Hops have been used as a preservative and bittering agent in beer for well over 600 years. While hops are most often used in the boil, the U.S. craft beer revolution and rise in popularity of India pale ale has seen broad use of hops in the whirlpool and for dry hopping. But what about adding hops to the mash? 

It is remarkably easy to add hops at the start of your mash. At mash temperatures, some bitterness will be extracted as they steep. Mash hopping at a typical mash temperature of 156 °F (69 °C) for 60 minutes will give you approximately the same utilization as a whirlpool addition at the same temperature and time. The utilization is quite low, however, typically around 10% of that achieved during an equivalent boil. So, a 60-minute mash won’t yield a lot of bitterness, but it may have other benefits. 

Mash Hopping History 

Mash hopping has a rich history, being widely used in lighter styles like lagers, pale ales, and Pilsners in the last 150 years to create a subtle bitterness without the harshness that might come from boiling hops. Going even further back, it was not uncommon to simply add grains and hops in the mash and skip the boil altogether when brewing.

Mash hops did show up occasionally in homebrew recipes from the 1970s and 1980s, as homebrewers tried to use historical techniques to create older beer styles. The practice fell out of favor by the early 1990s as Glenn Tinseth, Greg Noonan, Mark Garetz, and others developed equations for estimating the bitterness of hops used in the boil. Labs also made it easier to measure IBU levels. The net result was that brewers realized that utilization of hops in the mash was quite poor at the 10–20% level compared to a boil, and mash hopping seemed an expensive waste in comparison. 

Mash hopping faced another nail in the coffin in the early 2000s as the IPA revolution was taking off and brewers began to focus more on hop aromatics. Because all aromatic oils in a hop cone are volatile, meaning they boil off in a short period of time, brewers began focusing on early boil bitterness additions and then late hop additions for aromatics. Any aromatics from mash hops are effectively lost in a 60–90 minute boil once the mash is complete. The combination of poor utilization and no aromatics effectively killed mash hopping as a technique for many years.

However, that has changed in recent years as more advantages have been discovered. 

Mash Hopping for Beer Stability 

Having long been a skeptic of mash hopping, I was intrigued when Scott Janish, Co-Owner of Sapwood Cellars (Columbia, Maryland) joined me for a recent podcast episode (BeerSmith Podcast, Episode #305) to discuss mash hopping. Scott said he has recently been using a mash hop addition in many beers at Sapwood Cellars to improve the long-term stability of packaged beer and he covers this technique briefly in Chapter 14 of his book The New IPA. 

The basic concept is that the acids and polyphenols in the hops react with metals present in the mash. Malts all contain low levels of iron, copper, and manganese. While the metals alone are not necessarily a problem, these metals can combine with oxygen in a finished beer. The combination of metals and oxygen creates compounds that are highly reactive with other compounds in beer, leading to rapid staling as the beer ages. Reducing the metals, along with careful oxygen control throughout the brewing process, can significantly improve the shelf life and flavor stability in a finished beer. 

In The New IPA, Janish discussed studies that combined alpha and beta acids from hops with various metal ions and then measuring changes in concentration.¹ Hop acids were found to be most effective in reducing concentrations of iron and copper, but not terribly effective at reducing magnesium, manganese, calcium, or zinc levels. Alpha acids in the hops were found to be more effective than beta acids or isomerized alpha acids, suggesting that higher alpha hops used in the mash, before isomerization in the boil, were most effective in reducing iron and copper levels. 

A study by Zufall and Tyrell showed that manganese has the largest impact overall.² They did a series of experiments adding copper, iron, and manganese at various stages and found that manganese had a larger impact than copper or iron in oxidation of the finished beer. Since manganese, copper, and iron in the mash are primarily driven by the grains used, malt selection is also a consideration here. 

Janish recommends a hop rate of approximately 0.5 oz. (14 g) per gallon (3.8-L), or about 2 lbs./barrel for commercial sizes to reduce metals. 

While mash hopping has been shown to reduce iron and copper levels, and therefore improve long-term beer stability, it needs to be combined with an overall strategy for reducing oxygen levels at every phase in the brewing process. Mash hopping will only be effective if you have processes in place to reduce oxygen exposure, particularly post-fermentation, through steps like oxygen-free beer transfers, oxygen-free dry hopping, and carefully controlled packaging and bottling. 

Mash Hopping to Enhance Fruity Flavors (Thiols) 

Considerable research has been done to understand and enhance hop flavor and aroma. With the popularity of New England (hazy) IPAs, there has been a push to both select hops that feature tropical flavors and enhance the impact of those flavors in the finished beer. We’ve also seen a concerted effort to understand, categorize, and maximize the impact of all the hop aroma oils. 

Research into hop compounds has highlighted the importance of thiols in creating tropical flavors and aromas in beer. Thiols have been researched for some time in the context of wine, as they play a major role in the flavor profile of many popular styles such as Sauvignon Blanc. However, thiols are present in many hop varieties and malts, and play a significant role in beer aroma and flavor. To maximize the impact of thiols for styles like hazy IPA, there has been a resurgence of interest in mash hopping used in combination with specific, often genetically modified, yeast strains to free more thiols to create a big, fruity aromatic finish in the final beer. 

What Are Thiols? 

Chemically, a thiol is a sulfur version of alcohol. Where alcohols have an -OH group in their structure, thiols have a -SH group. Though thiols make up an incredibly small fraction of hop compounds, many of them are highly aromatic. They are so aromatic that most can be detected at levels measured in nanograms per liter. Aromas vary from tropical fruits to citrus and garlic. There are a variety of thiol compounds in hops, but researchers have focused on the “big four”: 3SH/3MH, 3S4MP/3M4MP, 4MSP/4MMP, and 3SHA/3MHA, each of which has its own aroma profile.  

Breaking down the individual thiol aromas, we have 3SH/3MH, which has grapefruit, citrus, white grape, and gooseberry aromas. Next, 3S4MP/3M4MP has passion fruit, grapefruit, and rhubarb aroma. 4MSP/4MMP has black currant, tomato plant, chive, and, in the extreme, a cat pee aroma. Finally, 3SHA/3MHA has passion fruit, citrus, guava, and body sweat aromas.³  

Free Versus Bound Thiols and Biotransformations 

Further complicating things, thiols in hops can be either free or bound. Free thiols are aromatic but bound thiols are an odorless precursor that are bound to amino acids. Some bound thiols can be freed during fermentation, but typically only in detectable quantities via specialized yeast engineered to free them. We have many hop varieties that have good concentrations of bound thiols, but these thiols remain bound unless the brewer takes steps to free them. Some pale and lager malts also have bound thiols, in particular 3SH/3MH, that can be freed using selected yeasts. 

Biotransformation is a term that describes a variety of chemical processes that take place during fermentation that change one compound to another compound. For many years, brewers have been selecting hops like Citra®, Columbus, and Cascade, which are high in specific compounds like geraniol, linalool, and citronellol that are easily transformed into an aromatic form during fermentation. These provide a great aroma impact on the finished beer and are a major factor in many modern hoppy beers. 

However, a second form of biotransformation can occur during fermentation that frees up bound precursor chemicals releasing them in their free aromatic form. This is the biotransformation we are targeting when using mash hops. We select hops high in bound thiols to use in the mash and combine that with specific yeast strains selected to release those thiols during fermentation. 

Hops To Use for Maximum Thiol Impact 

Lallemand produced a chart showing hop varieties high in various thiols here. I’ve included an extract below: 

Hops high in free thiols:

3SH/3MH (Grapefruit): Apollo^TM, Galaxy^®, Simcoe^®, Citra^®, Mosaic® 

3S4MP/3M4MP (Rhubarb): Nelson Sauvin^TM, Ekuanot^®, Hallertau Blanc, Mosaic^® 

4MSP/4MMP (Black Currant): Nelson Sauvin^TM, Apollo^TM, Citra^®, Galaxy^®, Mosaic^®, Simcoe^® 

3SHA/3MHA (Passion fruit): None 

Hops high in bound thiols: 

3SH/3MH (Grapefruit): Motue-
ka^TM, Saaz, Cascade, Citra^®, Hallertau Blanc 

3S4MP/3M4MP (Rhubarb): Hallertau Blanc 

4MSP/4MMP (Black Currant): Nelson Sauvin^TM, Aramis, Strisselspalt, Mandarina Bavaria, Simcoe^® 

3SHA/3MHA (Passion fruit): None 

Janish also published an excellent post highlighting the research of Aurealie Roland on bound concentrations of thiols found here. In it, Janish includes Roland’s chart of free versus bound thiols, highlighting the fact that 3SH/3MH is by far the largest concentration of bound thiols in many hop varieties. Many of these same hops also had 4MMP precursors. Here is a list of hops containing the highest 3MH precursors (grapefruit) in order of concentration: Calypso^TM, Saaz, Simcoe^®, Nugget, Cascade, Hallertau Perle, Hallertau Tradition, Citra^®, Apollo^TM, Hallertau Nugget, Eureka^TM, Bravo^TM, Hallertau Cascade. 

