6 Ways to Use Your Spent Grain

Nick Carr

Nick Carr on October 28, 2015   9 Comments

Brewer's Grain

Any home brewer switching to all grain has come to the problem of what to do with the pounds of spent brewer’s grain (SBG) left behind. Probably, at least at the beginning, many brewers just throw the grain away. But, more than beer can come out of a brew day.

Don’t let that spent grain go to waste. There are things you can do with it if so inclined, and even when you’re not, I guarantee there’s someone not too far away that would be happy to take it off your hands.

1. Compost it:

Probably the easiest way to put spent grain to work is composting it. In most cases spent brewery grain could be classified as a nitrogenous waste (fresh = green matter) on the same level as grass clippings. This means that they compost hot and will do best when layered with some carbonaceous waste (dry = brown matter) such as leaf matter or straw. A good rule of thumb here is to use a 2:1 ratio of green matter to brown matter.

Too much green waste — especially where wet grain is concerned — will likely create a very ripe spoiling mess. If this is of concern or you find the smell too strong add more brown matter. This will slow decomposition a bit, but should also cut down on the smell.

Pouring Water on Spent Grain

Photo Credit: JShontz / Flickr

One of the easiest ways to use spent grain as compost is to put it right in the ground. You can did a small ditch between vegetable rows or in flower beds, fill it half way with spent grain and cover it with dirt. In this way the microbes already in the garden can easily do their work on the newly arrived nutrients.

*Note on Nutritional Value: Several research papers including one from the Journal of Cereal Science and one from the University of Bucharest Romanian Biotechnological Letters (PDF) have investigated the nutritional value of spent grain. What they’ve found may surprise you.

Keep in mind that the nutritional value will change some depending on the grain used and your brewhouse efficiency. In general, it was found that spent grain consisted of:

  • Protein: 20 – 30%
  • Fiber: 20 – 70%
  • A notable amount of free fatty acids.
  • Decreased total carbohydrates.
  • Good levels of iron, magnesium, manganese, selenium, phosphorus (below 5%).
  • Also, Amelia Loftus’s book ‘Sustainable Homebrewing’ notes some studies that indicate gluten content is lowered extensively during malting. Though I could not track down any of the data, it’s an intriguing idea.

What all this indicates is that the malting process greatly breaks down the grain, making more of the nutrients accessible and usable for the body.

2. Baking:

Spent grain can be used in your own cooking and baking too. The Grain can either be used wet (usually after as much liquid has been pressed out of the grain as possible) or it can be dried and ground into flour. Do a little internet searching and you will easily find tons of spent grain recipes for bread, crusts, and plenty of baked sweets like cookies and brownies.

Wet spent grain can be used in low quantities in bread and other baked goods to add flavor and texture.

Drying it can be done over several hours in most conventional ovens. Set your oven at its lowest possible setting, usually somewhere around 170°F. Spread your spent grain over a cookie sheet at a thickness of about half an inch. Put the grain in the oven, but keep the door cracked so that moisture can escape. Check the grain every so often; stir it, check the moisture content, and insure you are not burning it. You want to dry the grain without actually cooking or burning it.

Another good option, if you happen to live in the desert southwest or somewhere else where you get plenty of daytime heat, is a solar oven. It might even be possible to do it on a hot dry day by just spreading the grain out on clean plastic sheeting or a trap.

After it has dried it’s time to mill it. This can be done in a grain mill, a food processor, or possibly even a coffee grinder. What settings and how long you grind will depend on how fine you want the flour. When the milling is done you’re ready to bake something.

Brewer’s Spent Grain Bread Nutrition

The study from the University of Bucharest specifically addresses baking with spent grain. In the study they bake bread with 5%, 10%, 15%, and 20% of flour milled from spent grain and then chart the changing nutritive value. What they found was that as little as 5% spent grain flour doubled the breads fiber content, increased the protein by as much as 88%, decreased the carbohydrates, increased the fatty acids, decreased the calories, and increased some of the mineral content. In short, the brewer’s grain increased the nutrient density of the bread.

You do have to realize that as you increase the percentage of BSG flour more of the brewing flavors will become apparent. Most studies have found that around 10% SBG flour in a recipe is the upper limit if what most of the participants enjoyed. But, of course the cocktail of volatiles are going to change with each different batch of beer. You may find you like a really high percentage of spent grain flour from a certain beer style.

