# Using Heat To Kill Yeast...



## komodo (28/6/10)

Ok so I've currently got a cider down and all is going well.

However I usually keg my brews but lately Ive been bottling some for picnics, bbqs, family events and for friends and family to try at home etc. 
I've been toying with the idea of making a cider using heat to kill the yeast when it gets to the desired sweetness/dryness/level of fermentation, then chilling and filtering then using a CPBF to fill some bottles.
Now I know I could just add lactose - but lactose intollerant people dont like that idea. I could add camden tablets - but I'm not real keen on that idea. But I thought heat might be a goer especially if i can heat hot enough to kill the yeast but not too hot to a.) drive off too much alcohol b.) get cooked apples taste in the brew.
I also want to kill the yeast because I'm making a double batch of this for my grandfather and I cant be 100% sure its going to be kept in the fridge and im scared that if i dont kill the yeast and fill with a cpbf im going to end up with bottle bombs in their shed especially if i try bottle conditioning. 

So does any one know what temperature I will need to hit to kill the yeast? how long i will need to keep it there? and is this a viable option?


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## haysie (28/6/10)

Try googling up Louis Pastuer and see what temps he succeeded at.


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## manticle (28/6/10)

Komodo said:


> Ok so I've currently got a cider down and all is going well.
> 
> However I usually keg my brews but lately Ive been bottling some for picnics, bbqs, family events and for friends and family to try at home etc.
> I've been toying with the idea of making a cider using heat to kill the yeast when it gets to the desired sweetness/dryness/level of fermentation, then chilling and filtering then using a CPBF to fill some bottles.
> ...



It's not a method I'm personally keen to try but it seems as if it's a bit more common in the US than it is here. There are a few threads on homebrewtalk about pasteurising cider for the same purpose. Fairly certain that anything above 50 degrees will kill yeast. Obviously this means the cider itself has to get to 50 degrees - no idea how long for though. Obviously you will get a still cider.

Also the above is meant to be a suggestion or guide on where to research. Please do not take what I say as gospel. My 50 degrees could be way out.


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## komodo (28/6/10)

Yeah Ive read 50 and 60 and also as low as 40 because the alcohol makes the yeast weaker and easier to kill.

Im not too concerned about it being still as I'll keg it and force carb then used a counter pressure bottle filler to fill the bottles. Ive actually been reading about filling the bottles and letting them naturally carb/condition then heating the bottles to pasturise once they reach the correct levels of carbination. Im a little scared to to this to fear of bottle bombs or under carbing or even just bursting the bottles during the process!

Time for more research me thinks. Hopefully someone with some experiance will be able to chime in at some stage here.


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## manticle (28/6/10)

Same forums I speak of also talk about racking multiple times to drop out as much yeast as possible. Definitely some people there who've done it with success.


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## unrealeous (28/6/10)

You could get yourself a second filter - 0.35 microns - which claims to filter out all the yeast and hence would stop further fermentation... Never tried it myself though.


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## benno1973 (28/6/10)

Can you use UV light to kill the yeast? Not sure what it costs or how to go about it, just throwing it out there.


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## Sunshine_Brewer (28/6/10)

You can pasteurise the bottles when they are full and carbonated. Just put as many in your boil kettle or stock pot full with water and maintain a pasteurising temp then all should be good. The main concern is the temp and how long you keep it at that temp, also make sure the temp is the same the whole way though the kettle/pot ie. no cold spots etc...


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## dabre4 (28/6/10)

You would need to heat more than 50C. I work in thermal processing, but the target organisms we aim for are a hell of a lot tougher then yeast. If you wanted to increase the shelf life of the cider the best method would be to bottle, then pasteurise in the bottle. I wont bore you with the maths, but heating beer in a bath at 100C will be much more effective then heating it at 90C or less. The rate of killing is logarithmic depending on the temperature. In a nut shell, if you pasteurise in a bottle I would dip the bottles in a bath of boiling water for 2-3 mins, then cool. If for example you were to heat them to 70C, you would need to hold it for 40 days to achieve the same level of killing as you would holding them for 2 min at 100C! I've been interested in trying this on a wheat beer to improve its shelf life. As for heating cider during fermentation, I cant say if that would have any effect on the brew or not, it could possibly work though. If you were to try it, Id heat it to near boiling (98C) and then cool is as quickly as you can. Assuming your heating at around 2C / min, there is no need to hold it at boiling as the time taken to slowly heat and cool would add to the rate of killing. 

