Yeast Attenuation

[Crusader-Rob]

Interesting notes regarding some of my recent attenuation. I'm unsure of reasoning, it could be incorrect mash temps or poor yeast health.

Recently: 

Patersbier: 1.045-1.014, mash temp 67deg C, 73% apparant (WLP530)

Scottish Ale: 1.057 - 1.024, mash temp 68, 58% Apparant (M/Jacks Burton Union)

American Pale Ale: 1.055 - 1.014, Mash Temp 66, 76% apparant (US-05)

The american Ale, doesn't really count as its 76%, which is not too bad. was a pretty tasty beer too.

the other ones are the issues I have. I'm tying to figure out why I'm not getting the attenuation recommended by the yeast. (WLP530 is 75-80%)

and my Scottish beer was up to 70-75%.

how can I improve my Attenuation?

[Ralph]

Are you aerating your wort in the fermentor?

Do you use a yeast nutrient?

Are you fermenting in a temperature controlled chamber?

What temperature? 

Are you rehydrating in water or sprinkling onto the wort?

Also are you sure your thermometer is calibrated correctly for your mash? If out by a degree or two it could effect attenuation?

The other thing is if the fermentation temperature is too low the yeast can drop out/stop working a bit early, especially with flocculant english style yeast like Burton Union. I have used Burton Union a couple of times recently. I will have a look at what attenuation I got when I am home.

[Crusader-Rob]

I pump my siphon to transfer from kettle to fermenter it's splashes around a lot then once I've cleaned up I use a sanitised whisk and stir vigorously for a couple of minutes. I used yeast nutrient in Saturdays brew to see if it makes a difference.

I use a frdige to ferments in with heatpad and STC1000.

US-05 I've been sprinkling I sometimes rehydrate, but I think I'm getting a bit lazy.

How do I check Calibration?

Fermentation temps is right, maybe I need to check the calibration of my STC as well?

I use BIAB, I maybe need a better method of aerating my wort once in the fermenter as well.

[Ralph]

Nah. I BIAB and transfer to the fermentor and simply use the gravity drop from the hose to the liquid surface to aerate the wort at the moment and I get good attenuations. I am looking into getting some oxygen but have not got there yet.

How do you measure the temp in the cabinet? Are you measuring the air temp or the actual temperature of the fermentation?

Check calibration by getting a thermometer that you trust is calibrated and put the 2 thermometers into a cup of water. Check they read the same. Check it at different temperatures (i.e. boil the jug for a hot temp and put some ice cubes in the water for a low temp)

What temperature do you ferment at? How long was the lag time? Do you ramp the temperature up towards the end of the active fermentation?

[Crusader-Rob]

My temp stil is stuck to the side of fermenter with bubble wrap as well. Ferm temp speeds on yeast type and recommendations.

[Ralph]

ok, and what temperature did you ferment each strain at?

[Peter Smith]

I use exactly the same process each brew and find that us-05, saison 3711 , wheat beer us-06  3056 3068 1010 and irish 1084 in guiness clone all atten very well.      I have had no luck with whitbread  ale 1099 or the youngs esb wyeast PC   both dropping clear well short of target....  I am wondering if its a first gen underpicth thing with uk ale yeast?  

[Andrew Graham]

For the Scottish Ale how many packets of yeast did you use? According to Mangrove Jacks Ales of original
gravity over 1.050 should use 2x 10g packets per 25 litres. Check out the Yeast booklet if you haven't already. Doesn't provide % attenuation but is worth a read:

http://cdn.shopify.com/s/files/1/0195/8620/files/MJ_Craft_Series__A...

[Crusader-Rob]

2 packs pitched into 1.057 wort, the wort was originally to be 1.063, but missed og by a considerable margin.

should of still attenuated ore, i mean the beer is nice enough, it just wasn't what i intended. I'm just looking for advice on how to make my attenuation better, and for things to end up where i want them. within reason.

I'm a little surprised with the WLP530 abbey ale to be honest. based on what happened the krausen almost went into the airlock, so i had near on 8 litres of foam in my fermenter, super agressive, then ended at 1.014 rather than the predicted 1.010 by beersmith (i was expecting more 1.012 though.)

[Paul Finney]

I'd second the testing your thermometers, especially the one you use in your mash. I tested mine recently and found it was 3 degrees out.

The easiest way to test is lots of ice in a bowl and add some water. It should read 0, or very close to.

If that is all good, then it could be your pitching rates.

I have noticed with some of the British yeasts that they flocculate very early and you need to swirl the fermenter, or find a way of getting them back into suspension. I have had a few beers overcarb as once they were bottled the yeast got back to work and ate more than just the sugar put in for carbonation.

[Ralph]

by the way, the Yeast book is a very good read. There are a whole lot of factors involved...

[Peter Smith]

there is a paragraph in the book that says, temp control is the most important element, (even tho they go on and list another 20 issues etc) a 1C change in temp is a BIG THING for yeast while fermenting,  it states that homebrewers have a tougher job then pros,   it takes a lot more precision to hold 23L at a certain temp point then 5000L...   thermal mass etc.

My youngs yeast turned into cottage cheese as it floc    I just have repeatable results with some yeasts and dont with uk ales,   still hunting a great uk ale yeast.....    vs say 1084 which is a beast...

I put my temp up 1C each day my ale yeasts still drop out   8(

[Brett Mason]

I got about the attenuation with the mangrove Jacks Burton union in a mild. Had a really lag time too. that was with rehydrating and a reasonable amount of aeration. I think it is the yeast in that case.