Wednesday, 22 June 2016

Brewing a Gose (using Lactobacillus plantarum capsules)

I've been promising myself over and over that I would start brewing more sour beer styles; I really love drinking them, and have only attempted a few different ones in the course of my homebrewing career: a Flanders Red that turned out pretty great (1/2 the batch aged on cherries), a Berliner Weisse that wasn't nearly sour enough, and an Oud Bruin that I've finally been drinking the past six months, that I'm pretty happy with. When you're brewing sours by pitching a mixture of bugs and yeasts, you can end up with some truly wonderful beers... the problem, however, is that it can take one hell of a long time till the beer is where you want it. Both the Flanders Red and Oud Bruin were a good 16-20 months before I bottled them.

The solution? Kettle souring. I'm sure most if not all of you have heard of this method by now; it's quickly gained a lot of momentum in the commercial and homebrewing communities. In a nutshell, you mash and sparge as usual, bring the wort to 190 F or so to pasteurize, chill down to a warm temp to pitch your Lactobacillus (the ideal temp will depend on the strain), pitch the Lacto and keep the wort warm until the pH drops to where you want it (3.3-3.5, roughly), transfer back to your kettle and boil the wort briefly to kill off the Lacto, then chill as usual and pitch a neutral yeast strain or Brettanomyces to ferment out the beer. I couldn't explain it any better than many who already have; check out the Milk the Funk wiki on Sour Worting, as well as their Lacto wiki - highly informative and extremely-well researched. Mike Tonsmeire's American Sour Beers is also an excellent resource, one of those books that I keep going back to again and again.

The idea behind all this is that you can sour the wort within several days, and if you then boil it, you don't have to worry about bacteria coming in contact with your kegerator, post-fermentation equipment, etc. Of course, if you don't care, you don't have to boil the wort; just pitch your regular yeast and be done with it. If your wort pH gets down quite low, say, below 3.4, using a Brett strain is a good idea since it ferments better in the presence of acidic wort than a lot of Saccharomyces strains do.

Will this method give you as complex a sour beer as the standard, "old-fashioned" way? Probably not. But if you're looking to brew a hoppy sour, a sour with fruit, or something similar, it's a great way to give you a tasty sour beer without the months of waiting. Or so I've heard; I'm certainly no expert. But I have had several commercial version of kettle-soured beers that were great; I really do love the hoppy sour beers that are coming out now, and more and more breweries are coming up with their own twists on the "style".

But what about a Gose? A lot of brewers have brewed this German style - sessionable, tart, salty - via the kettle sour method, with great results. I've had several commercial Gose beers and have really enjoyed many of them; it's something I've always wanted to brew, so I thought it would be a great one to try with a faster-souring method. I was initially going to order another pack of Lactobacillus from Wyeast (or maybe White Labs), but I had been reading more and more about people sourcing Lactobacillus from Swanson Probiotic capsules. Unlike a lot of probiotics that you see, these ones only contain one type of Lacto, Lactobacillus plantarum, a species that is surprisingly quite effective at lower-than-usual temperatures, between 80-90 F. For someone like me, who doesn't have a lot of options for keeping wort hot (above 100 F), this is a great option. I quickly ordered the capsules on Amazon, and then kind of forgot about them until recently.

I finally got around to making a Lacto starter in April. Of course, there are different thoughts on the approach you should take; the Milk the Funk wiki mentioned above has a very detailed one that I did not see in time. Ultimately, I ended up taking the approach that Ed documented in his attempt: four Lacto plantarum capsules in 1 L of wort. No need to set it on a stir plate of course; I simply set the flask on a heating pad for a few days, where the temp stayed at about 90 F. After 48 hours or so, the pH was down to 3.53. I was hoping to go lower, say 3.3 or so, but even after adding another capsule, it didn't budge. 3.53 isn't horrible, so I decided to press on and brew the beer.

NOTE: Just to make clear, depending on your Lacto source, you sometimes have to be very careful about keeping as much oxygen as possible out of your wort, starter or otherwise. Apparently with the L. plantarum capsules, this isn't an issue. Just keep in mind that if you're sourcing Lacto from grains, it's very important to purge with CO2 whenever possible, so you don't end up with the vomit, cheese, or fecal aromas/flavours from other organisms popping up due to exposure to oxygen.