To this list we can add additional work done by Yakima Chief, which published their Survivable Compounds study based on the 2021 crop year and highlighted which compounds survived best in both whirlpool and dry hopping. Included in the list was 3MH/3SH. The hops that did the best include:  Cryopop^®, Chinook, Krush^®, Sabro^®, Idaho Gem^TM, and Comet.

For mash hopping we are primarily concerned with bound thiols, as most of the free thiols will be lost during the boil. We can see from the Lallemand lists that many hops like Hallertau Blanc, Nelson Sauvin^TM, and Simcoe^® have high levels of both free and bound thiols. While the Yakima Chief work was done only using hops in the whirlpool and dry hop phase, it does give us an indication of hops that may also contain bound thiols that can be transformed during biotransformation. However, your best bet might be to start with the Roland or Lallemand list of hops high in bound thiols when selecting hops for mash hopping. 

Selecting Yeast To Use With Mash Hopping 

Since the mash hopping technique relies on freeing bound thiols via the biotransformation process during fermentation, you need to select the right yeast for this technique to work. Aromatic thiols are bound with amino acid precursors and require specific  enzymes from yeast to free them. This depends on specific genes present in the yeast strain. 

Some yeasts do a reasonable job processing bound thiols. For example, the Lallemand hop chart mentioned earlier also contains a short list of their best strains for freeing bound thiols. These strains include LalBrew Diamond, Farmhouse, Nottingham, Voss, and Verdant. 

To specifically address the issue of bound thiols in hops, some yeast providers have experimented with genetically modified yeast to activate the IRC7 gene and effectively enable β-lyase production (this enzyme frees thiols bound to the amino acid cystein). Omega Yeast was one of the pioneers in this area, launching their Cosmic Punch OYL-402 yeast strain, which is a modified variant of their popular British Ale V OYL-011 strain. This strain that they call a “thiolized yeast” is designed to free bound thiols from their precursors during fermentation, creating a more aromatic fruity finish in the beer.

Omega later launched Star Party OYL-404, a variation of their West Coast Ale I OYL-004 as well as Lunar Crush OYL-403, their first thiolized lager yeast that is a variant of their Mexican Lager OYL-113. Most recently, they launched Helio Gazer OYL-405, which is an even more potent thiolized variant of ale yeast designed for hazy IPAs. 

Omega did some experiments with mash hopping as well, and found that using Cascade hops in the mash along with Cosmic Punch delivered a 3SH level almost 10 times the level found using their standard parent strain British V. When they ran the same experiment using both yeast strains and traditional whirlpool hopping, they found approximately a 3x difference in 3SH levels. So, in their experiments, mash hopping outperformed whirlpool hopping for delivering 3SH in the finished beer when using a thiolized yeast strain.⁴  

Other yeast labs have started introducing thiolized strains. Berkeley Yeast offers their “Tropics” line including London, Vermont, and Andechs (low diacetyl) strains designed to free tropical flavors. Escarpment Labs also has a strain called Thiol Libre designed to free thiols.  I’m certain other labs are working on additional modified strains to free thiols. 

For those who prefer non-genetically modified yeast, can’t get them in homebrew sizes, or because of local laws about GMO, White Labs has their Tropicale Yeast Blend WLP077, which is a non-GMO yeast blend selected to release bound thiols. It again relies on the IRC7 gene, and in side-by-side tests against their standard California Ale WLP001 yeast was shown to release very high levels of 3SHA thiol.⁵ 

Mash Hopping for Thiols in Practice 

Let’s say you want a fruity, hazy IPA, what would your mash hop schedule and quantities look like? Janish suggests 1–2 lbs. per barrel, which is about 2.5–5 oz. in a 5-gallon batch (or 70–140 g/19 L). For your first attempt, I would stick with a hop variety high in 3SH/3MH precursors like Calypso^TM, Simcoe^®, Saaz, or Cascade.  

Next, you need to select a thiolized yeast to use. If you are not opposed to genetically modified yeast, I would probably select one of the Omega thiolized strains like Helio Gazer or Cosmic Punch. The best non-GMO option I could find was White Labs Tropicale Blend. Since these yeasts also do a good job biotransforming whirlpool hop additions, I would select a whirlpool hop variety high in 3SH/3MH thiols, and for a hazy IPA it is always appropriate to add a healthy dose of aromatic dry hops. 

Is Mash Hopping Worth It? 

Given its long history and several modern breakthroughs, I would say that mash hopping has evolved significantly from its roots but is still applicable for modern brewing. Mash hopping as a method for adding just bitterness or to control pH is a poor use of hops, but mash hopping to enhance long-term shelf stability or free thiols can be effective.

If we look at mash hopping as a technique to reduce metals in the finished beer, which slows oxidation and staling, I think the technique is an important one, especially for commercial brewers. While mash hopping won’t fix problems with oxygen that occur later in the brewing process, it can be an important element in enhancing shelf stability in a brewery where you already have good oxygen control processes in place. For homebrewers, the technique is probably less important as many homebrewers’ beers face larger risks from oxygen post-fermentation when transferring and packaging their beer — and correcting these potential issues is a higher priority. 

When we explore mash hopping as a technique to enhance fruity flavors in styles like hazy IPA, it looks like a winner. If you select a hop variety high in bound thiols and then combine mash hops with an appropriate thiolized yeast you can get a measurable impact in free thiols and aroma in the finished beer. 

References: 

¹ Janish, S. (2019) The New IPA: Scientific guide to hop aroma and flavor. (pp 207-209). ScottJanish.com.  

² Zufall, C. and Tyrell, Th. (2008) “The Influence of Heavy Metal Ions on Beer Flavor Stability.” J. Inst Brew 114(2), 134-142: www.themodernbrewhouse.com/wp-content/uploads/2016/11/Metals-and-Beer-Stability.pdf 

³ “A Thiols Checklist” Hop Queries: www.hopqueries.com/archives/a-thiol-checklist-hop-names-included

⁴ “All About Thiolized Yeast” Omega Yeast: www.omegayeast.com/all-about-thiolized-yeast 

⁵ “WLP007 Tropicale Yeast Blend – New Thiol Releasing Non-GMO Yeast Blend” White Labs: www./blog.whitelabs.com/wlp077-tropicale-yeast-blend-new-thiol-releasing-non-gmo-yeast-blend 

Brewing beer from all-grain takes significantly more time than brewing an extract beer. Some of the extra time comes from added steps in the procedure. More time is also needed to heat the larger volumes of water needed to brew an all-grain beer. You also have to clean the additional equipment used in brewing an all-grain beer. Although it takes more time, there are many advantages to brewing “from scratch.” You are free to brew any style you want and fully customize your recipe. And it is easier to brew an all-grain beer than most people think. Learn the basics in this video.

Brewing is fun and we all get our jollies in different fashions. Brewing is tradition and traditions must be respected and rituals performed. And for those brewers who hew to the twin pillars of masochism as fun and tradition above all else, there is no sacrament as sacred and profound as decoction mashing. 

True decoction believers claim profound impacts on flavor and benefits to beer quality that no simple mashing profile with modern ingredients could ever match. But as two very lazy people who enjoy brewing but not “BREWING,” we think they’re crazy. (That’s OK, we’re crazy as well, you’ve just gotta appreciate that everyone is crazy in their own special way and allow them their fun.) 

Let’s break this situation down and figure out a happy meeting place with some portion of the benefits without all the extra tedium.

Decoction Mashing 101

Much modern brewing operates under delightfully straightforward techniques and with stunningly easy to use ingredients. But out of millenniums of brewing history, that’s only been the case for the century+ (modern science, instrumentation, engineering, and agronomics really changed the brew deck). Regardless, mashing is mashing — crack grains, make a big bowl of porridge at the right temperature to spring starches from the barley, and activate the enzymes necessary to transmute those starches into yeast fodder, aka sugar. 

