During mashing, enzymes break down complex carbohydrates in the grain into simpler sugars that yeast can digest. Achieving a ‘high efficiency’ means that most or all of the available complex carbohydrates have been modified by the enzymes and extracted into the wort. Conversely, a ‘low efficiency’ indicates that a significant portion of the total available carbohydrates remains in the grain and is not extracted into the wort. An extraction rate of over 70% is considered good, and above 80% is considered high.
While several factors contribute to mashing, the initial mixing of the grain with water is crucial for achieving high efficiency. Enzymes require water to access the carbohydrates, so ensuring that the grain bed is thoroughly wet and fluid is essential for maximizing enzyme exposure. If the grain is not properly wet and contains dry clumps (referred to as ‘dough balls’), mash efficiency will be reduced because the enzymes cannot access the carbohydrates in the dry areas. Similarly, if the grain bed is compact, water will not circulate easily, resulting in slow enzyme access to the carbohydrates. This also leads to poor or low efficiency, as only a small percentage of the total sugars in the grain will make it into the wort.
This is why the crush size of the grain is important. A finer crush creates a larger surface area and better exposes the complex carbohydrates in the grain, but it also leads to more compaction and stickiness in the grain bed. On the other hand, a coarser crush size allows for better fluidity but has less surface area, resulting in poor exposure of the complex carbohydrates. A compromise is to aim for a crush size of 1.1-1.2mm/0.043-0.048″, which opens up the grain without pulverizing it. The image on the left illustrates a good crush size.
Thoroughly mixing the mash is necessary for wetting the grain and creating a light grain bed that facilitates proper water and wort circulation. Our Mash Mixers are the best tools we have discovered for achieving thorough mixing and creating the ideal grain bed. Using a drill to operate them is faster and easier than using a mash paddle, without the risk of blisters.
Other tips include adding the grain gradually (to avoid excessive mechanical agitation that can lead to a more compact bed), adding toasted or dark malts after the lighter malts (to keep them near the top of the grain bed, as they tend to fragment more during crushing and become more sticky), avoiding overmixing the grain during mashing in (only mix enough to remove air pockets), and keeping the mixer away from the false bottom on the colander (as this can cause grain to clog the perforations or wedge wire). When mashing with a wedge wire false bottom, before adding the grain, connect the pump line and open the bottom valve to release any trapped air bubbles, then tap the wedge wire to release any additional trapped air bubbles.