Using acid malt to make a gose

[jceg316]

I want to make a gose, my last attempt to kettle sour yielded terrible undrinkable results and I was looking for a better way to get the sourness into the beer. BYO suggests mashing all the base grains, then once the mash is finished, adding acid malt and mashing a further 45 mins. A couple of questions:

How much "sourness" does this give? The style isn;t hugely sour so I'm not looking for the sweaty sock experience, but something to balance with the salt and coriander. How much depth does this sourness give?

One problem I think i had with my last kettle sour was the pH was too low for the yeast so it took ages to ferment and created a lot of off flavours in the process. I guess this is gonna happen again as the acid malt will make the wort acidic. BYO recommends a German ale yeast, so I'll probably go for Safale K-97, is there a way to strike a balance?

 

[stz]

Hey hey I've got 60L at 42C as I type, I brewed yesterday, my first attempt at a gose. I've probably read the same stuff you have and while initially attracted by the relative simplicity of the aciduated malt + lactic to taste on pack combo for the desired sourness I discounted it. While I can deal with it feeling a little like cheating, the amount of aciduated malt would have had to be substantial. With grain being a bit of a wildcard element if I under did it I'd have had to use more straight lactic acid than planned and I've never been happy with how that tastes. Rule of thumb is 1% will drop the mash 0.1pH. It has weak diastatic power which is why I'm assuming BYO suggests a normal mash first at a normal pH with normal conversion then the aciduated malt for effect. Lets say your mash is at 5.2 and you want your beer at 3.7, you'd want 15% aciduated malt. There is an element of experience involved in this because pH typically drops post boil, typically drops post fermentation, it would be wise to be conservative and then adjust with straight lactic if you aren't where you need to be.

For those reasons I decided to kettle sour using a yoghurt starter. Using aciduated malt as you describe is pretty much just using it for the lactic on the grain, no biological activity, but I'd take a guess that it is a better sour than straight lactic acid as the malt is aciduated by allowing it to sour naturally.

I've made a few kettle sours using l. plantarum probiotics (underwhelming) though viability and cell count was probably the culprit. I've made quite a lot more using crushed grain which while it sours like a beast, is a bit of a dice roll. Odds can be improved by the usual methods, o2 purge, anaerobic environment, high temperature, but ... yeah it is a dice roll! Usually I reach desired level of sourness within 48 hours, but the longer it goes the more obvious become the signs of ... unwelcome activity. My last one threw an incredible krausen and fermented 5 points, my last two threw no krausen and fermented no points. The deciding factor for me is how well you can maintain the heat. If you can't and leave it for 5 days to sour, you'll likely have a significant wild yeast fermentation with associated 'yummy' off flavours.

On the yeast front I've always at least double pitched and been fine. If you are using dry hydrate or make a starter, definitely don't just chuck it in dry. You should always hydrate anyway. I'm planning to use bruxellensis. Starting with a need for 22x 10^6 per cells per ml I need 132x 10^10 cells for my pitch, my brux slurry is 200x10^6 @ 80% viability per ml which is what? 6.6L of slurry? It is quite a lot. If you consider US05 15x 10^10 per packet ... 8.8 packets in 60L? I've definitely used 3 packets in 22L before and been fine. I'm using brux because I've got about 50L of slurry hanging around at the moment and believe it will compliment the flavour, but no way believe it to be a historically accurate pitch .. I guess I'm not even really concerned about the yeast choice in a gose, ester formation will be heavily suppressed by the low pH, minor detail.

 

[jceg316]

@stz thanks for your reply. So you don't think acid malt is a good replacement? I've tried twice using sour yeast in the kettle but both times it failed. I use a grainfather so I can hold temperature fine but can't purge O2, I'm not sure how much of an issue that is in reality and whether my problem came from that.

I can't add yoghurt because a lot of people that drink my beer are vegan and I wanna keep it available to them.

 

[stz]

I think that historically gose was made as a low abv and barely hopped brew and for whatever reasons ended up with not insignificant lactic character on serving, probably because of contaminated yeast, equipment or something about their process and it was absolutely fine. Because it was lactic activity on the back end it would probably have gotten worse with time, the salt helped, the hops helped, warm weather would have made it worse, but was just a bit drink fresh!

Irrespective of that there now exist different ways to get that sour character in the beer. You can dose it with straight lactic acid and/or aciduated malt, brilliant if you don't want to play with LAB, keeps the brew day quick and simple, creates a tart character without modifying equipment or process. You can sour up front, which is great you can control exactly how sour it gets by boiling it when it is sour enough, it isn't going to get any more sour, you can reach levels of sour which wouldn't be as easy with aciduated malt, you have less chance of contaminating equipment, but you need a decent kettle souring process. You can sour during or post fermentation which is awesome, it is arguably more traditional, it is easier than a kettle sour, you've got to balance your LAB type/s and amount with your hopping and yeast, consider temperature and be prepared for it to take a lot of time to develop significant lactic character and potentially go too far, but that is cool, it just requires a little experimentation.

I discounted the acid malt method because it just seems like cheating. I also didn't think of the mash normally, then stir in the aciduated malt trick and had concerns about a low mash pH. I'm sure the flavour will be better than straight lactic and I'd give it a go, I'm sure excellent beer can be made using any of the methods. Big point for me in your shoes would be if I didn't have a reliable kettle souring method I'd avoid kettle souring in order to make better beer.

You mention sour yeast, what was it?

 

[jceg316]

I know what you mean about cheating, but I try to focus on the end result. I once made a milk chocolate mint stout and used chocolate liquor or something for the chocolate flavour instead of cocoa nibs, didn't quite feel right, but it was a great beer with a really good chocolate flavour (tasted like After Eights).

I'm gonna give the acid malt route a test and take it from there. I love sour beers so will one day be experimenting with that, but for a straight up sour I'll add yeast/bacteria post fermentation and do it the "right" way. With a gose it's a bit different because it's not supposed to be hugely sour.

 

[Sadfield]

There's a third way, and that is to pitch a lactobacillus culture with your normal yeast. The empirical evidence around the interweb appears to be, the more complex the souring method, the more complex the flavour. I've used 20% acidulated malt before and I'd describe the result as slightly tart/zesty, and a bit one dimensional, probably OK for a basic Gose.

 

[jceg316]

There's a third way, and that is to pitch a lactobacillus culture with your normal yeast. The empirical evidence around the interweb appears to be, the more complex the souring method, the more complex the flavour. I've used 20% acidulated malt before and I'd describe the result as slightly tart/zesty, and a bit one dimensional, probably OK for a basic Gose.

It is an option, maybe for the future, in my experience I've ruined plastic fermenters by having beers go sour on me and not being able to get rid of whatever bug is in there and ruining future brews. TBH I didn't try too hard to get rid of it. From what I've read it's best to give a sour beer a year or more to condition. Having said that when a beer has gone sour on me I've bottled it after a month or two and it's been fine, but I don't know what bug is in there.