How much yeast do i need ?

[ozgu]

Hello,
I will make my second beer, and it will be a Russian Imperial Stout.
I want to use Fermentis Be-256 yeast as dry, and batch size will be around 20 liters.
So, my question is, how much yeast is enough for that kind of beer ? 11,5 gr., or more ?
Also, what is the criteria when deciding right amount of yeast according to gravity and batch size ?

Thank you.

 

[TBC27]

There are calculators on the interwebs to help you with this. I use this one - https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

 

[Qhrumphf]

Standard "rates" are approximately 0.75 million cells per ml pet degree Plato for ales and 1.5 million (double) for lagers.

For a really big beer, i would target 1 million/ml/°P.

As far as how much actual yeast thay means to use, a calculator will be easiest as said above.

Depending on how big you're going, I would probably use two packs and potentially a third, rehydrated before pitching.

 

[ozgu]

There are calculators on the interwebs to help you with this. I use this one - https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

Standard "rates" are approximately 0.75 million cells per ml pet degree Plato for ales and 1.5 million (double) for lagers.

For a really big beer, i would target 1 million/ml/°P.

As far as how much actual yeast thay means to use, a calculator will be easiest as said above.

Depending on how big you're going, I would probably use two packs and potentially a third, rehydrated before pitching.

Thank you for your replies.

Actually, i have checked that calculator but, there are some recipes which are i want to take as references, and according to the majority of those recipes, merely a packet of yeast (11,5 g.) is enough. So, that is why I am not sure about amount of yeast.

Also, when I try to calculate the yeast amount with Brewersfriend's calculator, 11,5 g. is fairly not enough, and i need to make a yeast starter with about 2 packet yeast (23 g.) for 1,100/1,090 o.g. and ~21 liter batch.

 

[505-Brewer]

You need more cells so you make a starter or add more packets of yeast. The math wont lie. Its the truth machine. You want a big beer - it cost more yeast.

 

[IslandLizard]

Making starters from dry yeast is generally considered to be futile as the cost of DME (@ ~$2 per 2 liter starter) is almost as high as buying another pack of dry yeast (~$4 each), while making a starter involves a lot more work, time, and effort. But not futile in every case, such as this one, 5 gallons of a high gravity beer.

A yeast calculator tells us a 5.5 gallon batch of 1.100 wort needs around 620 billion cells at a recommended pitch rate of 1.25 million cells per ml. That would be 9 packs of Be-256 going by her advertised cell count of 66 billion cells per 11 gram pack. That's almost ridiculous of course. Even if a pack contains double the amount of cells or more, which has been proven not to be all that unusual,* we'd still need 4 or 5 packs. Still quite a few, but possibly more bearable.

* As documented, actual cell count in a dry pack, as "guaranteed" by the manufacturer, can be understated by as much as a factor 2 to 3, so you can likely do with half or even fewer packs.

Making an appropriately sized starter from a single pack of dry yeast can guarantee the active yeast cell count you'd need.

Since we're fermenting a very high gravity beer with ale yeast at ale temps, we use a pitch rate of 1.25 million cells per ml of wort and use a stir plate.

• If we estimate 66 billion cells, per manufacturer, a 4 liter (1.037) starter is needed to end up with 629 billion cells in one single step.
• If we estimate 132 billion cells, double the amount per manufacturer, a 3.5 liter (1.037) starter is needed to end up with 622 billion cells in one single step.

So either way we'd be safe and end up with around the estimated number of cells required.

Alternatively, for example, if you don't have a stir plate and/or the required vessels, you can brew a 5 gallon batch of a small beer (~1.050) with 1 pack of Be-256 yeast and use the resulting yeast cake for your big beer.

You also need a source of (pure) oxygen to oxygenate your wort well (12-18 ppm of Dissolved O2) when pitching yeast, and again, 12-18 hours later. Shaking the fermentor or whisking the wort won't do it.

Needless to say, you need ferm temp control and patience.