# Potassium Sorbate



## jbumpstead (20/6/09)

Hi folks,

Am wanting to put down an apple cider. The plan is to brew an apple cider (recipe yet to be confirmed preservitive free apple juice, glucose, water...), then ferment until achieving desired sweetness/ABV, then use Potassium Sorbate to kill off the yeast and stop fermentation.

I'd then need to force carbonate and either keg or use a counter pressure bottle filler.

I've never used potassium carbonate before though, and heard very little about it. Is it a safe addition to the brew? Is it effective in killing the yeast and avoiding bottle bombs later on?

Any advice appreciated.

Bumma.


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## Bugglz (20/6/09)

So make sure all the yeast is dead you have to use potassium sorbate and sodium metabisulfate (campdon tablets).


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## Airgead (20/6/09)

Bumma said:


> Hi folks,
> 
> Am wanting to put down an apple cider. The plan is to brew an apple cider (recipe yet to be confirmed preservitive free apple juice, glucose, water...), then ferment until achieving desired sweetness/ABV, then use Potassium Sorbate to kill off the yeast and stop fermentation.
> 
> ...



The short answer is No. Sorbate is a yeast inhibitor. It will kill a bunch of yeast and is used in winemaking to stabilise finished wine. What it won't do is kill ALL the yeast. Eventually the sorbate will wear off and any remaining yeast will start to ferment the residual sugars. Same goes for sodium/potasium met. Mixing the two is better but still not 100% reliable. To really do what you want you need to sterile filter. 

Mind you, if you store the kegs/bottles cold the yeast should go dormant anyway. The cold mixed with sorbate will probably do what you want. Mind you if it gets warm again you could have problems.

How much residual sweetness were you planning on leaving behind? You may be able to use a lower attenuating yeast (like an English Ale strain or a specialist sweet cider strain to do the job. That way the yeast ferments all it can, leaves behind some residual and unless you end up with wild yeast in there it won't ferment any more.

Cheers
Dave


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## pdilley (21/6/09)

In laymans terms think of them as:

o *Potassium sorbate* = Taking your pet to the vet to have its balls cut off. It interrupts the yeast cells ability to replicate itself.

Its really a salt and when added to your wine will form sorbic acid which does the deed. Any yeast already alive will continue living and continue being able to ferment out sugars into more ethanol and CO2 but they will eventually die off. Because people want to stop additional fermentation dead in its tracts you also need to add the next item.

o *Potassium metabisulfite* = Putting hydrogen peroxide on a cut and watching it fizz killing all germs that are already alive and active.

It forms sulphur dioxide gas, a rather powerful anti-oxidant and like hydrogen-peroxide oxidising the cellular walls of germs on your cut, the sulphur dioxide gas oxidises the cellular walls of the yeast (an other microbes) in your wine.

This kills off any living yeast cells hence this is why you add both together at the same time.

Another important use in brewing is its ability to react with the chloramines in the water and help remove its nasty effect on phenols and other off flavours. Thankfully the local water here has no chloramines added.




As Dave mentioned, they eventually will [basify/come out of solution] so you use them together in a measure amount so you can kill off as many yeast cells as you can (Pot met) and any that make it through, keep them from multiplying into new yeast cells [Pot Sorbate]. Filtering is kicking a dog when its down and making sure you get as many yeast cells out of solution as you can.

If not mentioned, its used in double strength at bottle time as wine makers are a group that want to make sure the deed is done before the aging begins. It can also be used as a santiser for equipment. Bad for Dave's wife or others with allergic reactions to the sulphates in most wines.



Because some people don't want to add more "salts" to their wine they prefer the Pot Met, otherwise you can use Sodium metabisulfite if this is not an issue for you or if this is the only form you can find available locally.


Maybe an easy way to remember is the "Sore" in sorbate and poor Fluffy's nuts  or maybe I should not go there 



Cheers,
Brewer Pete


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## jbumpstead (21/6/09)

Brewer Pete said:


> In laymans terms think of them as:
> 
> o Potassium sorbate = Taking your pet to the vet to have its balls cut off. It interrupts the yeast cells ability to replicate itself.
> 
> ...



Thanks Dave and Pete,

Very good insight into the two. I'm not after a terribly sweet cider, but I also don't want it turning out like champagne, too dry, or undrinkable.

