Brewing Hard Seltzer: A Must for Craft Breweries Everywhere

It is the year 2021 and times have changed over the past few years in countless ways. In the craft beer industry, one of the most notable changes is the advent and rise in popularity of Hard Seltzers. What many originally dubbed as a “fad” just a few years ago has taken the craft alcoholic beverage market by storm and shows no signs of slowing. The data is clear: consumers are looking for a change and looking to lighter, lower alcohol, lower calorie options. Hard Seltzer has taken the lead to fill that change in consumer preference. If you are not brewing one yet or planning to, holding out for longer will only put your craft brewery at a disadvantage to your competition in the coming years.

With that said, I wanted to take a moment to dive into a little bit of the technical brewing considerations of Hard Seltzers. While it may seem like a simple proposition: Water, sugar, ferment, finish, serve – brewing a clean, clear, hard seltzer is actually a technical brewing feat of its own. Without the right recipe, ingredients, and processes in place, one can be on the wrong end of a stalled fermentation, or poorly fermented batch resulting in off-flavors or aromas. To avoid this and to make the best hard seltzer you can, I wanted to share a few tips and considerations from my own experience in brewing hard seltzers.

What is a Hard Seltzer?

Let’s start by defining what a Hard Seltzer is, shall we? The typical hard seltzer is a clean, clear, beverage, neutral in odor and taste, brewed by fermenting dextrose or another simple sugar to a low-high strength alcoholic beverage base that usually ends up between 4.5-6.0% ABV. Finished hard seltzers typically come in at under 100 calories (per 12 oz pour), most of which come from the alcohol itself, and a small amount coming from the sugars left from fermentation. Though higher alcohol, highly fruited seltzers can yield higher caloric content. Once the base is fermented, the product can be finished and served as is or processed further with the addition of fruit, flavoring, spices, juices, and other adjuncts to achieve desired end product flavor/aroma combination. Simple enough, right? Though the list of steps is short, much like brewing traditional craft beer, the devil is in the detail when it comes to hard seltzers. Both ingredients and processes will impact the outcome in a big way. Since hard seltzer is largely water, sugar, and alcohol, any mistakes in recipe or fermentation will come to the forefront very quickly. Some examples include high sulfur compounds, acetaldehyde, fusel alcohols, and other mainly fermentation related possible off flavors.

The Base Sugar Mixture 

Much like the malt bill in your traditional beer recipe, the base sugar mixture is where you get most of (if not all of) your fermentable sugars. It is also what will impact the flavor profile of your seltzer (outside of fruit/adjuncts) the most, with the goal being a neutral flavor in the end. A common practice, much like brewing traditional beer, is high gravity brewing. Meaning brewing a high gravity sugar mixture that is then diluted down to working gravity or ABV later in the brewing process. High gravity brewing has been a common industry practice for centuries, and was made popular in the modern era by macro breweries as a means to increase brewing efficiencies. It also happens to be best practice for brewing seltzers as well. The most common base sugar to use for brewing seltzers is Dextrose (corn sugar/glucose), as it is a highly fermentable simple sugar that is readily available and economical. Theoretically, any simple sugar would do such as sucrose, rice, high fructose corn sugar, honey – though brewing with some of these leads to different color and flavor attributes, and in the case of honey, you end up in mead territory. Sticking to dextrose is recommended for the cleanest, clearest end product. Dextrose can be added at a rate of 6.7 lbs. per 1 degree Plato per bbl to achieve starting gravity desired. Typical starting gravity for a 5% ABV solution would be approximately 11 degrees Plato. As mentioned above, high gravity brewing can be utilized to brew at a higher gravity, then dilute down to working strength. This will require several fermentation and process considerations to maintain cleanliness, avoid excess O2 pick up, and dilute to proper gravity/strength as well.

Boiling the mixture is required to sterilize prior to fermentation to ensure there are no competing yeasts or bacteria and avoid risk of off-flavors and aroma. Yeast nutrient is important to add as well. Since dextrose is a simple sugar, it does not provide the same mineral and protein content that malted barley does. Yeast will need these nutrients to ensure a healthy and complete fermentation. Most traditional brewing yeast nutrient mixtures will provide the necessary DAP(Diamonium Phosphate), FAN(Free Amino Nitrogen), Zinc, Calcium, and proteins needed to keep the yeast healthy in this effort. Once the mixture is boiled for 10 mins, it can be run through the brewhouse heat exchanger and knocked out the same as any other beer. KO temperature will vary depending on the yeast strain chosen.

Fermentation

The most important factor in brewing a hard seltzer comes down to a clean, healthy fermentation. The yeast strain used plays a vital role in the end product. That said, any yeast will ferment dextrose with success. A house ale strain tends to be a popular choice due to regular availability and economical aspect of this option. However, using brewers yeast comes with it’s own limitations as well. Typical brewers yeast does not perform well in higher alcohol and lower pH applications, and can result in stalled fermentations. Because of this, I typically recommend using fresh distillers yeast at a higher pitch rate than normally instructed. This is doubly true for nutrients used during the brewing process. Using fresh yeast each time can be a little bit more of a costly proposition, but it will ensure consistent and complete fermentations each time. Yeast fermented in a seltzer should not be reused or repatched into another beer or seltzer, as the yeast quality is more likely to be poor due to a lack of nutrients in comparison to beer.

Conditioning and Filtration

Once fermentation is complete, the seltzer will need to be stripped of any remaining flavors, aromas, and haze components imparted by the yeast. Typical aroma compounds are green apple and sulfur, which can be removed by “scrubbing” the mixture with CO2. Scrubbing is the process by which CO2 is run through a liquid and by doing so removes volatile flavor and aroma compounds. Most notably, sulfur, green apple, DMS, and others. This may be done if yeast does not fully clean up its byproducts made during fermentation. Haze and yeast particulate are best removed by a centrifuge or filtration of the product. The result is a clean, clear, neutral mixture of water and alcohol to dose with fruit or flavoring as preferred.

Flavoring and Finishing

There are a variety of fruit and flavoring combinations to get infinite results in the end product. I will not go into depth on those rates as they can vary wildly, but it is important to keep in mind the potential for additional haze components and displacement of alcohol content when adding these after fermentation or filtration. Feel free to contact us for recommendations on fruit and extract dosing rates, as well as how to keep your COGS to a reasonable level during this process. Like dry-hopping a beer, this expense can easily eat into your profits.

Once the mixture has been fermented, conditioned, filtered, and final flavors/ingredients added, the seltzer is ready to be carbonated and packaged for serving! While typical beer is carbonated to a CO2 volume level of about 2.45-2.7 depending on the style, seltzer is carbonated to a level closer to that of soda (2.9-3.1 vol of CO2). However, this can present issues of over carbonation when packaging or serving the final product. Carbonate your finished beverage accordingly depending on the equipment you have to package or dispense your seltzer.

Final Thoughts

Much like beer, the process of brewing seltzer is simple at its core. However, in order to do so successfully, it is on the brewer to execute consistent, technically sound, finely tuned brewing and fermentation processes. Utilizing the correct ingredients and yeast strain in conjunction with these processes is paramount to success. It may take some trial and error along the way, or you can hire a consultant with the expertise to save you time and money to avoid these costly trials!

At Plato Brewing, we can provide guidance on this process from start to finish. Need help brewing a seltzer to keep your brewery in line with the times, or just want to tighten up your current process? Contact us at www.plato.beer/contact for more info!