Brew Day Hour 2: Sparge the Mash

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  • Today’s topic: Detailed look at how to sparge the mash and separate the sugary beer wort.
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After the mash, the next major part in the beer-making process is separating out the sweet liquid we’ve made and sparging the mashed grains. Don’t let that word “sparge” intimidate you — it might sound like an 18th century affliction and a pirate’s worst fear, but it’s just a fancy way of talking about rinsing residual sugars from the surface of the mashed grains. Grab a strainer, it’s time to sparge!

(Image credit: Melissa Ryan)

Talk Like a Brewer

Mash out: Raising the temperature of the mash to 170° in order to stop enzymatic activity and loosen up the sugars before sparging.

Sparge water: Fresh water, heated to 170°F, used to rinse residual sugars from the grains, and added to the beer wort.

Sparging: The process of rinsing residual sugars from the grains with fresh water. (Homebrewers tend to refer to the process of separating the wort and rinsing the grains, collectively, as “the sparge.”)

Wort: The sweet liquid made during the mash and collected after rinsing the grains. This is essentially unfermented beer.

(Image credit: Henry Chen)

What Happens During This Hour?

The main goal of this hour of the brew day is to separate the grains from the liquid, and then to make sure we’ve rinsed all the sugars from the grains. This is actually a three-part process: the mash out, separating the grains, and the sparge itself.

The Mash Out

Once the hour of mashing is finished, we need to raise its temperature up to 170°F — called “mashing out” or “the mash out.” This stops all the enzymatic activity and also loosens up the sugars, much like warming sticky honey to make it easier to pour. Keep a careful eye on the temperature here — you don’t want the mash to get much hotter than 170°F or you can start extracting some astringent tannins from the grains. Tannins aren’t harmful, but they add a flavor like over-steeped black tea to your beer. Not very ideal.

Separate the Wort from the Grains

To separate the sugar-filled liquid — now called “wort” in brewer’s lingo — from the grains, just set a large strainer over your fermentation bucket and pour the grains inside. Be careful — they’re hot! The grains will catch in the strainer and the wort will collect in the bucket underneath.

The Sparge

Finally, you’re ready for the sparging step itself. The dictionary definition of “sparge” is “to sprinkle,” and for our brewing purposes, it means pouring hot water gently and evenly over the surface of the grains. This rinses away any extra sugars from the surface of the grains, and the water is added to the total volume of the wort.

Once you’ve finished rinsing the grains with the sparge water, clean the brew pot, transfer the strainer of grains over to the pot, and pour the wort over the grains one more time to make doubly sure you’ve gotten all the sugars. This also helps filter out some of the grain sediment from the mash step that might have fallen into the wort. Work quickly while the wort is still steaming hot — once it cools down, it gets sticky and recirculating it through the grains becomes fussy.

Once you’re done with this step, the grains can be discarded or composted. You can also add a cup or so of the used grains to baked goods, like pizza dough or muffins. Be careful, though — the grains have a lot of fiber, and too much can give you some digestion troubles.

Why Is Sparging Important?

If we didn’t sparge, we’d end up with a significant amount of sugar left behind with the grains. These sugars will feed the yeast and eventually give us alcohol, so we want to get as much of it into the final beer wort as possible. Besides, we worked hard to make those sugars — we should get to keep them!

(Image credit: Melissa Ryan)

What to Do: Sparging the Grains

These general directions apply to any batch of beer you brew (though the process is slightly different for larger, 5-gallon batches and requires some different equipment).

Flip through the slideshow above for step-by-step photographs of each step of this process.

Before you begin:

It’s extremely helpful to mark the sides of your 2-gallon fermentation bucket with 1-gallon and 1 1/2-gallon measurements so you can quickly gauge the total volume of wort. If your bucket didn’t come with these measurement markings, do it yourself by filling the bucket with 1 gallon and 1 1/2 gallons of water, and marking the water level for each on the outside of the bucket with a permanent marker.

  1. Warm the mash to 170°F (“mash out”): After the mash step is complete, put the pot on the stovetop over medium heat, and gently warm the mash to 170°F. Stir the mash gently to get rid of any hot spots and then take the temperature in a few different spots to make sure you’re getting an accurate reading. Don’t be tempted to increase the heat to make this step happen faster — I’ve found that this often makes the mash heat too quickly and it’s easy to overshoot the 170°F temperature goal.
  2. Meanwhile, warm the sparge water: While the mash is heating, fill another few pots with water and heat them to 170°F over high heat. You’ll need about 1 gallon of sparge water, though the exact amount varies.
  3. Separate the wort from the grains: Place a large strainer over your fermentation bucket. Carefully pour the hot mash into the bucket — the grains will catch in the strainer and the wort will collect in the bucket.
  4. Sparge the mash: Carefully pour the hot sparge water over the grains — pour slowly and try to rinse the grains evenly. Continue until you’ve collected about 1 1/2 gallons of total wort in the bucket; use the measurements marked on the side of the bucket to gauge the total volume.
  5. Recirculate the wort through the grains: Quickly clean the brew pot and transfer the strainer of grains over to the pot. Pour the hot wort through the grains. Again, go slowly and try to rinse the grains evenly.
  6. Finishing up: Place the pot with your wort on the stove. Transfer the strainer with the used grains back to the bucket. You’ll collect another cup or so of wort as the grains settle, and you can add this to the wort any time during the hop boil, which is the next stage of the brew day.

The used grains can be discarded, composted, or used for baking. If you’re using them for baking, cool completely and store in a covered container in the fridge for up to three days, or freeze for up to three months.

(Image credit: Melissa Ryan)

Troubleshooting the Sparge

My mash went above 170°F while I was mashing out.

It’s OK! You might notice some extra bitterness and astringency in your finished beer, but it will still ferment and taste just fine.

I forgot to warm the sparge water while mashing out!

Remove the pot of mash from heat and keep it covered while you warm your sparge water. If necessary, heat the mash back up to 170°F once the sparge water is ready, and then continue on with the next step.

I forgot to mark the side of my bucket — how do I know how much wort I have?

Just do your best to eyeball it. When your 2-gallon bucket is three-quarters full, you have enough wort.

The sparge is going really slowly.

Make sure your sparge water is warmed to 170°F — if it’s not quite hot enough, sparging goes more slowly. If the temperature is OK, it might be that your grains were crushed a little too finely, which is OK but makes sparging a pain — just carry on as best you can and remember to ask the clerk at your homebrew store to grind the grains more coarsely next time.

Recirculating the wort through the grains is going really slowly.

Most likely, your wort has cooled off a bit too much, which makes the liquid more thick and syrupy. The easiest thing to do is continue recirculating the wort, and then rinse the grains with a cup of very hot water to make sure no sugar is left behind — just extend the hop boil a few extra minutes to evaporate the added liquid. You could also just skip recirculating the wort through the grains; you’ll have some extra sediment in your wort, but it’s not a huge issue, overall.

Brew Better Beer: A Companion to Beer School

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