super sensitive to heat as hops are, so you don’t need to necessarily fridge your grains.
However, if you don’t plan to use grains any time soon like next month or two, it’s recommended to drop the temperature to a similar level as you would do for beer storage. Freezing is not necessary unless you really need to preserve the grains for the next year.
Moreover, humidity is another danger so if you ever store your grain in a fridge or any other wet place, make sure the grains are perfectly dry as the humidity creates mold.
Mold, like all fungi, is contagious and it’s difficult to sort the good from the bad grain, especially because the probable reason why parts of grain got mold on it, is because the entire grain is affected by humidity. If you ever suspect the humidity might be present, dry the grains as soon as possible to save them.
3. Rodents and bugs
Bugs are nasty but rodents are even worse. Having a bug infestation is a terrible experience because if bugs such as moths lay their eggs between grains, it’s over and you have to throw everything away. The worst scenario is when you put one infested bag near others only to find that every other bag got infested in no time.
If the bugs are not a problem, then the rodents will find their way to cause a problem and you won’t be able to stop them if you don’t plan in advance.
Storing bags of grains in a rodent-friendly area means it’s probably too late to save the grains as the rodents are quick and they can obliterate your grains overnight. What makes rodents the worst type of pest is that they don’t care about plastic protection layers as their little teeth can chew through everything but steel.
So, think about this, try to store the grains above the floor in a clean room and be careful when you leave the doors and windows open so as not to invite undesired company.
Mill your grains and don’t depend on a 3rd party
Grains should be milled as close as possible prior to a brew day. If you mill the grains too soon you start a countdown where the grains slowly but surely decay, but hopefully, you’ll use them before they degrade.
I like to order my grains pre-milled when I plan to use them in the same week so I don’t have to do another task at home.
If the store from which you get the grains offers this service it’s great, but at the moment the grains leave the store they slowly begin to decay as they are exposed to oxygen (and possibly humidity) and lose their natural protection from a husk.
Moreover, sometimes they keep grains in a warehouse for weeks before the delivery.
You can see why it’s recommended to mill your grains instead of letting them slowly decay before you use them.
I always receive my grains with plenty of air in the bag as they don’t come in a vacuum, and as I can see this is a practice of most stores, which isn’t ideal.
Solution? Find a reputable store that puts quality first, use them as soon as possible, or mill your own grains!
When you crush your grains your word is final and you don’t depend on any store policies. You can get plenty of grains in bulk and save money with bulk discounts and then mill a couple of pounds before a brew day as the rest of the grains will remain protected as they are unmilled.
Final take
It’s important to note that the storage times for milled grains are generally shorter than those for whole grains due to the increased risk of oxidation and loss of freshness once the grain is ground or crushed.
Therefore, for the best brewing results, many brewers prefer to mill their grains just before brewing to maximize flavor and quality.
Additionally, always check for signs of spoilage or pests when using stored grains, and when in doubt, it’s best to discard them to ensure the quality of your brew.