Distilling

The production of fermented alcoholic drinks from starch­containing raw materials has been practised for centuries. The choice of raw material differs around the world: in North America, maize (corn) and rye are the ingredients for whisky, whereas in the UK, barley is used for malt whisky and other cereals for grain spirits; in Scandinavia, potatoes and to a lesser extent grain are used for the production of akvavit; in Germany, wheat is used for Kornbranntwein, whereas potatoes and grain are used for other types of spirits; in the Far East, rice is used to make sake.

But whatever the raw material, starch is still the basic ingredient. Starch is composed of long chains of glucose molecules and these have to be broken down into smaller molecules that the yeast can transform into alcohol. This process can be carried out by enzymes in two stages – liquefaction and saccharification.

The decline of malt

Enzymes have traditionally been provided by adding malt. However, since the late 1960s there has been a dramatic change and in many countries malt has been totally displaced from distilling operations by the use of industrial enzymes. The advantages of using industrial enzymes instead of malt are many.

A few litres of enzyme preparation can be used to replace 100 kg of malt. Enzymes are therefore much easier to handle and to store. In terms of raw material costs, savings of 20-30% can be expected when switching to commercial enzymes.

Furthermore, industrial enzymes are supplied with a uniform, standardized activity so distilling becomes more predictable and there is a better chance of obtaining good yields from every fermentation. The quality of malt, on the other hand, can vary from year to year and batch to batch.

Finally, industrial enzymes perform better than those found in malt. Microbial amylases are available with better activity at the low pH values found in the mash. Extremely thermo­stable amylases are available that go on liquefying starch at 100°C long after malt enzymes have been destroyed.

In view of these advantages, it is hardly surprising that commercial enzymes have replaced malt in all but the most conservative parts of the distilling industry.

Starch liquefaction

Before enzymes can attack the starch, it must be gelatinized. This is usually done by pressure cooking.

Potatoes, for example, are heated to 150°C at a pressure of five atmospheres. When the pressure is released suddenly, the cell walls of the potatoes literally explode, releasing the starch. In this case, the enzymes are added to the mash tun after cooking, but in other cases a highly heat­stable enzyme can be used in the cooker itself.

Recently, the old non­pressure cooking method has been gaining in popularity, especially in smaller distilleries. Instead of temperatures around 150°C, the maximum temperature is from 60°C to 95°C. There are obvious energy savings and there is no need to invest in pressure vessels.

Whatever the processing technique, alpha­amylases are used to break down the gelatinized starch into short molecular fragments (dextrins).

Starch saccharification

The second step is saccharification. An amyloglucosidase is used to attack the starch molecules and the dextrins. This enzyme is capable of achieving the complete degradation of the starch into fermentable sugars (glucose).

During fermentation, these sugars are converted into alcohol by the action of yeast. The alcohol is then distilled off.

Aiding fermentation

Enzymes can also be used as processing aids. Starch­containing cereals, in particular maize (corn), tend to be low in soluble nitrogen compounds. This results in poor yeast growth and increased fermentation time. The addition of a small amount of protein­splitting enzyme to the mash overcomes this problem.

Fuel alcohol

In countries with surplus agricultural capacity, ethanol produced from bio­mass may represent a sensible substitute, extender or octane booster for traditional motor fuel. While sugar­based raw materials such as cane juice or molasses can be fermented directly, this is not possible for starch­based raw materials. They have to be broken down into fermentable sugars first.

Though the equipment is different, the principle of using enzymes to produce fuel alcohol from starch is exactly the same as when producing alcohol for drinking purposes.

Product Range

The standard Product Range for the Alcohol industry looks as follows. Most products are available in liquid as well as solid form, and in different concentrations. Please contact your local sales office for further details as well as with inquiries about special products not listed here.

Please note that all products listed are not necessarily available in all countries. Contact your local sales office for details.

BAN (Bacterial Amylase Novo)
For medium-temperature liquefaction of mashes containing starch.

Fungamyl®
A fungal alpha-amylase that shortens fermentation time.

Liquozyme®
A bacterial alpha-amylase for high-temperature liquefaction of mashes containing starch.

Neutrase®
A bacterial protease for improving yeast growth.

SAN Super®
For breaking down dextrins completely to fermentable sugars.

Termamyl®
A bacterial alpha-amylase for high temperature liquefaction of mashes containing starch.

Cellubrix®
A cellulase and cellobiase preparation for transferring cellulose material into glucose.