what i don't understand about yeast

[rantan]

i've read on various forums and in fact on some yeast packets, that one pack is not suitable to ferment for more than 5 gallons. now that raises questions, such as why not?
we all know the yeast breeds, thats why we get lots of air in the fresh must to help that happen. so if it breeds enough for 5 gallons, why not for 10 or 20 or more?
are they saying that if you have two 5 gallon buckets of must, add a packet of yeast to one and a few days later when it is bubbling like mad swap a pint from each, that the second one will not ferment, or that it will be in some way inferior?
another question that comes to mind is, how do they produce yeast if they do not breed it and breed it and breed it? i can't think of any other way
so is my thinking wrong or is it away to sell more yeast?

[cpfan]

If that's the only thing you don't understand about yeast, you're doing pretty good.

My understanding was that the winemaker wants the yeast to reach a certain colony size relatively quickly because a strong yeast colony will defeat many spoilage agents. Starting with too little yeast may not allow this to happen.

Given the price of yeast versus the cost of the other raw ingredients, I don't mind spending an extra $1 on yeast (sorry don't know the UK pricing). But then I usually make 23 litres (5 Imp gallons) or less anyway.

The yeast breeders do that in a sterile environment that most of us can not afford to reproduce.

Steve

[Richard S]

A packet of yeast is enough for 1 - 5 gallons if you pitch the yeast straight from the packet. I think I have read somewhere on here about creating a yeast starter but not pitching it all then topping the starter up. In other words, yes you can breed the yeast and keep using it. You would need to have several types on the go in order to cover different wine styles. The thing is, good quality yeast is quite cheap so why bother, it's just a load of extra hassle.

EDIT.

I know that some winemakers do this sort of thing but like Steve says, it's the ingrediants that usually cost the most. It's a crap idea, buy some yeast.

[Duffbeer]

Steve is right here, the idea is to have a very active and dominating yeast colony before any wild yeast/bacteria can take a hold, you may well ferment 5 gal with just a few flakes/grains but the lag period would put you at risk of infection/wild yeast fermentation.

Richard is also right you can make an ongoing starter by only using 1/2 of a started yeast culture topping up and then refridgerating, the down side here is if one yeast starter becomes infected unknowingly then everything you add it to will become the same.

Personally I agree with both the cost saving isn't worth the risk.

[Mamgiowl]

I'm inclined to agree, but if you can't get to an HBS too easily it makes sense to try to eke out yeasties to cover more than 5 gallons. I have done this in the past with no detriment to the wine that I could detect. Just means getting organised and preparing starters beforehand.

And don't say use the internet - if you only want a couple packets of yeast, postage can more than double the cost.

[rjb222]

I'm inclined to agree, but if you can't get to an HBS too easily it makes sense to try to eke out yeasties to cover more than 5 gallons. I have done this in the past with no detriment to the wine that I could detect. Just means getting organised and preparing starters beforehand.

And don't say use the internet - if you only want a couple packets of yeast, postage can more than double the cost.

If you are going to propagate yeast there is one rule that must be followed. Sterilization not sanitation I have read alot on doing this I use liquid yeasts for beer brewing quite often these are very expensive but propagate easily and a colony can be kept going for quite awhile before mutating into a new strain.

[lockwood1956]

It's all about having a viable colony of yeast in terms of numbers of cells, in a short time frame (24 hours or less) So using the extra packets is an insurance policy.
however as allready stated, you can pre-prepare a starter and get a good colony going and pitch this instead, the numbers will be greater due to extra length of time the colony has grown.

regards
bob

[rjb222]

Good point Bob I was thinking on the lines of keeping a viable batch going.