Distilling is a process of alcohol (primarily ethanol) concentration in order to make a strong spirit which can be aged, flavoured and bottled for enjoying at suitable occasions. The base for the alcohol can be from any fermentable source. Typically, barley malt is used for Scotch whisky production but cane sugar (gins) , molasses (rums), rye (bourbon), corn syrup (gins), potatoes (vodkas), stone fruits (rakia, iriki), Tequila (agave syrup) and rice (sakes spirits) are all used.
Production efficiency
The production of the “wash” (in brewing = wort) is similar at the start to brewing. The distiller will specify a high diastatic power (DP) malt; this indicates the ability of the natural enzymes present in the malt to hydrolyse the remaining starch in the kernel after malting to fermentable sugars in the mash. A fixed weight of grain will therefore yield a fixed amount of spirit so if the spirit yield can be increased from the same weight of grain, the distiller can get more volume for the unit price paid for the malt. Hence production efficiency is increased and production costs decrease. Various processing techniques can be employed to achieve this although some are prohibited through law, e.g. enzymes in Scotch Whisky distilling in Scotland.
Recommendations
The first technique is the use of calcium ions in the mash. The role of calcium in mashing is well understood in it’s ability to enhance the natural enzyme activity in saccharification. A level of 150ppm or higher (15g/hl) in the mashing & sparging liquor ought to be achieved. Having a water test done by an accredited laboratory then enhancing the calcium concentration through the addition of salts like calcium sulphate or chloride to reach this level should be done.
The second technique is the use of saccharifying enzymes. Probably the most useful enzyme in distilling is called amyloglucosidase (AMG). Amylase, glucanase and a range of others play a key role in breaking down the remaining starch after malting to maltose and maltotriose. These enzymes work slowly and methodically, controlled by the specific linkages in the molecular chains of starch. AMG works faster, it is not limited by such molecular bonding. It breaks everything down to a glucose and fructose which are preferentially metabolised by yeast. In this way, extra starch can be turned into fermentable sugar and thence to alcohol, enhancing spirit yield.
The third recommendation is closely tied to the first two and that is the need to understand the fundamental principle of enzyme action, both the naturally occurring ones in the mat and any additional ones employed as process aids. This is that enzyme activity is governed by pH and temperature. Applying the correct regime in the mash ensures optimal enzyme activity. This can be simply achieved by analysing the mashing liquor, determining the alkalinity (as CaCO3) then treating the water so that a pH of 5.2 +/- 0.1 is achieved in the mash. This, combined with a mashing temperature of 63-66°C, will ensure the maximum efficiency of saccharification.
The final recommendation is the correct yeast selection for the desired spirit outcome following fermentation. One that will ferment all available sugars to alcohol is ideal and there are now an increasing range on the market. Typically, the yeast should be able to ferment to between 16 – 18%abv on a regular and consistent basis without the need for yeast nutrition. Occasionally these are required and can be easily added to the wort at start of fermentation.
How do I start?
- Send a sample of your incoming raw liquor to Murphy & Son Laboratory, Alpine Street, Old Basford, Nottingham, NG6 0HQ and for a small cost we will send you our analysis and a recommendation for treatment to get the correct pH and calcium level in your mashing and sparging liquor.
- Spirit yield can be further enhanced with the use of enzymes. The following are all proven for use in the distilling operation:
- Yeast selection. A wide range of distilling yeasts can be found on our website at: Fermentis Distilling Yeast Archives – Murphy and Son
- Yeast nutrition. Occasionally this may be required to boost yeast performance in difficult washes like molasses for rum or corn syrup for gins. A good selection of yeast nutrient additions can be found here: Yeast Nutrients (Dry) Archives – Murphy and Son.
To wrap it up
Production for the distiller, like all production activities, has its continual challenges. These take the form of meeting sales demand, achieved outcome in a timely manner to the correct quality and costs to be kept as low as possible, as well as many others.
The application of the above learning through the use of Murphy & Son Ltd know how and products will benefit the distiller in all departments.
