Brewing NABLABs

Q: I have been looking for maltose- and maltotriose-negative yeast to brew a low-alcohol Pilsner recipe from BYO. The yeast recommended is White Labs WLP603 (Torulaspora delbrueckii) or SafAle LA-01, and I can’t find those yeasts in a homebrew size. Every maltose-negative yeast is either the 500-g size or unavailable through any online retailer or homebrew shop I have searched. Any tips on what homebrewers can do?
— Mike Seward • Barrington, Rhode Island

Mr. Wizard says…

A: Before I answer this question, I want to say that I sometimes sit on questions because great questions come in waves and this one was sent into the mailbox earlier this year. It’s rarely the case where new information comes about while questions sit in the inbox, but in this case the body of knowledge related to non-alcoholic (NA) brewing is growing at a rapid pace. Bottom line is that this is a timely question and I have some thoughts about this topic.

I am not surprised that you haven’t been able to find a source for these yeast strains because none of these suppliers are selling them into homebrew markets. There is one major challenge when brewing beer with maltose- and maltotriose-negative yeast strains, simply referred to as maltose-negative strains; the biggest risk to stability comes from garden-variety brewing yeast.

Because breweries, both home and commercial, are rife with brewing yeast, the risk of contamination is high. When beer produced using a maltose-negative strain is contaminated with a regular brewing strain, over-carbonation and the possibility of exploding packages is a clear and present danger. The only currently acceptable stabilization process is pasteurization. This may change in the future as alternative approaches are examined, but those currently do not exist. Some breweries and research facilities are serving unpasteurized NA beers fermented with maltose-negative yeast in dedicated draft systems where temperature control is used to minimize the risk of re-fermentation and monitoring is used to check for the signs of re-fermentation.

Another concern with NA beers is the growth of pathogens. That’s the other reason that commercially produced NAs are pasteurized. I will come back to this topic later but want to pivot to some other points first.

If I were writing this answer earlier this year, I probably would not have thought much about the actual alcohol content of the beer as a real concern to homebrewers. However, the alcohol content of these beers is of concern to many of the people who drink them. The term NABLAB is used around the world these days to describe non-alcoholic and low-alcohol beers. Although definitions are not universal, most countries define beers with ABVs between 0.5 and 2.5% as “low alcohol.” When alcohol is less than 0.5% ABV, the term “non-alcoholic beer” is used. The term “alcohol-free” or “zero-alcohol” is reserved for beers with no measurable alcohol.

Consumers who are serious about how they consume or do not consume alcohol must be able to rely upon the producers of NABLABs to properly adhere to these product classifications. Because I drink beer, I am one of those consumers who is not overly concerned about drinking something that may contain 0.7% ABV instead of 0.4% ABV. But brewers cannot make assumptions about others and need to be precise with labeling. If your interest in brewing NA at home is related to brewing beer for a friend or loved one who cannot or does not want to consume alcohol, you really should stick to purchasing these beers from a commercial producer unless you are willing to have your beer analyzed before serving.

You specifically asked about using maltose-negative yeast because that is the method discussed in Kara Taylor’s article. However, there is another method available to homebrewers that does not require special yeast or equipment — high temperature mashing. This method involves mashing in at ~176 °F/80 °C, resting for about 15 minutes, collecting, boiling, and cooling wort as usual, and fermenting with whatever yeast strain you want to use. Because there is essentially no beta-amylase activity, very little if any fermentable sugars are produced during the mash. This very high temperature also quickly stops alpha-amylase activity and results in starchy wort. Halting alpha-amylase is important because alpha-amylase does produce some glucose, maltose, and maltotriose because its action on starch is random.

I recently brewed two beers using this method. Although I knew what I was doing, I was still surprised by the cloudiness of the wort. Not seeing anything during fermentation, although not surprising, was also odd. Although there are compounds in wort that yeast metabolize during the short fermentation, the lack of appreciable fermentable sugars means that alcohol production is all but eliminated and the fermentation appears non-existent. While the beers both finished with a veil, neither are extremely hazy.

Much of the focus of NABLAB production is aimed to eliminate worty aromas and flavors common to these beers. One method that works surprisingly well is kettle souring. Lactic acid bacteria apparently metabolize some of the worty precursors and reduce the concentration of aldehydes in the finished beer. And the interesting thing is that this action occurs in kettle soured wort that is not obviously sour. This means that pH can be monitored and the process stopped with wort boiling before the wort is sour, allowing the method to be used in just about any style.

My recent NA brews used kettle souring. In one brew, a Pilsner-style NA, I dropped the pH to 3.9 (my target was 4.0) and in the second brew, the base for a berry-flavored sour, I dropped it all the way down to 3.2. I used kettle souring in an attempt to reduce worty aromas — this was a success — and to lower pH for safety reasons discussed later.

The 2025 Summit — a joint conference uniting members of the American Society of Brewing Chemist (ASBC) and the Master Brewers Association of the Americas (MBAA) — featured numerous presentations related to NABLAB production. The one topic related to NABLABs that has brewers and industry experts concerned is the risk posed by spoilage and pathogenic microorganisms, especially when it comes to draft beer. Because in-keg pasteurization is not possible and the very real challenges associated with properly cleaning and sanitizing kegs, keg couplers, and draft lines, many brewing experts and brewers believe that NABLABs should only be served from cans or bottles. Although some brewers are conducting research into the use of liquid preservatives, in-package pasteurization is the only preservation method universally accepted for these beverages.

Some small-scale producers use batch pasteurization to process cans and bottles of NABLABs. I can address that process in another column, but for the time being I will just leave you with the knowledge that batch pasteurization is something that can be performed at home. A very conservative level of batch pasteurization for a typical NABLAB is in the 80–120 PU range.

Whether producing low-fermentable wort using the hot and fast mash method or using a maltose-negative yeast strain, I believe that certain practices should always be followed brewers, and others should be avoided when producing NABLABs.

DO:

• Boil wort for at least 30 minutes
• Heat-sanitize the wort cooler
• Reduce wort pH to <4.2
• Adjust finished beer pH to <4.2, if required
• Add all hops before wort cooling
• Heat-pasteurize finished product

DO NOT:

• Dry hop — this simply is an unnecessary risk
• Add unpasteurized fruit purees or any fermentable sugars if your goal is <0.5% ABV
• Barrel age

I know that commercial craft brewers read this column. If you are one, know that I am a big proponent of this growing category of beer. I sincerely want brewers to continue elevating these beers without incident. It’s really amazing how many excellent-tasting products are currently being produced. Brewers are going to do whatever because these products are only regulated by the TTB and the industry does not want to see that change — that’s why producers of these products are so concerned about possible issues in the market.

Caution flags and raised voices, however, will not prevent brewers from experimenting with these beers at home and taking the easy way out by packaging in kegs and not pasteurizing. If you decide to roll the dice, read the literature, understand the risks, clean your kegs by completely disassembling, sanitize your kegs after reassembly, use new draft lines and picnic taps, and store your keg and dispense rig in a cooler at <38 °F/3.3 °C. Finally, have a party and drain the keg asap.