Mash Filters: Down to the Very Last Drop

A mash filter can increase brewhouse efficiency greatly, giving brewers much more room to get more creative with their recipes. Here, we sat down with Brouwerij West to learn more.

John M. Verive Jan 24, 2017 - 11 min read

Mash Filters: Down to the Very Last Drop Primary Image

Brewers, it’s been said, don’t make beer—they make wort. It’s the yeast that transforms the sugary liquid into beer, and brewers are mere shepherds once fermentation is underway. While winemakers need only crush grapes and collect the sugary juice, brewers must liberate the fermentable sugars locked inside the kernels of grain during the mash. This controlled steep in hot water hydrates the crushed grains and allows the enzymatic transformation of starch into sugars before the sweet wort is separated from the leftover grain solids—a process called lautering—and then boiled to complete the process.

Most American craft brewers and homebrewers approach lautering by leveraging an important characteristic of the barley kernels: their fibrous husks. But, as the homebrewers who employ the brew-in-a-bag technique will tell you, there’s more than one way to make wort. Brouwerij West in Los Angeles is turning to Old World techniques and a new piece of equipment to shorten their brew times, increase the efficiency of their brewhouse, and allow for more flexibility in their recipes.

Brian Mercer, founder of Brouwerij West, has always been inspired by Belgian brewers. Before launching the brewery, he ran a business that imported authentic Belgian candi sugar for American brewers. When it came time to build his own brewery in the Port of Los Angeles (prior to 2016, Brouwerij West’s beers were brewed at established breweries around the country), he decided to employ a bit of brewing technology that he first saw at Chimay Brewery in Belgium: a mash filter.

In contrast to the more common lautering practices where the wort is filtered by the husks in the grain bed layered on top of the false bottom of the mash or lauter tun, the mash filter mechanically separates the wort from the spent grains with pressure and cloth filters. It’s a technique that was pioneered in early twentieth-century Belgium by Philippe Meura, and today mash filters are mainstays at large breweries around the world because they facilitate much faster and more efficient brewing.


Brouwerij West employs an automated 17-barrel brewhouse built by Wisconsin’s Aegir Brewing Systems that is designed with a small-scale Meura 2001 Hybrid mash filter at its core (pictured at top, with the Aegir brewhouse in the background and the Meura mash filter in the foreground). The mash filter itself is a 15-foot-long coffin-shaped frame that is connected to the brewhouse with pipes, hoses, and Ethernet cables. Brewers run the system from a master control computer that manages everything from grist hydration to mash temperature steps to post-boil whirlpool speeds. It’s a level of automation that, like the mash filter, is usually only seen at much larger breweries.

The system allows Brouwerij West some exciting creative freedoms when designing beers. Brews using 100 percent wheat are trivial to produce on the mash filter brewhouse, as is a grist heavy with spelt, rye, oats, or unmalted grains. Grain bills that would give a brewer nightmares about stuck mashes, hours-long lauters, and hundreds of pounds of rice hulls (which are often used to stand in for barley husks to improve lautering) are run-of-the mill at Brouwerij West.


Another major draw of the mash filter system is its extremely high efficiency. Ninety-eight percent or more of the grains’ sugars can be extracted in the mash—an impressive number compared to our standard homebrewing efficiency of 72 percent—largely because the grain is so finely crushed during mill-in. Instead of using the roller mill typically used in a brewery to ensure that the grain is crushed uniformly without overly damaging the husks important in lautering, Brouwerij West uses a hammer mill (above) that turns the brewing grains into a fine flour. The very small particle size is the key to the high brewhouse efficiency.


The mash filter frame (above) holds forty-five plates that each contain a fine cloth filter and an inflatable membrane. The number of plates used for a brew varies with the size and amount of grain in the mash, and when arranged in a horizontal stack, the plates create chambers where the actual filtering takes place. The thick mash is pumped into the plates, and clear wort runoff begins before the filter is even full—no vorlauf required. It takes less than 10 minutes to fill the filter with mash. In another 15 minutes, all the mash is transferred out of the mash tun, and the first pneumatic compression begins. The membrane bladders in the plates inflate, compressing the grain beds against the filter and extracting the last of the first wort. As with a typical lauter, sparging comes next, and the compressed grain beds are rinsed with hot water as the internal bladders deflate, allowing the filter to fill with sparge water. Once the prescribed amount of sparge water is sent through the filter, the bladders inflate again and compress the remaining sparge water from the grain beds.


