Fermentation management

[blond.chap]

Hi guys and girls,

Just thought I'd post a bit of what I've been learning lately on fermentation control. This is mostly from discussions and research on winemaking rules of thumb. It's obviously less vital in fermenting for distillation, but might help some people out. For beginners, don't worry about this stuff too much, keep it simple while you're starting. This is strictly for people who have the time and interest. If you're happy throwing the ingredients in and letting it go, that works too.

For those who'd like the quick version, my advice is:
- Don't use too much sugar, 1kg per 5 Litres is about right
- Check the pH, and adjust to 3.5 or below
- Keep the fermentation at 15-30degC, especially near the end
- Use the temperature to try to get roughly a 0.01 drop on your hydrometer per day
- Use your wash ASAP following completion of fermentation, if you can't, then rack it off of the lees and keep in a sealed container (as full as possible), if you have access to CO2, then maintain a gas blanket on the top as soon as fermentation has completed.

The reason that fermentation control has some relevance to distillation is that poor control will result in more generation of ethyl aceteate (heads), proponols and butanols (tails). The more heads and tails you have in your drink, the more booze you have to cut out. You'll also form more acetaldehyde and acetic acid if fermentation isn't controlled, reducing your yield of ethanol.

Stepping through the dot points above one by one:
Sugar concentration: Too much sugar puts pressure on the yeast, can cause them to metabolise through alternative pathways, producing components like hydrogen sulphide (rotten egg smell), acetic acid (vinegar), ethyl acetate (nail polish), if you go to a high enough concentration you'll cause the yeast cells to lyse. Too little sugar and you'll get a low yield.

pH: pH is a measure of acidity, more specifically the free hydrogen ions (H+) floating about in your liquid. It influences the chemical reactions which can occur and how fast they occur. If you keep the pH at or below 3.5 the yeast will be comfortable to ferment, but other moulds, bacteria and fungi are inhibited. If allowed to develop, these other cultures will compete with the yeast for the sugar and may produce off aromas/flavours. Note however that in some cases, development of certain bacteria may be desirable for complexity of flavour, in this case you may need a higher pH. One example is rum, where Lactic Acid Bacteria contribute to the flavour, mainly where you’re using a dunder pit.

Temperature and fermentation rate: Similarly to the paragraph above on sugar concentration, too high a fermentation temperature may stress the yeast and/or make the fermentation progress too quickly. This can impart undesirable characters and decrease yield. If the temperature is too cold, the yeast will go dormant and you’ll get a delayed fermentation, which also increases the risk of bacterial infection. For the same reason, keep the temperature high toward the end of fermentation, otherwise the ferment can get “stuck”. And you’ll have trouble restating it, potentially leaving residual sugar, which can be a food source for spoilage bacteria.
Using the wash quickly: The longer you leave the wash, the more chance of bacterial infection there is (as discussed above). You also give the alcohol a greater chance to oxidise, converting ethanol to acetaldehyde (ethanal) and acetic acid (ethanoic acid). Acetic acid will also react with ethanol, giving ethyl acetate, the compound responsible for heads aroma/flavour. For the same reason, avoid splashing fermented wash around the place too much.

Please feel free to add to this, I definitely haven’t covered all components of fermentation management and I’m not by any means an expert.
If I get the time, I’ll do some pH measurements on common washes and post them to let you guys know whether pH adjustment is necessary (as accurate pH meters are pricey).

[dogbreath vodka]

Hey BC
Good thread

Water Quality
The town water you use may contain chlorine which inhibits the yeast.
While not imperative - it is good to use water that has stood for a day or longer (I usually wait a week).

Sugar
BC I tend to go on the light side perhaps 1kg to 6ltrs.
In a 25ltr wash I'd use 4kg of sugar
That will give you a yield of 9.4% so the yeast isn't stressed.

1kg/5ltrs = 11.8%
1kg/6ltrs = 9.8%

DBV

[Zak Griffin]

Good thread mate, very interesting. A couple of points in there that most of us here wouldn't have considered :handgestures-thumbupleft:

[bt1]

it pays to read the yeast specs before settling on a over all rule for the process.

For example an EC1118 yeast it happy upto 18% yields with ideal conditions.

For temps again it's yeast strain dependant, A EDV46 a rum dedicated yeast rehydrates at upto 40c and is happiest running hotter at 30 -35c. It's also high yielder specifically bred to cope with higher overall sugar levels around the 15% yield mark.

I'm no fan of a 3.5pH stat as whilst fermenting the wash gets more acidic, as a target end 3.5 pH fine depending again yeast used.

I guess like most aspects of this hobby pays to do a spot of reading on what your using and well understand what ideal is for your situation.

bt1

[waza]

:text-yeahthat: :text-+1: especially the ph.