The legend of decoction mashing basically goes like this: Back before thermometers were a thing, you could only reliably tell the temperature of water when it came to a boil or was freezing — everything else was educated guesswork, so brewers used a mashing process that depended on observable phenomenon (aka “this stuff is boiling!”) and repeated trials to discover what steps made the best beer with the ingredients at hand. Malt is the other part of the story — older malt varieties grown with older, less managed growing practices produced crops that were less ideal for brewing. Malting techniques didn’t create full modification of the barley, which meant less enzymatically powerful malt, thus it needed more mechanical intervention to properly produce suitable wort. 

In other words, “We have no practical thermometers, wooden mash tuns, and dodgy malt, so how do we make great beer?” 

The answer, at the time, was, “We’ll boil the grain!”  

The general process for homebrewers goes like this:

• Strike your mash at your desired starting temperature. 

• Let the mash rest for a short period.

• Pull a “thick third” of the grain and liquid and bring it to a boil in a second kettle, stirring consistently for 15 minutes. 

• Stir the boiling mash back into the main mash, bringing the temperature of the combined mash up.

• Repeat with thick or thin (more liquid) thirds as needed to run through your rests and convert the mash for lautering. (Usually, that last decoction to prepare for mash out is a “thin” portion to denature the enzymes, which flooded the liquid when mixed with the grain.)

Please recognize that under the umbrella of “decoction mashing,” every brewer probably has multiple versions of what a decoction mash looks like, so if this doesn’t look like how your Opa talked about brewing, don’t write us!

It should be clear that decoction is a hot, sticky, and laborious process. Scalding mash gets
slung around. There’s so much stirring and so much gooey, piping hot grain that when compared to a traditional single-infusion mash, decoction mashing feels desperately, showily “extra.” 

So why do it? Proponents argue that decoction lends a certain je ne sais quoi to the final beer; an undefinable sense of deeper and richer sips. It allows for more efficient extraction of starches, and the resulting sugars (and malt proteins) get exposed to high heat for long periods, leading to the formation of those lovely “brown tasting” melanoidin compounds and extra color and destruction of clarity-
hindering proteins. Even negative aspects of decoction like oxidative damage or tannin extraction from the boiled grains have potential flavor impacts that are perceived as fundamental.

Does it Matter?

Now the tricky bit — so far, we’ve talked the process and the perception, but we know that the brain is a machine that lies to fit what we think we should be tasting. What does the science say? Turns out, it’s a mixed bag. There are plenty of studies showing perceivable impacts, and others showing none. There are even studies showing that, yes, it makes an impact — but tasters prefer the simpler mashed beer. One of Denny’s first experiments ever was a decoction experiment coordinated through the Home Brew Digest (there’s a blast from the past) and it showed no discerned difference. Drew was involved in another experiment that had Beer Judge Certification Program (BJCP) judges noticing a difference, but non-trained beer enthusiasts unable to decipher it.

In other words, decoction’s importance appears to be in the taste buds of the beer taster and in the enjoyment of the brewer. Neither of us feel the need in our brewing to endure the process. 

Are There Other Options?

We’ve established that decoction mashing is a fair bit of extra labor, time, and expense (for commercial brewers, at least, as it requires more wages and more fuel costs!), so it shouldn’t be a surprise that a number of different techniques have been developed to replicate some portion of those fabled decoction results for a lot less hassle. To follow is a rundown of the alternatives, from easiest to hardest. 

Ingredient Substitutions

The easiest and most oft claimed solution to the decoction question is, “well, you want melanoidins — just use that malt that’s called ‘melanoidin malt.’” And using it, or a similar highly toasted malt like aromatic, in restrained quantities (under 5% of the total grist) will give some extra “oomph” to your beer. Just add it into the mash with the rest of the grains and away you go. 

Purists (and frankly, even we) would tell you that melanoidins are just one part of the “magic” of decoction, and thus using a special melanoidin malt will give an incomplete profile, but it is a cheap and easy way to boost your beer’s perceived maltiness and mouthfeel. Just watch the amounts as they are intense malts.

Boil Down

We’ve advocated for this next technique many times before when wanting to replicate the flavors of a long boil without the long boil. Pull the first gallon (3.8 L) of your runnings and bring them to a boil in a separate pot. While the main mass of the beer is getting to the boil, reduce the gallon (3.8 L) to around a quart (1 L) for concentrated sticky sweet flavors. Add the newly “enhanced” malt syrup to the boil and continue on. When doing this, just keep in mind the additional wort that will need to be collected to hit your final volume due to the higher-than-usual boil-off rate.

Again, this is an easy technique with an interesting impact, but it’s more caramel and lip smacking burnt sugar than it is the vaunted “deeply bready and toasty” flavors of a decocted mash.

Pressure Cooker Decoction

Let’s say you really want to decoct but just really hate the stirring aspect, what do you do? Take advantage of the pressure cooker revolution. If we’re to judge by the flood of “Instant Pot” cookbooks out there, then at this point there should be approximately 1.42 electric pressure cookers per American household. Why not revive an old technique of using a pressure cooker to decoct your mash?

To pull this trick off (with a stove top model or electric), scoop a thick portion of the mash (say, one quart/liter) into a heat-proof vessel that will fit in your cooker. Place a trivet at the bottom of the cooker and a little water and then your mash vessel. Run your pressure cooker at high pressure (electric models tend to run between 11–12 PSI and stovetop models at 15 PSI) for 15 minutes. Allow the pressure cooker to release naturally and then stir the super-heated grain back into your main mash. 

You may be saying, “Hey, isn’t that just a decoction with extra equipment?” Why, yes, it is. But the glorious part about it is you can walk away from the pressure cooker and not stress over constant stirring (as long as your pressure cooker’s safety devices work).

And even still, folks will tell you that it’s not quite the same because you don’t lose moisture during the pressure run, but those same folks won’t be pleased unless you only stir the mash with a mash paddle carved from a tree hewn from the forests of Bavaria (or Bohemia in a pinch).

Pseudo Decoction

One last alternative. What if we just “faked it?” There are a few different mashing schemes that attempt to replicate the impact of a decoction, minus the labor. There’s the Schmitz process that has you strike your mash like a regular infusion mash. Give it time to get incorporated and the malt hydrated (~15–20 minutes) and then pull as much enzyme-rich liquid as you can from the mash to somewhere safe and kept warm. Then, like a reckless adventurer of old, boil the grain, stirring vigorously for 15–30 minutes depending on your lack of sanity. Cool the mash back down to your mash temperature and stir the liquid back in and proceed like you haven’t just lost all reason.

A more reasonable variant of the whole thing comes from longtime beer experimenter, Kai Troester, whose blog braukaiser.com, while no longer updated, is a wealth of beery experimentation with an eye towards German brewing. Kai flips the equation on the Schmitz process and recommends creating a thick initial mash of half your grain and a little less of the water. Boil that initial mash for 20–30 minutes before mixing in the remaining water and malt to bring everything down in temperature and proceed with conversion. 

If you follow Kai’s process, we recommend that you add the water first and then the remaining grain because you’re depending on the second half of your malt for enzymatic power to convert everything. To that point, you’ll want to make sure you have enough high-Lintner value malts in the second half (Pilsner, pale, etc.) to ensure that you can still convert. Generally, this would only be a concern with a malt bill heavy in adjuncts or toasted malts (e.g., a hefeweizen gets a bit tricky, and a completely Munich-driven malt bill is probably a no-go via this process).

One Last Reason to Understand Decoction

Having spent much of this column trying to convince you of the folly of spending your hard-won time on an old-fashioned mashing technique, there is one good practical reason to be comfortable with decoctions. Yes, practical, as in not just for the sake of knowledge and “I’ve done everything in brewing” ticking behavior. 

For years, Drew was an apartment brewer with a woefully underpowered natural gas stove. Missing infusion temperatures took forever to correct and getting to mash out dragged. So, he borrowed a trick from a fellow homebrewer, Cullen Davis, and used a small decoction to add extra heat. Just drag a part of the mash to a small pot and run a small decoction step to heat up the main mash. Never forget, one of the greatest skills you can cultivate is flexibility and adaptability. 

You can open up a whole new world of brewing ingredients beyond malted barley and wheat when you master using a cereal mash to convert starch to sugars in grains such as corn, rice, oats as well as sweet potato, pumpkin, sorghum, millet, and rye. While many of these ingredients were looked down upon as just cost-saving measures used by large commercial brewers, homebrewers can explore new flavors by experimenting with cereal mashes to unlock new sources of sugars for yeast in your beers. BYO’s Technical Editor Ashton Lewis shows you how to do your own cereal mashes at home.