Putting together a recipe was pretty easy; the grist is just a 50:50 blend of Pilsner malt and Wheat malt, with some Acid malt added in to bring the mash pH down to ~5.4. Goses are usually pretty low-ABV; most seem to be < 5%, so I aimed for an OG of only 1.033, and mashed pretty cool at 150 F. Once the vorlauf, sparge, etc. was complete, I brought the wort up to 190 F or so for a few minutes, then immediately chilled it down to 100 F. Racked into a Better Bottle, I pitched the entire 1 L of Lacto starter and set the whole thing on a heating pad, with a heat belt attached, and let 'er go. I was able to hold to the wort temperature in the high 80s F with this method. After a few days, the pH was 3.69, and it didn't get any lower than that. Again, not 100% ideal, but it did taste slightly tart, so I transferred the wort back to the boil kettle and continued.

A traditional Gose features the addition of both salt and coriander in the boil. The typical approach appears to be 1/2 an ounce (14 g) of each, but I've had many homebrewed Goses that didn't strike me as salty enough. You don't want to be drinking beer that tastes like sea water, but you DO want to notice it. A friend had recently brewed a Gose using 3/4 oz (21 g) of salt, which brought it closer, but not quite there (in both our opinions). I finally settled on a bit more - 25 g - along with 14 g of freshly-ground coriander seed, added during the last 2 minutes of the boil. For the hops, I wasn't looking for much bitterness for this style; since I was only planning on boiling the wort (after soured) for 5 minutes, I added 14 g of Polaris at 5 min, giving 8 IBUs. The wort was then chilled to the low 60s F, and I pitched a full package of rehydrated US-05. I didn't feel fermenting with Brett was necessary; with a pH of only 3.69, US-05 could easily handle the job. However, it's best to still err on the side of caution and pitch more yeast than is necessary in this case, hence the full pack of US-05 for a 1.033 beer.

It didn't take very long, of course, for fermentation to be complete (FG was 1.006). Now, I had to decide where I wanted to go with this beer. I had originally planned on splitting the batch - dry-hopping half with Citra, and keeping the other half plain. However, I knew it wasn't going to be as tart as I had hoped, so I figured it best to add something else to the plain portion. Lots of options, naturally, but I settled on fresh lime zest. I figured it would work well with a Gose, giving the beer an almost Margarita-like quality to it, thanks to the salt (no, do not start thinking about Bud Light Lime-a-Rita!).

Another question... how much lime zest to add? You don't need a lot; lime zest is pretty potent stuff. Mike Tonsmeire mentions in his book to start with 0.5 g/L when adding citrus zest. I was looking at about 10 L of beer, so I went with just a touch more, 6.5 grams (0.65 g/L), to make sure I noticed the lime (hopefully without it tasting like pure lime juice). I racked the beer like so: half into a 3 gallon Better Bottle, and the other half into my dry hop keg, where I added the Citra. I added the zest to a mesh bag and dunked it in Star San for a couple of minutes, before dangling in the BB with dental floss. A smarter way, I now know, is to simply dunk the limes and your zester in Star San before zesting. Oops!

After about 5 days, I kegged the Citra dry-hopped portion and bottled the lime zest portion. Now that I'm drinking both, I have to say that my preference may be for the lime Gose, which surprises me. Both are refreshing, palate-cleansing beers; light and easy-drinking, the salt level is spot-on. I don't get much coriander from either beer; admittedly, the coriander seeds weren't the freshest, but they smelled great when I was grinding them. Maybe going to 0.75 oz next time would be a better amount? As for the sourness level, the beer is definitely tart, but I'd like to see it with more tartness. Not a lot - you don't want Lambic-level sourness - but a bit more would be just the ticket.

The Citra Gose is enjoyable enough, but despite a dry-hop of 2.5 oz (the equivalent of about 5 oz for a 5 gallon batch), I'm not getting near as much Citra in the aroma or flavour as I would expect. Meanwhile, I think I lucked out in my lime zest addition for the other half - there's definitely a really nice, obvious lime presence, but it didn't come out on the heavy side, which I started worrying was going to happen. I ended up naming that one "Margarita Gose", as it comes about as close to a Margarita beer as you would want.

