For those in the world of whisky production, understanding the mashing process is paramount. Namely, because it takes place at the early stages of the process, its impact has huge residual implications for everything downstream – from yield to finished flavour.
Here, we delve into the mashing process using malted grains for those starting up their operations or just keen to get an overview of what goes on.
We’ll showcase the steps, the science, and the subtleties that go into turning humble grains into your favourite spirit.
The mashing process – an overview
Mashing, at its heart, is about unlocking starch from malted grains and converting it into fermentable sugars. The journey begins after milling the grains, which you can more about in this article: Grain Intake& Milling
Let’s go over some of the essentials for wheat, barley and rye…
Mashing is the process of extracting starch from malted grains and converting it into fermentable sugars to produce whisky. To state the obvious, but for that you’ll need grain (in the form of grist), water and heat.
The ‘liquor to grist ratio’ determines the consistency of your mash. The recommended mix is 2.5 to 3.5 L of water per kg of dry grist. Finding a balance is key and deviating from this can negatively affect both enzyme activity and the mash consistency. All new distilleries should find their happy balance. Start at one kg of grist to three litres of water and adapt from there.
Different grains have unique starch granule shapes and gelatinisation temperatures. That said, the primary enzymes involved are α-amylase and β-amylase, which have specific pH and temperature conditions under which they operate optimally.
The process of converting starch involves three stages. Don’t worry if this is too complex to full understand in a single sentence, we’ll cover more on each below.
Gelatinisation: Transforms the starches in grains to facilitate sugar production. (Different grains have unique starch granule shapes and gelatinisation temperatures).
Liquefaction: Hydrates the starch granules to allow the enzymes to work their magic converting starch to sugars.
Saccharification: Enzymes break down the starch into sugars. The conditions for these enzymes, like temperature and pH, are critical.
Key items of equipment you need to carry out a mash are:
- Grist delivery system. This can be a hopper that feeds the grains before milling or a manual addition of pre-milled grist. It transfers grains like malted barley into the mashing vessel, at a preset rate and in the right quantity.
- Temperature-regulated water. Ensures the mashing water is at the right temperature.
- Mashing vessel. Equipped with stirring tools and a perforated base, this vessel separates the liquid wort from the solid residue. E.g. a mash tun.
- Measurement tools. Devices to monitor and control the temperature, pH, and other crucial conditions for enzyme activity.
Mastering the mash
Let’s delve into some of the specifics mentioned above to better understand them, as well as to help guide those new to the process with some insight as to what to look out for.
Water-to-grain ratio:
Often referred to as the ‘liquor to grist ratio’, this dictates the consistency of your mash. A higher ratio gives a thinner mash, while a lower one makes it thicker. As we stated earlier, most aim for a mix of 2.5 to 3.5 L of water per kg of dry grist because this is the optimal balance.
Getting it wrong has implications –
Adding too much water can lead to the mash temperature changing too quickly to easily control (not good for ensuring heat-sensitive enzymes are kept within careful parameters). This leads to a wort that’s got insufficient sugar per L.
Meanwhile not having enough water leading to a chunky mash that’s hard to stir. This leads to suboptimal gelatinisation (as the heat is not evenly distributed), as well as lack of liquefaction (as the water is not evenly distributed nor in sufficient quantities). You need adequate hydration as it its the vehicle that facilitates that enzyme-driven conversion.
Ideal grain conditions & gelatinisation
Malted grains contain complex starch structures, predominantly made of amylose (25%) and amylopectin (75%). After milling, the crushed grain reveals starch granules varying in size and unique starch shapes depending on the type of grain.
Because of this, the conditions that are ideal for one to gelatinise (in essence for the starch structure to unwind, allowing itself to become liquefied because the water can enter deeper into the starch polymers) are different.
How a mash gelatinises is a big part of why distillers spend so long perfecting their grist.
| Source | Gelatinisation Temp (˚C) |
| Rye | 60-65 |
| Barley | 61-62 |
| Wheat | 52-54 |
Time
While extending the mashing time doesn’t necessarily increase extract (there’s an optimal time for the enzymes within their stated ranges, after which the wort concentration plateau’s), it can yield more fermentable sugars, as the sugars in the wort will be broken down further.