Q: I brew 10-gallon (38-L) batches, so there is quite a bit of grain used in every batch. I find that as I slowly dump the crushed grains into the mash tun while gently stirring, occasionally the grain falls in as a larger clump and yields dough balls. These can be difficult to break up without splashing/adding oxygen to the mash. I’ve got a couple of questions related to this: Is there a better way to control the grain addition to the mash tun? Would a homemade grist hydrator prevent the dough balls? Also, would a grist hydrator introduce hot-side aeration (HSA)? Is HSA even an issue on such a small scale? 
— Neal Steward • Springville, New York

A: Dough balls are an undeniable nuisance to brewers of all sizes because the malt in the dough ball is not wetted and does us brewers no good. 

Unless you are stirring with unrestrained vigor, hot-side aeration is not something to lose sleep over. A few things that may help you out include using a mash paddle that is designed to help minimize these pesky clumps, smashing the dough ball into the mash paddle with a spoon, blasting the dough ball with targeted and judiciously applied jets of water from your favorite hose nozzle, or sequentially adding a bit of water followed by a bit of malt to spread your additions out. Some of these methods double as stress relief for cranky brewers!

Grist hydrators are common in commercial breweries of nearly all sizes, but they are not inexpensive to purchase or easy to build without access to stainless welding. Unless you are a gearhead looking for a project, I don’t suggest the grist hydrator route. Thanks for the question, Neal, and hope you solve your dough ball woes with one of the low-cost, manual methods.

Q: I would like to know if I should do a protein rest for grain bills with over 25% wheat. I have heard conflicting advice and cannot seem to get a clear answer either way.
— Richard Bray • Omaha, Nebraska

A: This is a great question, Richard. The short answer is no, you do not need to do a protein rest when brewing with more than 25% wheat. However, many brewers want to use a protein rest for several reasons. To give this question a proper discussion I will briefly differentiate raw wheat from malted wheat, touch on what “the protein rest” means to the practical brewer, and finish with why brewers may choose to use this rest when brewing wheat beers.

When it comes to brewing with wheat, there are four main types: Raw wheat, flaked wheat, torrefied wheat, and malted wheat. Raw wheat is what comes out of the field when wheat is harvested and threshed to separate the wheat berry from the husk and stem. Flaked wheat is produced by steaming then smashing wheat berries into flat bits, whereas torrefied (or torrified) wheat is produced by using radiant energy to intensely heat and puff wheat berries. Both processes partially gelatinize wheat starch. Torrefied wheat has more flavor than flaked wheat and can also be flaked after torrefication, making it difficult to know which flakes are steam-rolled and which are torrefied. Malted wheat is hydrated through steeping, germinated, and kilned like other malted grains.

The primary differences between the three unmalted wheat types and malted wheat, is that the unmalted types contain undegraded cell wall material, lack alpha amylase and other enzymes developed during germination, and are exposed to minimal heat during processing. In practical terms this means that the unmalted types may lead to difficult wort separation due to beta-glucans, will dilute malt enzymes in the mash, and dilute “malty” flavors associated with malted grains. And because wheat usually contains more protein by weight than barley, unmalted and malted wheat types contribute more protein to wort than malted barley. It’s also important to recognize that wheat, unlike barley, loses its husk when “combined” or harvested.

Let’s take a break from stating facts and look at the protein rest using more specific terms. The protein rest is used to reference mash temperatures in the 113–131 °F (45–55 °C) range. Originally named for the increase in amino acids measured after mashing in this temperature range, the protein rest is not just about protease activity. Lipoxygenase, beta-glucanase, arabinoxylanase, and ferulic acid esterase are other enzymes active at these cooler mash temperatures. Depending on a brewer’s intent for using a low temperature rest, different names may be used to describe the same rest.

Using unmalted grain and want to avoid headaches associated with beta-glucans? Consider using a “beta-glucanase rest.” Want to boost the clove-like aroma of your summer hefeweizen? Extend that “ferulic acid rest.” Or are you looking to boost the amino acid content of your rice lager wort? Time to drop in a “protein rest.” But if you are brewing with lightly kilned malt, beware of lipoxygenase activity at lower mash temperatures because it can lead to the development of wet paper aromas from the formation of trans-2-nonenal (now E-2-nonenal because of changes in stereochemical nomenclature).

Now it’s time to dig into your question. Should you use a protein rest when using wheat? The official answer has changed; it’s now “it depends.” First, why are you using wheat in your beer? And are you using unmalted wheat or malted wheat?

Let’s assume you are using unmalted wheat because it’s great for beer foam, is relatively easy to use, adds a nice snap to lighter-colored beers, like wit, and is a good source of protein for the hazy beers. These goals can all be achieved without the protein rest. However, you may run into an issue with wort separation because unmalted wheat contains undegraded cell walls that are rich in beta-glucans. Adding a rest around 113 °F (45 °C) may be something to consider because this temperature is ideal for beta-glucanase activity. You will also have other enzymes active at this temperature and need to be aware of what they may do for your brew. If you are looking to reduce wort viscosity and improve run-off and yield, the pros are likely to outweigh the cons.

Using the same basic example, consider a problem where extract yield is low when using 40% unmalted wheat and a single temperature mash. One explanation is that the beta-glucans and high-molecular proteins that bind starch granules into the matrix of the endosperm need to be digested. We’re back to another benefit of using a low-temperature rest in the 113–131 °F (45–55 °C) range. But low yield also occurs with poor conversion, i.e., failure of the iodine test to show a negative reaction. Incomplete conversion can be caused by enzyme dilution, and adding a protein rest won’t fix that.

I am a big fan of hefeweizen and will finish this discussion with an example using malted wheat instead of unmalted wheat because German brewers only use malt. If we want to give plenty of ferulic acid for weizen yeast to convert into 4-vinyl-guiacol, the best thing to do is mash in where ferulic acid esterase can do its thing by freeing up ferulic acid from arabinoxylans. Again, we are back in the same temperature range. Adding a 30-minute rest at 113 °F (45 °C) is a technique used by weizen brewers to boost clove notes.

Some brewing questions lack clear answers because there is no single way to tackle the problem. But when it comes to questions about the protein rest, things become murky because the term we use to describe rests in the 113–131 °F (45–55 °C) range are not about a single topic. With that, Richard, it’s time to brew with wheat!

Mash chemistry is one of those final pieces of the brewing puzzle that many homebrewers, and even some pros, choose to ignore. Perhaps they think it is too complicated. Or maybe they are just lazy. Either way, it’s a shame because all-grain brewers brew their best beer with at least a basic understanding of how grains, minerals, and acids affect mash pH. It’s also fairly simple once the basics are understood — no chemistry degree required! Though, of course, it certainly wouldn’t hurt.

You might recall from high school chemistry that pH is a logarithmic scale that expresses the alkalinity or acidity of a substance. pH is considered neutral at 7. A solution under pH 7 is considered acidic, while over pH 7 is considered alkaline. 

Distilled water clocks in at pH 7 right out of the distillation process, but as it picks up CO₂ from the atmosphere, its pH will drop to around 6.5 because CO₂ is acidic. Dissolved minerals can likewise lower or raise the pH of water. Dissolved minerals are the primary driver of water’s pH. The pH of most municipal water will hover between 6.5 and 8.5, determined mainly by dissolved minerals.

However, the pH of water is of minor importance to brewing. What’s important is the mash pH, which can change drastically depending on the grist bill.

When we add pale malt to our brewing water, it will lower the pH because pale malt is mildly acidic. Mashing pale malt with almost any potable water source will lower the mash into the pH 5–6 range. Most likely, it will drop the range between 5.4–5.8. And that’s great! Because this is within the enzymatic conversion range. Practically, that’s all you have to do: Mix your grain with hot water, and mashing will take care of itself. Voila!

But, if we want to make the best beer possible, the range of pH we are looking for is a bit narrower — for most light beer, we are looking for a pH range of about 5.2–5.4, and for most dark beer, we are looking for a range between 5.4–5.6.

As mentioned, pale malt is mildly acidic, so when mixed with water it lowers the pH. Darker malt, especially roasted malt, is even more acidic. Combining a 100% Pilsner malt grist with distilled water will give us a pH of about 5.75. If we mix a stout grist with lots of roasted malts in distilled water, our pH may drop below 5 because of the acidity of dark malts.

