# Wild yeast maximum temperature tolerence



## Draedan (May 28, 2011)

Good morrow colonial companions

I have a question regarding the "kill" temperature for wild yeasts, my recipes do not rely on using metabisulphates to kill the unwanted bacteria and yeast but I add hot water directly to the must at the start, allow to cool before using the yeast.

So I simply want to dip a thermometer into the mix to determine if I have killed off everything I need to before fermentation.....


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## Tom (May 28, 2011)

Only way to kill the yeast by temp is to boil it. Sticking a thermometer does nothing. K-Meta stunns not kill yeast long enough to add a yeast starter. Not heard of recipies calling for NO k-meta.


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## Draedan (May 29, 2011)

Hi Tom

Seems you have answered many of my stupid questions tonight but I have a few biochemist friends 1 of whom specialised in yeast cultures, optimum temperatures as their major - he thinks with the yeasts he worked with none would survive over 60 Celcius even if only exposed to 1 minute of temperature gradient increase to its medium, so assuming I add 99.5C boiling water to my main ingredient ie grapes or whatever - then obviously this cools the solution to say 70C immediately and then a slow decline begins as the water cools to ambient surrounding temperature. My friend says this is enough to sterilise the must before a new starter yeast is introduced.

To be honest I have not lost 1 batch due to wild yeast formation yet, I have done around 40 batches of 5 litre size, so if this is wrong I have been very lucky right ???
I still obviously sterilise my gear before and after use with metabisulphate but never add it to to initial must.

With thanks

Lee
Thanks

Lee


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## Tom (May 29, 2011)

OK some luck involved. 
Now if you add water to Grapes you are thinning the must. How much boiling water are you adding to what quanities?
The 1st question is vauge at best. Please give detailed info on what kind of wine and quanities. 
To give a definitive answer withought all the info is guessing. I still stand by what I said with the info I have.


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## Deezil (May 29, 2011)

It would depend on the ratio of must : water. As Tom pointed out, the ratio of must to boiling water is most likely going to create a inferior final product to reach the temp needed (unless you add acids, tannins, and sugar to make up for the thinning - if done, all you've weakened, really, is the flavor... Still an inferior product in my book). I could be wrong (waaay waaay off, maybe):

If you have 3 gallons of 70F degree must, and 1 gallon of boiling water (212F), you come out with about 105.5F once mixed.. 

Certainly high enough to kill or shock (depending on heat loss rate) most of the commercially available yeasts in the States, but not enough to do in some of the nastier bacterias (that need to be boiled to die) I've heard of in my lifetime. I wouldn't want to thin anything any farther than that 3:1, must to water; i added 3 gallons of water to about 8 gallons of peach juice (1st batch, got greedy & wanted 'more wine') & i find the final product not quite up to my expectations (surprise surprise? lol). Some of the richer juices - elderberry comes to mind - are actually better with an addition of water, but most arent.

If you're avoiding K-Meta for allergic reasons, i can understand. Where you're taking the "no K-meta" approach, I've begun the "No water added" approach. Hopefully you took something positive from my ramblings


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## JasonH (May 31, 2011)

Sulfites will protect your must while it cools and during the time you wait for your pectic enzyme to break it down. They will also protect your wine from oxidation. It creates and environment in the must where your wine yeast can thrive above all other microbes. I highly recomend you add it anyway.


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