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Partial Mash Brewing Tutorial

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Partial Mash Brewing For Gluten Free Malted Grains

by Brian Kolodzinski – Updated February 2018

There is a great passage in Dave Miller’s book ‘Homebrewing Guide’ that says working with extracts is “as easy as reconstituting orange juice from frozen concentrate”. The reason this passage is so great is because it makes the brewing process to a new brewer a little less intimidating. It does not say brewing beer is an easy process, but that the major step of creating a wort when working with extracts, is relatively easy. And that is important because there are a lot of steps in the brewing process, and the use of extracts will help build your confidence in brewing.

Compared to conventional brewing which has multiple malt and extract options, gluten free brewing currently only offers multiple malt options. The different malts are necessary to craft the wide range of beer styles that conventional brewers enjoy. Therefore you may find good cause to venture into partial mash, “partial grain” and eventually all-grain brewing.

Partial Mash: If working with extract is similar to reconstituting orange juice, then working with malt when partial mash brewing is similar to brewing a cup of tea. The only step added while brewing a beer using the partial mash method is to steep malt in your brew kettle before adding the extract. This simple step adds body, head retention and significantly diversifies the flavor profile. However, steeping gluten free malt for the short period of the partial mash process does not allow the malt to attribute much if any fermentable sugars to the wort. Therefore, all the fermentable sugars primarily comes from sorghum syrup and any other extracts, syrups or sugars added to the wort.

“Partial Grain”: Don’t bother googling this term because we are pretty sure we just made it up! For a number of years, we have been trying to find ways to help partial mash brewers get more bang for their buck while also improving their beer. Gluten free malts are craft malts, there are not any inexpensive mass-produced malts as compared to conventional brewing. The same 4-6 lbs of specialty malts that are steeped in a brew kettle for the partial mash process could be mashed in a 2 gallon cooler mash tun (depending on dimensional weight) and produce 20-35% of the fermentable sugar in your wort! The wort collected from a 4-6 lbs grain bill would get the full benefit of the mash process and contribute significantly more to the beer style and flavor profile than the partial mash process. Additionally, it would reduce the amount of sorghum needed in the recipe by 20-35%. Using less sorghum syrup could make it easier to achieve most beer styles because the specialty malts would influence the flavor profile more profoundly.

Brewers interested in the “partial grain” method can buy a premade 2 gallon cooler mash tun such as the one sold by Home Brew Stuff (we have no affiliation; they are simply the only place that sells them to our knowledge) or buy a conversion kit (which we have been unable to find for a 2 gallon cooler). Another option is to build your own, which is what we did, but there are some challenges in finding some parts for a cooler this small. We also recommend wrapping the cooler mash tun in Reflectix to maintain the target mash temperature. “Partial grain” brewers should follow the ‘Single Infusion and Higher Efficiency Step Mash Brewing’ (on our all-grain brewing tutorial page) tutorial steps 1-9 before continuing with the ‘Partial Mash Brewing’ tutorial steps 9-22 below.


  • Minimal equipment needed for brewing beer:
  • 20 qt. brew kettle
  • reusable nylon mesh bag
  • large metal stirring spoon
  • measuring spoon set
  • glass measuring cup
  • food-grade plastic bucket or glass carboy
  • airlock
  • sanitizer
  • thermometer (preferably digital with temperature alarm)

Optional equipment:

  • additional food-grade plastic bucket or glass carboy
  • wort chiller
  • wort chiller pump
  • metal fine mesh strainer
  • brewing siphon
  • digital scale

Reading a Recipe

In order to brew beer it is important to be able to read a recipe and know some basic terminology. Typically when you read a recipe there will be an ingredient list which may include a grain bill. A grain bill is simply a list of just the grains used in a recipe, and will only be included in partial mash or all grain recipes. Partial mash recipes are those recipes that use a combination of grains and extracts to produce the fermentable sugars needed to make beer; while all grain recipes solely relies on grains to produce the fermentable sugars. If a beer does not use any grains it is an extract recipe, meaning it uses syrup and solid sources of fermentable sugars.

Most recipes will include some of the following information:

  • ABV: Alcohol By Volume.
  • Boil: Total amount of time which the wort boils.
  • Final Gravity (FG): The ending gravity after fermentation, used to calculate the alcohol content of the finished beer.
  • IBU: International Bitterness Units are the measure of bitterness in the beer.
  • Original Gravity (OG): The starting gravity prior to fermentation, attributes to the potential alcohol content of the finished beer.
  • Primary Ferment: Refers to the time the finished wort ferments following the brewing process.
  • Secondary Ferment: Refers to the time the finished wort ferments after primary fermentation.
  • SRM : Standard Reference Method for determining the color of the beer; also used to describe the color of an ingredient such as malts and grains.
  • Yield: The final volume of beer collected after conclusion of the brewing and fermentation processes.