Spent Grain Bread

Photo Credit: ThwartedAgain / Flickr

3. Stock Feed:

If you happen to own or know someone that owns stock animals such as horses, cows, pigs, sheep, etc. spent grain can be a good source of feed. Ruminants (cows, sheep, and pigs) will process it better than the horses, and there are a couple caveats to this one:

  1. Use the grain as quickly as possible. Wet spent grain will start to spoil pretty quickly. How quickly will depend on temperature and other factors, but if you feel like its spoiling or you see it going moldy don’t use it for feed! Better to be cautious and stock the compost then have sick animals.
  2. This is supplemental feed and should not, in any way, make up the bulk of what the animal is getting to eat. Remember, most of these animals are not naturally grain eaters, so be sure to supplement with low protein roughage such as hay or time in the pasture.

4. Flock Feed:

Many of the same things are true of feeding spent grain to poultry as feeding it to stock animals. Spent grain is a good source of selenium which has been shown (PDF) to be important to poultry breeding and egg/meat quality.

The percentage of spent grain in poultry diets can range from 2% to 20%. It is best to feed only what the poultry will be able to finish in one feeding, especially if feeding wet grain. If the poultry can’t finish the grain over the course of a day, it is likely whatever is left will go rancid, so adjust the amount until you have it about right.

You can easily freeze small amounts of wet grain and thaw it as needed for poultry feed. And you can mix it with their regular feed or some seeds (flax, sunflower, etc.).

If you happen to have bird feeders you could supplement the regular birdseed mix you use with spent grain, too. Though, in this case you’d want to dry it first so that it would keep longer.

Ways to Use Spent Grain

Photo Credit: Span112 / Flickr

5. Grow Mushrooms:

Another interesting use of spent grain is as part of the substrate used to grow edible mushrooms. Because of the spent grains high nitrogen content it is necessary to mix in some sort of carbonaceous matter (much like composting) such as straw or wood chips (a ratio of 1 part grain to 4 or 5 parts straw works well).

Much like brewing, it is very important to sanitize your materials to keep “bad” organisms at bay. To do this you would heat the mixed substrate in a large pot of water (your brewing kettle will probably work great here, especially if you have a false bottom and spigot on it). So, heat the water (substrate submerged) to about 160°F then put a lid on, turn off the burner, and let it sit for 45 minutes to an hour.

Drain the water and let the substrate become cool to the touch. Once cool, inoculate it with mushroom spores (Oyster mushrooms are one of the most common grown this way), and pack it into a container of some sort (also sterilized).

This could be a plastic bucket, large plastic bags, a metal bucket, or even a wooden crate. Whatever you use, holes will have to be punched or drilled in it to allow the mushroom spores “windows” to grow from (check out some pictures online and you’ll see what I mean).

Once the container is packed with the inoculated substrate it is important to put it in the right environment. The area you keep your growing mushrooms should be somewhere between 70 and 90°F. Maintain a slightly damp moisture level and a slightly higher humidity by putting the container in an enclosed space (tenting plastic sheeting over and around the container can accomplish this easily.

Different mushrooms grow best in different substrates, conditions, and some take longer than others to grow. The basics are all here but if you really want to give mushroom cultivation a serious go, do a little research on the internet and — just like in brewing — don’t be afraid to experiment. Just be sure you are actually growing EDIBLE mushrooms.

6. Dog Treats:

You can use your spent grain as filler for homemade dog treats as well, but please be aware that hops are very toxic to dogs, so never use spent grains that have come in contact with hops. You can find all kinds of spent grain dog treat recipes online, but try to avoid recipes that use soy or wheat and don’t make your treats out of the grain from wheat ale. Barley and oats are more digestible for dogs.

Spent brewers grain can be a valuable resource. If you find you cannot use your spent grain in any of the ways listed above and you are brewing regularly it might be worth while putting feelers out into you community to find others out there that might be able to benefit from your beer baking endeavors.

Local farmers or gardeners would likely be happy to take spent grain off your hands. You could make a batch of dog treats for a friend that has a dog if you don’t own one yourself. Maybe you have a family member that loves baking and would be thrilled to get some spent grain flour. If you try, I guarantee you will find something better to do with your spent grain then simply throwing it away.