Tin beer brew time question.

[Yt2]

Hi Guys,
I have a few questions on fermenting kit beer.

1. If I half the amount of a tin kit and put in half the amount of yeast would it still take the same amount of time to ferment?
2. If I half the amount of a tin kit and put in the full amount of yeast would ferment in half the time?
3. If I did dot point 2 above would it tase any different?
Cheers Yt2...

 

[MHB]

You need to understand how yeast works; it’s different to what you appear to think.

Yeast doesn’t want to make alcohol at all, that’s it responding to an environment where it can’t reproduce which is what it really wants to do.
In a wort yeast will make yeast until it runs out of any one of a number of "nutrients" that it needs. We as brewers make a wort, in it are things we want and some stuff we don’t want but that yeast will metabolise. The most important are Oxygen, Lipids (fats/oils) and some Proteins (among others).
Part of being a good brewer (or kit manufacturer) is to have all the bits and bobs in balance so that the yeast eats (metabolises) all the things we want removed from the wort at about the same time.
It also reaches a large enough population to turn the remaining sugars into alcohol in a timely manner, without making too many nasties like Diacetyl.
We are left with a wort that will make good tasting beer without much of the stuff that could cause harm to the flavour (see above).

In theory if you added 1 yeast cell, or 1,000,000, you would end up with the same amount of yeast (roughly) by the time the vital nutrients were used up in yeast reproduction.

The problem is that during reproduction the yeast will make some off flavours along with some we like (i.e. esters that give fruity flavours and aromas). Smaller pitches (amounts of yeast added at the start) will spend longer getting up to population and will make more off flavours.
The other big problem is that the smaller the pitch, the bigger the chance of bacteria getting a start. As bacteria can reproduce at least 20 times faster than yeast, a small number at the start can become a raging infection pretty quickly. Note there probably has never been a wort that isn’t infected to some extent, fortunately most of the things that get a start in our beer are benign.

And here come the really clever part:-
Yeast when it can’t reproduce will start making a really powerful bactericide (Ethanol) that kill its neighbours so that when conditions change it can have somewhere to live. Its conducting chemical warfare and that makes us happy

Add all the bits up and that’s why there are recommended amounts of yeast to add, and recommended amounts of oxygen to dissolve in your wort. Not so important for dry yeast but really matters if you are reusing a yeast slurry from another brew.

Sadly kit makers supply a bare minimum of yeast (often less), most brewers opt for better and bigger yeasts.
The amount of yeast to do the best job is usually given in the form of cells/mL/oP
Cells - number of yeasties; mL - the volume in millilitres; oP - the wort gravity in Plato
To get from SG to Plato the rough enough equation is SG=(4*oP)/1000+1. We can rearrange this into
oP=(SG-1)/4*1000
If your SG was 1.050, oP=(1.050-1)/4*1000 = 12.5oP

The "standard" pitch for Ale is 0.4-1Million cells/mL/oP. If you are given a range and don’t have a dam good reason, start in the middle say 0.7M/mL/oP
If you were doing a half sized brew say 11L with an SG of 12.5oP
You would want 700,000*11,000*12.5 = 96,250,000,000 cells in a simpler form 9.625x10^10
In the attachment you can see that US-05 (one of the best selling dry yeasts) there are 6x10^9 cells/g
From there 9.625x10^10/6x10^9 cells/g says you should pitch 16 grams
As it comes in 11.5g packs, you can see why I said kit makers skimp, I would use a whole pack in a half brew.

You can also see it says 50-80g/hL (hL=100L) or 5.5-8.8g in 11L
There have been some pretty lively discussions on AHB over the years on this subject - let’s not start another war (please).

One of my favourite sayings about brewing is "Everything ends up in the glass"
If you change the amount of yeast (or anything else) it will change your beer!
Mark


Sorry
Rainy Sunday too much time on my hands, I hope you didn’t expect simple answers to brewing questions.
Recomended
Ale 0.40-1.00 Million cells/mL/oP
Lager 1.00-1.65 Million cells/mL/oP
Dissolved Oxygen 8-12 ppm (mg/L same same) 10ppm is the sweet spot.
M

 

[Yt2]

Hey Mark,
What a great learn!
I thank you Sir...

 

[Yt2]

Ok, one question was not answered.
Let's say I use half of a tin and put in the full yeast pack, will it ferment quicker?
The reason this is I are trying to figure out a way to cut fermentation time as I travel in a caravan for months at a time and I rarely sit in one location for 6 days. Six days is our limit when we are off grid in the outback.
I would be looking for an 11.5 litre brew and take 2 X 5L kegs & 1 X 2L keg.
Is it possible to get fermentation done in 4 days?

