Home Distillation of Alcohol (Homemade Alcohol to Drink)
Sugar
(paraphrased from the Teachings of David - emails to the "Distillers" newsgroup April '00 from
David Reid)
The type of sugar used in the wash can result in a different flavour of the alcohol.
To change the alcohol profile and to get away from the sweetness you are best to change
the composition of the raw material you are using for your wort.
Using a % of dextose in the mix to replace a certain % of sugar will give you a
fuller and rounder profile. At the end of the day it may all be alcohol but there
are also slight nuances which are discernable to some peoples taste and more pronounced
for others.
Introduction
Sugar molecules are formed from carbon, hydrogen, and oxygen by the process
known as photosynthesis. Yeasts convert sugar molecules into alcohol and
carbon dioxide (CO2) by means of a simple enzymatic action. There are many
forms of sugar and the name the whole family is known under is saccharide.
Under certain conditions sugar molecules have an attraction for one another
and 2 small molecules combine and form a bigger molecule. Sometimes these
molecules combine and then sometimes combine again etc creating complex
saccharide molecules or chains.
Small simple sugars are called monosaccharides,
* when 2 simple sugars combine they are called disaccharides, and
* when 3 or more combine they are called polysaccharides.
Large polysaccharide molecules consist of thousands of small monosaccharide molecules;
pectin, gums, and cellulose are examples of these.
Monosaccharides
Monosaccharides are simple sugars and there are many different kinds with
each sugar molecule containing 3, 4, 5, or 6 carbon atoms with each being
named after these number of carbon atoms eg. pentose = 5, hexose = 6. The
two main sugars we are concerned with namely glucose and fructose are hexose
monosaccharides. Glucose is the sugar that provides the sugar for the human
body. Fructose as well as being a component of sucrose is found in many
different kinds of fruit and is the principle one in honey. Fructose is also
sometimes known as levulose.
Glucose is the main common simple sugar and is a part of many different
disaccharides and polysaccharides eg. corn starch (most common source).
Disaccharides are composed of 2 simple sugars combined together which can
either be similar or dissimilar sugars eg. Maltose = 2 glucose molecules
(dimer or double molecule of glucose), sugar or sucrose = 1 glucose + 1
fructose molecule. Normally disaccharide sugars must be hydrolyzed and split
into their simple sugar components before they can be fermented. In the case
of sucrose (sugar) they are split into equal numbers of glucose and
fructose molecules. Glucose has a Relative Sweetness level of 70 while
fructose has double that level at 140. By switching a certain amount of
glucose for sucrose it can be seen that it is relatively easy to adjust the
Relative Sweetness level before one starts fermentation.
Just try switching a certain amount of the glucose for the sugar say 20 to 25% initially (probably kg for kg) and go from there. You should end up with a less sweet alcohol.
Disaccharides
Disaccharides are produced commercially by the incomplete hydrolysis of
larger more complex polysaccharides ie. the hydrolysis process is halted
prematurely rather than being taken to the final stage of being further
split into glucose and the other components sugar/s. It can also be produced
by combining 2 monosaccharide sugars by means of a condensation reaction to
form disaccharide sugars. Microorganisms such as yeast produce enzymes that
hydrolyze sucrose.
Lactose is another disaccharide (milk sugar) and is only found in milk from
mammals. It is made up of 1 glucose sugar and 1 galactose sugar molecule. In
the case of NZ and Australia it is the major source of commercially
available spirits. It is easily hydrolyzed and has practically no sweet
taste having a Relative Sweetness of 40. It is therefore very easy to
combine with most spirit bases without changing the profile. To hydrolyse
lactose you need the enzyme lactase which allows the feedstock to then be
fermented by the common Saccharomyces cerevisiae yeasts. A principal source
of lactase is the yeast Kluyveromyces fragilis which is more commonly used
to ferment lactose directly to ethanol.
Polysaccharides
Polysaccharides are large complex molecules containing 3 or more
monosaccharides (and in some cases number more than several thousand simple
sugar molecules) which are used by living organisms to store energy. They
also form part of cell structural fibres. Starch consists of many glucose
monosaccharides hooked together in both linear and branched forms. Pectin,
gums, and cellulose are some of the other main polysaccharide molecules.
Unfortunately cellulose is normally only fermented by xylose fermenting
yeasts or bacteria so at least 30% of any plant materialis is generally
always unfermentable. For polysaccharides to be fermentable they need to be
split or broken down (hydrolyzed) again into simple sugars. This can be
acheived by enzymes, acids, or heat.
Quite often the process is a joint one combining two or all three of these.
The main enzymes used or part of alcohol fermentation are Alpha amylase,
Beta amylase, Glucamylase (Amylogglucosidase), all of which are used to
break down amylose (major component of starch) and amylopectrin
(other major component of starch which is less
easily hydrolyzed due to its large branched chains nature of construction).
In addition other enzymes that are used are Beta glucanase, Lactase (milk
sugar enzyme), Maltase, and Protease. Zymase is the complex of enzymes
produced by yeasts which are responsibler for the fermantation of sugars to
ethanol.
Acids that are involved or used in fermentation are Tartaric, Malic (wine),
Succinic, Lactic, Citric, Proprionic, Sulpheric, and Hydrochloric.
Relative Sweetness
Chelsea Refinery (NZ Sugar Co. Ltd.) {find URL} quotes the following Relative Sweetness of the following:
Sucrose
100
Glucose
70
Fructose
140
Invert Sugar
110
Lactose
40
Maltose
50
Hence by switching some dextrose for sucrose the final product will taste less sweet. A lot of brewers use from 20 to 25% dextrose and some even more. The % used is kept dowm somewhat because of the slightly higher price. I (DR) myself have been using dextrose (dry powder form) for some time now and notice I seem to get a less sweet tasting alcohol. Obviously the difference in finished alcohol is marginal and nothing like the Relative Sweetness figures quoted.
