W34/70 Lager Query

[TheUKCrazyhorse]

Hi all - hoping someone might be able to help/offer some advice here?

I've been brewing my own lager recipe for a while now, originally on a ~100L kit, but now using equipment that has a 300L capacity (although I've been brewing a fair bit below that), without any issues. The last two batches I've made (around 250L-270L) have gone a bit ...funny though. Not bad exactly - I mean they seem fairly drinkable - just not lager...

The recipe I'm using is as follows:
~50kg Crisp Pilsner Malt
~10kg Crisp Maris Otter

Then Saaz hop additions of 380g at 60, 30, 15 and 5 minutes.

My usual brew day consists of an hour mash at around 65C, recirculating the wort for the full 60 minutes. I'll then sparge and transfer my wort into the kettle and boil for an hour. I have a (bad?) habit of overshooting my SG by a fair whack these days, so I usually top up the kettle at the end of the boil to bring the gravity down towards my target and also to help cool the wort. I then pump the wort through a plate heat exchanger into a washed and sanitised FV. The plate exchanger isn't the greatest for cooling the wort, so I usually get it as close as I can and then leave the liquor overnight to come down to ambient temps (which over the last couple of weeks has been about 10c, ideal for lager... or so I thought...)

I usually syphon off around a gallon of wort into a glass demijohn and add my W34/70 to it and give it a good shake. This then goes into a warm (20c) cupboard overnight. I'll then pop in the next morning, when a good head of krausen has appeared in the demijohn and tip it into the main FV.

Up until the last couple of batches of lager, this method has worked great. What I've noticed on these last two times though, is that I've ended up with a really hazy, fruity beer at the end - almost looks like an NEIPA. As I said above, it isn't bad - its citrusy, fruity, juicy even - but it isn't lager. After this happened the first time, I siphoned two gallons of wort off and added those the day after brewing - same outcome.

The beer has been sitting in the FV for around 2 and a half weeks so far. After around a week, the gravity had dropped from 1.045 to around 1.030. I left it a few more days and it came down a little more (to about 1.028) - at this point I fired up some heaters and was able to bring the temp up to 20c. After another few days, the gravity dropped to 1.010, slightly above my expected FG 1.008. So far, there's no sign of the beer clearing up at all and I don't think lagering it will help either - to be honest, even if it did clear up, it doesn't taste at all like a lager so I don't see the flavour clearing anyway.

My question then is: has this happened to anyone else? Or does anyone have any idea what has caused this? My initial suspicion is underpitching of yeast, but I'm not sure. Just the fact that the beer seems to have changed so much during fermentation has thrown me a bit. I do a lot of brewing - mainly ales, which are a lot more forgiving than the lager - but I'm stumped here.

Thanks in advance and apologies for the reams of text above.

 

[smcc]

why 20degrees?

https://www.fermentis.com/wp-content/uploads/2019/11/SafLager-W-3470.pdf
it states 12-15max, I would probably go for the lower end of that range

the higher temp range will probably be causing the yeast to produce esters not normally associated with lager fermentation

 

[foxbat]

why 20degrees?

https://www.fermentis.com/wp-content/uploads/2019/11/SafLager-W-3470.pdf
it states 12-15max, I would probably go for the lower end of that range

the higher temp range will probably be causing the yeast to produce esters not normally associated with lager fermentation

As I read it he's using 20C in two places:

To grow a starter. That's perfect - he wants to maximise growth, not make beer. Though I would not be tipping in a whole gallon starter that's been fermenting at 20C. I'd prepare it earlier, let it ferment out, chill it and decant off the spent 'beer'. However, he says it's been working fine and these are very large batches where 1 gallon isn't that much compared to the total volume.

Raising from 10C to 20C after the main part of the fermentation is done and the yeast is still up and about ready to consume its own by-products. This is normal practice for a diacetyl rest - very important for lagers. However 20C is higher than you need, somewhere around 16C would be fine and would be less of a risk of overheating the wort if his temperature sensors are inside it. Personally I let the temperature free-rise for the diacetyl rest as much as I can.

 

[Hanglow]

1 gallon of starter into 250l of lager is a vast underpitch. As is 2 gallons.

What are you doing to aerate your wort? You really need pure o2 for something that size if adding a starter and a starter for that beer would be close to a full size homebrew batch, of not bigger

To be honest if you want to keep things simple then get the 500g packs of yeast that they sell, you can then add that to your batch in one go which should be enough at 10c. I think they are about £60 or so. If brewing again close to when packaging you can reuse the yeast

 

[TheUKCrazyhorse]

Thanks for the responses so far.

@smcc - the first 20c is just to get the 1 gallon starter going. I then bring the whole batch up to around 20c to try and get it to finish fermenting and as foxbat says, for a diacetyl rest.

@foxbat - thanks for the tip; I may try to keep the temp at around 16c if/when I try brewing this again. I went for 20c mainly because I've made this recipe before during the summer months (in smaller amounts) when the temps are higher inside my unit and it worked out fine. I guess I just assumed (wrongly) that I'd be golden using the same temps on the larger amount.

@Hanglow - I do actually have a 500g box of the yeast on hand; we've used it a few times, so it'll be less than 500g now. I didn't think I'd need quite as much as that though, if I was making starters beforehand.

I think that you've all just confirmed my suspicions that it is a (vast) underpitch of yeast thats the issue. I've brewed maybe half a dozen times using my new kit since we bought it October last year, most of those sessions were ales - and pitching a gallon starter into each has been absolutely fine. I did make a smaller batch of lager to test the kit (~120L) and pitched a gallon into that and it turned out as probably the best batch I'd made (maybe a little chill haze in it, but tasted great). In my head I figured if I doubled the batch size, doubling the starter would be enough to get it going. I guess going forward, I need to reduce the batch size to something more manageable and see how that goes.

Thanks for all the answers here - much appreciated.

 

[smcc]

the actual ideal temp for Diactyl rest is 14, you will see everyone in homebrew forums talking about 20s but having done the diploma brewing course at brewlab our instructor who had 30 years in the industry told us optimal temp range for this is actually way lower. prior to Covid at the brewpub where I was working we make similar batch size about 400l of helles and dunkles and it will never reach 20

 

[Hanglow]

You can also not do a diacetyl rest at all, by pitching more yeast and fermenting colder, making sure to never temperature shock the yeast and do any lagering with extract remaining. Most homebrewers and commercial brewers want to get their beers out as soon as possible though so go the quick route, you can get by that way with less equipment too

 

[TheUKCrazyhorse]

@smcc & @Hanglow - thanks again for the replies here. Very helpful.