Often, it’s a factor that needs to be considered as part of the larger distillery operation and the full chain of events from mash to distillation. It is not one that can be looked at in isolation and in the sole context of perfecting a mash.
Liquefaction & saccharification
Once the gelatinisation has occurred, liquefaction gets underway. The hydration of the starch granules exposes the amylose and amylopectin chains and allows the enzymes to break down the starch into sugars. This is known as saccharification.
The efficiency of this process and of the enzymes is governed by pH, temperature, and time. Enzymes, in general, are vulnerable to heat, often losing their activity towards the end of the mashing process.
For example, α-amylase thrives at a pH of 5.6-5.8 and temperatures between 70˚C-75˚C. However, β-amylase prefers a pH of 5.4-5.5 and temperatures of 63˚C to 65˚C.
Each enzyme has a preferred temperature range, and deviating from it can decrease its activity. Similar to temperature, if pH isn’t in the ideal range, the enzyme won’t work as well.
Ensuring these conditions are met ensures optimal breakdown of starch chains. It also explains the reason that mashing is a step by step process of gradually increasing temperatures – not a single soak in a hot bath and stir type of affair.
| Enzyme | pH | Temperature (˚C) | Inneficent Temp (˚C) |
| α-amylase | 5.6-5.8 | 70-75 | 75-80 |
| β-amylase | 5.4-5.5 | 63-65 | 68-70 |
| Limit dextrinase | – | 55-60 | 65 |
The two predominant enzymes that distillers look at are α-amylase and β-amylase. However, malted barley has other enzymes, like limit dextrinase and α-glucosidase, which further aid in the conversion process and are carefully monitored, nurtured and integral to a good mash.
The reason for this is that Limit Dextrinase will enhance the overall extract and fermentability as while it’s inactive at mash pH, it becomes functional in the fermentation vessel when the pH drops, say, to 4.5.
This is what we referred to earlier as secondary conversion.
Five areas can you focus on to better understand and / or implement a successful mash
Milled grain quality and consistency
Grasp the composition of malted grains, primarily consisting of amylose and amylopectin. This will help understand the need to start with the appropriate milling of the grains to expose the starch granules effectively.
Water-to-grain ratio
Grasp the significance of maintaining an ideal ratio for consistent mash. There are good reasons why almost all will aim for a mix of around 3 L of water per kg of dry grist.
Temperature control
Understand the need for temperature-regulated water systems to ensure the mashing water is at the ideal temperature. This leads to ensuring you monitor grain-specific gelatinisation temperatures (e.g., barley at 61-62˚C) and implement the right conditions for enzyme activity (e.g., α-amylase between 70˚C-75˚C).
Starch conversion
Mashing is all about facilitating the stages of gelatinisation, liquefaction, and saccharification by ensuring every grain of starch contacts water for optimal enzyme-driven conversion (stirring / sparging etc.)
There’s two levels to it – it’s not just all in the mashing stage. It’s key to be aware of other enzymes like limit dextrinase and their conditions for optimal performance. They need to withstand the mashing phase for to allow secondary conversion in the fermenting vessel / washback.
Mashing vessels
Mash-tuns / Lauter tuns and other mashing vessels are complex items of equipment. They need to be equipped with ways to pipe in water, as well as efficient stirring tools to facilitate proper mixing. Many have inbuilt temp and pH controls too – as well as ways of assisting cleaning (CIP devices).
Lastly, the perforated base in a mash tun is something you have to factor in for effective separation of liquid wort from solid residues will come into play at the end of a mash (more on that in the article about Wort Separation & Cooling)
And there you have it – you can now see why mashing is a fundamental and intricate part of whisky making, essential for converting starches into fermentable sugars. Two big areas to remember are:
1 – The process involves key steps like gelatinisation, liquefaction, and saccharification, each playing a role in the transformation of grains into whisky.
2 – The mashing process demands attention to detail, such as the water-to-grain ratio, temperature control, and understanding the properties of different grains.
Mastery of these elements allows distillers to optimise starch conversion, paving the way for high-quality whisky. Hopefully this guide has provided some top line insights into the science and craft of mashing, offering valuable knowledge for both novice and / or curious distillers!