In say all that, this would achieve commercial pasteurisation and could potentially be overkill.


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## komodo (28/6/10)

^ this is what I was talking about earlier Sunshine_Brewer. Have you any experiance with doing this? My concern is how can I tell when its ready to be pasturised. My understanding is that different vessel sizes condition at different rates. So I dont understand how I could tell when they are ready and how to avoid bottle bombs?


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## manticle (28/6/10)

Doog said:


> You would need to heat more than 50C. I work in thermal processing, but the target organisms we aim for are a hell of a lot tougher then yeast. If you wanted to increase the shelf life of the cider the best method would be to bottle, then pasteurise in the bottle. I won't bore you with the maths, but heating beer in a bath at 100C will be much more effective then heating it at 90C or less. The rate of killing is logarithmic depending on the temperature. In a nut shell, if you pasteurise in a bottle I would dip the bottles in a bath of boiling water for 2-3 mins, then cool. If for example you were to heat them to 70C, you would need to hold it for 40 days to achieve the same level of killing as you would holding them for 2 min at 100C! I've been interested in trying this on a wheat beer to improve its shelf life. As for heating cider during fermentation, I can't say if that would have any effect on the brew or not, it could possibly work though. If you were to try it, I'd heat it to near boiling (98C) and then cool is as quickly as you can. Assuming your heating at around 2C / min, there is no need to hold it at boiling as the time taken to slowly heat and cool would add to the rate of killing.
> 
> In say all that, this would achieve "commercial" pasteurisation and could potentially be overkill.



Is there an issue with holding glass bottles in boiling water for two minutes?
Is there an issue with a potential change in flavour?
What advantages would this give to a wheat? My impression was that wheats rely on yeast for distinctive character and that their 'drink em young' characteristic came from the tendency of that yeast to drop out combined with their very low hopping.

Not trying to question your expertise - obviously this is your field (or close enough to) but these are the queries that spring to mind.


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## Sunshine_Brewer (28/6/10)

Komodo said:


> ^ this is what I was talking about earlier Sunshine_Brewer. Have you any experiance with doing this? My concern is how can I tell when its ready to be pasturised. My understanding is that different vessel sizes condition at different rates. So I dont understand how I could tell when they are ready and how to avoid bottle bombs?



Pasteurise when the beverage is tasting the optimum. You should not get bottle bombs if you pasteurise correctly.

Just try it! put some in a safe place and work what temps work best for you. I don't think you need to get above 70 degrees.
It's the time thAT IS IMPORTANT.

I have seen this done commercially on ginger beer, 500 plus bottles(330ml) put into hot water bath temp reaches 60-70 then a pasteurising points system is tallied/worked out based on time and temp.


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## dabre4 (28/6/10)

Is there an issue with holding glass bottles in boiling water for two minutes?
Nope, I've done this before, the main concern would be not putting them straight into cold water.

Is there an issue with a potential change in flavour?
Can't comment here, I agree that there is definitely potential and a very good point

What advantages would this give to a wheat? My impression was that wheats rely on yeast for distinctive character and that their 'drink em young' characteristic came from the tendency of that yeast to drop out combined with their very low hopping.
You could be right. I agree 100% on drink em young, my impression was that the flavour diminished over time due to the remaining yeast, hence if you put them to sleep after they had added all their bannana, etc, the flavour would remain. How do you explain wheat beers that sit on the shelf for so long, but seem to keep their flavour. As I said, this was my impression, I could be off in la la land. :blink: 

Not trying to question your expertise - obviously this is your field (or close enough to) but these are the queries that spring to mind.
No problems, as I said I haven't had experience killing yeast, only bacteria, so I could be off the mark.


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## barls (28/6/10)

Kaiser Soze said:


> Can you use UV light to kill the yeast? Not sure what it costs or how to go about it, just throwing it out there.


your forgetting about skunking


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## felten (28/6/10)

barls said:


> your forgetting about skunking


There usually isn't any hops in ciders


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## barls (28/6/10)

right missed theft that its cider


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## komodo (29/6/10)

Still not 100% confident on how to tell when the bottles are carbonated enough if pasturising in the bottle. I guess a suck it and see approach is the only way to go. 

My concern with dunking the bottles into 95+ degree water for a couple of minutes is that when you put a glass of water into a sink of hot water it takes conciderable time for the water in the glass to match the temperature in the sink. Obviously with hotter water this changes - but still i wouldnt have thought 2 minutes at 95 degrees would be long enough. 
Hmmmm more food for thought


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## drsmurto (29/6/10)

Komodo - Any reason why you aren't keen on campden tablets?