Would it matter if the ship was shaken out of it if we moved location?

 

[Yt2]

Can't anyone help me to be able to brew a half brew while travelling around Australia?

 

[bradmcm]

Yes, adding more yeast will mean a faster fermentation time up to a point. You can keep adding sheep to a paddock but after a certain number the grass won't be eaten any faster. You won't really get to that point though with the amount of yeast you're adding. KIt manufacturers give you barely enough with the tin anyway. So yes, doubling yeast content or even more will mean your fermentation will finish faster.
As for fermenting in a moving vehicle... I suppose it will work but I don't know how well the fermentation will go. Agitation will increase cell growth, that's why stir plates are used to make starters. SImply put, yeast has two phases, the first is aerobic where the yeast reproduce using the dissolved oxygen in the wort and then switch to anerobic once the oxygen runs out and then eats the sugars to produce the alcohol and carbon dioxide. I don't know what the yeast will do if you keep splashing it about throughout the fermentation. Will there be enough splashing to re-aerate the wort? Will it cause oxidation, or will the yeast scavenge it? Will there be any detriment to yeast switching back and forth between aerobic and anerobic? Ship crews used to ferment beer on board so it can't be too bad but it would be a different kind of movement to the Strezlecki Track.
Maybe some other gurus can weigh in on that one.

 

[Yt2]

Yes, adding more yeast will mean a faster fermentation time up to a point. You can keep adding sheep to a paddock but after a certain number the grass won't be eaten any faster. You won't really get to that point though with the amount of yeast you're adding. KIt manufacturers give you barely enough with the tin anyway. So yes, doubling yeast content or even more will mean your fermentation will finish faster.
As for fermenting in a moving vehicle... I suppose it will work but I don't know how well the fermentation will go. Agitation will increase cell growth, that's why stir plates are used to make starters. SImply put, yeast has two phases, the first is aerobic where the yeast reproduce using the dissolved oxygen in the wort and then switch to anerobic once the oxygen runs out and then eats the sugars to produce the alcohol and carbon dioxide. I don't know what the yeast will do if you keep splashing it about throughout the fermentation. Will there be enough splashing to re-aerate the wort? Will it cause oxidation, or will the yeast scavenge it? Will there be any detriment to yeast switching back and forth between aerobic and anerobic? Ship crews used to ferment beer on board so it can't be too bad but it would be a different kind of movement to the Strezlecki Track.
Maybe some other gurus can weigh in on that one.

Thanks bradmcm,
If I could get the fermentation done in 3 days 4 max, I would be happy to sit that long.
In view of what you said above it would be best to force carb the keg rather that secondary carbing?

 

[terminal2k]

get the fermentation done in 3 days 4 max

If you can keep your fermenter warmed, a kviek strain should be able to complete a ferment in that time.

 

[Yt2]

Great news thanks...

 

[Paddy Melon]

Just a thought Yt2, I know you want to get the process completed whilst stationary but bradmcm gave me a thought. If you are able to suspend the fermenter in your van maybe on a spring and rope set up, movement would be minimized, just like a hammock at sea, therefore reducing the risk of oxidation. Just a thought. Excuse my rudimentary 2 minute design but it gives you an idea.

 

[yankinoz]

Hi Guys,
I have a few questions on fermenting kit beer.

1. If I half the amount of a tin kit and put in half the amount of yeast would it still take the same amount of time to ferment?
2. If I half the amount of a tin kit and put in the full amount of yeast would ferment in half the time?
3. If I did dot point 2 above would it tase any different?
Cheers Yt2...

Short answer:
1. Yes.
2. That would not halve the time, but would probably reduce it with a kit yeast, for the reasons MHB gave.


I'd say h

 

[Coalface]

Ok, one question was not answered.
Let's say I use half of a tin and put in the full yeast pack, will it ferment quicker?
The reason this is I are trying to figure out a way to cut fermentation time as I travel in a caravan for months at a time and I rarely sit in one location for 6 days. Six days is our limit when we are off grid in the outback.
I would be looking for an 11.5 litre brew and take 2 X 5L kegs & 1 X 2L keg.
Is it possible to get fermentation done in 4 days?

Would it matter if the ship was shaken out of it if we moved location?

get yerself some kveik, if you can keep your fermenter around 30c you'll be able to ferment in 4 days, you can then dry the slurry and freeze it for future use.

 

[Naboo]

Another vote for Kveik. Give Voss a go and see if you like the beer it makes. Probably your best bet in your fermentation time frame.