Aerate, or not aerate - does it make a difference?

[FlippinMental]

I have one of those DIY compressors, sporting a small reservoir. Can I use it to blast air into the wort prior to pitching the yeast?

I’ve not had any trouble with yeast kicking in, normally seeing activity within 12 to 24 hours – or is this a bit on the long side?

I also had opportunity to try yeast from a local brewery, it produced really great beer, if I may say so myself, but what surprised me is that the yeast head stayed at the surface for the entire fermentation period. It was ale yeast and didn't settle well in the bottle, but a cracking ale loosely based on Royal Oak. Is this unusual?

FM

[Seveneer]

I read somewhere that those diy compressors have oiled internals that may taint the air going into your wort. I can't say for sure this would happen as I don't use one myself but, for peace of mind, it may be worth getting an aquarium pump instead. They're cheap and they work brilliantly.

/Phil.

[David Edge]

Flippin Mental:
> I also had opportunity to try yeast from a local brewery, it produced really great beer, if I may say so myself, but what surprised me is that the yeast head stayed at the surface for the entire fermentation period. Is this unusual?

No; this is what is meant by 'top-fermenting' or 'top working' when describing British ale yeasts. The dried yeasts we get (even for ales) are generally bottom fermenting and so we home brewers get a big surprise when we meet a genuine top working yeast. Fermentis have produced one ot two dried top workers lately, T-58 for example.

[mysterio]

I blast straight O2 into my wort. In general I've found noticably better attenuation when using liquid yeasts, but no difference when using dried yeast.

[David Edge]

Mysterio:
>I blast straight O2 into my wort. In general I've found noticably better attenuation when using liquid yeasts, but no difference when using dried yeast.

That may be because 11g sachets of modern dried yeasts have enough cells for fermentating 25 litres whereas liquid yeasts are a little (to a lot) short depending on how hard a time they've had in transit.

[mysterio]

Could be. I always thought the reason was - partially at least - dried yeast are selected for their hardiness and consistant results. I'm sure theres something about built in sterols during the drying process but I try not to get too bogged down in the science.

[Ross]

I blast straight O2 into my wort. In general I've found noticably better attenuation when using liquid yeasts, but no difference when using dried yeast.

Dried yeasts have the reserves they need built into them, therefore there is no requirement to aerate a wort when using dried yeasts. For liquids, good aeration is important & as DaaB said, use a sterile filter if using a pump.

Cheers Ross

[David Edge]

Ross:
>Dried yeasts have the reserves they need built into them, therefore there is no requirement to aerate a wort when using dried yeasts.

always assuming
You pitch an appropriate amount and so don't need much growth
The yeast hasn't been knackered in the distribution chain and thus you need growth
You plan to pitch a second high gravity wort (IPA, barley wine) onto the old yeast and therefore need some growth
You know absolutely everything there is to know about fermentaton science and can explain why some highly competent brewers can't get S-04 to work unless they aereate mightily (some get on fine)

Building up sterols is something Lallemand make great play of and I would imagine Fermentis do the same, but I would not assume that you could say the same of any random packet of 'Brewers Yeast' you buy. In fact given the poor performance of such yeasts in competition I have strong doubts.

So let's not shut off a possible avenue that could be the salvation of a brewer in distress. I know someone who dropped for twenty years because The Master said so despite continued lousy fermentation performance! (and in fact if you read what Graham said on the subject carefully you'll see he really said "It works for me, but it depends".

How about:
when dried yeast in good condition is used at the recommended pitching rate in a wort of balanced composition aereation is not normally necessary.

[Ross]

How about:
when dried yeast in good condition is used at the recommended pitching rate in a wort of balanced composition aereation is not normally necessary.

Certainly can't argue with that David

I'm interested in your comments about dried yeasts doing badly in competition? Certainly not the case here in Aus. I'd have thought it more to do with accomplished brewers generally turning to liquids. I'm one of the few that generally prefer using dried & use it 95% of the time, only switching to liquid when I can't get a certain characteristic I want. My dried yeast beers regularly win in competition against their liquid counterparts.

cheers Ross

[BarrowBoy]

Flippin Mental:
> I also had opportunity to try yeast from a local brewery, it produced really great beer, if I may say so myself, but what surprised me is that the yeast head stayed at the surface for the entire fermentation period. Is this unusual?

No; this is what is meant by 'top-fermenting' or 'top working' when describing British ale yeasts. The dried yeasts we get (even for ales) are generally bottom fermenting and so we home brewers get a big surprise when we meet a genuine top working yeast. Fermentis have produced one ot two dried top workers lately, T-58 for example.

This also goes a long way to answering the query/concern I raised on the Wadsworth 6X thread last night. My worries are receding......

