A Focus On Enzymes: Micro-fermentation technique for non-alcohol beers
Non-alcoholic beer (NAB) is beer with very low or no alcohol content (less than 0.5% ABV in the U.S.), which in the past were generally known for their poor taste. However, in recent years, major alcohol companies including Heineken, AB InBev, and Molson Coors have started promoting more and more NAB options; for instance, as sponsors of sporting events.
NABs are now becoming increasingly popular. The preference for low- and alcohol-free beverages has been driven up not only by greater interest in health and warnings about alcohol consumption, but also by younger consumers interested in alcohol-free gatherings. In this scene, NABs are seen as more crafted, sophisticated, and flavorful than seltzers or sodas, and therefore more appealing. Lower alcohol content also provides a lower-energy alternative, with an approximate 60% reduction in calorie content between a pale ale and its low-alcohol counterpart. So, whether for lifestyle choices or personal reasons, the low- and non-alcoholic beer market has skyrocketed and is expected to continue to grow in the coming years as more adults become interested in this category.
Smaller craft brands, which used to exclusively brew high-alcohol craft beer as a way to distance themselves from mainstream ale and lager beers, have also arrived on the scene. Their bigger struggles, however, are the production cost on a smaller scale and the organoleptic limitation of the dealcoholization process. Other methods, in which the production of alcohol is instead prevented, could represent a cheaper and more feasible alternative on a smaller scale, but also have their organoleptic faults to be circumvented. More on some of these other production methods feasible on a small-scale, such as using maltose-negative yeast, can be found in the September 2022 issue’s “Mr. Wizard” column. Table 2 describes many production means to produce NABs although many are equipment-intensive, require massive capital investments, and some may cost a lot to operate. My goal was to produce a shelf-stable NAB product using one of the changed mashing processes.
Changing the Biochemistry
For producing lower-alcohol beer, changing the ability of the enzymes to release sugars and the yeast to ferment will result in a less alcoholic final beer. The simplest method is arresting fermentation by cold crashing, centrifugation, or microfiltration. Other options are changing mashing temperature that alters the ratio between fermentable and non-fermentable sugars and/or choosing alternative yeasts that do not consume maltose: In both cases less alcohol is produced. All these beers have a detrimental residual sweetness that not only can impact overall quality but also be dangerous in the case of refermentation in package.
This is the reason why a newly conceived protocol, exploiting new ideas and integrating these strategies has been a particular interest of mine: To deliver a craft non-alcoholic beer full of sought-after aroma and flavors.
Designing the Grain Bill
When applying these biological methods you typically start with a lower concentration of fermentable carbohydrates. This is because it is anticipated that sugars will not be completely consumed, and the resulting beer will have a lower ethanol content. In the design of a new recipe or in the adaptation of an existing one, you should aim for 3.3 °P (1.013 SG) initial gravity for your wort. In order to do it but keep the malt flavors and color you are aiming for, you reduce the amount of base malt, while keeping the same amount of specialty malts such as Vienna, Munich, wheat, or crystal.
No dextrin malts are allowed, as they don’t undergo sufficient amylolysis during malting. Amylolysis is the process of initial degradation of starch into amylopectin-based ordered structure, making starch more soluble, without any other enzyme intervention.
The Mashing Process
Mashing is the process of mixing the crushed malt or grains with water and heating it to convert the starches in the grain to sugars. The temperature of the mash is important as it affects the conversion of the starches to sugars as well as the extraction of flavors and aromas from the grain. The mashing temperature of my ale is typically between 152–160 °F (67–71 °C). Brewing outside of this “window,” allows for less conversion of carbohydrates to fermentable sugars.
For producing lower-alcohol beer, changing the ability of the enzymes to release sugars and the yeast to ferment could result in a less alcoholic final beer.
In order to produce a real NAB, the enzymes need to be deactivated completely! Allowing amylases to work for even a very limited amount of time could result in more ethanol than 0.5%. So the mashing temperature has to immediately be 176 °F (80 °C) at mash-in to block any enzyme activity, and the mash time reduced to 15 minutes to extract color and aroma but not excessive tannins. Doing so, you allow gelatinization of starch and solubilization of the amylose, amylopectin, and dextrins to happen but not the saccharification, leaving behind only a small fraction of fermentable sugars.
For these reasons, a thinner mash is preferred and then once the grains are removed you can proceed to bring the wort up to volume (sparging is optional and cannot extend the time). Boiling and hop regime are business-as-usual, keeping in mind the absence of ethanol increases the bitterness perception and therefore lower IBUs are suggested (15 IBUs is a good starting point, mainly from whirlpool hop additions).
The devil is in the details: Due to the lower amount of grains, the wort is going to have a higher pH. It is imperative to check and adjust the pH with an acid (e.g., phosphoric or lactic) to the normal range 5.2–5.4 during mashing to limit extraction of undesired tannins. This needs to be done again to a pH less than 5.6 before the hop additions, to limit harsh bitterness. Because of the lower buffer capacity of this wort, even small water addition can increase the pH to 5.8–6.
