Testing my limits: First-time yeast harvesting, hop stand, and underpitching adventure

[Uriel homebrewer]

Hi everyone,

For the first time since I started homebrewing, I’m trying to harvest yeast, reuse it in a test batch, and experiment with a hop stand at the same time. I have no idea how this is going to turn out, but I’d love to get some feedback from more experienced brewers.

My main goal is to explore the aromatic side of brewing, and what better way to do it than with a small experimental batch where there's no fear of ruining it?

The recipe for this experiment is a straightforward pseudo-SMaSH variant:

• Malts: Pilsner and CaraPils.
• Hops: Magnum.
• Yeast: Harvested Voss Kveik (M12) from a previous Oatmeal Porter.

The Magnum hops I bought have a nice citrusy profile that I want to experiment with during a hop stand. At the same time, I want to drive those fruity yeast esters by intentionally underpitching the harvested M12 Voss Kveik—regardless of whether it goes perfectly or not.

If anything good comes out of this experiment, I plan to use it to tweak and improve my regular recipes. Either way, it's all about having some fun and learning. Looking forward to your thoughts!

For this experimental batch, I’m not going to build a water profile from scratch. Instead, I’ll just use bottled water with a profile that’s close enough, only adjusting the pH. I’m targeting around 21–25 IBUs and a BU:GU ratio of approximately 0.45. No recirculation, no gelatin—just Irish Moss for clarification.

Harved Yeast ------> Beer to improve with tis expertiment

My last beer turned out great, except it was a bit 'flat' in the aroma department. It has just the right amount of bitterness, a clean white bread aroma, and it's highly drinkable, but I feel like it's missing that special something. That lack of aroma punch is exactly why I'm running this experiment.

 

[Donoroto]

My experiences with magnum is that it adds bitterness, not aroma. My expectation for your beer will be an unremarkable but decent drinkable beer. Yeast will not contribute much (which is ok), carapils will add some malt flavor and sweetness, and magnum might add something besides bitterness.

Re-using yeast is fine, just remember the yeast will need oxygen to ferment well. Mix in some air when adding it to the fermenter: shake, stir, whatever.

Please post a link to your recipe for more detailed comments.

If you want citrus, consider adding some Cascade at the end of the boil (5 minutes). (Cascade doesn’t bitter as well as magnum, so you might also keep the magnum).

2Ma2H ??

 

[Uriel homebrewer]

Thanks for the feedback!

Regarding the Magnum, it’s actually the only hop I have on hand right now, and I bought a large amount that I need to use up. When I opened the bag, I noticed a surprisingly distinct citrusy profile in this specific batch, which is why I got curious and wanted to see if a hop stand could pull some of that out—even if it's traditionally just a bittering hop.

As for the yeast, my idea with underpitching is to intentionally stress the Voss Kveik in a controlled way to push those fruity, citrusy esters. Usually, I pitch at a normal rate to keep it clean, but this time I want to see the other side of it.

Basically, I’m putting this whole batch together using leftovers and remnants I have sitting in my pantry, just to experiment and learn without spending extra!


RECIPE:
Style Name: Experimental Beer
Boil Time: 60 min
Batch Size: 5 liters (fermentor volume)
Efficiency: 70% (brew house)

STATS:
Original Gravity: 1.048
Final Gravity: 1.009
ABV (standard): 5.23%
IBU (tinseth): 23.42
SRM (morey): 4.5
Mash pH: 5.27

FERMENTABLES:
1 kg - Swaen Pilsner (90.9%)
0.1 kg - Goldswaen light (9.1%)

HOPS:
3 g - Magnum, Type: Lupulin Pellet, AA: 14, Use: Boil for 45 min, IBU: 22.58
1 g - Magnum, Type: Lupulin Pellet, AA: 14, Use: Hop Stand for 10 min, IBU: 0.84

OTHER INGREDIENTS:
1 g - Irish Moss, Time: 10 min, Type: Fining, Use: Boil
1.5 ml - Lactic acid, Time: 60 min, Type: Water Agt, Use: Mash

YEAST:
Mangrove Jack - Kveik Yeast M12
Starter: No
Form: Harvest
Attenuation (avg): 79.5%
Flocculation: High
Fermentation Temp: 32 C


MASH GUIDELINES:
1) Strike, Start Temp: 69 C, Target Temp: 64 C, Time: 90 min, Amount: 3.9 L
2) Batch Sparge, Start Temp: 90 C, Target Temp: 75 C, Time: 15 min, Amount: 5.5 L
Starting Mash Thickness: 3.5 L/kg
Starting Grain Temp: 22 °C

