Yeast - and the flavour it imparts

[Stonch]

Sorry for being such a serial poster chaps, I feel like I'm leeching knowledge and putting nothing back...

What I'd like to know this time is how much flavour different types of yeast can actually impart? You hear lots about breweries having special magical yeast strains that do wonderful things.

For one thing, does using two types of yeast in one brew - by repitching to move a stuck fermentation, but using a different type from a different supplier - actually make a difference? Is the practice best avoided?

Should I be hung up on yeast, or just see it as more or less much of a muchness?

[Garth]

Sorry for being such a serial poster chaps, I feel like I'm leeching knowledge and putting nothing back...

hey, don't worry Stonch, simply send a bottle of your next brew to every regular posting forum member, making sure it's at least 6% alcohol, simple

IMO breweries tend to use the same strain of yeast as they have for years as it does have an impact on the final product, and if they started using a different yeast their beers would almost certainly taste different, but as you say, I can only comment on the dry yeasts I have use, but Nottingham ferments fairly dry and is quite neutral tasting, S-04 ferments slightly sweeter and gives a good solid sediment ideal for bottling and T-58 can impart a slight peppery spicy flavour suited to some beers.

btw my local brewery, Durham Brewery, (about a quarter of a mile away) uses dried Nottingham for all their brews

[Jim]

There's no doubt that yeast affects the flavour of beer. Breweries go to a great deal of trouble to find a suitable strain, and once they have it they like to keep it.

The best way to see this for yourself is to make identical brews with a few different types of yeast.

[mysterio]

IMO, yeast makes a big a contribution to the flavour of beer as any of the other ingredients. Sometimes it's about what it doesn't produce, like in the case of a lager where the yeast flavours are restrained, other times the focus is specifically on the yeast flavours like in the case of a Bavarian wheat beer. I don't doubt that many breweries have their own unique strains, but many of these are now available to homebrewers through American yeast companies. Others probably guard them, although I can't think of any yeast off of the top of my head that is sought after and not available. For example you can easily buy the yeast Fullers use.

Two big factors affecting flavour is how much sugar the malt attenuates, usually in the region of 60-80%. This affects the sweetness or dryness of the beer and therefore the balance. Most yeasts will add their own 'signature' flavours to the beer, mostly in the form of esters which normally taste fruity (plums, grapes, pear, that sort of thing). Sometimes you'll get phenolics, especially in the case of some Belgian beers (spicy, leathery, smoky).

IMO, using a yeast to re-start a fermentation is probably best avoided, best to get it to ferment out completely in the first place as that's the sign of a healthy fermentation, resulting in probably a better beer.

[SteveD]

Sorry for being such a serial poster chaps, I feel like I'm leeching knowledge and putting nothing back...

Don't talk b0llox! Your beer blog is great. A top read. Plus, the job of a community like this is to share knowledge to improve the craft overall. You're taking part in that, so fire away.

What I'd like to know this time is how much flavour different types of yeast can actually impart? You hear lots about breweries having special magical yeast strains that do wonderful things.
[/quote] Quite a difference. A huge component of beer flavour is determined by the yeast, it's handling, and the specifics of the fermention, particularly the temperature schedule. For example, if you made up a bavarian hefeweizen, but fermented it with Fuller's yeast you absolutely would not recognise it as a hefe in a million years.

For one thing, does using two types of yeast in one brew - by repitching to move a stuck fermentation, but using a different type from a different supplier - actually make a difference? Is the practice best avoided?

It might change it a bit, but if it stuck at say 1/2 to 1/3 gravity the initial character forming would have been done before the sticking, so it wouldn't be very noticeable, IMO, particularly in a strongly flavoured beer like a stout, etc.

Should I be hung up on yeast, or just see it as more or less much of a muchness?

Well, The Brewer makes the wort, the yeast makes the beer. It's very important and the entire brewing process is geared towards making the yeast happy. Breweries go to great lengths to ensure their yeast is in top condition and consistent. As homebrewers we need to ensure our yeast is appropriate to what we're after, so that we like the beer it produces, and that by giving it what it wants it doesn't make life difficult for us.

(1) Make sure you have enough. 2x11g packs of good yeast for normal beer, double for OG 1060+ Good brands of dried ale yeast include Safale-04, Danstar Nottingham, and Gervin English Ale (same strain as Nottingham).

(2) Store it in the fridge

(3) Activate it exactly as per pack instructions

(4) They say that some dried yeast doesn't need the wort to be aerated prior to pitching. Maybe so but I'm not sure if I'd risk it, and it doesn't hurt to get some O2 into the wort prior to pitching. Run from one FV to another via the taps a couple of times, and thrash it around with your paddle as it comes over. (Save the foam - you could have a fermenter full - stick the lid on and when it collapes add back the wort, later that evening, after the yeast has gone in)

(5) Pitch it, and let it get on with it. You can skim the brown trub off the top if you like. Sterile spoon.

(6) Keep the fermentation temperature ideally between 16c and 20c. Too low and the fermentation will be slow, too high and it will race, might stick, and might produce odd flavours.

So, don't obsess about yeast, but treat it with respect.

Hope this helps.

Steve

[ColinKeb]

try a few and see what you like best, ive found dried gervin ale yeast best for me but every other brew i try to use a different liquid yeast to see if i can find one better, mind you i only tend to brew bitters or ales if i was doing a belgiun beer i would use a special yeast.
experimenting is half the fun