[Kimbo]

Good post B.C.
Im going to put a copy of this in the Noobs section :handgestures-thumbupleft:

[Urrazeb]

Hey BC
Good thread

Water Quality
The town water you use may contain chlorine which inhibits the yeast.
While not imperative - it is good to use water that has stood for a day or longer
DBV

Not to derail but more to clarify.. some water Co's also add chloramine to the water for the fact that it doesn't dissipate to open air.

I would recommend using vitamin C to neutralise chlorine and chloramine if anything. Though letting it age will help, the vitamin C does it instantaneously.

Lemon arguably contains enough available vitamin C and will lower Ph as well if needed- two birds with one lemon :handgestures-thumbupleft:

This is something I am going to be doing to optimise my washes. I was in the shower the other day and could taste the chlorides :romance-kisscheek: I immediately thought of my poor yeast, just trying to do their job :teasing-blah:

[tipsy]

some water Co's also add chloramine to the water for the fact that it doesn't dissipate to open air.

I would recommend using vitamin C to neutralise chlorine and chloramine i

Campden tablets are supposed to be good for chloramine

[tipsy]

The reason that fermentation control has some relevance to distillation is that poor control will result in more generation of ethyl aceteate (heads), proponols and butanols (tails). The more heads and tails you have in your drink, the more booze you have to cut out. You'll also form more acetaldehyde and acetic acid if fermentation isn't controlled, reducing your yield of ethanol.

This is a great point Blondie, as a beer brewer we have had it drummed into us that high ferment temps will cause ethyl acetate. But home distillers don't seem to worry as much :think:

[Urrazeb]

Because we can cut it out to a degree tipsy. Brewers have to drink the lot, fores/heads/hearts and tails so I would expect A LOT more care went into beer :handgestures-thumbupleft:

[tipsy]

Because we can cut it out to a degree tipsy. Brewers have to drink the lot, fores/heads/hearts and tails so I would expect A LOT more care went into beer :handgestures-thumbupleft:

I totally agree, but it does make you think.
Make less of it and get a better yield at a slower ferment.
Ferment quicker with a bigger head cut.... :think:

And then take into account the desired esters (rum ferments, Belgian beers) and I don't know where we stand. :razz:

[blond.chap]

Glad you guys find it interesting, bit of a late reply, I've been away from computers for a while.

Hey BC
Good thread

Water Quality
The town water you use may contain chlorine which inhibits the yeast.
While not imperative - it is good to use water that has stood for a day or longer (I usually wait a week).
Good point, if you leave a glass of water from my tap for a few hours you can really taste the pool water flavour

Sugar
BC I tend to go on the light side perhaps 1kg to 6ltrs.
In a 25ltr wash I'd use 4kg of sugar
That will give you a yield of 9.4% so the yeast isn't stressed.

1kg/5ltrs = 11.8%
1kg/6ltrs = 9.8%
Yeah, whatever you're comfortable with. It's worth trying a few different concentrations and seeing if you can notice a difference. I'm ok with 12% personally.

DBV

it pays to read the yeast specs before settling on a over all rule for the process.
For example an EC1118 yeast it happy up to 18% yields with ideal conditions.
True, but my conditions are never ideal, and I'm more comfortable getting a lower yield. Still spirits turbo yeasts will ferment up to 23%, doesn't mean I want to drink that

For temps again it's yeast strain dependant, A EDV46 a rum dedicated yeast rehydrates at upto 40c and is happiest running hotter at 30 -35c. It's also high yielder specifically bred to cope with higher overall sugar levels around the 15% yield mark.
Most yeasts do suggest rehydration at 35-40, I imagine it's good for the aerobic phase. For a typical yeast strain, it will survive and ferment from roughly 12degC to 43 degC, with a peak fermentation rate at around 27degC. In the wine world there are 2 ways of managing fermentation rate. The first is a cool ferment, where you cool the yeast to slow it down, the further it gets from 27degC, the slower it ferments, until it gets too cold and goes dormant. The second option is a hot ferment, where you slow the rate by heating it up, similarly, the closer you get to 43, the slower it goes.
Anecdotally, a hot ferment will generate more congeners than a cool one. For a rum wash this may well be a good thing, for a neutral wash it won't be.

Long winded way of saying I agree, it does depend, but if you want to cut down heads and tails and maximise ethanol yield, I'd be going with a slow cool ferment.


