Since 1870 we’ve lived and breathed malting. With this passion and expertise, and by combining traditional and modern techniques, we create an impressive range of malted and non-malted products, including several unique and exclusive barley malts.
There is nothing more we love than talking to brewers and distillers so if you have any questions, or would like to arrange a call with a member of our team, please feel free to get in touch – we would love to hear from you!
About Me
Mike is the sales manager for Wales and the West of England and is located in Wigan.
You can read my bio by clicking the button below
In the times before thermometers, it was said that the brewer could tell the correct temperature of the mashing liquor by its reflection; too cold and it did not reflect well, too hot and the steam blocked the view. This simple solution to a problem gave birth to the single-temperature infusion mash on the mash tun.
Traditionally made from wood, which gave great insulation properties, they were prone to warping and quickly became made from gun metal or stainless steel. Simple round vessels with a false bottom sitting about 50mm from its base, they are a single vessel used for mash conversion and wort filtration producing fantastic wort quality while being cheap to buy and run.
The key to a Mash Tun is modified malts, perfect for the UK, because that’s what we do.
Before the grist can enter the Tun, it needs to be preheated. This ensures minimal temperature loss helping to keep the mash at the desired temperature. It also helps to reduce the mash temperature, reducing local overheating as the liquor is mixed with the grist helping to reduce enzyme denaturing.
Utilising a courser grist, from a simple 2 or 4 roller mill, there are several ways the brewer can mix the mash. They can fill the tun with mash liquor and then slowly add the grist while stirring to avoid any dough balling. They can add liquor via a hose pipe to grist as it falls from a malt sack, in a skillful juggling act, or in the case of larger vessels, use a steels masher. First used in 1853, the steels masher consists of a tube around 460mm in diameter and houses a screw and rotating rods which mix the mash liquor and grist. The mash exits through a 90o outlet into the tun. Grist flow is controlled via a slide and the liquor temperature is closely controlled to give the correct conversion temperature.
The plates are covered before mashing and a thicker mash of between 1.7 to 2.5 ltrs/kg is used. The course grind, thick consistency and aerated mash from the mixing will continue to hydrate during the early stages of conversion making it appear to float. As we are using modified malts the effect on polyphenol and lipid oxidation is small.
Getting the mashing process correct is critical as further opportunities to mix or heat the vessel are limited. If you are using any enzymes, it can be a good idea to dilute them into a large container and attach a tap. You can then let the enzymes run into the tun as you are mashing helping to distribute the addition throughout the mash. The only opportunity to heat the mash would come from under-letting, assuming the mash is not too thin, which can raise the temperature by a few degrees.
Mash temperatures are generally between 63oC and 68oC (145.4oF to 154.4oF) with 65oC (149oF) being the standard temperature. The mash depth sits between 2-2.5 meters but can vary outside of this. Once the conversion stand is complete and confirmed via an iodine test, the wort is discharged via pipes at the true base of the Tun into a trough or a grant. Taps or a valentine tube control the flow which is slow to begin. The cloudy wort is returned to the top of the mash. This can add fines to the bed which can increase filtration issues. Not dealing with the fines here can add to greater losses further in the process. As the mash volume in the tun drops, sparge liquor is added to flush out the remaining sugars. The standard temperature is 78oC (172.4oF) which raises the mash temperature to about 74oC (165.2oF). As the mash temperature rises, any smaller starch granules in the mash will gelatinise and alpha amylase will still be active to convert them, ensuring we don’t see any starch issues. Small starch granules are less of an issue with UK malt. The proportion of small to large starch granules increases with the protein/nitrogen content of the barley. As UK malt is low in protein/nitrogen, it’s not often we see any issues with small starch granules failing to convert.
Once the wort is collected into the kettle, the spent grain will be discharged via rakes – if you are lucky enough to have them(!) or, more likely to the craft brewer, it’s time to grab the spade and remind yourself where the beer allowance came from!
So, slower process times and more manual input when compared to an MCV, but with arguably better wort quality and lower install and running costs, the Mash Tun remains the workhorse of the craft brewery. Whether producing traditional British cask-conditioned beer or full-flavour DDH, the simple Mash Tun has been producing the best quality beers for centuries, and there are no signs of it stopping.
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