The typical recipe will list the ingredients in the order in which they will be used in the brewing process. And because timing is critical to the brewing process, the ingredient will be accompanied by the time in the process that the ingredient is used. However, when brewing beer, the time starts at the maximum boil time and counts backwards. Therefore an ingredient that is used first, or at the start of the boil, may be denoted with “60 minutes”; while subsequent ingredients will be denoted with a time less than the first ingredient.

Differences in Brewing Gluten Free Beer - Updated October 2020

Brew In A Bag (BIAB): Conventionally, the BIAB method combines the total grain bill with the strike water to produce the mash. The calculations need to be precise because when you pull the bag of grain out of the kettle, the target preboil volume is left behind. We conducted a series of BIAB test batches which we wrote about on our blog. We are working on specific recommendations, but in the mean time we recommend you read our latest blog 'BIABing with Anthony from Texas'. What we did learn from our test batches is this method creates a much dirtier wort because the grain bill cannot act as a filter as it does in a conventional mash tun. This unfiltered wort results in a lot of additional trub that needs to be included in the recipe calculations. Also, because there is no sparge, a higher amount of fermentable sugars remains left behind in the grain bill. This may require using a larger grain bill to compensate for this loss.

Enzymes - Termamyl, SEBAmyl BAL 100 and SEBAmyl L: We conducted a series of test batches using different amounts of different enzymes and at this time recommend Termamyl, SEBAmyl BAL 100 and SEBAmyl L. Either the Termamyl or SEBAmyl BAL 100 must be used in conjunction with SEBAmyl L or you may not get fermentable sugars. Remember, gluten free malts have little to no natural enzyme activity; and require the addition of enzymes to the mash in order to turn starch into sugar for the yeast to convert into alcohol. No enzymes = No sugar = No alcohol! Please read our blog Diastatic Power & Enzymes in Gluten Free Malt and Increase Efficiency By Adjusting Your pH for a more in depth look at the use of enzymes in brewing gluten free beer. Dose recommendation: pitch 15-25 ml each enzyme (for up to 5 gallon batch)

Enzymes - Ceremix Flex and Ondea Pro: There's a new enzyme in town, and it's a real game-changer for the gluten free home brewing community! Ondea Pro provides some crucial missing enzymes that will significantly improve gluten free mash processes. Please read our blogs Introduction To Ondea Pro Liquid Enzyme Complex by Jason Yerger and JP Bierly; and How Ondea Pro Works: Some Preliminary Thoughts by Aaron Gervais. Ceremix Flex (NOT to be confused with Ceremix Plus MG, Ceremix 2X L or Ceremix 6X L which share a similar sounding name but are in no way the same enzyme) allows brewers the flexibility to avoid cereal cooking steps when using high-gelatinizing malts including corn, rice, sorghum and other gluten free malts between 52C and 80C. When Ceremix Flex and Ondea Pro are used together in a rising step mash most brewers experience at least 100% efficiency by unlocking additional PPG potential that the other enzymes simply cannot reach. Dose recommendation: pitch 10-20 ml each enzyme (for up to 5 gallon batch)

Grain Absorption Rate: We recently collaborated with an undergraduate senior chemistry student, Ben Barnes, from Southern Oregon University to ascertain the water absorption rate of each style of gluten free malt. Each sample of buckwheat, millet and “naked” rice malts included 15% rice hulls; while rice malt (the non-“naked” variety) naturally contains 37.5% rice hulls. They were each separately “mashed” for 120 minutes and then carefully measured to determine how much water was absorbed by the malt. Please read the findings on our blog: 'Assessment of Water Absorption Across Various Gluten-Free Grains'

Grain To Hull Ratio: All gluten free grains contain a hull. However, the hull of millet and buckwheat is very minimal as compared to rice. Hulls provide circulation during the mash and filtration during lautering. Millet and buckwheat require the addition of 10% rice hulls to the grain bill to ensure proper circulation and filtration. Rice malt on the other hand has a surplus of hulls. Rice malt contains approximately 62.5% grain to 37.5% hull. You can use this ratio information to calculate how much hull you are obtaining from rice malt in your grain bill; and deduct that amount from the rice hulls you would otherwise need to add to millet and buckwheat malt.

