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March 18, 2020

Top Crop Beer: Kveik IPA

top_crop_kveik_ipa_homebrew_recipeHomebrewing often takes patience. Typically, you’ll spend a day brewing, weeks fermenting, and a few more days to bottle or keg your beer for carbonation and serving. The delayed gratification of the homebrewing process could potentially turn some away and can lead to emergency situations where you want to share some beer with friends but your tap lines are dry. That’s what happened here at the Clawhammer World Headquarters a few days ago, so we made a recipe that gave us a completely finished IPA in just about a day. This is the third beer we’ve made as a part of our “3 Day IPA” series where we’ve made 3 IPAs in 3 days using Kveik yeast. Read on to see how we made this one.


We brewed this beer with Clawhammer’s 240 volt electric BIAB homebrew system. Watch us use it in this brew day video below.

Full Brew Day Video

Water

We started our brew day by adding 7.9 gallons (23.85 liters) of Asheville city water to our kettle. We adjusted our water chemistry specifically for the water that we were using in order for our finished beer to have a flavor according to style. Everyone’s water chemistry will be different, we recommend using this water chemistry calculator or using brewing software such as BeerSmith to calculate your own.

Grains

This recipe has a very simple grain bill. All you need is 13 pounds (5.8 kilograms) of Pale Malt and 10 ounces (283 grams) of acidulated malt. Acid malt will help drop the PH of our wort which is important to the final flavor of our IPA.

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Putting weighed out grains in our mill. For BIAB systems like ours, we recommend finely crushing your grain in order to get the right efficiency.

Mash

We mashed for a shorter time than usual when we made this beer. Instead of a typical 60-minute mash, we did a 30-minute mash at 158° Fahrenheit (70° Celsius). According to an “Exbeeriment” on the Brulosophy website, there was no perceivable difference between a beer that was mashed for 60 minutes and one that was mashed for 30. Since we wanted to get all these beers done fast, we decided to try a 30-minute mash out for ourselves.

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Mashing in

Hops

Once our 30-minute mash was over, we pulled our grains out and bumped the temperature up on our digital brewing controller to start a boil.

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Pulling out grains after the mash

Just like our mash, our boil was also only 30 minutes. Before doing this, we read another Exbeeriment on the Brulosophy website. This one compared two American Pale Ales, one that was boiled for 30 minutes and another for 60. Just like mash times, there was little perceivable difference between the two beers. 

However, Brulosophy’s Exbeeriments test only one recipe on one small group of people. They don’t necessarily prove anything, but rather suggest that many traditional parts of brewing are arbitrary and can be changed without ruining a recipe. Our intention with these shorter mash and boil times is to have a finished beer as quickly as possible.

At the very beginning of our 30 minute boil, we added 1 ounce (28.3 grams) of Ekuanot Hops. These hops have 15% alpha acids which will add just the right amount of bitterness to our beer.

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Weighing out our 30-minute hop addition

Once our 30-minute boil was over, we hooked up our plate chiller to cool the wort down to 95° Fahrenheit (35° Celsius). As the beer was chilling, we added our last two hop additions.

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We use a wort plate chiller to chill our wort - it works by running cold groundwater next to hot wort without mixing the two

Our first hop stand addition was a 1 ounce (28.3 grams) addition of Ekuanot. The other was a 2 ounce (56.7 grams) addition of Medusa hops. Medusa hops have 3.8% alpha acid content, much less than Ekuanot.

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Adding hops for a hop stand

 In order to aerate and extract more flavor from our hops, we pointed the spray valve on our kettle lid into the hop basket. We let the wort circulate through the hop basket for ten minutes at 95° Fahrenheit (35° Celsius) before moving on with our brew day.

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We let the spray valve circulate through our hop basket for 10 minutes

For a typical, non-Kveik yeast brew day, we would transfer our wort into a separate fermentation vessel and aerate it by shaking. Since Kveik yeast ferments at higher temperatures than usual, we’re fermenting this in our brewing kettle in order to maintain a steady high temperature.

Yeast and Fermentation

The yeast pitching process of this brew day was the most experimental part. In order to start the fermentation of this beer, we harvested yeast from the top of another beer that was fermenting in an adjacent kettle. The practice of harvesting yeast from the top of an open fermenter for storage purposes is well documented online. However, there’s not as much evidence of people taking yeast from one batch and directly putting it in another batch. 

The yeast in our donor beer is a unique mixture of Hornindal Kveik yeast and Voss Kveik yeast from the Omega Yeast company. Kveik yeast ferments between 72 - 98° Fahrenheit (22 - 37° Celsius) and the Voss strain ferments extremely fast at high temperatures. The only drawback to a high fermentation temperature is a reduction in hop character. Fermentation for our donor beer and our new beer will take place in a heated brewing kettle. We did not transfer our wort into a separate fermentation vessel.

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Hornindal Kveik Yeast

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Voss Kveik Yeast

Despite this top cropping process being a bit of an experiment, it’s really easy and straightforward. First, you’ll want to open up your donor beer once it's about 25% fermented. You may notice that we didn’t do this in our brew day video. Do as we say, not as we do. At this point, you may see some hop debris or proteins floating around on the top. Use a sanitized spoon to scoop those out and then let the beer continue fermenting.

The top cropping process really begins once your donor beer is at peak fermentation, also known as high krausen. At this point, your donor beer should have a big foamy head on it filled with viable yeast.

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The krausen of our donor beer

Using a sanitized spoon, we scooped the krausen off of the donor beer and put it into our fresh batch of wort.

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There’s not a definite answer as to how much krausen to put into your fresh batch. Some sources online state 50 ml - 150 ml and others suggest scooping around half of the krausen. During our brew day, we just did a few scoops with no measurement.

Ideally, you want to scoop just enough yeast to get the second batch going, but not too much to mess up fermentation of your first beer. If you take too much yeast away from the donor beer, you run the risk of creating diacetyl. Diacetyl is an off-flavor that can leave your beer with an artificial butter taste, but it is often removed naturally from most beer if fermentation finishes properly.

After top cropping an adequate amount of yeast into our fresh wort, we mixed everything together and fermented at 98.6° Fahrenheit (37° Celsius). We checked the gravity about 27 hours after the top cropping process and had a reading of 1.011, meaning we had a finished IPA in just about a day.

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The final gravity of our Top Crop Kveik IPA, sitting right at 1.011

Why Top Crop?

Top cropping is just a different method of harvesting yeast. Many people will harvest and wash yeast from the bottom of a fermenter. You can learn how to do that in this video. However, there are many drawbacks to this process. The yeast at the bottom of a fermenter is not all viable and is mixed in with leftover trub and sediment from the wort. In order to harvest this yeast, it has to be washed and separated from everything it's mixed with. 

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A still from our yeast harvesting video - yeast, sediment, and trub are at the bottom of a fermenter

Top cropping simplifies the yeast harvesting process. When you’re scooping yeast from the krausen into another batch or into a jar to save it, all of that yeast is viable and healthy. It’s not mixed with anything undesirable. Everything in the krausen is clean and ready to be pitched into fresh wort.


Tasting

This beer ended with an ABV of 4.73% and plenty of citrus flavor. Our first impressions of this beer’s flavor profile were lemon, lime, and orange making it a bright IPA with an ABV perfect for day drinking on a hot summer day. This beer is also by far the best out of all 3 of the beers we made in our 3 Day IPA series. Something must have happened during the top cropping process to make this one better than it’s donor beer. We’re just homebrewers here at Clawhammer, not scientists or doctors, so who knows what made this one the best. This just goes to show that experimenting with your brew day and getting a little weird with your recipe can yield good results.

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