Yeast amounts

[pmclaren11]

Hello again,

I was just wondering if different yeast amounts will affect FG?

For example I have a Morgans Cortez Cerveza brewing and instead of using the lager yeast that came with the tin which was I think 13g, I used a Muntons Premium which is only 6 grams (this was for 23 lts).

Will this affect the FG (eg, be higher than if i used 13g of yeast?)

Thanks in advance,

Cheers,

Paul.

[drsmurto]

Possibly.

The bigger issue is the off flavours (esters/phenols) produced by a yeast when its stressed. Under pitching causes the yeast to work harder which stresses it out man.

The general rule for dry yeast is 0.5g/L for an ale (hence most kit yeasts are 11.5g as the 'normal' batch size is 23L), 1g/L for a lager (although if you pitch warm you can in theory use 0.5g/L and then slowly reduce the temp down to lager fermentation temps over 24-48h).

[pmclaren11]

So is my beer stuffed? The wort tastes great at the moment. It's been fermenting for a week..

[warra48]

No, it's not stuffed. You are making beer. It will still be drinkable. As you say, your wort tastes great at present, so that's a good sign.

I'd leave it for at least another week in the fermenter. (I usually bottle ales at between 2 to 3 weeks in primary, lagers 3 to 4 in primary plus lagering). Yeast has a remarkable capacity to clean up its own by-products given sufficient time.

The under pitching may potentially produce some off flavours (esters/phenols) as mentioned by DrSmurto, but shouldn't lead to your batch being ruined.

Don't fret, but just put it down to your ongoing experience towards improving as a brewer.

Next brew, when you pitch a decent amount of yeast, you might notice the improvement in your beer compared to this batch.

[pmclaren11]

Thanks guys, I love this forum!

Cheers,

Paul.

[pmclaren11]

Actually, could I pitch some more yeast now or is it too late?

[warra48]

Well, you could, but after one week, I don't think your beer will have much for new yeast to feast on.
The difficulty is that at this stage you shouldn't oxygenate your beer, so the yeast won't have any oxygen to grow.
On balance, I wouldn't do it.

PS: I did this with one of my brews, an AG Märzen, early last year. I couldn't get it to drop below 1.020. I had used a White labs liquid yeast. Dropped a pack of dry lager yeast after about 2 weeks, and it did precisely nothing. Ended up bottling it in Pets after lagering, still at 1.020.

[pmclaren11]

Thanks again,

I will leave another week then keg. I will more than likely bottle a few for the first time in PET's - can these explode?

Tasted it again just now and tastes good enough to drink tonight!

Cheers.

[warra48]

Pet bottles will take a lot of pressure, probably more than glass, but if it gets too high, they can burst.
However, they're a great deal safer than glass in that respect.