High Gravity Brewing: Brewing a beer with a high original gravity, typically above 1.075, is considered “high gravity” brewing. This is sometimes also referred to as “big beer” and common beer styles include gluten free versions of Barley Wine, Imperial Porter and Stout, Scotch Ale or Wee Heavy, Imperial IPA, Wheat Wine Ale, Barrel Aged Beer and Belgian Style Golden Strong Ale. There are additional challenges with brewing high gravity beers including more elaborate mashing techniques, using more hops, and high alcohol tolerant yeast, just to name a few. Please read our blog High Gravity Gluten Free Brewing by fellow GFHBer Matt S. from VA who has done extensive research in brewing big beers.

Monster Mills MM-2Pro Gluten Free Edition: GFHB and Monster Brewing Hardware have teamed up to offer the only roller grain mill specifically designed for gluten free malt! This is an exclusive offer ONLY available through GFHB and is NOT available on the Monster Brewing Hardware website. This roller mill design has been modified for the smaller buckwheat, corn, millet and rice malts used in brewing gluten free beer. Each Monster Mills MM-2Pro Gluten Free Edition roller mill includes a base and hopper. Please read our blogs Increase Efficiency By Improving Your Grist by JP from Bierly Brewing; and Setting Up Your Monster Mills MM-2Pro GF Malt Edition.

Partial Mash / Partial Grain: Conventionally, partial mash brewing consists of steeping a small amount of malt in water for a short period of time before adding an extract to create your wort. We have expanded this brewing method to conducting a mini mash with the specialty (non-base) malts that allow the malts more of an opportunity to impart flavor while increasing maltiness, mouthiness and head retention. This method fully utilizes the malts giving you the most bang for your buck; and reduces the amount of sorghum syrup required since considerable fermentable sugar comes from the malts! We refer to this process as “Partial Grain” and it is a standard brewing method for all of our 3-In-1 recipe kits.

Water To Grain Ratio: We have been recommending a ratio of 1 quart water to 1 pound grain for the last several years. While conducting a series of BIAB test batches, we noticed a significant reduction in conversion. Later, fellow GFHBer Anthony from Texas confirmed our findings that excessively thin mash conditions dilute the enzymes requiring liberal amounts of enzymes to achieve the desired efficiency. Please read the findings on our blog: ‘BIABing with Anthony from Texas’ . We recently ascertained the water absorption rates of gluten free malts which findings can also be found on our blog: ‘Assessment of Water Absorption Across Various Gluten-Free Grains’ . We now recommend 1 to 1.25 quarts water, or greater, to 1 pound of grain as appropriate for the specific grain bill.

Yeast & Yeast Nutrient: First thing first, if you are brewing gluten free beer, you will need to use dry yeast. Please read our blog Yeast Must Knows For Brewing Gluten Free Beer for information about which yeast to use for which beer style, and recommendations on how to properly use your selected yeast including using yeast nutrient.

Please follow our progress on our blog and tutorials for updated brewing recommendations!

Partial Mash Brewing

Now that you have your equipment and can read the recipe, you are ready to brew a partial mash beer. The next step is to buy a kit or ingredients. You will have more brewing options when buying the ingredients yourself outside of a kit. While kits are convenient and easy to use, you will be limited as to the types of beers you can make with a kit simply due to the sheer number of recipes available and the limited numbers of kits. When you buy supplies for a beer recipe, use the recipe as a shopping list. You will most likely need to buy more supplies than the recipe calls for, and have to measure the amounts out when you get home. A digital scale is the most precise way of doing this. And don’t worry about the extra ingredients as you can always use them in future beers.

Before you start brewing it is important to first clean you work area and sanitize all the equipment. Sanitation is the most critical step in brewing as it prevents unwanted contaminants, mainly bacteria and wild yeasts, from getting into your beer and destroying it. Contaminated beer can be dangerous to consume and should always be disposed of. Sanitize equipment using a sanitizer designed specifically for brewing, and avoid using bleach. Bleach is alright in an emergency but should not be considered for use as a regular sanitizer. A good idea is to buy a spray bottle and fill it with sanitizer as well. Sometimes you may forget a piece of equipment and need to sanitize it quickly.

View our Video Tutorials on YouTube here!