[David Edge]

Ross:

I'm interested in your comments about dried yeasts doing badly in competition?

Ah! I was did say 'random Brewer's Yeasts' - I'd better explain that more carefully.

Certain well-known named strains are very popular and used in sufficient quantity for me to have statistical confidence (p>0.9) that they are better than the average dried yeast. These are S-04, Nottingham and (ok, not a named strain) Munton's Gold.

There are several other dried strains from high quality suppliers like Fermentis, Brewferm/Brupaks and Lallemand (Windsor) that are not used in sufficient quantity to test their success statistically, but I have no reason to believe that they do not perform just as well when used appropriately.

There are sundry other yeasts - 'own brands', kit yeasts, yeasts repackaged from bulk (one fears without the necessary care), bread yeasts etc which hardly win any prizes at all. These are my 'random' yeasts.

Liquid yeasts do a little better in competition, but like you I suspect the difference can be put down to the people who will pay GBP5 for a yeast will tend to be the more skilful brewers anyway. I quite agree that dried yeast is the yeast of choice; liquid is for the times you want sulphur or whatever. That said I think my next big step forward is to find a dried yeast that doesn't rob a beer of its hop nose. US-05 has been suggested. I split a batch between Fullers and US-05 and the Fullers was miles better. Likewise Ray Ashworth (founder of Woodfordes) tried Charles Wells against Nottingham with a similar result. Note in both cases we used fresh yeast from the brewery, not an equivalent strain from a US supplier!

I am desperately keen that people don't get the idea that they shouldn't enter a competition unless they use liquid yeast. I can only recall one CBA champion brewer who used a liquid yeast for her winning entry - Les Williams with her Belgian Ale to the Wheeler Tripel recipe. That sort of beer does need the right yeast!

[David Edge]

Daab:

What are you thoughts on those who suggest that the wort shouldn't be aerated and definately not with O2 but instead the starter wort should be injected with O2 and made in a controlled manner such that you are pitching at least the correct amount of yeast so that no growth is required in the fermenter?

They are obviously people with a knowledge of brewing and microbiologically that is way above my head. I wouldn't dare to pronounce a universal truth so confidently. Yeast growth creates more esters, an important flavour component of British ales so I can't see a general argument for only growing yeast in a starter environment. However, even the more enlightened US brewers have reservations about some of the aromas and tastes I like - not just esters, but diacetyl in moderation and sulphur - so perhaps it's good advice for them. A lot of these Fixations come from people who are trying to produce 'Bud with a little more taste' - such effects will be far more pronounced in such beers.

I'll try most things but i'm not convinced enough to experiment with this method, is it worth a try?

It won't produce an undrinkable beer - indeed I doubt it will have that much effect so suggest you split a batch and compare the halves. I suppose if a brewers sanitation were marginal the reduced lag time woulf give a much better result. The lessons you draw from a single batch experiments must be tentative, but at least with split batches you can be reasonably confident that the two worts are otherwise very similar. But don't forget that with a split batch you've effectively doubled the pitching rate... If you're a kegger, you'll need to make two batches, mix the worts and drat - have two on at once. Somebody's got to do it.

[slurp the apprentice]

I am one of the lucky ones i never bother stirring my wort at all i usually sprinkle s-04 on top and leave it to it.My theory about different attenuation experiences with the same yeast is down to the differences in water quality.To test this theory all we need is to transport water from poor attenuation areas to brewers who usually have good attenuation and vice versa then get them to brew with the imported water .I am interested in what type of wort liquor [Hard,soft] the yeast manufacturers use to test their yeast with .Do yeast manufacturers make yeast that prefers their local water as thats what they use when the test it and the lucky ones like me have water with similar characteristics?

[dartgod]

I went from just mixing up and shaking my wort to making yeast starters that were aerated with pure O2 and then I also aerated the wort before pitching and have significantly reduced lag time, the fermentations are more vigorous, and my attenuation has been at the high end of the manufacturers specs. Does it really make a better tasting beer? That's debateable but it greatly reduces the chance that a little nasty will get the upperhand on the yeast in the fermentation process........the way I look at it is that it can't hurt and it's part of my brewing process now.

GOODBREWING.......

[slurp the apprentice]

I used to buy s-o4 from local home brew shop which has a reputation of selling goods out of sell buy date so i wouldn't think this would account for my good fortune re attenuation now i get my s-04 in a brick and keep it in the freezer which i have been informed could be detrimental to the yeast cells ,so i seem to get good attenuation even after abusing the yeast.If anyone wants to send me a known out of date packet of
s-04 i will try it out to see if this does affect attenuation but i still believe its the water or whats not in it thats the main factor in attenuation.WE could run a poll on whether you get good attenuation or not with S-04 and link this to hard/soft water areas this might support or blow my theory