When to rack to secondary?

[Tortue]

Hi, beginner brewer here. I'm looking for some advice about when to, or if I should, move to secondary fermentation.

I have a 20 litre Czech-style lager (my first lager) that's been sitting in primary for 13 days. It's been in the cellar at a steady 16°C, sometimes spiking at 18°C on hot days. I'm using Saflager S-189 which works from 9-22 °C but favours a fermentation temp. of 12-15°C.

At this point there is no airlock activity. Original gravity was 1.040. Gravity today is 1.009, giving an apparent attenuation of 80%.

After tasting the sample I'm getting a not unpleasant flavour of green apples, which I'm guessing is acetaldehyde? I'm also getting a dominant alcoholic flavour which would encourage me to remove the trub. The beer is yellow-orange and very cloudy.

My questions are, would the beer benefit from longer in primary? Is it ready to rack to secondary? Should I skip secondary fermentation and go straight to lagering in bottles in the fridge?

Thank you for your advice.

 

[JerryP]

Hello Tortue,

Welcome!

Firstly, secondary is not really ever required unless you are doing something specific like adding fruits or other fermentables. It was often recommended in older brewing texts, but has pretty much been dismissed now. All it usually does is add a step where you could oxidise your beer and risk contamination. There is, on a homebrew scale, no real need to remove beer from the trub - again this came from big commercial brewing with very tall fermentors where the pressure on the yeast which settled out was extremely high. I have left beers in the fermentor on the yeast for more than a month and not noticed any issues.

I am not familiar with the Saflager strain, but that still sounds a little high temperature wise to me for a lager. The more important temperature is that of the beer, rather than room temperature - this will always be a bit higher. If you are getting alcoholic flavour, this could be higher alcohols (fusel) from too high a temperature, or from other yeast stress. It is hard to say from the description. Either way,

The green apple is a classic descriptor for acetaldehyde, so you could be right there. From the look of your gravity readings, fermentation is complete, so leaving longer is not likely to help - yeast will clean up by products like acetaldehyde during fermentation - once they have stopped they will not do anything more to clean these up.

It is possible that your yeast pitch was too small and the yeast did not have enough reserves left to complete clearing up these by products, or again it could be down to stress from the temperature. How much yeast did you pitch? Did you use a yeast calculator to work out your correct pitch rate?

Another suggestion gong forward would be to look at some kind of temperature control for your fermentation - particularly if you want to brew lagers. One thing from recent studies is that a steady temperature is far more important than an exact temperature. Temperature swings from 16-18°C is fairly drastic. Brulosophy have done some interesting experiments on this.

If you are bottling (and bottle conditioning), it is possible that some of the acetaldehyde will be cleaned up by the yeast during this - it might be advisable to pitch half a pack of dry yeast when adding your priming sugar to ensure you have some fresh yeast though. Fusel alcohols may age out somewhat, only time will tell how much.

Good luck!

Jerry

 

[Tortue]

Hi Jerry,

Thanks for all your advice and your quick response!

I can now see that when I said fermentation had stopped, it was a false alarm. Last night, I swapped out the blowoff tube for an airlock and, after a few hours, the escaping gas had blown all the water out of the airlock (my initial reason for fitting a blowoff tube). The lid of the fermenter bucket is swollen. I'll take another gravity reading in a couple days to compare. Although, at 1.009, can it have much longer to go? The yeast strain reportedly has a very high attenuation rate.

To answer your question, I pitched one 11.5g packet of dry yeast for 20 litres, according to the manufacturer's instructions. Rehydrated within 10°C of wort temperature. The calculator asked for 11g.

From what you and others have said, I've decided to skip secondary fermentation.

My questions now are, should I leave the beer in primary for another 3-4 weeks to allow for clearing? Should I move immediately to a diacetyl rest, before storing the lager at a colder temperature?

Thanks again for any advice you might have. Others, please feel free to pitch in!

 

[Bigcol49]

Hi!
If I was planning to lager the brew for a few weeks, I would definitely transfer to a secondary vessel. If you are kegging it, the keg could be the secondary vessel, as long as you have enough kegs to tie one up for a few weeks.
One further point - if you have the facilities, cold crash the brew before transferring.

 

[JerryP]

Hello Tortue,

As Bigcol said, you will want to transfer to a keg or bottles before lagering. But you do not want to do this until you are certain that fermentation is finished.

For the yeast, checking the Brewer's Friend calculator (https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/), for 20 litres of 1.040 lager using Saflager S-189 dried yeast you would want around 3 packs of dried yeast. BF estimates that there are 104 billion cells in a 11.5g pack, and that you need 315 billion. So you are a fair bit under the pitch rate in my opinion. What calculator were you using?

I am surprised that you are seeing much activity after the beer has reached 1.009, but give it time then. For a diacetyl rest, there is not much to do but keep it at a slightly higher temperature for a few days. Then once you are certain fermentation has completed, you can move it somewhere cooler or cold crash to encourage the yeast to floculate before bottling or kegging.

If bottling (which it sounds like you are), keep the bottles in a similar temperature to the fermentation for a week or so after bottle to allow the yeast to consume the sugars and carbonate the beer. Then move them somewhere cooler for lagering / conditioning.