A 2016 Attempt at Spontaneous Fermentation - Brain Sparging on Brewing


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February 7, 2017

A 2016 Attempt at Spontaneous Fermentation

Winter has finally shown up with an end to 70F+ November days. Nights finally drop into the thirties which is a good range for throwing out a coolship. So far I haven't had good luck with attempts at spontaneous fermentations but I will take blame for those misfires. Some were experiments of just leaving wort out to see what happens. Then there was the batch two years ago that I cooled too fast and ended up with a poorly attenuated and bland. In between that time and today a lot of great information is available about the mechanics of coolships and spontaneous fermentation (largely thanks to Milk the Funk) that hopefully will help get something at least drinkable.

Tackling spontaneous fermentation is a big goal for my homebrewing. I am very happy with the results of my other mixed fermentation beers, both using lab blends and blends of dregs. Spontaneous fermentation carries such an allure as an interesting process and cool factor (pun not intended) that I can't resist.

What I don't want to do is keep throwing five gallon batches at the process to get it right. I mean, I should, but I don't have the space for that many carboys to see how they pan out. Plus, that would means blending even larger volumes and that's just more than I am prepared to tackle. So one part of my continued experimentation is seeing if it is possible to effectively coolship smaller volumes. It would be a lot easier to manage a full spontaneous fermentation project (dare we call it lambic??) in one gallon increments instead of five to ten. The obvious problem is that smaller volumes cool faster than larger volumes of wort and the cooling rate affects the mixture of yeast and bacteria. Adjusting the surface area to slow cooling rates risks reducing innoculation rates which diminishes the biological diversity. So that is an issue. 

Attempted technique to coolship one gallon of wort

Using the information on the MTF Wiki on coolships I worked out some numbers to try to get this even close to a range that makes sense. As the wiki explains, one of the big problems on a homebrew scale is the dimensions of many commonly used vessels play against our favor by allowing cooling to occur too fast with too little innoculation. Kettles are often a great option because the geometry more closely matches commercial-sized coolships.

For one gallon batches I typically use my five gallon kettle which doesn't work here as a very good coolship. The size of the kettle is good but with so little liquid inside the liquid dimensions change to favoring a large surface to volume ratio that is good for innoculation but bad for controlled cooling. I also worry that the distance between liquid surface and the top of the kettle may act as a shield from inviting the right guests.

My solution for this problem is to transfer the wort to a six quart stock pot from the kitchen. The dimensions more closely align with a normal brewing kettle full of wort and the metal is thicker which will help retain heat slightly better. I'll also wrap it with towels to help insulate and slow cooling.

I am still concerned the cooling will go too quickly in the stock pot, especially through the 140-60F range where the good inoculation happens. To cure that problem I will transfer the wort to my two gallon cooler mash tun because it has superior insulation. The liquid dimensions will be about the same so it's all upside. I'll preheat the mash tun to avoid temperature loss through the transfer.

Quick note on the recipe

For this recipe I will follow fairly typical lambic wort production technique. The biggest exception will be using pale malt rather than pils malt merely because I am trying to work through the sack of pale malt in the house. Hours of turbid mash fun. The only suitable aged hops I have on hand are from my homegrown hops. Most of my older hops are cascades which are a little higher in alpha acids than typical lambic hops but not so high I think it will be a problem.

One Gallon Lambic Wort Recipe #1

Batch size: 1.1 gallons
ABV: 4.4%
SRM: 3
Est. OG: 1.47
Est. FG: 1.002

Grain BillPoundsOuncesSRMPct. Grist
Pale Malt10250.00%
Unmalted wheat10150.00%
Water Profileppm
Yellow Bitter--Brussels
PH: 5.5
Water AdditionsMashSparge
Epsom Salt.4g.4g
Canning Salt
Baking Soda.3g
Calcium Chloride.3g.3g
Pickling Lime
Lactic Acid1.2ml

