Home Distillation of Alcohol (Homemade Alcohol to Drink)

Fermenting

Summary
Ferment the mash/wash at a constant 25oC, using 1.5g/L of good yeast.

Use an airlock to let CO2 out but not let air in.

Let the yeast settle out, and possibly even filter the wash before putting it into the still.



Fermentation is the conversion of sugar to ethanol and carbon dioxide by yeasts (wort to wash).


Theoretically 10 kg of sugar will produce 6.5 L (5.1 kg) of ethanol and 4.9 kg of carbon dioxide. In doing so, some energy is released (about 2.6 MJ/kg of ethanol) too.

Yeasts are single-cell fungi organisms. The most important ones used for making ethanol are members of the Saccharomyces genus, bred to uniform, rapid fermentation and high ethanol yields, and be tollerant to wide ranges of temperature and pH levels, and high ethanol concentrations. Yeasts are facultative organisms - which means that they can live with or without oxygen. In a normal fermentation cycle they use oxygen at the start, then continue to thrive once it has all been used up. It is only during the anaerobic (without oxygen) period that they produce ethanol.

There are three phases to fermentation once the yeast has been added:
  1. an initial lag phase, where little appears to be happening, but the yeast is adjusting to its new environment, and begining to grow in size
  2. after about 30 minutes, the yeast begins to reproduce rapidly and the number of yeast cells increases exponentially (thus known as the exponential growth phase). Carbon dioxide is released in large quantities, bubbling up through the liquor. As the fermentation proceeds, the yeast cells tend to cluster together (flocculate).
  3. The last phase is a stationary phase during which nutrients are becoming scarce, and the growth rates slow down. The evolution of carbon dioxide slows down, and the yeast settles to the bottom of the fermentor.
For more information about fermentation, see Fermented Fruits and Vegetables - A Global Perspective

Yeast produces 33 times more alcohol while reproducing than when resting (so most of the gains are in the first couple of days, then you're just relying on the large numbers of yeast finally present to slowly work their way through the remaining sugars)

Once the nutrients have run out, and the fermentation has become "stuck" or sluggish, it is then too late to provide either nutrients or new yeash. If this happens really early during the fermentation, then you're in trouble.This is because when a yeast is deprived of a nutrient, it grows as best as it can with what is available, and then growth comes to a halt. Those cells are then put together with less than satisfactory levels of (lets say) protein due to deficient nitrogen. Their enzyme content is less than adequate, and they don't metabolize well at all. Growing cells are ~33 x faster at ethanol production than non-growing cells. Supplementation at that point does not reinitiate growth in the older cells. By that time the medium is higher in alcohol and still deficient in some nutrients. Some cells may even have died. Even supplying the combination of BOTH nutrients and new yeast won't get the activity restarted again. So the trick is to ensure you have enough nutrients available at the start of the fermentation.

You end up with about 2g per litre of yeast (eg 40g in a 20L wash) This is why you don't get the full 51.1% conversion of sugar to ethanol, and gives some idea of the amount of nutrients - particularly nitrogen - that you need to supply.

Bakers yeast will produce a maximum of around 14% alcohol, whereas the "turbos" can generate up to 20% alcohol. Obviously you'd use different amounts of sugar for either case. Its not that the Turbo makes a higher % from less sugar, its advantage is that it can handle the higher concentrations (first of heaps of sugar, then later, the high alcohol %), and hence you need proportionally less water. Hence you end up with more alcohol in your 20L wash, because you are able to put more sugar in. Only use the Turbo's if you're after a "neutral" alcohol. If you're trying to make a flavoured spirit, (eg corn whisky, brandy, rum, etc) then use a yeast which will help give you the flavour profile that you desire.

While making the ethanol, the yeasts will also make very small amounts of other organic compounds - including other alcohols, aldehydes, esters, etc. These are known as the "cogeners" or the "fusel oils". It is the presence of these that give the alcohol its flavour. So when trying to make a neutral spirit, we'd try to minimise their presence, but if making a whisky, rum, brandy etc, then we need a very small proportion of them present.

