When it comes to whisky, the quality of the grain and how it’s processed (the milling) can significantly impact the final product. It’s also where things can go wrong, quickly and cost a lot of money and time in wastage. Let alone in damages if it triggers a fire.
This mini-guide is designed for those who buy in malt grain rather than undertake the malting process themselves. Here, we’ll cover everything from the intake of grains, quality checks and storage protocols. Crucially, we’ll look into the milling process that precedes the mashing stage.
If you are planning your process for your new build, get a notepad out as it’ll give you all the questions you need to answer to get your process designed safely and efficiently.
Grain intake and quality checks
So, you’ve found a malted grain supplier. You have spoken about your requirements and have ordered the right amount of grains, in the exact type of spec you are looking for. Great.
Upon receiving a shipment of grain, the first step is to match the batch with its certificate of analysis. Even if everyone has the best of intentions, mistakes happen, and issues (unintentional or otherwise) arise.
Carry out visual checks for red flags like excessive dust, dampness, foreign objects, or signs of pests. Quality control at this stage is vital irrespective of your scale.
It’s challenging and expensive to rectify issues once the grain is stored, especially in silos. The last thing you want is to add a bad batch into something storing good grains, and not know about it until much later. By that point you may have sandwiched the bad with other good batches thereafter too… It’s a nightmare and It’ll all have to go.
This is also why you should set out clear storage protocols. Start with the obvious – grains should be stored in dry, pest-free conditions. Whether you’re using silos or giant bags, the conditions should be free from infestation. Ideally, off the floor too, to avoid potential water contact.
While rodents might be easy to spot, insect infestations are not. Think about quarantine procedures and whether that’s needed. It can be as complex as isolated storage parameters and lab tests, to something as rustic as adding a feline mouser to the team and keeping bags separate…
Inventory management is also key. Keeping stocks at a minimum level and efficiently turned over is advised to manage costs and ensure contamination risks are low.
Milling process
Milling converts grain into what is known as ‘grist’. The main aim is to expose the starchy endosperm by breaking away the husk. This is crucial because it makes the conversion of starches into fermentable sugars during mashing more efficient.
The type of roller mill you choose can have a significant impact on the final product. Each type of roller mill offers its own set of benefits and trade-offs.
Types of mills
Two-roller mill: The most basic and least expensive option. It crushes grains between two rollers but offers limited flexibility in controlling particle sizes.
The disadvantages are clear – a lack of finesse in what’s possible with the grist.
That said, one of the main attractions of a two-roller mill is its lower upfront cost. If you’re a small-scale distiller or just starting out, this could be a decisive factor. They are relatively straightforward to operate, making them suitable for those who may not have complex needs or the ability to invest in specialised training.
With fewer components, two-roller mills generally require less maintenance, which could be beneficial for smaller operations where manpower is limited.
Four-roller mill. Suitable for well-modified malts. It uses two additional rollers to reduce the size of coarse grits, providing better control over particle size. This can be crucial for distillers looking to achieve specific textures and mash ratios.
Typically, it offers the middle ground – a small increase in budget for a more advanced milling machine.
Six-roller mill. Similar to a four-roller mill, but the additional rollers and sieves give you even more control over particle size, which could be advantageous for specialty grain varieties. Generally, six-roller mills are bigger, more robust and capable of handling higher volumes. This makes them ideal for larger distilleries with more extensive production needs.
Hammer mill. Best for distilleries using green malt or other unmalted grains. It uses metal hammers to crush grains into smaller pieces.
The milling process and what’s being made: The Grist
The end result of the milling is grist – a mix of different sized grain particles ranging from husks to fine powder. Regular grist analysis is important for maintaining quality and consistency in your mash. It is especially important when switching to a new batch of raw material.
It might sound like a basic check – but the simple act of looking at it allows you to judge the composition.
You need to do that with some more accuracy than simply eyeballing a big bag and running your hand through it. Most will have grading sieves for the job. Grading sieves, commonly known as plansifters, provide a detailed breakdown of grist particle sizes.
In simple terms, they are a set of five sieves, gradually getting smaller. The milled components are added to the top, and separate along the way (large husk pieces at the top, small bits of crushed endosperm, and some flour at the base).
As the milled grist directly influences the mashing process, the quality of milling affects the efficiency of sugar extraction. It is a good reminder that no process in the entire chain from grain arrival to maturation can be looked at in isolation.
Milling and grist is optimised for the next step and needs to be judge in the full context of processes downstream.
Safety and compliance
Mitigating risks
When it comes to the handling, storage, and milling of grains for whisky distillation, safety can never be a secondary concern. In fact, because it involves powder (flour) in a confined space (the mill) – it should be a very specific explosion and fire concern!
Non-compliance with health and safety regulations not only puts people and property at risk but can also result in hefty fines and legal issues.
Regular audits by external providers and inspections by local authorities can be daunting to invite in, but they help maintain a high level of safety and compliance ensuring that your distillery exceeds industry standards. Put a call in and get someone round.
Here’s a more detailed look at the essential safety measures that should be part of your distillery’s standard operating procedures if you are dealing with grain.
Grain elevators
Grain elevators facilitate the efficient movement of large quantities of grain, but they are also potential sites for dust explosions if not properly managed. Install spark detection systems and fire suppression measures in these elevators. Regular cleaning to remove dust and periodical safety checks should also be part of the protocol.
Magnets
Foreign metallic objects can sometimes find their way into grain supplies. They may be seemingly microscopic, but these objects are not just contaminants. They can also cause sparks that may lead to explosions.
Installing strong magnets at key points in your grain handling process can capture these metallic items. These magnets should be cleaned and checked regularly to ensure they are functioning correctly.
Dust extraction units
Grain dust is more than just an irritant and an issue for workers (inhalation etc); it’s a combustion risk. Dust explosions are a serious hazard in grain handling facilities.
Dust extraction units should be strategically placed at points where dust is most likely to accumulate. These units need regular maintenance checks and occasional performance assessments to ensure they are operating at peak efficiency.
In conclusion, the process of handling, storing, and milling grains for whisky distillation is critical for maintaining quality and efficiency in production.
Proper grain intake, quality checks and storage protocols help avoid contamination and wastage. Choosing the right type of milling equipment is essential for achieving the desired grist composition. Regular grist analysis ensures consistency in the mashing process.
Furthermore, adhering to safety and compliance measures, such as managing dust and using grain elevators and magnets effectively, is vital for both operational efficiency and safety.
Overall, each step from grain arrival to grist formation plays a significant role in the quality of the final whisky a distillery makes.
If you are learning about how the process is carried out we have more articles aimed for new distillers and those setting up a whisky distillery. Have a look at Mashing and Wort Separation for the next two parts of the chain!