Sticking with these two examples, if we add a weak acid such as lactic acid to the Pilsner mash, we can lower the pH of that solution closer to 5.2–5.4. Likewise, if we add a weak base, such as sodium bicarbonate, to our stout mash, we can raise the pH to 5.4–5.6. How much acid or base we need to affect the pH depends on the makeup of the grist since malt will act as a buffer and resist the change. If the water is high in dissolved minerals, especially carbonate and bicarbonate, these will also serve as a buffer.

Buffers in the Water and Mash

Back to our foggy high school chemistry class, recall that buffers in a solution act to resist pH change. When adding an acid or a base to the mash, the pH first appears not to change. Envision the mash represented as an empty glass, and the water added to it represents the pH. The glass can only hold so much water. Drop by drop, you add water until it reaches a point where it overflows. You can think of the mash working the same way: You add acid or base milligram by milligram, and very little change happens until suddenly the buffers in the mash can’t resist anymore, and the pH changes drastically.

In the example of the stout or Pilsner grist, we used distilled water as a theoretical example. Real-world mashes use water with at least trace minerals since they improve enzymatic action and yeast health.

Distilled water has almost no buffering capacity, but dissolved solids in our water can act as buffers, specifically carbonate and bicarbonate. This means that when we add our Pilsner malt or our stout grist to our tap water, the pH will be affected by the buffering capacity of these dissolved solids, which will resist the pH change.

Consider the water that flows from your faucet: Tap water that has low mineral content has minimal buffering capacity, similar to, but not quite as extreme as, distilled water. In contrast, water high in minerals — especially carbonate and bicarbonates — will have more buffering capacity. Carbonate and bicarbonate are the big playmakers here and are the dissolved solids that mainly affect the water’s alkalinity. The alkalinity is responsible for most of the buffering capacity in our water, which directly affects the pH of the mash. Therefore, highly alkaline water has a very high buffering capacity and resists
pH change.

In contrast, low alkalinity water has much less buffering capacity, and the pH can be easily changed. What makes things interesting is that the alkalinity of your water will determine what color beer it is best suited to brew, meaning where the pH will fall into range without (or with minimal) mineral or acid additions. This information can be found in your water report.

Water Report and Alkalinity

There’s lots of information to unpack in a typical water report, but only a few items are helpful for brewing. The information also isn’t necessarily standardized in the way it is presented and might read differently depending on your municipality. But every report should list an approximation of the following:

Calcium (Ca²⁺)
Magnesium (Mg²⁺)
Sulfate (SO₄^2-)
Sodium (Na⁺)
Chloride (Cl^–)
Bicarbonate (HCO^3-)
Alkalinity, or Alkalinity as HCO^3-
Hardness, or Hardness as HCO^3-

Calcium, magnesium, sulfate, sodium, and chloride all have some effect on the final beer’s flavor and, to a lesser degree, the mash pH (we will get to these in a moment). But it’s the bicarbonate (HCO^3-) that has the most impact on the mash alkalinity and, therefore, the mash’s buffering power. So much so that if your water report doesn’t have a value for “bicarbonate/HCO^3-,” you can substitute the value given as “alkalinity” or “alkalinity as CaCO₃” since the majority of alkalinity will usually be bicarbonate.

The alkalinity of your water will determine what color of beer your water is best suited to brew. Water between 0–50 ppm (mg/L) levels is ideal for extremely pale beer. For pale to amber beers, 50–150 ppm (mg/L), and for dark beers, 150–300 ppm (mg/L). Higher alkalinity will help to neutralize darker and more acidic malts and target the mash into the proper enzymatic pH range.

“Hardness” or “hardness as HCO^3-” refers to water’s calcium and magnesium concentration. While “alkalinity as HCO^3-” and “hardness as HCO^3-” are not the same, they are somewhat linked. For example, boiling water high in “hardness” can cause some of the bicarbonate and/or carbonate to bind with the calcium and/or magnesium, precipitating some of it out as calcium carbonate and lowering the water’s hardness and alkalinity. This is known as temporary hardness. It was once a standard method to soften brewing water while reducing its alkalinity (the layer of calcium carbonate will be seen on the bottom of the kettle after the boil and time to settle). However, homebrewers will probably find it easier and less energy-intensive to dilute their water with distilled or reverse osmosis (RO) water instead of boiling to reduce hardness and alkalinity. It’s also more accurate.

For instance, if the alkalinity of your water is 100 and you split it 50/50 with distilled water, the alkalinity will be at 50 ppm — within the range of pale beer so that only a tiny amount of acid will be needed (if any) to hit your pH. You can use whatever ratio of distilled or RO water you like to get your alkalinity to your desired ppm, but remember, if you use all or close to all distilled or RO water, you need to add some minerals back in — most likely calcium, at the very least, for yeast health.

Checking the Mash pH

As stated, as long as it is between the “normal range” of about 6.5–8.5 pH, the pH of your water is of little concern. What matters is the pH of the mash.

The best way to check the pH of the mash is with a pH meter that has been properly calibrated between 4.01 pH and 7.01 pH using calibration solutions. Every pH meter brand is different, and the calibration and usage instructions must be followed. The pH meter should be calibrated before every brewing session.

When checking the mash or wort pH, it’s best to cool the sample to room temperature for an accurate reading. A correction must be made if the sample is too hot or too cold. A pH reading at mash temperature will be off by about +0.2 points. A sample at refrigeration temperature will be off by about -0.01.

Disposable pH strips are better than nothing, but their accuracy may be suspect, and the reading challenging to determine. Be sure to use pH papers within the 4.01 pH and 7.01 pH range.

Lowering the pH in the Mash

Remember: The alkalinity of the water acts as a buffer to the mash, and the mash acts as a buffer to anything we add to adjust its pH. Also, recall that for a pale beer, the ideal alkalinity of our water is under 50 ppm. 

Water alkalinity under 50 ppm doesn’t mean that adjustments won’t be needed on pale beers to bring the pH between 5.2–5.4. It just means that smaller adjustments will be required. Likewise, just because the alkalinity of water is over 50 ppm doesn’t mean you can’t brew pale beers. While dilution with distilled or RO is preferred, it isn’t always possible. Many brewers with high alkalinity use acids, acidulated malts, etc., to lower the pH of their mash to the desired range. The higher the alkalinity of the water, the more acid or acidulated malt, etc., will be needed. The problem is that the more acid added, the more potential it has to change the beer’s flavor.

Because each mash and water source is different, it is difficult to calculate how much acid will be needed for any given mash to make adjustments. Based on input, the brewing water software can estimate how much acid is required to adjust the mash to your desired pH. If you don’t have access to software, then the best way to adjust the pH in your mash is to add the acid a drop or two at a time, stir well, and check to see if it has made a difference. Obviously, the smaller the mash, the smaller the amount added. Likewise, the higher the alkalinity of the water, the more acid is required. Once the capacity of the buffering power is reached, pH change happens rapidly.

Lactic acid

Is a common food-grade acid used to adjust the pH in the mash since the flavors it provides are pleasant when under a certain threshold. But, if too much is used, it can create a sour “twang” that can detract from the beer.

Phosphoric acid

Is another common food-grade acid used to adjust the mash pH. In beer, it is almost flavorless. Malt naturally releases phosphates during the mash, which resembles phosphoric acid’s flavor.

Acidulated (or acid) malt

The Reinheitsgebot (German Law of Beer Purity) doesn’t allow any acid additions to be introduced when brewing, so the Germans found a clever way around this: Acidify the malt with a mild lactic acid fermentation.

Every 1% acidulated malt (by weight) of the total grain bill reduces the mash pH by 0.1 points. If your water is high in alkalinity, you can use up to 10% acid malt in the total grain bill without off-flavors.

Sauergut

German brewers have also skirted the Reinheitsgebot by souring a small portion of wort, called sauergut, and adding it to the mash to lower the pH. Sauergut can be made by adding a pure pitch of Lactobacillus or a small amount of barley malt (already naturally crawling with Lactobacillus) to the sample portion. The wort will then acidify and sour, as quick as in just few hours when kept about 108–112 °F (42–44 °C). A common practice is making the sauergut 12–24 hours before brewing, letting the sauergut sour to around pH 3.5 or under, and then portioning it off into the main mash to adjust the pH as necessary. Many brewers find adding sauergut to their mash is an easy way to adjust the pH and put a unique flavor print on their beer.

Minerals to lower pH

Calcium chloride (CaCl₂) and Calcium sulfate, aka gypsum (CaSO₄), can also lower the mash pH, but since they are flavoring salts, their flavor needs to be taken into consideration first. The amount of CaCl₂ or CaSO₄ needed to make pH changes may put them out of the acceptable flavor range unless using water with extremely low alkalinity. Their usage will be discussed later.