Fusel oil concentration in the wash can be up to around 0.24 g per Litre from 20% sugar (eg about 3.2 mL from a 20L wash)

Fusels increase depending on ...
* yeast strain (eg Saccharomysce cerevisia makes more than S.carlsbergensis)
* temperature (higher temp = more fusels)
* increased aeration and agitation (news to me ! so don't over-stirr it !)
* wort composition (nitrogen sources and readily metabolised sugars)

The most common limiting factor for yeast growth is a lack of nitrogen. Nitrogen is approx 9% of the cell mass. Most common form to add it is as the ammonium ion, as the sulphate and phosphate salts (phosphorus is approx 1-2% of the cell mass, and sulfur 0.3-0.5% so these are needed too - this is a nice way of getting all three in there). Add the ammonium phosphate at a rate of 25-50 gramms for a 25L wash.

The second most common limiting factor is a lack of oxygen, but it only needs it until high cell numbers are present (eg during the first day) (so make sure that you've aerated the wash well just prior to adding the yeast, but don't do this too much later in the game) "Splash filling" is enough to do the job.

Bacteria can double in number every 20-30 minutes, but yeast takes 3 hours (so guess which one will win the race if an infection gets started and you don't deal to it. Another technique to help with this is to use a lot of yeast - when using Bakers yeast, use at least 150g for a 20L wash.

Theres a fair bit of choice available as to which yeast to use. I'm personally inclined to use the "Turbo" yeasts, which are pre-packaged with all the nutrients etc necessary. Thats because I'm only ever doing sugar-water washes for pure neutral spirits, and I find it easy, convienient, and reliable. I don't try and reuse it a second time, as I only distill every couple of months, and can't be bothered storing it for that long. If however you are doing more of a grain or fruit based mash, and interested in flavours, then consider some of the other yeasts.

Ted recommends Jack recommends ... Ken recommends ..."SAF-DISTIL.B-28" from D.C.L.Yeast

Nutrients

A slightly acidic environment is enjoyed by yeast, and also inhibits the development of bacterial contaminants. The pH of the brew should be adjusted to between 4.0 and 4.5 prior to fermentation, using citric or lactic acids.
If using citric acid ....
To get a pH of you need to use grams per litre
ie grams in a L wash to use



Nutrients also need to be present. Yeast cells require phosphorus, nitrogen and potassium, as well as amino acids and vitamins, for metabolic processes. The extent to how much is required depends on the feedstock being used. The nitrogen requirement may be supplied in the form of amino acids, ammonia, or ammonium salts. If the solids are separated from the sugar solution prior to fermentation (or say starting only with sugar) the bulk of the protein will be removed, and hence a potential nitrogen source lost. Ammonia or ammonium salts are the preferred source of of additional nitrogen if its needed, however avoid using excessive amounts because it can kill the yeast. Both nitrogen and phosphorus can be supplied by ammonium phosphate (commonly available as a fertilizer). Many fermentations will proceed satisfactorly without vitamin suppliments because the fermentation medium contains sufficient of these nutrients, however in most cases, cell growth is enhanced when B-vitamins are added.

One recipe for nutrient ale salts is This mixture is hygroscopic (attracts water), so keep it in a cool dry place with a good lid.

The "Great New Zealand Home Wine Making Book" suggests to ... "buy some ammonium sulphate or ammonium phosphate, and some pottassium phosphate or potassium sulphate and add 2g (1/2 teaspoon) of each to every 4.5 L. Another valuable addition is vitamin B1. You can buy these as tiny 3 milligram tablets from your local chemist or pharmacy and add one of these each 4.5 L" ...

Concerning the use of Urea in nutrients, Des writes : Also, don't use too much nutrient. It won't make the yeast work any faster, once you've supplied its needs. What can happen instead is that the excess Ammonium disulphate can react with (eg corrode) the copper in the condenser during distilling to produce ammonia and copper sulphate, which will turn the alcohol blue, and smell of ammonia. If this happens, make sure you strip down your tower, and clean it well. The blue alcohol can be cleaned up by adding some citric acid (50g per 5L) (which will react with the ammonia to produce ammonium citrate which will precipitate out along with the copper leaving hydrogen sulphyte and or sulphide), and then filtering it through some coffee filters to collect the flocculant; the alcohol will then be ok to redistil.

Matt suggests
Brians recommendation is

Using Yeasts

When the temperature of the wash has dropped below 26 °C, add the yeast. Do not add the yeast too soon - if the temperature is above about 34 °C, it will kill the yeast.

You're aiming for around 10 million yeast cells per mL of wash. A 25L wash at 1.080 will therefore need about 3 cups of slurry. Get this amount by using the slurry left over from the previous run. See the comments below in the Reusing Yeast section.