A much simpler approach than messing about with temperatures that may or may not do the job.

*hugs his collection of chemicals* :wub:


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## Fourstar (29/6/10)

DrSmurto said:


> Komodo - Any reason why you aren't keen on campden tablets?
> A much simpler approach than messing about with temperatures that may or may not do the job.



I think he might be fearful of the cider tasting like rotten eggs.


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## drsmurto (29/6/10)

Fourstar said:


> I think he might be fearful of the cider tasting like rotten eggs.



And that's a bad thing why? :icon_drool2: :lol:


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## Fourstar (29/6/10)

DrSmurto said:


> And that's a bad thing why? :icon_drool2: :lol:



better than century eggs! :icon_vomit: 

Went to Yung Kee Restaurant in HKG, who's specialty is in roast goose. They present you with free century egg on arrival and the waiter shows you how to eat it and politely stands there until you do. I think its a way they go about punishing the whities who come to eat there. :lol: 

It tastes like egg expect the yolk is like an ammonia filled custard bomb and the texture is all wrong! Im glad they give you a biiiiiig chunk of pickled ginger with it. I needed it!


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## komodo (29/6/10)

Yeah not really keen on the campden tablets. I've used them in the past and not been 100% happy with something about the cider afterwards. I know they are supposed to dissipate after 24-48 hours but...


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## Mr.Moonshine (29/6/10)

My concern in respect to this would be the bottles exploding. My basic understanding of chemistry and brewing tells me that CO2 is absorbed more into liquid at a cold temperature than at a hot temperature (hence why if you leave a bottle of coke in the sun it'll most likely fizz over- the CO2 is coming out of solution). This is also the reason why you chill the beer down to very cold before giving it a fast carbonate in a keg.

Correct me if I'm wrong, but unless the bottles are champagne or very strong (or if the cider is very lightly carbonated), putting the bottles into a bath of boiling or near boiling water would cause them to explode? Something akin to putting a can of soft drink in a fire/boiling pot?

Just my 2c, the idea is solid but you're angling more at a still cider than a carbonated cider from what I can see. Also, if the yeast are dying, won't they autolyse or produce off flavours of some sort?

Cheers,

Mr.Moonshine


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## Airgead (29/6/10)

My 2c worth - The original aim here was to stop fermenattion at a desired level of sweetness then carbonate and bottle. If you are looking at plunging botles into boilign water then its already too late for that - the cider will have fermented out.

If you want to stop fermentation using heat you need to do it from the fermenter. My suggestion woudl be to use 2 counterflow chillers (if available) - one hooked up to a soirce of very hot water and the other to a source fo cold water - run the cider through the hot chiller to heat it to pasturisation temps then straight through the cold chiller to get it back down to cold again as soon as possible.

A sterile filter may be an easier way of stripping the yeast out.

Cheers
Dave


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## Mr.Moonshine (29/6/10)

I like Dave's idea, in that by putting the beer through a hot coil then a cold coil you kill off the yeast and then are able to bottle. Personally, in maintaining sweetness the three methods I have used are partial fermentation (which is basically the same as back sweetening in a way), natural sweetners and artificial sweetners. The partially fermented cider was not too bad at first ( some of the members of my brewclub thought it was too sweet), but over time as it was obviously fermenting in the keg it had some weird off flavours. I figured it was the same as backsweetening in the sense that if there were extra fermentables that it would reach the same end point as if it had less fermentables and then I added more into the keg, but still the flavour was a bit off and overall the cider was still fermenting in the keg, so overtime it turned into super dry, almost winey cider (extra fermentables did include white sugar).
The natural sweetened ciders have turned out probably the best, as the lactose isn't too sweet and adds a bit of body. One technique you may consider is using less fermentable ingredients in order to acheive a desired level of sweetness. I spoke to some cider makers at the beer and brewer show, and they told me that pear juice in a cider is a good idea as the pear juice not only adds a level of smoothness, but is also not entirely fermentable and therefore adds a level of sweetness and body.
Finally the artificial sweeteners are under testing. my most recent cider was done up with about 850ml of pear juice in 20l, with champagne yeast and 20ml of a liquid artificual sweetener from coles. It's sweetness is about right I reckon, but the body is lacking so it seems a little cloying. It's still young so I'm going to see how it goes with time.


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