Filter Press in Beer Brewing Process

Most craft brew houses use a false bottom on their mash tun to filter spent grains from the wort. To increase production throughput, a brewery will often look to double and triple batching in a brew day, adding a dedicated lautering tun to free up their mash tun for the subsequent batch. Both methods still rely on a gravity-fed lautering process, which comes with its share of drawbacks: slow lautering, stuck sparges, and losses in efficiency as valuable sugars are left behind. Let’s take a look at the press, how it works, and its advantages over a false bottom to help you decide if a mash press is right for your brewery.

What is a Filter Press?

A filter press (or mash press) is made up of a series of plates mounted horizontally on a frame, sized to hold the full volume of grains coming from your mash tun. The alternating membrane and chamber plates form a series of cavities with the feed and output sides separated by reusable filters. As the mash is pumped through a port running down the center of the plates, the chambers fill and capture the grains, allowing the wort to pass through the filters to the outlets in the corners of the plates.

Once all of the mash has been pumped into the press, the feed valve is closed and compressed air is supplied to the squeeze manifold. This pressure causes the membrane plates to expand, squeezing the mash and extracting more wort from the grain. Finally, sparge water is pumped through the press to increase extraction efficiency and to achieve your pre-boil volume.

Why Use a Filter Press?

Filter presses have several advantages over false bottoms. Because of the increase in filtration surface area, they can easily handle grain bills with high percentages of oats, wheat, rye, and alternative starches that often result in stuck sparges with a false bottom.

With filter media down to 1 micron, a filter press can handle a finer mill of your grains. This leads to an extraction efficiency that can be 10-15% higher than a gravity lauter, with efficiencies as high as 98% achievable. Consider a 10BBL (pre-boil volume) mash tun producing 15° Plato wort. Adding a filter press would enable you to produce the same 10BBL of wort using less grain and water, a greater volume of 15° Plato wort using the same amounts of grains and water, or a full 10 barrels of a higher gravity wort – a great solution if your mash tun limits your pre-boil volume on bigger beers.

Finally, because your lautering speed is not limited by the risk of stuck sparges, a mash press can shorten your brew day, especially for double and triple batching. Once the first batch is in the kettle, a setup that includes a mash tun, press, boil kettle, and whirlpool tank can produce subsequent batches every two hours. This not only leads to a shorter brew day but can reduce production costs and enable a greater amount of creative freedom in your brewing process.