Mash schedule

Mash water volume: 1 gallon
Sparge water volume: 0.85 gallons

1. Begin heating all mash water
2. Dough in 25 oz at 131 for rest at 113F for 15 minutes
3. Raise mash water to boil
4. Add 25 oz boiling mash water to raise to 126F for 15 minutes
5. Remove 13 oz from mash and add to kettle #2. Raise and hold at 190F
6. Add 38 oz boiling mash water to mash to raise to 149F for 45 minutes
7. Remove 38 oz from mash and add to kettle #2. Continue to hold kettle #2 at 190F
8. Add remaining 38 oz mash water to mash to raise to 162F for 30 minutes
9. Begin heating sparge water to 190F
10. Transfer liquid in mash tun to kettle #3 and begin heating to boil
11. Add contents of kettle #2 to mash tun and rest for 20 minutes
12. Drain contents of mash tun to kettle #3 and continue to heat
13. Sparge as usual and combine all runnings

Boil schedule

90 minute boil
0.70 oz aged hops at start of boil

Cooling schedule

1. Transfer wort to six quart stock pot, straining out hops
2. Wrap/surround stock pot with towels and place outside
3. When temperature of wort declines to 170F heat one gallon of water to 160F
4. Pour water in two gallon cooler to preheat cooler
5. When wort reaches 155F remove water from cooler and transfer in wort
6. Wrap cooler with towels and replace outside until wort is below 50F
7. Transfer to fermentation vessel

Brewday and Fermentation Notes

Brewed 11.19.16

Preboil volume: 2 gal
Preboil gravity: 1.028
Mash efficiency: 78%

Hops: 0.55 oz mixed 2014 cascade and mt. hood from garden plus 0.15 oz 2011 belma

Recorded temperatures for several hours roughly every thirty minutes. Did not expect to drop temperature so quickly. Transferred to cooler after one hour (11pm). Preheated cooler with approximately one gallon of water at 160F and sat in the cooler for ten minutes. Water dropped to 144F before dumping.

Sent outside at 9:55pm, brought in at 9:30am the following morning. Temperatures dipped in the very early morning to mid-30s so the wort probably got down to similar temperatures before the sun came up and started to warm. I went to bed around 2:30 so that's why readings stopped.

Temperatures were consistently dropping by four degrees once the ambient temperature held constant at 37F and the wort temperature coasted into the mid-eighties. Projecting that data forward the wort likely hit the mid to upper thirties sometime around 6:00am. Cooling is not linear so it possible the cooling slowed later in the night to less than eight degrees per hour and the wort never dropped below the final reading the following morning at 47F. 

11/19/16 9:55 PM39F212F
11/19/16 10:30 PM39130
11/19/16 10:50 PM39114
11/19/16 10:55 PM39113
11/19/16 11:20 PM38103
11/19/16 11:55 PM3792
11/20/16 12:25 AM3784
11/20/16 1:00 AM3777
11/20/16 1:30 AM3773
11/20/16 2:00 AM3769
11/20/16 2:20 AM3766
11/20/16 9:21 AM4747

Fermentation Updates

Within five days active fermentation appeared with fluffy white krausen. Went away after a few days. Approximately a week later the same thing happened. 

12.19.16: Thirty days out tasted the beer. Sweet-sour. Bitterness is prevalent, somewhere between APA and IPA. Mildly phenolic. Lingering mushroom flavor. Tastes similar to other wild yeast cultures. So far none of the weird clumps that plagued my last attempt at a spontaneous fermentation.

7.27.17: Approximately nine and a half months old. Thin, white pellicle. Aroma is funky, slight cherry pie. Taste is thin and bitter; slight acidity. Mushroom/earthy flavor lingers. Mouthfeel is thin. No expected brett flavor yet, despite aroma. Could be good, could be bad. Definitely needs more time. Not thrilled with the thin mouthfeel.

11.2.17: A couple weeks shy of one year old. Pellicle slightly thinner. Beer is crystal clear. Still a fair amount of bitterness remaining. Acidity is improved but still light. Mushroom flavor has diminished but remains noticeably. Cherry flavor developing. Feels a little less thin.

1.28.18: Thick white pellicle, clear beer. Strong mushroom flavor dominates. Definitely picking up a little acidity but not much. Tannins present as the beer continues to dry out.

3.27.18: Same appearance. Aroma is mushroom and musty with a hint of cherry pie. Flavor is similarly strong mushroom with mustiness and a little horseblanket. The acidity is a little more present but still very mellow. Tannins have dropped out a bit. Not terribly complex but seems to still be heading the right direction.

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