I'm no fan of a 3.5pH stat as whilst fermenting the wash gets more acidic, as a target end 3.5 pH fine depending again yeast used.
It's true that the pH drops during fermentation, but unless you want some bacterial flavour (like LAB for rum), I don't see a reason not to be safe from the start, unless a specific yeast can't handle it

I guess like most aspects of this hobby pays to do a spot of reading on what your using and well understand what ideal is for your situation.
I totally agree, what's best for rum certainly isn't going to be what's best for neutral etc.
bt1

Good post B.C.
Im going to put a copy of this in the Noobs section :handgestures-thumbupleft:
Cheers mate, hope they like it

[Aidymiles]

Hey BC
Good thread

Water Quality
The town water you use may contain chlorine which inhibits the yeast.
While not imperative - it is good to use water that has stood for a day or longer
DBV

Not to derail but more to clarify.. some water Co's also add chloramine to the water for the fact that it doesn't dissipate to open air.

I would recommend using vitamin C to neutralise chlorine and chloramine if anything. Though letting it age will help, the vitamin C does it instantaneously.

Lemon arguably contains enough available vitamin C and will lower Ph as well if needed- two birds with one lemon :handgestures-thumbupleft:

This is something I am going to be doing to optimise my washes. I was in the shower the other day and could taste the chlorides :romance-kisscheek: I immediately thought of my poor yeast, just trying to do their job :teasing-blah:

I'm sorry to say but vitamin C doesn't actually kill off chlorine or chloramines. :laughing-rolling:
Chloramines are chlorine molecules that have attached to other molecules in the water and are the byproduct of using chlorine to sterilise the water.
The easiest ways to get rid of both is to air the water, boil it or RO if you have one or UV.
I've worked in commercial swimming pools for over 15 years in Melbourne and we have tried just about anything you can think of to rid the pools of chloramines from vitamin C to magnets. We did a test during the drought to see what would work on clearing the backwash water of chlorine and chloramines so we could re-use it.
Expensive lab results showed airing completely cleared chlorine/chloramines after 24 hours, bubbling down to 12 hours and RO as quick as it can be processed. Boiling speeds up the gassing off Chlorine/chloramines significantly (15 min) but we didn't test that as its too expensive to boil 20,000L 3x a week and UV only breaks it down but doesn't get rid of it completely. :handgestures-thumbupleft:

[CH3CH2OH]

Great thread

[dogbreath vodka]

I'm sorry to say but vitamin C doesn't actually kill off chlorine or chloramines.

Expensive lab results showed airing completely cleared chlorine/chloramines after 24 hours,

Good to know.
:D :D
Old fashioned "Take some time" can help many processes in this hobby. :handgestures-thumbupleft:

DBV

[Urrazeb]

Hey BC
Good thread

Water Quality
The town water you use may contain chlorine which inhibits the yeast.
While not imperative - it is good to use water that has stood for a day or longer
DBV

Not to derail but more to clarify.. some water Co's also add chloramine to the water for the fact that it doesn't dissipate to open air.

I would recommend using vitamin C to neutralise chlorine and chloramine if anything. Though letting it age will help, the vitamin C does it instantaneously.

Lemon arguably contains enough available vitamin C and will lower Ph as well if needed- two birds with one lemon :handgestures-thumbupleft:

This is something I am going to be doing to optimise my washes. I was in the shower the other day and could taste the chlorides :romance-kisscheek: I immediately thought of my poor yeast, just trying to do their job :teasing-blah:

I'm sorry to say but vitamin C doesn't actually kill off chlorine or chloramines. :laughing-rolling:
Chloramines are chlorine molecules that have attached to other molecules in the water and are the byproduct of using chlorine to sterilise the water.
The easiest ways to get rid of both is to air the water, boil it or RO if you have one or UV.
I've worked in commercial swimming pools for over 15 years in Melbourne and we have tried just about anything you can think of to rid the pools of chloramines from vitamin C to magnets. We did a test during the drought to see what would work on clearing the backwash water of chlorine and chloramines so we could re-use it.
Expensive lab results showed airing completely cleared chlorine/chloramines after 24 hours, bubbling down to 12 hours and RO as quick as it can be processed. Boiling speeds up the gassing off Chlorine/chloramines significantly (15 min) but we didn't test that as its too expensive to boil 20,000L 3x a week and UV only breaks it down but doesn't get rid of it completely. :handgestures-thumbupleft:

I never said kill off, I said neutralise.

http://www.iuhoakland.com/Chloramine.pdf Last page

http://www.pure-earth.com/vitashower.html Second paragraph

http://www.vitamincfoundation.org/forum ... =3&t=11197 Good post on it

There is a lot of info on the web if you'd care to take a look.

The neutralisation of chloramines from absorbic acid (vitamin C) is though, temporary. But it's enough for the yeast to get a good start on fermenting and multiply to a stage that it is not adversely affected.

I wouldn't use pool water to ferment with either :teasing-tease: :teasing-neener: :laughing-rolling:

[Marbled]

Top thread. Like it.

I found a great use for the carbon filters thing that came with the T500 kit, I now use it to filter all the water I put into brews and washes.
I hate waste.