  1. Mill your grains to release the starches within the grain. It is recommended that you use a mill gap setting of 0.65 – 0.70 mm for millet and buckwheat, and a mill gap setting of 0.90 – 0.95 mm for rice malt.
  2. Mix your milled grains with rice hulls, as needed, until the grain bill contains 10-15% rice hulls. The rice hulls will allow for proper circulation and filtration. Tips & Tricks: Read our Blog about 'How To Calculate Rice Hulls For Proper Circulation & Filtration'
  3. Calculate your brew kettle water volume and strike temperature. Remember to account for the grain temperature and any thermal loss. Tips & Tricks: Read our Blog about ‘How To Calculate The Perfect Strike Water For Your Next Mash’
  4. Add the water to the brew kettle and add your blend of malts and rice hulls in a nylon mesh bag. Then add 15-25 ml (for up to 5 gallons) Termamyl or SEBAmyl BAL 100, and 15-25 ml SEBAmyl L enzymes together stir briefly until incorporated. (DO NOT add enzymes to strike water as the high temperature will damage the enzymes rendering them less effective).
  5. Cover brew kettle and let rest for 30-45 minutes during which time some conversion will occur, and allow time to infuse the malt with the water. Wrapping the brew kettle in Reflectix will greatly help maintain the target mash temperature.
  6. Before mashing concludes, prepare the 168F sparge water.
  7. Upon conclusion of mashing, uncover brew kettle and remove nylon mesh bag leaving behind the wort.
  8. Sparge grains by slowly pouring sparge water through grains one quart at a time.
  9. Once all the wort has been collected, place brew kettle with wort on a heat source.
  10. While wort is coming to boil, prepare the remaining ingredients in premeasured amounts so they may be added at the appropriate times. Once the wort is near a boil, add the extract as instructed per the recipe. The temperature of the extract will reduce the water temperature and you will again need to allow it to return to a boil.
  11. Allow the wort to come to a rolling boil. This is the stage that you are waiting for a hot break, and may occur for 5 minutes. This is also the first stage that your wort may boil over. A boil over is when the hot break billows over the side of the brew kettle. Reduce the temperature of the wort to control.
  12. After the hot break has been achieved and you have allowed the wort to boil for up to five minutes, you are ready for the first addition of your hops or other ingredient. When you add your first addition of hops, start by only adding a small amount. The alpha acids in the hops may cause a boil over. You may notice the head of the wort temporarily build up again. Once the head has subsided it is safe to add the rest of the hops addition. Add all ingredients as instructed per the recipe.
  13. Before the boil time has expired, you will want to prepare you ice bath or wort chiller. An ice bath is a way to cool the wort without any additional equipment. It is exactly what it sounds like, a sink of ice cold water that you place the brew kettle. You never want to allow any water or other contaminates in your wort. With an ice bath, you bring down the temperature of the wort by using cold water to draw the heat out of the wort. This uses a lot of water and a lot of ice, and does take some time to complete. Another option is to use a wort chiller to pump ice cold water through the wort and draw out the heat. A wort chill conducts temperature more efficiently, and with a constant supply of cold water it reduces the temperature of the wort very quickly.
  14. Once the boil time has expired, immediately cover the wort and begin to bring down the temperature of the wort. This is the stage that the wort is most vulnerable to contaminants such as bacteria and wild yeast. Make sure anything the wort comes into contact with is sanitized.
  15. Before the temperature of the wort has reached the range which you will pitch your yeast, you first must prepare the yeast. Some yeast may be dry pitched, meaning the contents may be poured directly into the wort. While other yeasts need to be prepared or started. Follow the instructions on the yeast package.
  16. Once the wort has reached the temperature range which the yeast me be pitched, it can be transferred to the primary fermentation vessel. You can rack the wort using a siphon, or pour the wort using a metal fine mesh strainer. Either way, you want to leave as much sediment behind while collecting as much wort as possible.
  17. Now that the wort has been transferred to the primary fermentation vessel, it needs to be prepared for the yeast. Using a medal spoon or whisk, stir the wort vigorously for 4-5 minutes. This aerates the wort and should produce a frothy head.
  18. Pitch the yeast.
  19. Cover the primary fermentation vessel and insert the airlock.
  20. Allow the wort to sit undisturbed in a dark area at 68-70 degrees for at least one week. This will also be the most active period of fermenting.
  21. After one week you may rack the wort to a secondary fermenting container.
  22. After another week the wort can be racked to a bottling bucket and bottled with priming sugar where it will continue to age.

Congratulations, you have just brewed your first partial mash brew!


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