The Fermentation
The fermentation process for this non-alcohol beer is the same as for regular beer, except that the yeast can only convert a limited amount of sugars into alcohol. In this protocol, yeast fermentation is restricted by the higher amount of unfermentable sugars (amylose and dextrins) and the amount of ethanol is directly correlated to the limited glucose, maltose, and maltotriose present in the wort. The desired attenuation is from 3.3 to 2.7 °P (1.013 to 1.010 SG).
Because fermentable sugars are already limited, the choice of the yeast can be focused on aroma production, which usually falls (but is not restricted) to aromatic dry wine yeast for speed of fermentation, ease of use, and especially their higher ester production in the first phase of fermentation. The addition of yeast nutrient rich in amino-acids, compared to the “inorganic” ammonium sulfate or phosphate (such as DAP or diammonium phosphate), will also boost the aroma production (e.g., isoamyl alcohol, 2-phenylethanol, and relative acetate esters).
Big dry-hop additions are a dangerous attraction, because of their glycoside molecules that have aromatic compounds and (fermentable) sugars that can be released. At the end of fermentation, before carbonation, add a small amount of lactic acid to drive the pH down to 3.9 in order to increase the protection of your beer against spoilage microorganisms, now that ethanol is not present.
The Tasting
In order to evaluate this process, we brewed a single malt (Weyermann Pilsner malt), single hop (Magnum hopped to 20 IBUs) “base” wort and fermented one batch with a California ale yeast and the second batch with a wine yeast plus nutrients (FT CITRUS + N – Fermobrew Citrus + Fermoplus DAP free, AEB). Both of the beers ended up with less than 0.4% ABV and were judged for different characteristics (from 0–5 scale). The industry panel tested these two beers against three commercial examples (Chart 1) and found many of the undesired characteristics were addressed by this method.
Sweetness and malty perceptions were reduced and the aroma intensity paired or exceeded the counterpart. The lack of body and bitterness can easily be addressed by developing the complexity of the recipe. For example, finely tuning the initial amount of grain or by the addition at the end of gum arabic and/or maltodextrin, which are both body enhancers (1.7 cal/g and 4 g/cal respectively). Similarly, the bitterness sensation can be reduced by using aromatic hops towards the end of boiling. So, did the NAB that we produced taste better than the commercially available alternatives? There is no definitive answer to this question, as everyone’s taste buds are different. However, this experiment gave a good indication that with this method you can craft your own non-alcoholic beers at home.
Killing It NAB
(5 gallons/19 L, all-grain)
OG = 1.013 FG = 1.010
IBU = 16 SRM = 2 ABV = 0.04%
Ingredients
2.1 lbs. (1 kg) Pilsner malt
0.5 lb. (0.23 kg) Vienna malt
0.25 lb. (113 g) crystal malt (20 °L)
½ tsp. yeast nutrients (10 min.)
2.1 AAU Perle hops (60 min.) (0.35 oz./10 g at 6% alpha acids)
1.5 oz. (43 g) Saphir hops (0 min.)
SafAle US-05 or LalBrew BRY-97 (West Coast Ale)
Step by Step
You are looking for 85% of the total volume to be water, so roughly 15.8 qts. (15 L). Heat brewing water to 185 °F (85 °C) then add grains slowly. Treat brewing water with acid to adjust pH to 5.2–5.4. Hold for 10 minutes, then begin a 5 minute vorlauf. Sparging is optional. Add water to the kettle to reach boiling volume. Readjust the pH to make sure wort is under 5.6. Boil for 60 minutes with a 20 minute post-boil whirlpool.
Ferment as you normally would, at below 64 °F (18 °C). The goal is to reach a final gravity of ~1.009–1.010. If you want to dry hop, be sure to cold crash prior and dry hopping cold. Be sure that the final pH is under 4 to guard against spoilage organisms. You may consider adding gum arabic or maltodextrin as a body enhancer if needed.
References
- Müller, Magdalena, et al. “Physical methods for dealcoholization of beverage matrices and their impact on quality attributes.” ChemBioEng Reviews 4.5 (2017): 310-326.
- Stewart, Graham G., Inge Russell, and Anne Anstruther, eds. Handbook of Brewing. CRC Press, 2017.
- Mangindaan, Dave, K. Khoiruddin, and I. G. Wenten. “Beverage dealcoholization processes: Past, present, and future.” Trends in Food Science & Technology 71 (2018): 36-45.
- Salanță, Liana Claudia, et al. “Non-alcoholic and craft beer production and challenges.” Processes 8.11 (2020): 1382.
- Pilarski, Dylan W., and Dimitrios I. Gerogiorgis. “Progress and modelling of cold contact fermentation for alcohol-free beer production: A review.” Journal of Food Engineering 273 (2020): 109804.