WATER REQUIREMENTS:
Strike water volume at mash thickness of 3.5 L/kg, 3.9L
Mash volume with grains, 4.6L
Grain absorption losses, -1.4L
Remaining sparge water volume, 5.5L
Pre boil volume, 7.9L
Boil off losses, -2.2L
Hops absorption losses (first wort, boil, aroma), -0.2L
Post boil Volume, 5.6L
Kettle losses, -0.3L
Hops absorption losses (whirlpool, hop stand), -0.1L
Misc. losses, -0.2L
Going into fermentor, 5L

Total Water Needed: 9.3L

 

[Craigerrr]

I would personally use the magnum for bittering only, and use something like Simcoe, Mosaic, or Citra for your flavor/aroma addition. If you want to maximize aroma add some to the ferementer near the end of fermentation. Although the word citrus is a descriptor for magnum, it wouldn't be the main flavor/aroma that would result from using it as you show in your recipe. Note that the following specifies Citrus "zest". Underpitching is a good practice with VOSS.

 

[Craigerrr]

More about underpitching VOSS

How to Underpitch Successfully
Add Nutrients: Because the yeast undergoes massive cell division, it requires a lot of food. Always add a high-quality yeast nutrient to prevent stalls or off-flavors.

Temperature Control: Pair your underpitch with a warm fermentation (35°C / 95°F is a sweet spot). Warmer temps pair synergistically with underpitching to produce maximum fruitiness.

Oxygenation:
Underpitching requires healthy yeast replication, so ensure your wort is well-aerated or oxygenated at the start.Patience for

Conditioning: Despite the fast fermentation, underpitched kveik can leave behind a "green beer" with harsh yeast bite. Give the beer a few weeks in the keg or bottle to mellow out and let the fruit flavors shine.

 

[Sunfire96]

Voss kveik tastes like rancid orange juice to me. I discovered Lutra dried yeast by Omega and haven't used any other kveik since then

 

[Craigerrr]

Voss kveik tastes like rancid orange juice to me. I discovered Lutra dried yeast by Omega and haven't used any other kveik since then

You can definitely get this from VOSS, especially if you ferment at typical Ale yeast temperatures. It isn't for everyone for that's for sure. The first time I used VOSS, not having any experience or knowledge, I used it on a Coffee Porter which I bottled. It had a very unpleasant citrus flavor initially. After a couple of months in bottles it actually settled out and tasted like it should.

 

[Donoroto]

Given that you only have magnum, and this is an experiment, go for it. You may find it needing to age due to a hops ‘bite’, a harsh acidic bitterness that does fade with time and carbonation. The citrus from kviek is not a sweet orange, more an acidic tangy orange.

Nothing ventured, nothing gained. Good luck.
Please let us know how it goes!

 

[dmtaylor]

Looks like a fun experiment. Enjoy!

For whatever it's worth, I have dry hopped with Magnum before and I thought it turned out great. People who don't think it would make a great late hop because it's intended "for bittering only" should just try it, you'll be pleasantly surprised.

 

[Semper Sitientum]

What’s considered an underpitch? Let’s use 11g. for a 5 gallon batch as an example. How do you calculate?

 

[Uriel homebrewer]

Voss kveik tastes like rancid orange juice to me. I discovered Lutra dried yeast by Omega and haven't used any other kveik since then

If you want to ferment fast and clean, you can overpitch or control the temperature to avoid that taste. If you ferment under 30° Celsius, you get a clean profile. That is what I usually do.

 

[Uriel homebrewer]

What’s considered an underpitch? Let’s use 11g. for a 5 gallon batch as an example. How do you calculate?

For an underpitch, a good rule of thumb is to use half of the required yeast. For example, if a standard calculator tells you to pitch a certain amount, you can intentionally cut it in half to stress the yeast and get those fruity esters.
To clarify, this is specifically for Voss Kveik. Since this is my first time harvesting yeast, I am going to use just a teaspoon of the slurry for this 5-liter batch.
For context, I usually use 5g of dry yeast for 10-liter batches and ferment below 30°C to avoid esters. That's what I usually do. But for this experiment, I want to do a free-rise fermentation without temperature control to see how it behaves.

 

[Uriel homebrewer]

Looks like a fun experiment. Enjoy!

For whatever it's worth, I have dry hopped with Magnum before and I thought it turned out great. People who don't think it would make a great late hop because it's intended "for bittering only" should just try it, you'll be pleasantly surprised.

That's why I want to experiment! Even if it's labeled for bittering only, I find its aroma really nice and worth exploring. Everyone gets so caught up in those categories, but if it smells good, it's worth giving it a shot.

 

[Mont Y. Märzen]

I've only ever used Magnum early (first wort) but I fully support this experiment! Please report back if indeed you get the citrus you are seeking!

Beware, Magnum also throws Menthol. I've experienced it. (was perfect in a Cascadian Dark Ale/Black IPA!) Don't be surprised if you get some. That may or may not be welcome. (I got it from Magnum at First-Wort with a 90 minute boil)

Be sure to get your hop stand temp down first though, no higher than 145℉. I learned this from a pro-brewer. High-alpha high-oil hops will flare off just about everything you are wanting to capture if you drop them hotter. (those expensive hops are practically wasted in that case, or at least not used efficiently)

Stand for at least 20 minutes, 30–45 won't hurt.