Raising the pH in the Mash

The pH of the mash should only need to be raised when brewing amber or dark beers. For stouts or porters, high alkalinity is necessary to land in the 5.4-5.6 zone. If the water source is already high in alkalinity, only minor adjustments will be needed (if any). Sodium bicarbonate (NaHCO₃) and calcium carbonate (CaCO₃) are the most common minerals to raise the alkalinity. 

Calcium carbonate (CaCO₃)

Is largely flavorless and does a great job raising alkalinity in nature due to time and dissolved CO₂ from the atmosphere. In the brewery, calcium carbonate will not dissolve well in tap water. More of it will dissolve in the mash due to the lower pH, but much of it will precipitate out. It will raise your calcium and may increase your alkalinity, but it is difficult to say how much. Because it is unpredictable, it’s not the best method of raising alkalinity. Since calcium is soluble, 1 gram of calcium carbonate per gallon (4 L) should raise calcium by about 50–55 ppm (mg/L). Since the carbonate is less soluble, 1 gram per gallon (4 L) may increase your CaCO₃ by as much as 160 ppm (mg/L), or it could be much less, depending on how much gets dissolved.

Sodium bicarbonate (NaHCO₃)

Or baking soda, will dissolve well in both brewing water and the mash and does a consistent job of raising the alkalinity and the pH of the mash. The problem is that it must be added judiciously since it will increase the sodium and affect the beer’s overall flavor. The flavor threshold of sodium varies from person to person, but a good rule is to keep the sodium (Na⁺) under 100 ppm (mg/L) lest the beer taste “salty.” One gram per gallon (4 L) of sodium bicarbonate in distilled water will raise the carbonate to about 190 ppm (mg/L) and the sodium to about 75 ppm (mg/L). For dosage, a good rule is not to go over 1.25 grams per gallon (4 L) to avoid issues with excessive sodium. If more alkalinity is desired, but the sodium is hitting the threshold, the brewer should try blending in some calcium carbonate.

Minerals for Beer Flavor 

The other minerals on the water report don’t do as much to affect the mash pH, but they do play a nuanced, though vital, role in beer flavor. As an analogy, let’s use table salt: When cooking, the right amount of salt makes the dish “pop.” Not enough, and the flavor is bland and boring. Too much, and the meal is inedible. Using minerals in brewing can have similar consequences.

Calcium sulfate (gypsum)

Gypsum profoundly affects beer’s “dryness” and can accentuate hop bitterness and, to some extent, hop aroma. It is historically the most popular flavoring salt used in brewing.

One gram of gypsum per gallon (4 L) of water will add about 60–62 ppm (mg/L) of calcium and 145–147 ppm (mg/L) of sulfate. It’s best to stay below 350 ppm (mg/L) of sulfate. While many brewers add gypsum indiscriminately to their mash (and even wort), remember that it is not a magical flavoring salt and can be overdone, creating harsh and unpleasant flavors. 

Calcium chloride (CaCI₂)

Calcium chloride emphasizes malt character while softening hop flavor or bitterness. It is nearly flavorless but will “sweeten” and “round” malt flavors when used at low levels. Calcium chloride is a valuable tool to raise water’s calcium to acceptable levels without raising sulfate.

One gram of calcium chloride per gallon (4 L) of water will raise the calcium to about 70–72 ppm (mg/L), while raising the chloride level to about 125–127 ppm (mg/L). It is best to keep the chloride level under 250 ppm (mgLl) for most beers, as too much chloride can make a beer taste salty or chemically.

Epsom salt (MgSO₄)

Epsom salt is used to raise magnesium (Mg) or to raise sulfate (SO₄) without raising calcium. It is commonly employed to recreate the classic Burton-on-Trent water profile for British-style ales (along with gypsum). However, Epsom salt must be used sparingly because magnesium can have a laxative effect — which could create quite a surprise at an inopportune time for the unsuspecting drinker.

One gram of Epsom salt per gallon (4 L) of water will raise the sulfate to about 101–103 ppm (mg/L) and the magnesium to about 24–26 ppm (mg/L). It’s best to keep the magnesium under about 35 ppm (mg/L).

Salt (sodium chloride, NaCI)

Non-iodized table salt affects flavor and can make the beer taste more “full” and “round.” If your beer tastes “thin,” adding a little salt may fill out the flavors and make for a more tasty beer. Be sure to use only non-iodized salt since iodine can affect yeast health. 

Salt will raise the sodium levels as well as the chloride levels in brewing. One gram of salt per gallon (4 L) of water will increase the sodium (Na⁺) by about 102-104 ppm (mg/L) and the chloride (CI) by about 158–160 ppm (mg/L). While people’s flavor threshold to salt will vary, keeping sodium under 100 ppm (mg/L) is best. Avoid salt when using sodium bicarbonate since it can quickly raise sodium to unacceptable levels.

Sodium bicarbonate and calcium bicarbonate

Neither of these salts should be used as flavoring salts. However, they can affect flavor when combined with other salts: Calcium bicarbonate raises sodium, and both salts raise calcium. Watch your sodium and calcium levels when using these salts in conjunction with others.

Sulfate-to-chloride ratio

The sulfate-to-chloride ratio should be considered for any beer style, especially hop-forward beers. For example, hazy pale ales typically use a 1:2 sulfate-to-chloride ratio to emphasize the “softness” of these beers. On the other hand, a West Coast IPA may use a 2:1 sulfate-to-chloride ratio to accentuate dryness and hop bitterness.

You can use whatever sulfate-to-chloride ratio you like (1:3, 1:1, 4:1, 0:1, 1:0, etc.); it’s up to the brewer to experiment with these ratios to see what works best for their beers and their tastes.

Calcium Levels in the Mash

As alluded to, calcium is an essential mineral in beer, but not necessarily for flavor. Calcium in the mash positively affects the enzymes and improves enzymatic function while acting as a yeast nutrient.

Calcium also reacts to oxalic acid, a troublesome organic acid released during mashing. Calcium binds with oxalic acid to form calcium oxalate, aka beer stone, which will precipitate out of the mash. It’s important to handle it in the mash so it doesn’t form in fermenters or packaging. Beer stone forms a brownish deposit that can harbor bacteria, create nucleation points where CO₂ collects, and cause excessive foaming and gushing. It is tough to remove without harsh acids.

To avoid problems with beer stone and provide yeast health and speedy mash conversion, be sure every mash has at least 50 ppm (mg/L) of calcium (calcium sulfate, calcium chloride, or calcium carbonate).

Water Chemistry Software

If you have your local water report, it’s easy to input those numbers into water and mash chemistry software to see how your water alkalinity affects the pH of your beer recipe. It also makes it easy to decide on RO or distilled water dilution ratios or mineral additions. Some can estimate how much acid or minerals are needed to bring your pH into the desired range. Some of the software is free online, while others are spreadsheets that can be downloaded for a small fee. Many recipe software programs and apps also include water chemistry software in their package. 

This is an edited excerpt from Keith T. Yager’s Unlocking Homebrew: The Four Keys to Tasty Beer (self-published, 2024).

Q: I have been brewing for several years and utilizing the BIAB (Brew-in-A-Bag) method. My quest has been looking for a way to use my propane system to hold my mash at the desired temperature during the entire mash. I think a propane controller hooked up to a thermometer that is in the mash or thermowell would work. I have seen “camping” propane water heaters that use batteries with a digital temperature set to maintain a specific water temperature. But two problems are 1) the setup can’t get temperature up to mash temperatures and 2) I don’t want to run mash through the tubes. Do you have any ideas or advice?
— Bob Weschler • Bumpass, Virginia

A: I think I have a solution to your quest that will work well without costing much money. All you need for this project is your propane burner, a pot, an immersion wort cooler, a temperature controller, such as an Ink Bird or a Baylite unit with a heating output plug, and a submersible water pump rated for high-temperature applications. You may have most of these gizmos laying around already. The pot can be your brew kettle or a smaller pot dedicated to mash heating, the immersion cooler can be used both for mash heating and wort cooling, and the temperature controller can be used for other brewing functions like keezer control. The only item that may fall into what Alton Brown of “Good Eats” calls a mono-tasker is the submersible water pump; the good news is that these little dudes are easy to find out on the interweb for about $50.

