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UDV
04-08-2008, 05:00 PM
I have a problem that's two sided and I haven't seen anything on the forums that really covers it.

I now have about a gallon and a half of spent lees from 2 or 3 beer batches, and 2 mead batches that was done a few weeks ago. I carefully washed and saved all of the lees into a 1 gallon jug and once in a while i throw some dextrose in there and it will actually ferment again.

My question is, what is this actually good for? Consensus on old posts is that reusing spent yeast is a no-no that could lead to off flavors. Originally I was putting all of this old yeast in a big fungi free-for-all-war and let the strongest yeast survive. It was most of a silly idea but I don't have the resources to actually do much with them short of throwing the whole mixture into my compost pile. Is there some recommended practice to handle the environmentally sound reuse of them?

I have a similar problem with corks. Consensus is that you shouldn't reuse old cork for a variety of reasons. Cork is biodegradable, and does that mean I can just use the old ones for composting, or is there some mechanism, organization, etc that takes these back for some kind of reuse? Is it just better to grind them down a bit and throw them in a compost pile and let nature take it's course?

As far as all the other consumables involved in beer and wine, bottle tops and champagne wire are easily recyclable, and bottles well... You can never have enough empty bottles.

wildaho
04-08-2008, 05:22 PM
Spent yeasts, grains, fruits and harvested hop bines always go on my compost pile. The yeast in particular really helps the pile break down even more quickly. I haven't tried to compost the corks though. I would imagine that they would take a while to break down. It would be kind of like throwing in a chunk of wood in there.

I will occasionally re-use a yeast cake from a beer in primary, but only once. I don't save it, I just rack off the old beer and then immediately add the new freshly chilled wort. It's a great way make sure really big beers take off. Note: if you do this, always start with a lower gravity beer in the first batch and go to a higher gravity batch for the second.

Medsen Fey
04-09-2008, 10:49 AM
I usually just dump the lees in my flower beds or around the fruit trees. If I get lucky, perhaps some of them will go feral and I will have some quality yeast floating around my yard that might allow me to do some fermenting without having to use commercial yeast - somewhat like what Wayneb was able to do.

Just for fun, you might take a sample from your jug and use it on a small batch to see what flavor develops from this free-for-all yeast selection you have done. Maybe you will have selected a really hardy, but really tasty strain. Let us know what you get if you try it.

Angus
04-09-2008, 03:24 PM
I suppose the "no-no" factor with reusing yeast is something that it would be good to get input from the experts on. I spoke to a brewer who is now working in a distillery in Kentucky, and he told me that he regularly used yeast up to the 8th or 9th generation in his Meads and Beers. Perhaps the important thing to define is the description of "off flavors".

The goal, as I see it, of using new yeast every time we brew is to ensure two things: one, we reduce the likelyhood of contamination from unwanted organisms getting into the yeast during racking; and two, we are able to increase the chances of repeatability between batches by reducing the chances of mutated yeast. The off flavors we encounter by reusing yeast a second time may be caused by these mutations and may not be bad or nasty, just different.

So can we reuse yeast a number of times and still get a good batch of Mead? I think so, as long as we follow two simple rules.

1. Take extra extra care when racking, and then harvesting the yeast to reduce the chances of spoilage organisms getting into the mix.
2. Ensure you give the original yeast a really healthy environment in the first batch so as not to stress them, which could encourage mutations that will change their fermentation characteristics and therefore flavor (flaaaaaave).

Experts - is there something else that could negatively affect the yeast? Is there anything that can be done to improve the yeasts viability in subsequent batches?

Angus

Note - from the BYO website, some advice on reusing yeast in beer. Can hold true for Mead - Link (http://www.byo.com/mrwizard/1471.html)

wayneb
04-09-2008, 04:29 PM
Any yeast surviving to the end of fermentation in a batch of mead has seen everything from a nutrient rich, zero alcohol environment all the way to a % ABV that would kill off all but the hardiest cells. As the concentration of ethanol in a mead must rises, the yeast change the structure of their cell walls to be less permeable to ETOH. From what I've read, those changes are not reversible. I believe that the only thing you can do is to pull a yeast sample from the must before the alcohol level gets so high as to induce these changes -- say at the 1/2 sugar break or thereabouts, where the yeast are exposed only to 6-8% ABV. Coincidentally, that is the point at which most beermakers are done with their batches... so it could be that what works for many beer brewers (re-using the trub as starter for a new batch) won't work so well for wine and mead makers.

Again, it might be worth some experimentation to see what, if anything, you might end up with if you use mead yeast lees for several concurrent batches, but with the price of yeast about 2% of the cost of a batch, that seems like a lot of trouble for not much gain -- and potentially the loss of an entire batch of must. I'm inherently a risk taker, so I might get around to trying it some day -- but I have other experiments lined up that are higher on my priority list right now.

wildaho
04-09-2008, 05:11 PM
Many brewpubs re-use their yeast for several generations. They take extra care to wash the yeast and most do cell counts, check for mutants and other tests before re-pitching.

But, as Wayne pointed out, the alcohol levels in most beers are significantly less than what we work with in musts. Wort is inherently higher in nutrients as well and so the yeast in beer rarely gets as stressed as it would in a must.

When I mentioned the re-use of a yeast cake in a beer below, it entails using the cake from a 6%-7% beer to start a 12%-14% beer. The first batch doesn't significantly stress the yeast and you have a massive cell count to insure the higher gravity wort gets a good start. (Note: always use a blow off tube or a bucket if you use a yeast cake, it can be explosive!)

From posts I've read from people that tried to go the other way (10% to 5%) they encountered all kinds of off flavors, some to the point of being undrinkable.

I can understand wanting to re-use yeast with beer. I prefer liquid yeasts for beer and at $7.50 a pop, it can easily amount to 1/4 to 1/3 of the cost of the $15-$30 for the rest of the ingredients.

But $1.50 for a package of dry yeast compared to a $40-$60 batch of mead, well, I'd pretty much call that disposable!

If anybody does try an experiment with this on meads, please keep us posted! I would recommend the stepped gravity approach that works in beer though if you do.