So, I'm happy with the amount of salt used (I don't think I'd change it at all), and the amount of lime zest. I'm still torn on the Citra addition; maybe one can only expect so much hop presence to come through in a beer like this? The equivalent of a 5-oz dry hop for a 5 gallon batch seems like plenty to me. If I tried again, I think I'd experiment with adding some Citra at flameout for a 15-20 minute hop steep; yes, you'd give the beer more IBUs this way, but maybe it would work.

I would also like both beers to be more sour. Again, NOT a Flanders Red or Lambic sourness, but just a hair above where they are now. Now that I've been reading more on the subject, I think a couple of things would need to change for next time on this front:
  1. Use phosphoric or lactic acid to lower the wort pH - There's a couple of reasons why this is a good idea; one is because for someone with water like mine, the wort pH comes out higher than ideal, especially in lighter-coloured beers. Lowering the pH, at least slightly, kind of gives the Lacto a head start, if that makes any sense (this applies to the starter and final wort). On top of that, it's been shown that lowering the wort pH to ~4.5 before pitching the Lacto can help aid in reducing foam degradation (see the Milk the Funk Wiki link for more details). If you can get it, I'd use phosphoric acid, as it won't affect the taste like lactic acid can.
  2. I think it's possible that the Lacto starter was too warm for the L. plantarum to lower the pH where I wanted it. I'm not positive here; the evidence would indicate that L. plantarum is still fine up to 90 F, and probably up to 100 F; but I can tell you that I've brewed a hoppy sour since this beer, and accidentally had the heat pad unplugged for the starter, where the pH jumped from a seemingly-stalled reading of 3.9 to 3.3 in a short matter of time. More on that in a future post.
Overall, though, I'm enjoying both of these beers, and for my first foray into kettle souring, I'm quite happy. The capsules worked well enough for me to warrant using them again, especially now that I know to try a slightly different approach next time.

Recipe Targets: (5.5 gallons, 75% efficiency) OG 1.033, FG ~1.009, IBU 8, SRM 2.9, ABV ~3.2%

Grains:
1.4 kg (47.9%) Bohemian Pilsner
1.4 kg (47.9%) Wheat malt
125 g (4.3%) Acid malt
+ 100 g Rice hulls

Hops:
Polaris - 14 g (20% AA) @ 5 min

Citra - 70 g dry hop for 5 days (in dry hop keg) for 1/2 of the batch

Misc:
1/2 tab Irish Moss at 5 min
14 g freshly-ground Coriander seed at 2 min
25 g Sea Salt at 2 min

Lime zest - ~6.5 g in secondary after fermentation is complete, for 5 days for 1/2 of the batch

Bacteria/Yeast: Lactobacillus plantarum capsules (4) in a 1 L starter; after souring, wort fermented with 1 pack rehydrated US-05

Water: Fredericton city water, carbon-filtered; 5 g Gypsum and 5 g calcium chloride added to mash

- Brewed on April 19th, 2016, by myself. 50-minute mash with 9.5 L of strike water; mash temp on target at 150 F. Mashed-out for 10 minutes with 5 L of boiling water to 168 F. Sparged with ~3.75 gallons of 168 F water for final volume of ~5.75 gallons.

- Pre-boil gravity at 1.033 (target 1.032). Heated to ~195 F, then chilled to 100 F. Racked to carboy, pitched Lacto starter, attached heat belt and set carboy on heating pad. Four days later, the pH had dropped to 3.65 - with the heat belt and pad, the temp was about 80 F, so I had panicked and turned on a space heater in the room, which brought it up to around 90 F or so.

- 26/4/16 - Transferred wort back into kettle, brought to a boil. Started 5 minute boil, added hops, coriander and salt at time above. Chilled down to 62 F and poured into BB. Aerated for 60 seconds and pitched yeast at 64 F. Fermentation visible by next day, continued for two days and then petered off.

