Partial Mash Homebrewing | American Homebrewers Association

In this homebrewing tutorial we teach you how to make beer at home using the partial mash process, sometimes referred to as “mini mash.” When partial mash homebrewing, a portion of the fermentable sugar is derived from grains through a “mashing” step, while the rest of the sugars come from malt extract. This process is ideal for the extract homebrewer looking to get familiar with the mashing step of all-grain brewing. Partial mash brewing can also be used by homebrewers of all levels if a high gravity beer recipe calls for more grains than your mash tun can hold. For more in depth information on making beer at home, grab a copy of How To Brew: Everything You Need to Know to Brew Great Beer Every Time (Fourth Edition) by John Palmer.

Step 1

Review

Read through the homebrew recipe and steps of the brewing process entirely before starting your brew day to ensure maximum efficiency.

This tutorial will walk you through the entire brewing process for Belgian Bombshell, a lighter Belgian blonde ale. The same steps can be applied to any partial mash recipe, although instructions for other beer styles and fermentation and packaging processes will vary.

Step 2

Gather supplies

Ensure you have all the brewing equipment and beer ingredients necessary to brew the recipe.

Ensure you have all the homebrewing equipment and beer ingredients necessary to brew.

You will need the following equipment:

Boil pot (2+ gallons)
Spoon
Grain bag
Thermometer
Fermenter and airlock
Siphon/tubing
Bottling equipment
Hydrometer

Step 3

Clean equipment

Using unscented cleanser, thoroughly clean all brewing equipment.

Debris on equipment can harbor microorganisms that can spoil a batch of beer, even with proper sanitation.

Step 4

Heat water

The water that the grains will be mashed in is referred to as the strike water.

Heat 1.75 gallons of water in a pot to 160-162°F (71.1-72.2°C).

When the grains are added, the water temperature will typically drop 8-12°F, which will bring you down to the target mash temperature of 152-153°F (66.7-67.2°C).

Step 5

Bag grains

Place the base and specialty malts into a steeping bag. It is ideal for the bag to be draped over the kettle, secured and left open for easy stirring. The bag can also be tied off like you would when steeping specialty grains if this is not possible.

Step 6

Mash

Stir in all of the grains thoroughly, ensuring the mash is completely saturated and free of dry clumps.

When you stabilized your mash temperature around 152-153°F (66.7-67.2°C), cover the pot and let stand for 60 minutes.

Attempt to keep the temperature from rising/falling.

Step 7

Remove grains

After the 60 minute mash period, remove the lid from the pot and stir the grains if possible.

Separate the grain solids from the liquid wort (unfermented beer) by pulling out the mesh bag and allowing it to drain.

The process of separating the liquid from the solids is referred to as lautering.

Step 8

Add extract

Stir in half the extract until fully dissolved, ensuring no clumps collect on the bottom of the boil pot.

Step 9

Top up water

Depending on your target pre-boil volume, top off your boil kettle to the appropriate volume.

For this recipe we will conduct a full boil, meaning no additional water will need to be added to the fermenter.

This recipe assumes a 6 gallon pre-boil volume.

Step 10

Bring to boil

Bring the wort to a rolling boil.

Step 11

Add hops

Once the wort reaches a rolling boil, add the 60 minute addition of hops.

Note: hop additions are typically labeled with the time of the addition from the end of the boil.

Step 12

Add Irish moss

After 45 more minutes, add the amount of Irish moss called for by the product’s instructions.

Step 13

Add remaining extract

After 5 more minutes, add the remaining malt extract to the boil kettle.

Ensure the extract does not clump or collect on the bottom of the boil pot.

Step 14

Add wort chiller

After the extract is completely dissolved, place your wort immersion chiller in the boil kettle as a sanitation measure.

The immersion chiller will be very hot once the boil is complete, so handle with caution.

Step 15

Add hops

With 5 minutes left in the 60 minute boil, add the late hop addition.

Step 16

Chill

After the full 60 minute boil, chill the wort to around 70°F (21.1°C) as quickly as possible, using the wort immersion chiller already in the boil kettle

Note: Anything that comes in contact with the wort after the boil is complete must be sanitized in order to prevent chances of infection.

Step 17

Sanitize equipment

While the wort is chilling, take this time to sanitize the rest of the already cleaned equipment that will come into contact with the wort post-boil.

Step 18

Transfer

Once the wort has been chilled to around 70°F (21.1°C), transfer the wort into a clean and sanitized fermenter.

Step 19

Take hydrometer reading

Using a clean and sanitized cup or wine thief, pull a sample of wort large enough to take a hydrometer reading. This reading is your Original Gravity.

It is not recommended to return the sample to the batch of beer due to risk of contamination. If you must return the sample, make sure the hydrometer and the vessel holding the sample are thoroughly cleaned and sanitized prior to testing.

Step 20

Pitch yeast

Sanitize the yeast package or yeast starter vessel, and carefully pour (pitch) the yeast into the carboy with the chilled wort.

Step 21

Seal fermenter

After the yeast is pitched, seal the fermenter with a clean and sanitized airlock and bung.

If using a bucket fermenter, a carboy bung may not be necessary.

Step 22

Shake fermenter

Once the fermenter is sealed, give it a shake for a minute or two to provide oxygen which is vital to yeast cell growth and quality fermentation.

Step 23

Store fermenter

For the next 1-2 weeks, the yeast will be fermenting the wort into beer.

Store the fermenter in a location that can maintain a temperature of 65°F (18.3°C) with minimal disturbance and protection from light.

Splashing the wort after the initial pitching of the yeast can instill flaws in the final product.

Allow temperatures to rise into the low 70s°F near the end of fermentation.

Step 24

Monitor fermentation

Signs of fermentation should be visible via a bubbling airlock after 12-72 hours. The bubbling is caused by CO2, a byproduct of fermentation. If the bubbling slows down or stops, it doesn’t necessarily mean fermentation is complete.

Another visible sign of fermentation is the formation of frothy foam on top of the wort called kraeusen.

The sure-fire way to know if fermentation has ceased is to use a hydrometer.

Step 25

Boil water

Bring 2 cups of water to a boil.

Step 26

Weigh priming sugar

Using the Bottle Priming Calculator, determine how much priming sugar you need for the volume you are bottling.

Step 27

Add priming sugar

Once boiling, add the priming sugar (dextrose), and boil for 10 minutes.

Step 28

Transfer to bucket

After 10 minutes, remove from heat and add the priming sugar solution to your already clean and sanitized bottling bucket.

Step 29

Transfer beer

Using clean and sanitized equipment, such as an auto-siphon, rack the beer from the fermenter into the bottling bucket—avoid splashing.

Get the liquid to whirlpool in the bottling bucket in order to evenly mix the sugar without splashing.

Avoid transferring the solid contents at the bottom of the fermenter (trub) into the bottling bucket.

Step 30

Attach bottle filler

Attach the clean and sanitized bottle filler to the spigot of your clean and sanitized bottling bucket with a small piece of clean and sanitized food-grade tubing.

Step 31