If using dried yeast, it can be helped along by letting it soak in about 1C of warm (24 °C) water for about an hour beforehand. Use a high alcohol yeast such as for champagne, or the new proprietary alcohbase or "turbo" yeasts which can generate up to 21% alcohol (who needs distillation ?). If the pack you're using is one of those small ones, it will pay to grow it up to a suitable size before using it (see Teds comments below).

Close the fermentor, and use an airlock. Keep the temperature around 28 C, and the specific gravity should drop to approx 0.980 - 0.990 g/mL and have ceased bubbling within 5 days.

Jack H recommends .. If the fermenter doesn't bubble, check that the lid is sealing well. If you squeeze the container when you put the lid & airlock on, the water should move up in the airlock, then drop again when you let go. If it doesn't, then the lid isn't on correctly.

For excellent discussions about yeast, and how to get the best out of it, see the Turbo yeast and AllTech web pages.

Donald advises ...

Temperature Control

Temperature control is very important during fermentation. Yeast is a living organism, and will die if too stressed. Both alcohol and temperature stress it. With no alcohol around, it won't die until about 40 °C. At 14% alcohol, it will die at 33 °C, and at 25 °C if in 20% alcohol. So keep it below 25 °C at ALL times. Lower temperatures will also result in less volitiles. When the temperature has been kept below 30 °C the production of fusel oils is minimal, and is extremely small if kept below a maximum of 25 °C. This is where you get into a bit of a trade-off; if you keep it too cool, it will take heaps longer, with greater time for the risk of infection etc to set in. At 25 °C, it will take 3 days to ferment 0.24 kg/L sugar, but at 15 °C it will take nearly 2 weeks.

An easy way to maintain the temperature in cooler climates is to wrap a water bed heating pad around the fermentor, and tape the thermostat to the side of it before wrapping it all in a blanket. Other people just keep their fermenter in the hot water cupboard. Another way is to keep it in a small cupboard or box with a light wattage lightbulb to supply a lttle heat (but shield the bulb so that the beer doesn't become light-struck). Some even use immersion heaters like those for tropical aquariums - but these can be tricky to sterilise, you need to get the wires through the lid in an airtight manner, and if you lift them out of the brew without turning the power off, they can quickly overheat and burn-out (an expensive exercise in forgetfullness).

If using the Turbo yeasts, pay particular attention to the temperature. These babies can raise the temperature of the wash by 5-8 °C, so don't add them until the wash has cooled to about 18-20 °C.

If you are fermenting large volumes, you may need to actually cool the wash, either by dropping in frozen 2L softdrink bottles of water, or getting fancy like big brewers, and running cooling water pipes through the fermentor. The larger the amount you are trying to ferment, the harder it wil become to control, yet it is critical that you try to keep it all at 25 °C plus/minus only 1 °C. You may find washes larger than 200L difficult to control & keep cool.

Oxygen

During fermentation, yeast has a couple of choices. If it has oxygen available to it, it will be able to reproduce quite rapidly (doubling every 3 hours). If there is only limited oxygen available, it will turn its task to producing ethanol and other products (about 1300 in all), like higher alcohols (sometimes called fusel oils), esters, organic acids, and carbonyl compounds. To get good initial growth of the yeasts, you want to have a bit of oxygen available - but you can do this simply by stirring the wash vigorously when disolving the sugar. Once you have added the yeast, it is critical to seal the container such that air cant get in, but you can still let the CO2 out, by using an airlock. To minimise the amount of other volitiles produced, make sure that you are using a yeast designed for the job, and keeping it happy with nutrients & with a stable temperature.

Fizz writes ..

Stuck Ferments


If your fermentation peters out early in the story, it could be due to a couple of reasons. Do not add more sugar to a stuck ferment. It won't help.

You can still distill a wash which hasn't fully fermented out, but be prepared for some fun. It is likely to foam up heaps, and possibly block the column if you don't give it enough headspace, or use the "anti-foaming" silicon emulsions (wash conditioner) available in brewshops. Also, because not all the sugar has fermented, you're likely to get less alcohol out, and you may caramelise a bit of it on the element or the base of the pot (clean it well afterwards).