- 4/5/16 - pH reading 3.69. Split the batch by racking half into dry-hop keg and added 70 g Citra, other half racked into 3 gallon carboy (~10 L) and added 6.5 g lime zest (sanitized by dunking mesh bag, marbles and zest in sanitizer before adding to carboy).

- 10/5/16 - Bottled lime half with 60 g table sugar, aiming for 2.5 vol CO2 for 2.5 gal, max temp 70 F reached. Racked Citra half into serving keg and set carb to PSI 30 for 24 hours.

Lime zest on the left, Citra on the right
Appearance: As you can see from the picture, they look pretty identical. Both pour with a moderate-sized, white head that fades fairly quickly, as expected. The Citra head lasts longer, however... due to being force-carbed, or is the lime zest causing that head to fade a bit quicker? Lime body is just slightly darker, but both beers are pretty pale. Touch of haziness.

Aroma: Moderately salty, touch of coriander; the Citra portion has a light fruitiness and a little dank character. The lime beer definitely has the lime zest coming through in the aroma, more prominent than the salt; works very well.

Taste: Citra half: the Citra hits first, pleasant low fruitiness, followed by a moderate-low tartness on the tongue. Finishes lightly salty, with low to no bitterness. Dry and refreshing. Lime half: great amount of lime character in the flavour, followed by the saltiness to make it seem that much more maragarita-like. Same tartness as the Citra half... pleasant, but not quite enough. Great summer beer.

Mouthfeel: Both are light-bodied, with moderate carbonation.

Overall: Refreshing, easy-drinking; I enjoy both, but give the edge to the lime zest portion. I think the salt level is perfect, could use a bit more coriander. Expected and wanted more Citra presence in the dry-hopped version. And, of course, both could benefit from some more tartness.

7 comments:

  1. Going to have to try this. You mention a 1L starter for the lacto, that should get pitched into the mash and left to sit for the 24-48 hours before boiling right?

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    1. Not quite; you pitch the starter into your wort.

      So, mash, sparge, drain into your kettle as usual. Bring that to a boil for a few minutes or so (some say getting it to 190 F is enough, others say to boil a little bit), chill down to 100 F or so, THEN pitch your starter into that. Whether you first transfer to a carboy is up to you.

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  2. Shawn,

    This Lacto primer over at Sour Beer Blog is great: http://sourbeerblog.com/lactobacillus-2-0-advanced-techniques-for-fast-souring-beer/

    I use the same Lacto you use and have found the starter recommendations in the article above to really make the lacto happy.
    I use 4 capsules to make a 1 liter starter for my 2.5 gallon batches. It sours sufficiently in 12-18 hours. My wife likes her sours really sour so I don't boil the wort after souring and then usually dry hop after fermentation is over.

    The last Gose I made, which is still in primary, I used Brett C to ferment and omitted the coriander. The samples have been good and can't wait to dry hop and keg in the next couple of days. Although I may try some lime like you did. My wife likes the Key Lime Gose from Kent Falls Brewing a lot.

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    1. I actually read the article on that link just a week or so ago, and you're right, some great tips there! Thanks for reminding me about it, and bringing it to the attention of anyone reading.

      You have regular access to Kent Falls? Lucky... I've been wanting to try their beers ever since they opened, but that damn Derek is too busy to send me some. :D

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  3. Hi Shawn,

    I've made a couple Goses in the past, and they have both been among the most enjoyed beers I've made by my brew group. I inoculated both by chucking in a handful of uncrushed grain, and you're right: I had to be suuuuper careful about oxygen so as not to get the cheesiness. The lacto capsules you used had no problems or off flavours at all with oxygen? That's really great to hear!

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    1. That's right, no cheese, fecal matter, etc., and several people have tried both beers, with no complaints ("luckily", those flavours and aromas are easy to pick up on!). I was initially a bit skeptical on whether oxygen exposure with L. plantarum capsules would cause problems, but several people who had used them before assured me it would be fine. Worked out pretty well!

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    2. Awesome. The need for holding a high temp and the need to be so careful about oxygen are probably my two least favourite things about kettle souring, so I think it is a no brainer for me to pick some of these up. Thanks for the great blog post!

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