The basic setup uses your propane heater to heat a pot filled with water, the submersible pump to deliver hot water to the immersion coil (use high-temperature, braided hoses connected to the coil using hose clamps for safety), and the temperature controller to turn the pump on and off (pump must be plugged to the outlet designated for heating and the heating differential set to about 2 °F/1 °C). A good way to conserve water is to use the same water for mash heating and sparging. The water temperature is not critical if it’s about 10 °F (5 °C) hotter than your mash temperature set-point. You can either set your propane burner on the lowest fire to continuously heat the water or you can fire it on and off as needed.

In practice, consider using something like a metal grate to prevent the submersible from touching the bottom of the kettle and consider heating your water pot and immersion coil before mashing-in so that you don’t cool the mash with a cool coil. After your water and coil are hot, mix mash water and malt in your grain bag, let the mash sit for about 10 minutes to allow some mash thinning from enzyme activity, gently wiggle the immersion coil into the mash so that the coil is immersed, and drop the temperature sensor (make sure it is totally sealed and able to be dropped into liquid) into the mash.

Assume you start your mash at 149 °F (60 °C) and you have your controller set to 149 °F (60 °C) with the heating differential set at 2 °F (1 °C). When the measured mash temperature drops to 147 °F (55 °C), the pump will turn on and pump water through the immersion coil until the measured temperature is 149 °F (60 °C). Two practical problems with this design are short cycling of the pump and temperature stratification within the mash. The best way to address short cycling is to keep the differential setting to about 2 °F (1 °C) or greater. And the simplest way to deal with stratification is to gently stir the mash when the heating pump is turned on.

This basic setup keeps things simple without pumping wort or mash through a heater. It also closely mimics how commercial systems heated with steam operate. Hope this helps you get to where you want to go!

Q: I recently started omitting a protein rest from my mashing procedures since I have read that it is not necessary with our modern well-modified malts and it can detrimentally affect head retention. I have noticed that my original gravity (OG) is consistently 10 gravity points lower than when I include a protein rest. I measure OG with a refractometer and brew with a single-vessel system. I have noticed this with both German-style lagers as well as pale ales, which are the styles I mostly brew. My base malts are American 2-row or Maris Otter. Is there an explanation for this?
— John Henderson • Yakima, Washington

A: I have a solid explanation of what may be causing your problem but must admit that what follows includes one very big assumption. And that assumption is that your mashes typically drop in temperature over time. Even if you are using an all-in-one system where wort is heated either in the lower section of the mash tun/brew kettle or externally before it is returned to the mash, mash temperature often drops because these systems are not well-insulated.

Over the last three years I have brewed what I consider to be great beers using an all-in-one system. During this time of exploration, I have noticed things that are very different to what I became accustomed to during my 26 years of commercial brewing using mash mixers in a wide range of sizes. When a steam-heated mash mixer is used, mash temperature is uniform with a slow drop in temperature during rests. And when the temperature eventually drops below about 1 °F (1⁄2 °C) from the set point, mash is automatically stirred and heated back to the set-point. As cooking processes go, these temperature changes are slow to occur and tightly controlled.

My guesstimate about what is happening with your brews is that you mash-in at some temperature between 149–158 °F (65–70 °C) and hold for about 60 minutes before commencing wort recirculation. During your mash rest, you don’t stir and may or may not heat. And even if you do heat using an all-in-one brewing system, your system is measuring the wort temperature in the bottom of the mash/kettle and controlling the temperature to the set point. I want to put that on hold because you may not be using this sort of system.

It’s critical for yield for alpha amylase to be active in the mash where it reduces mash viscosity and increases starch solubility.

Let’s assume you are mashing in a non-heated vessel like an insulated cooler and performing a protein rest versus a single-temperature mash. With the protein rest, you mash in at about 122 °F (50 °C) and rest for about 30 minutes. Now it’s time to heat, and you add heat while stirring. The heat may come from hot water, hot mash if you are decocting, or external heat from a flame or electric element. Whatever you are doing, you are probably stirring your mash to keep the temperature uniform. And you are also exposing the starch being solubilized during the protein rest to beta and amylase enzymes.

The same basic process is different when you skip the protein rest because you probably do not stir your mash during your mash rest. Simply stirring the mash increases extract dissolution. And stirring the mash during heating steps helps to maintain temperature uniformity; something that all-in-one systems don’t do very well. Without jumping down a very deep rabbit hole, I have a few suggestions.

For starters, if you have an all-in-one system, measure the mash temperature and compare it to your set point. If there is a big difference, which I have seen in my own experience, determine the offset and increase your target temperature to provide enough heat from wort to make up for the mash heat losses to the environment. It’s critical for yield for alpha amylase to be active in the mash where it reduces mash viscosity and increases starch solubility.

If you are not experiencing much heat loss during mashing, extend your mash time to account for the time reduction when you dropped the protein rest. While you’re at it, give your mash periodic stirs to help move starch from your malt into wort. My gut tells me these details are the root of your issues. But because I work for a malting company, I would be remiss not to suggest checking your mill gap/malt crush, mash thickness (thinner mashes improve yield), and thermometer calibrations as part of this troubleshooting exercise. Hopefully this answer points you in the right direction in searching for those lost extract points!

Meeting a stranger from the internet can be a scary thing. And yet I found myself driving an hour and half to meet up with someone I barely knew to teach them a different way to brew beer than they were accustomed to. Luckily this guy wasn’t a serial killer, he was a YouTuber who goes by “CH” from Homebrew 4 Life. And while he had a lot of experience brewing beer, he had never tried brew-in-a bag, or BIAB, as people call it. CH had seen my small YouTube channel and noticed I used BIAB often and was hoping I could share my knowledge to teach him the way. I was more than happy to, as BIAB greatly improved my brewing experience and completely changed the way I brewed beer just a few years earlier. 

I got my start brewing beer like many others; a beer kit that turned out horribly, but nevertheless I was bit by the brewing bug. I began reading every beer book I could get my hands on and watching hours of BrewingTV videos on YouTube, trying to absorb as much as I could so that I could make better beer. However, at the time it seemed like in order to make better beer you needed to brew all-grain and that required a three-vessel system with all kinds of fancy stainless gear. All of which would never fit in my one-bedroom apartment in Chicago. But the more reading and watching I did, I eventually stumbled upon a different technique called brew-in-a-bag. 

In this new (to me) method, you don’t need three vessels, you just need one. Thanks to a mesh bag, you can mash all-grain batches in this single kettle, remove the grains by pulling out the bag, and then bring it to a boil. This revelation helped open the door to all-grain brewing without breaking the bank and without compromising space. I was sold and I immediately dove in on more research. 

Brew-in-a-bag’s origins trace back to Australia, pioneered by Patrick Hollingdale, amongst a few others about 20 years ago. Hollingdale did years of research and trials to develop the process. He is also the one that really helped spread the word of BIAB and it didn’t take too much convincing for many homebrewers that were looking for a simplified way to make beer, myself being one. 

The simplicity is what really drew me in. When you take a step back and look at BIAB it’s very much like making a giant batch of tea. You put the grains into a bag and steep them at a certain temperature for a certain amount of time, and then pull that “teabag” out (similar to all-in-one brew systems like the Grainfather, BrewZilla, and others, except instead of a bag they use a basket). The rest of the BIAB brew day is the same as any other brewing method beginning with the boil. All-grain brewing seemed unattainable to me but all of a sudden it made sense and I could start making high-quality wort; I just needed a few pieces of equipment to get started. 

BIAB Equipment

The first piece of equipment you need is the kettle. The kettle size is dependent on the size of the batch you want to make. If you’re looking to make the typical 5-gallon (19-L) homebrew batch, a 10-gallon (38-L) kettle is perfect. But BIAB is also great for small experimental batches, so something like a 2-gallon (8-L) kettle is ideal for 1-gallon (3.8-L) small-batch beers. The reason you need a kettle about twice the size of the batch is because you’ll be adding in all the grains and water at once, so you’ll want plenty of space to avoid an overflow. You can get away with using smaller kettles, and I’ll share some tips on that later, but if you’re in the market for a new kettle, spend the few extra dollars for the bigger size.

Next, and probably most importantly, is the brew bag. These days there are companies that make brew bags specifically designed for your kettle dimensions, but when I started brewing with this technique the only thing I needed to worry about was not getting one too small. Too big is no problem; many of these mesh strainer bags have strings that you can cinch to keep them tight on the kettle. Or you can always use some binder clips or a bungee cord on the lip of the kettle to keep the extra fabric tucked away. The bags can either be made from cotton or food-safe polyesters and, thanks to the power of the internet, they’re very easy to find. The important thing is that it’s reusable and can hold the weight of the crushed grain when wet without it ripping. I personally never concerned myself with “microns” or how small the holes in the bag are. If it works, it works!