Note that whisky is largely made from barley (simple sugars) and neutral grain alcohol which is mostly made from corn or maize (corn sugar = glucose). Bourbon likewise is is almost solely
corn or maize. Rum in comparison is almost solely made from sugar (sucrose). Compare the 2 and you will quickly get the idea. The difference is minimal rather than profound. After all alcohol is alcohol, is alcohol, is alcohol. It is just that it gives the finished alcohol a fuller and
rounder profile.
Note also that the majority of New Zealand alcohol made under licence here is mostly made from lactose which has a sweetness of 40.
Attenuation
While there is is not much published in regard to problems like this (at least if so I (DR) havn't seen or heard of it) with regards to spirits alcohol there is a lot of published data with regard to beer fermentation and the resultant products produced which is almost identical. It comes under what is called attenuation and is the main reason certain specific yeasts are used to produce specific beers.
Attenuation refers to the % of sugar converted to alcohol and is normally between 67 - 77% (Higher with actual sugar). This is determined by the composition of the wort (in your case actual sugars used) and the yeast strain used. In simple terms each yeast strain ferments different sugars to varying degrees resulting in higher or lower final gravities which affect the residual sweetnesss and body.
By playing around a bit with both the sugar/s composition and the yeast/s used it should be relatively easy to change this character aspect. By being precise and keeping good records you should after a while get to the stage where the results are repeatable and the taste more along the
lines you like and desire.
How do the different sugars contribute to the sweetness in the distillate ?
Because hardly any distillation is absolutely pure (ie. above 192.6 proof or 96.3% with the azoetrope) there is a certain amount of the congeners or contaminants (dont know if this is the right terms here) carried with it in the form of bonded molecules as virtually no fermentation goes to the absolute limit where everything is converted.
Alcohol therefore tends to show its origins. The simpler the sugars (ie. monosaccharides c/f dissacharides) the greater the conversion. Also the greater the purification (ie. alcohol %) the less this is noticeable.
This is why rum fermented almost solely from molasses or sugar syrup distilled at a lot lower % apart from the actual congeners is so distinctive and also why vodka tends to be vodka regardless of source. At the very high levels it is only those of us (DR) with very distinctive palates who can discern. The more complex and longer the makeup chain of the starting sugars the more difficult it is to convert. This is why we end up with what are called hung fermentations sometimes. I (DR) also believe with more complex sugars that some of the dextrins are not totally converted.
I (DR) believe somewhere there should be what I would call Tables of Fermentability that
deal with the properties of various sugars. Probaby in some wine book or similar. A good winemaker with the proper techniacal qualifications could probably tell us.
...When cane sugar is used, the acid
environment of the fruit juice allows an enzyme in the yeast called sucrase
(or invertase) to convert the sucrose into the simpler sugars glucose
(dextrose) and laevulose (fructose) which are then fermented. Although this
process takes place almost straight away, it can be argued that it is
better to use sugar that is already inverted. In practise this gives a more
even fermentation and thus an arguably better quality finished wine. The
amateur, however, need not worry about this as the difference is likely to
be negligible. Invert sugar is available to buy, though more costly than
the household variety. On the other hand it is possible to invert some
household sugar before adding it.
Put 8 lb of sugar in a sauce pan with 2 pt water and 1/2 oz citric acid.
Bring slowly to the boil, stiring frequently and boil for 30 mins.
Stir in another 2 pt boiling water and allow to cool.
This can now be stored in jars. When using allow 1¼ pints in place of each
lb of household sugar. Remember that each 4 pints will already contain ¼ oz
of citric acid.
so it seems that the invertase normally found in yeast combined with a
slight acid environment, and some heat from yeast activity, gives the
winemaker's yeast what it needs to break down the fruit sugars.
'UPS474' writes ...
I just did some poolside reading in an old homebrewing book.
Appearantly, white sugar must first be altered by the yeast enzyme
called invertase, before it can be fermented. It may be possible to
avoid the sweet aftertaste in homemade vodka I've been reading about
by using invert sugar instead of expensive corn sugar. Invert sugar
can be made by boiling 2 pounds of ordinary table sugar with one
teaspoonful of citric acid in one pint of water until the solution
takes on a pale golden color, then neutralizing the acidity with
about one teaspoonful of food grade chalk. Even if this doesn't get
rid of the sweet aftertaste, fermentation (especially when going for
20% mash with a turbo yeast) will probably take less time
Ted adds ...
Yes it does work well, but we can dispense with the chalk, yeast likes a low
pH of about 4.5. If your invert sugar is lower you might think about adding
chalk or sodium hydroxide(lye) to adjust the pH.
David says ..
Recently used this process myself to start a batch
after breeding up my starter yeast and was amazed how quick it is and how it
accelerates the fermentation process. Fermentation trap was bubbling away
merrily ten minutes after closing and locking the lid. Can't comment
regarding quality as fermentation is ongoing and havnt distilled the
finished wash yet.
Howard says ..
I always do this myself when I am making a wash.
I always invert the sugar and use a Turbo yeast.
I don't think it makes any significant difference to the purity of the
final result, but I think it speeds up the fermentation process a bit
though. I simmer my sugar solution for about
5-10 mins with a cuppla teaspoons of malic acid, (citric also works) to
bring about inverting.