I reckon the trick might be a combination of the ideas here. 

Potassium sorbate to stop the yeast mulitplying
Potassium metabisulfite to kill as much yeast as possible
Use a low attenuation yeast
Bottle in PET and keep cold for saftey
Run it through the filter

How long would you suggest between the additions and filtering/bottling?

Cheers


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## pdilley (21/6/09)

In light of all that lovely discussion, in order to make life as simple as possible for myself with ciders, I don't add Pot Met nor Pot/Sodium Sorbate to my ciders.

I set a target ABV I want starting at about 4.8% and going up from there (1046 - 1048 is your straight juice starting gravity of fermentable sugars). If I want higher than that ABV I add fermentable adjuncts (white sugar, brown sugar, dry malt extract, etc. depending on the flavour I want to get.)

I ferment out completely.

[decision point] - bulk age or age the cider in bottles, if bulk age then when bottling you will need a fresh dose of yeast added in order to naturally carbonate in the bottle when you do get around to bottling your aged cider.

I prime bottles and bottle into PET with a new recipe. If I bottle in glass I give my finished cider about 0.9 to 1.0 gravities of CO2 in solution at the get go and then calculate the priming difference to reach a low to medium carbonation level say 2.2 to 2.6 gravities.

I back sweeten at pouring time by filling the final serving glass with fresh apple juice and then adding the cider, swizzle and serve. I mix sweet (more juice) for SWMBO and mix dry (less juice) for me, all from the same opened bottle of cider.


If you want sweet from the bottle, you can back sweeten with sterilised lactose (not fermentable by yeast, but is fermentable by other bugs you don't want in your cider) and then bottle.

Using Pot Met and Pot/Sodium Sorbate is when you will be artificially carbonating with bottled CO2 in a keg, or making a still cider or still wine.

I think Dave has a different technique which he can share with us.


Cheers,
Brewer Pete


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## jbumpstead (21/6/09)

Thanks Pete,

Food for thought anyway. Your way does sound simple I must say.

Bulk aging is something I hadn't considered before, is that just an extended secondary?


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## pdilley (21/6/09)

Bumma said:


> Bulk aging is something I hadn't considered before, is that just an extended secondary?



Yes, its racking off of the flocculated yeast in the primary fermenter into a cleaned and sanitised secondary fermenter (mine are all glass). Making sure you have it filled up to the neck with no air gap (optionally put down a blanket of CO2 with bottled gas), bunged and left cellared for a year.

Cheers,
Brewer Pete


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## Airgead (22/6/09)

Brewer Pete said:


> I think Dave has a different technique which he can share with us.
> 
> Cheers,
> Brewer Pete



Yep. I don't add any sulphate to anything I brew as SWMBO is allergic. Since the cider is mostly for her it kind of rules that out.

I have it a bit easier as we both like a pretty dry cider. I do pretty much all my FG control with yeast. I find that the Wyeast 4766 gives me an FG of about 1.004->1.006 which is pretty much where I want it. If I want a sweeter cider I'll ferment with something with a really low attenuation like WLP002 which ends up at around 1.008-1.010. I ferment at the bottom end of its temp range to minimise "beery" esters. If I want a really dry cider I'll ferment with a champagne yeast which ends up at 1.000 to 1.002.

All my cider is kegged so that also gives me the option of crash chilling it to stop fermentation. All the yeasts I use are warm fermenters and will floc out below 12 degrees or so. As long as I never let it warm up again I can stop fermentation anywhere I like. That's not so easy in bottles, especially if you want to bottle condition. If you want to bottle condition, pretty much the only option you have to control FG is the yeast as you need the yeast alive and active to carbonate the bottles. Adding sorbate/sulphate will stop that and leave you with a still cider.

As BP says there is always the option of back-sweetning. I do that when I make my apple liqueur. I'll ferment it out bone dry then fortify with brandy to around 18-20%ABV then back sweeten with honey. The high alcohol inhibits the yeast and stops any further fermentation. You can also add a non-fermentable like lactose to sweeten as well. I can't as SWMBO is allergic to that as well. I have heard of people sweetening with artificial sweeteners (aspartame/saccharin/cyclamate/sucralose) but these people will burn in hell.

Cheers
Dave


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