That’s all you need to get started, but some other useful things are a thermometer to check the temperature and a spoon or something to stir the mash. And of course, you need some way to heat the kettle. Electric heat works, as does a propane burner for large batches. Smaller batches can even be done on a stovetop in the kitchen. If you’ve brewed a beer before you likely already have everything required for BIAB besides the bag. 

BIAB Techniques

From the first beer that I made with BIAB I knew I was onto something. The quality of wort I was able to get was beyond the extract and partial mashes I was used to. And the brew day was so simple I felt like I had put in some cheat codes or something to make brewing easier. All without sacrificing taste, it was just as good as what my friends were making on their big systems. So I kept on brewing in a bag, learning little quirks and tricks along the way and eventually started making videos all about BIAB on YouTube. That’s how my fellow YouTuber CH found out about the technique and decided to reach out. 

CH had for the most part been a three-vessel brewer, usually utilizing homemade systems. While he has dabbled in some of the all-in-one systems that have become popular more recently, I think he was still looking for an easier way to brew. A lot of the brewers I’ve talked with over the years that have given up or slowed their brewing down often cite time being the thing that kept them from brewing. Whether that was the time it took to set up to brew, the time it took to clean up, or just the investment time in maintaining their system. And to me BIAB is the ultimate timesaver because you’re only setting up, cleaning, and maintaining that one pot. The bag may get worn with time, but they are inexpensive enough to replace when needed. 

Luckily, CH had all the tools needed and just had to shop for a new bag. We started our brew day like every brew day — we heated some water up in our kettle to strike mash temperature. For this, you want to be a few degrees above your desired mash temperature as the grains will lower the temperature a bit. Once we were in the right range, we killed the heat and stirred in the crushed grains, little by little to avoid any clumps or dough balls. After making sure it was well mixed, we placed the kettle lid on top. 

One negative of BIAB is that unlike other methods that might use a cooler to help insulate and regulate temperatures, the quality of your kettle will greatly impact how well it holds the mash temperature. Cheaper kettles in some cases might drop about 10 °F (5 °C) over an hour mash. To combat this you have a few options. 

You can do what I did for many years and turn the burner back on when the temperature dips too low. Just be careful to stir the mash during this to help disperse the heat evenly. There is also a concern of scorching the brew bag if you have the burner on while the bag is in the kettle. I’ve never had that issue in all my time, but I’ve heard of it happening so just keep the burner on for a short time to be safe or lift the bag off of the bottom of the kettle while the flame is on. For this method it might be a matter of turning on the burner for a minute or two every 15 minutes if you have a thin-walled kettle.

The other method is to try and insulate the kettle. Sleeping bags or blankets held in place using bungee cords is an option that doesn’t involve an investment. Obviously make sure the heat is off and that whatever you are using to wrap the kettle won’t burn if it touches anything hot, but the idea is to wrap up the kettle tight to keep the heat in. It’s not a perfect solution but it works surprisingly well. Reflectix or other rolled insulation is another option homebrewers often use. Another creative insulation option was detailed in BYO back in 2015 and uses expanding spray foam to form a mold. Plans for building this are found online at www.byo.com/project/keep-mash-tun-insulated/

The best options of all are to invest in a quality brewing kettle with thicker walls or a temperature-controlled all-in-one system, but we’re trying to keep it cheap and easy here!

After the mash timer is up it’s time to remove the grains. In other systems you’d likely be removing the wort from the grains and transferring it into a boil kettle. Here we’re doing the opposite. At this point you’ll need some way to remove the bag safely. A pulley makes easy work of it, especially if you have difficulties lifting 11+ pounds (5+ kg) of grain plus any water that’s holding on (which will bring the weight to above 30 lbs./13 kg). When I started, I opted for some heat-resistant gloves, like the ones people use for grilling, and a strong cookie rack. This allowed me to pull up the bag without scorching my hands, then slide in the cookie rack so that it rested on the lip of the kettle, giving me the perfect spot to rest the dripping bag right above the kettle. With some practice you’ll get good at it, so you don’t have to lift the heavy bag so high. This also gives me the chance to squeeze the bag and get every last drop of wort out that I can. 

That’s exactly the trick I taught CH on our brew day together. I remember he didn’t have a cookie rack but I looked around his brewery and saw he had an empty metal storage shelf. He popped it off and we made it work. 

Speaking of squeezing the bag, you might have heard it releases tannins if you do this. From my experience I’ve never had that happen and I tend to squeeze the living heck out of the bag. I want to get as much wort out as I can because of probably the biggest downfall for BIAB — efficiency. 

Mash efficiency takes a major hit when it comes to brew-in-a-bag. Trying to hit 90%+ efficiency is a goal for many homebrewers I know, who may scoff when I tell them that I’m often hitting 65-70%. I am willing to sacrifice this numbers game for the overall simplicity. I can usually make up the difference and still hit my desired original gravity by adding a few more pounds of grain, which is a few more dollars worth of ingredients. I have noticed that when I am on my A-game, keeping the mash temperature right where I want it and even extending the mash for an extra 30 minutes, I can boost that efficiency up to 75%. But at that point I’m adding time, and time is money. These decisions come down to personal preference, but must be considered when building out recipes and planning brew days.

Speaking of which, I can’t say enough about how thankful I am for recipe calculators and apps. Talk about simplifying the process! These days all the major beer recipe apps have BIAB equipment profiles that automatically help determine how much water and grain you’ll need to hit a desired gravity. 

After wrapping up my BIAB brew day with CH I knew he was hooked. He was reiterating all the things I loved about it: The simple setup, the laidback brew day, and the quick cleanup. And for a while after, he too was brewing in a bag. Anything to simplify the brew day, especially if you are simultaneously filming the brew day, is a win. It also meant he could pair down his setup a bit, get rid of old coolers and gear that he wasn’t using anymore, and free up some space. 

Maybe you’re a homebrewer looking for a way to ease the work required on a brew day. Or maybe you’re more like me when I started, looking for a way to upgrade to all-grain with minimal equipment. BIAB is really an easy and inexpensive way to make beer. There are a few cons to work out, but for the most part the pros greatly outweigh them. And as long as it means it gets you into the brewery and you can keep making amazing beer to share, then it’s absolutely worth giving BIAB a try.

Common BIAB Questions

Having made a few videos on the topic of brew-in-a-bag, I get a lot of questions. So I thought I might share some of the most common ones I get in case you are wondering the same things. 

What if I have a smaller kettle (8-gallon/30-L), can I still make a full 5-gallon (19-L) batch?

Absolutely, you’ll just need to do a “pseudo-sparge” when you pull the grain bag. The way I like to think about it is to build my recipe for the full batch using brewing software to see how much total water I need. Then I’ll use about ¾ of that amount in the main mash, or however much you can use without overflowing the kettle. Then at the end of the mash I pull the bag out, resting it on a cookie rack over the kettle, and pour the remaining water over the bag slowly. This rinses the grains, dripping into the kettle, and helps get any trapped sugars from the grains into your wort while simultaneously raising the volume to the right pre-boil volume for the full batch. If you’re one to check mash gravity it will be a bit higher since it’s a more concentrated mash, but once you add the water you should be back on track!

What about grain crush size?

You can crush the grain as finely as possible with BIAB. In fact, this is another way to help with the general low efficiency of BIAB. I tend to set my mill gap as tight as it can go and while it might take longer to mill the grain you should end up with super fine particles. This would be an issue in other systems that can lead to a stuck mash or sparge but in BIAB it’s no issue since we are manually pulling out the whole bag. And if you want you can try double crushing; I haven’t seen a drastic improvement if your first crush is already quite fine, but it may help boost efficiency slightly. As Denny Conn says: “Crush until you’re scared!”

How do I clean up a BIAB setup?

Once I pull the grains and have squeezed the bag like it owed me money, I set the bag aside to cool for a little bit. Once it’s cool enough to handle I’ll dump out the grains into the compost and then give the bag a wash down with a hose. I like to hang my bag up outside to air dry and once it’s dry give it a good shake to get any remaining grain bits off. That’s pretty much all I do with the bag unless it’s looking a bit nasty or I let it sit too long with the grains, then I might give it a PBW soak. But don’t be afraid to replace the bag if it’s really looking weathered or has holes in it. 

For the kettle it’s like any other brew kettle — give it a soak and a scrub with PBW and it’s ready for the next brew day. All-in-all, BIAB gear is pretty low maintenance.