Either add a touch more for dry-hop after fermentation and cold crashing, or else drop your hop bag from brew day in a sanitized zip-lock and put it in the freezer during primary. (not the fridge) Then pull it out, thaw, re-sanitize for good measure, and use it for dry-hopping. There will still be oils left behind after the brew day stand. No need to throw them away.

Indeed, splash just a bit of saved Voss into your fermenter and *then* rack your slightly cooled beer onto it from as high as you can stand it and still get it into the fermenter instead of on the floor or counter. That should both mix the yeast in well and provide sufficient oxygen if you don't have a diffuser. 95–105℉ is fine and makes just about any Kveik, particularly Voss, happy. There is a strong chance you'll see lava-lamp activity before you are done cleaning up.

I also agree with letting the beer settle for at least a week, even if primary is done in 24–36 hours. Then slowly cold crash before dry-hopping. An extra week held cold won't hurt. And that is after carbonation.

While you are experimenting, and since you aren't using all-grain, consider ditching the citric acid for pH but measure your pH as usual and also after fermentation. Kveik tends to be tangy with a lower pH in the finished product. It might be possible to mitigate this by starting from a higher pH point than is traditional for brewing. But that is a bigger step and risk than you have outlined. And you might want the citric and the tang in this particular case.

 

[Uriel homebrewer]

I've only ever used Magnum early (first wort) but I fully support this experiment! Please report back if indeed you get the citrus you are seeking!

Beware, Magnum also throws Menthol. I've experienced it. (was perfect in a Cascadian Dark Ale/Black IPA!) Don't be surprised if you get some. That may or may not be welcome. (I got it from Magnum at First-Wort with a 90 minute boil)

Be sure to get your hop stand temp down first though, no higher than 145℉. I learned this from a pro-brewer. High-alpha high-oil hops will flare off just about everything you are wanting to capture if you drop them hotter. (those expensive hops are practically wasted in that case, or at least not used efficiently)

Stand for at least 20 minutes, 30–45 won't hurt.

Either add a touch more for dry-hop after fermentation and cold crashing, or else drop your hop bag from brew day in a sanitized zip-lock and put it in the freezer during primary. (not the fridge) Then pull it out, thaw, re-sanitize for good measure, and use it for dry-hopping. There will still be oils left behind after the brew day stand. No need to throw them away.

Indeed, splash just a bit of saved Voss into your fermenter and *then* rack your slightly cooled beer onto it from as high as you can stand it and still get it into the fermenter instead of on the floor or counter. That should both mix the yeast in well and provide sufficient oxygen if you don't have a diffuser. 95–105℉ is fine and makes just about any Kveik, particularly Voss, happy. There is a strong chance you'll see lava-lamp activity before you are done cleaning up.

I also agree with letting the beer settle for at least a week, even if primary is done in 24–36 hours. Then slowly cold crash before dry-hopping. An extra week held cold won't hurt. And that is after carbonation.

While you are experimenting, and since you aren't using all-grain, consider ditching the citric acid for pH but measure your pH as usual and also after fermentation. Kveik tends to be tangy with a lower pH in the finished product. It might be possible to mitigate this by starting from a higher pH point than is traditional for brewing. But that is a bigger step and risk than you have outlined. And you might want the citric and the tang in this particular case.

Thanks for the great tips! To clarify, I actually do use all-grain, so monitoring the mash pH is important for my efficiency, though I'll definitely keep an eye on how low the Voss drops the pH during fermentation. I always pull my hop spider out right after the boil to avoid extra bitterness anyway—it's just the fine hop bags that get blocked too quickly, so I'll go with a free whirlpool this time.

For the hop stand, I usually aim for 167°F to 176°F (75°C–80°C). For oxygen, my method is to use a jug to pour the wort from a height to get a good splash, and then I'll pitch the yeast below 104°F (40°C).

I always leave my beer fermenting for at least 7 to 10 days so it has time to clean up any byproducts. Since I love brewing clear styles, I always finish with a cold crash and gelatin to get a nice, compact trub and maximize my yield during transfer.

 

[Mont Y. Märzen]

To clarify, I actually do use all-grain, so monitoring the mash pH is important for my efficiency, though I'll definitely keep an eye on how low the Voss drops the pH during fermentation.

Sorry, got mixed up with another thread!

For the hop stand, I usually aim for 167°F to 176°F (75°C–80°C).

I would definitely recommend 145℉ and let it fall naturally from there during the stand. Since I switched to doing so, I find aroma is much more potent from any hop. But of course, go with what you are comfortable with. (Brülosophy did some trials with different temps, I don't think they went as low as 145, but they definitely found a difference below 175.)