After mash out and sparging are complete, the nearly dry spent grain drops from between the filter plates in sheets of dry cake (above). The whole process takes less than 45 minutes for a 17-barrel batch, saving considerable time over the traditional vorlauf–lauter–sparge process.


Brouwerij West began brewing on the system in February 2016, and after about sixty turns of the brewhouse, they’re still dialing in the system and their recipes. Mercer says the increase in brewhouse efficiency means they produce wort using about 30 percent less grain than would be needed on a traditional system, and there’s also about a 30 percent savings in water usage. Brouwerij West focuses on brewing Belgian-inspired beers, and they’ve had success using the mash filter on everything from low-strength table beer to a dense quadrupel that hits 21° Plato. While the efficiency and water savings are important upsides to the mash filter, Mercer says it’s the flexibility that he likes most. Many of his recipes use high proportions of raw barley and unmalted wheat, largely sourced from small farmers and artisanal maltsters in the Pacific Northwest.

“Raw grains have a different vibe than malted grain. You get a truer sense of the grain itself in the beer,” Mercer says, and that’s especially important for him because of the special varieties of barley, wheat, rye, and spelt that he’s using in Brouwerij West’s beers.

Like anything else in brewing, there are trade-offs and downsides to the mash filter setup, but they may not be what you’d think.

“Tannins. Everybody always wants to know about tannins,” says Brouwerij West Head Brewer Jeremy Czuleger. Common brewing wisdom says that crushing barley too finely will increase the extraction of polyphenols in the mash, and especially during sparging, which will create an unpleasant tannic astringency in the final beer.

Brouwerij West isn’t worried about tannins. Between the efficient mash and the speedy filtering and sparging process, the contact time between the hot water and the grist is much less, and polyphenol extraction is only slightly higher on the Meura system. Mercer says he did a lot of research before committing to the mash filter setup, but it was tasting that really convinced him not to worry. “I threw all the studies out,” he says. “When was the last time you tasted tannins in a Chimay?”


The biggest downside to the mash filter—apart from the upfront cost of the Aegir brewhouse and Meura filter—is the learning curve. Czuleger says a lot of trial and error went into the early batches to get the system figured out, a struggle that’s compounded because the systems are so uncommon among American craft brewers. “Everybody knows how a lauter tun works. I can’t just call up my friends across town to get help when I run into a problem [with the mash filter],” he says.

Mash filters are more often seen at large breweries making hundreds of thousands of barrels a year, where the large-batch sizes mean the improvements in efficiency lead to substantial cost savings. However, smaller-scale mash filters are becoming available to craft breweries that produce thousands of barrels of beer a year. Oregon’s Full Sail Brewing uses a Meura system, while Coachella Valley Brewing in California and Tin Man Brewing in Indiana use a similar system developed by IDD Process & Packaging, Inc.

Homebrewers, however, have less reason to turn to the mash filtering technique. Because many of the advantages of the mash filter come from gains in efficiency, homebrewers won’t see much cost savings on the 5- or 10-gallon scale. Plus, the brew-in-a-bag technique is an established alternative to traditional at-home lautering techniques.

At Brouwerij West, the mash filter system is a key to their Belgian-style beers and multigrain saisons that are about more than Belgian yeast strains and Old World ingredients. “So many of the classic Belgian beers have such simple ingredients,” Mercer says. “Those brewers achieve complex flavor through process and not lots of ingredients. That’s the approach we want to replicate.”


Meura Mash Filter System

Aegir Brewing Systems
All of Aegir’s brewhouses are designed around The Meura 2001® mash filter.

IDD Process & Packaging, Inc.
IDD’s HEBS (High Efficiency Brewing System) has at its core a specially designed mash filter.