Another way of knowing how far the fermentation has progressed is to measure the weight of your fermentor & contents. Half the sugar is expected to convert to CO2 gas and bubble away. Theoretically the yield is 48.9%, but practically this is 40% because some of the gas dissolves in the wort. So if you have added 5 kg of sugar, and the weight has only dropped by 1 kg, keep it going for a while longer (you expect 5 x 0.4 = 2kg weight loss).

Settling

Once fermentation has finished (eg final specific gravity of 0.990-0.980 reached), turn off the heat, and let the finished yeast settle over a couple of days to the bottom of the container. Siphon the clear wash into the still, and you're ready to go. Be careful to not disturb the yeast layer, because if it gets into the still it can result in bad smells and flavours. If in a hurry, you can use finings (eg gelatin - 2g in 100mL to settle 25L) to help settle/clear the yeast, or try placing the wash in the freezer, to chill it fast & knock the yeast down. Passing the wash through a simple filter, or even a couple of paper towels to clear out the remaining yeast will also help improve the quality you later get. The simplest (& often most effective) technique though is just time.

If you have to split the wash (say you've made more than the still can hold), just pour the remaining wash into a container that will hold the remains and be full. That is, ensure that the air in the container is minimalised. By eliminating the air in your container you will lessen the oxygen thereby lessening the chance of oxidation. This way you will be able to do the remains in a second run any time. The wash should be quite safe for weeks. Keep it sealed.

Alcohol Content of the Wash

You can easily calculate the strength of your wash, if you know your starting & final specific gravities (SG) - measure these with a hydrometer. The % alcohol is (Starting - Final) x 129. eg: if your sugar/water mix of SG=1.120 drops to 0.980, then you have a wash with (1.120-0.980)x129=18.1%.
If the SG started at and finished at
Your wash is % alcohol


Reusing Yeast

It is possible to reuse the yeast several time. Ted Palmer advises : See also The Microbrewery Laboratory Manual: Jack comments .... David Lamotte writes (to CraftBrewing@egroups.com (a brewing group for Australians/Kiwis at eGroups)) ... Donald advises ... Jack divulges his method for preserving yeast cultures...

Sloppin' Back

Re-use of yeast is an old moonshiners trick also known as "sloppin' back". This refers to adding the mash that was strained out of the wash just prior to distilling, or the sludge left in the bottom of the fermentor, to the next batch of mash.

As Sam explains ..
This can be a good source of infection for the next batch, but if it goes well, it will help boost the yeast count heaps, act as a bit of a source of nutrients (though its still best to add more of the real stuff like ammonia), and should help buffer the pH a touch (dropping it a few 10 ths). The yeast that you're reusing by this technique are those that have already shown themselves to be quite happy in that type of mash, and are ready to go for the next lot.

It appears that the "Turbo" yeasts are only designed to be used once, and not reused. Ola Norrman writes ...

Freezing Yeast Cultures

Matt reports

Mixing Different Yeasts

It is sometimes useful to use two different stains of yeast at the same time; one strain for flavor and another for the alcohol content.
Ray writes .. Ted suggests .. The Omnipresent Mecakyrios does similar ..

Yeast

Heres some more postings from Ted Palmer about using yeast ..

Amount of Yeast

Many if not most commercial distilleries use some form of brewers yeast. What should determine the type and AMOUNT of yeast is the make-up of your wash. A common problem isn't the type of yeast that you are using but rather how you are using it. A 1.060sg wash will be reduced just fine by any yeast so long as there are enough yeast cells per ml. and enough nitrogen to keep the cells healthy. In fact by repitching more activly fermenting yeast several times into a high gravity wash, a "beer yeast" can ferment up to 16 to 18 percent alc. If you use a packet of dry yeast then there are too few cells let alone heathy ones.

Here are a few guidelines for proper yeast use in any ferment:

Aeration

In order to properly "grow up" a series of yeast starters you must aerate the wash with sterile air or pressurized oxygen (O2). The reason for this is that yeast cells bud or reproduce only when there is enough oxygen present to grow. During fermentation yeast cells will still bud, but at a slower rate since it has to pull oxygen out of chemicals. The amount of O2 required is small, on the order of 20 microliters per ml. to support the budding phase.

So how do you put O2 in your wash?

Sterile air:
Pressurized O2: Aerating a fermenting wash will result in one hell of a lot of yeast and very little alcohol. Aerating a fermenting wash for even a short time will oxidize flavor components including ethanol!!!


Heres a couple of emails between Steve & Dr Clayton Cone that are hugely informative ..
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