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Hard Seltzer Made Easy

The summer of 2019 may go down in the annals of North American beer history as The Summer of Hard Seltzer, and not because hard seltzers over-took beer volume or converted bearded beer bros into hard seltzer sippin’ hipsters. The real significance of the popularity of these products in the market may be the mere fact that they exist in a sea of big flavor and that the category has done so well by appealing to a demographic that was largely ignored by so many of the arbiters of beer style. Hard seltzer’s popularity is a message from the market signaling demand for beverages that are lighter on the palate, skinnier on the calories, and less challenging to consume than big-bodied, highly-flavorful, calorically-rich beers. 

The New, Old Craze

Popular trends are interesting to analyze when the “new thing,” be it food, music, or beverage, is looked at without the bias of a name. Many “new things” are simply “old things” that have been tweaked, repackaged, and given a new name. In the case of hard seltzers, the new thing has more to do with process and taxation than it does with the liquid itself. Strip away the peripherals, and what is left is a simple cocktail similar to something like a vodka tonic.

There is one key difference, however, between a canned vodka tonic and a canned hard seltzer; tax classification. In the United States, alcohol taxation has much more to do with the source of the ethanol in a beverage than it does strength. In fact, there is no difference in the federal excise tax levied on beer based on beer strength, and only 16 states collect higher tax rates on “strong” beers, a distinction that varies by state. Another nuance of US alcohol taxation is the different licenses, and associated restrictions, required by beverage makers to legally produce and pay tax on various alcoholic beverages. For example, a licensed brewery cannot produce wine or distilled spirits without having a separate license. And when a producer does hold multiple licenses, special rules apply to how the facility is operated to help ensure that the different tax rates levied on alcoholic beverages are properly paid. What does all of this have to do with hard seltzer?

The popularity of bottled water and coffee drinks has been hard to ignore over the past decade. The price difference between something like a can of flavored seltzer and beer is pretty staggering when the cost of production is considered. To make a common non-alcoholic seltzer, filtered water is flavored with a dash of flavor essence, carbonated, and put into a can. Not much different than making soda, but the ingredient costs are lower because there is not much of anything in these drinks. Beer, on the other hand, is much more expensive to produce in terms of equipment, ingredients, labor, energy inputs, effluent treatment, cleaning chemicals, inventory costs related to fermentation and aging time, and taxation. Most brewers cannot help doing mental math when noting that something as simple as a cup of coffee at the local café costs about half as much as a pint of craft beer. So the idea of adding a shot of alcohol to these common and popular drinks has crossed the mind of many a brewer, but the taxation thing was an obstacle.

Back to the old thing with a new name topic. Zima was arguably the first malternative to make the big leagues when Coors introduced its clear concoction to the market in 1993. Zima, like malt-based wine coolers that were all the rage in the 1980s, was taxed as beer but had little else in common with other beverages in this tax class. Maybe it was the sweetness, the funky name, or the clear and cool package, but for whatever reason Zima floundered in the market and was officially retired in 2008 . . . and then un-retired in 2017. The key to producing a beverage like Zima is removing malt color and flavor. The easiest way to begin this process is to start with as little color and flavor as possible by maximizing the non-malt adjunct allowed for an alcoholic beverage to be taxed as beer. Flavorless beers have been the butt of many a joke about mainstream beers, but the truth is that producing very lightly flavored beer is not easy. And producing colorless beer requires special processes.

There are numerous patents from the past related to color removal from beer using ultrafiltration, reverse osmosis, and activated carbon. Many of  these processes were specifically developed to remove malt colors from wort or beer, not necessarily flavor, because the inventors wanted to produce beer without color. Today’s brewer may not quite get the point of this quest, but we can learn by reading patents from the past. One of the obvious takeaways from looking at these patents is that color removal requires special methods, and that an easier way to begin is to simply leave out the color compounds from the mix. If the objective is to reduce flavor and color, starting from a malt-free base seems logical, except for the pesky tax laws that require a certain amount of malt and hops in a “malt beverage.” It’s worth noting that these same rules do not apply to “beer” because malt substitutes are permitted and there is no hop requirement.

Hold the phone! What is this thing about a malt substitute? We all know that beer must contain malt because, well, that’s just how beer is made. Don’t ask; this is about taxation and not conformance to brewing tradition.

So, what is a malt substitute? According to the US Alcohol and Tobacco Tax and Trade Bureau (TTB) “. . . the definition of a ‘beer’ under the IRC [Internal Revenue Code] differs from the definition of a ‘malt beverage’ under the FAA Act in several significant respects. First, the IRC does not require beer to be fermented from malted barley; instead, a beer may be brewed or produced from malt or ‘from any substitute therefor [sic].’ Second, the IRC does not require the use of hops in the production of beer. Third, the definition of ‘beer’ in the IRC provides that the product must contain one-half of one percent or more of alcohol by volume, whereas there is no minimum alcohol content for a “malt beverage” under the FAA Act. 

“Accordingly, a fermented beverage that is brewed from a substitute for malt (such as rice or corn) but without any malted barley may constitute a ‘beer’ under the IRC but does not fall within the definition of a ‘malt beverage’ under the FAA Act. Similarly, a fermented beverage that is not brewed with hops may fall within the IRC definition of ‘beer’ but also falls outside of the definition of a ‘malt beverage’ under the FAA Act.”

Believe it or not, sugar (sucrose) as well as dextrose/glucose are considered malt substitutes by the current TTB definition of malt substitute. This has the fingerprints of a company with lobbying power written all over it, but I am more of a science writer than investigative journalist. What I do know is that breweries can produce hard seltzer, pay tax as if seltzer were beer, and sell these products without much ado about mashing.

A Food Science, Home-Approach to Hard Seltzers

Homebrewers who don’t need to worry about TTB regulations can make a simple hard seltzer starting with sparkling water and adding flavor extracts, citric acid, orange juice, and vodka.

Not to take the pizazz away from hard seltzers, but when viewed for what they are as opposed to how they are made, hard seltzers are basically garden-variety flavored seltzers plus about 5% ABV. The basic flavor palate of most hard seltzers I have tasted are mildly fruity, with little to no sweetness, a little acid zip, and no obvious hints of alcohol.

A convincingly “authentic” hard seltzer at 5% ABV can be made by the following recipe:

• (4) 355 mL (12-ounce) cans of carbonated water
• 0.2 mL lime extract
• 0.2 mL lemon extract
• 30 mL pulp-free orange juice (single-strength, not from concentrate)
• 1 g citric acid (powder)
• 210 mL vodka

Note: Some recipes are best-suited to metric-only units. Converting tenths of a mL or 1 gram into teaspoon or ounce equivalents is not particularly practical. No conversions to English units are used in this article. If you want to make seltzers, you must suffer through metric as penance!

This is a pretty basic beverage and not the type of thing that can be improvised on before all variations on them have been tried. Obvious permutations are the use of different fruits, but we are still left with a pretty basic beverage. This is the main critique of hard seltzers, but one that may not be a major deal breaker in a beverage market filled with different brands of water, carbonated water, and mildly flavored carbonated water. Just a reminder that creative marketing can always make up for the lack of real differentiation. Perhaps the most tempting variation on the basic seltzer theme is adding some sweetness. Definitely something to consider if looking for a tasty beverage, but not so tempting if keeping caloric content under 100 calories per 12-ounce (355-mL) serving. In the world of low-calorie marketing, the 100 calorie threshold seems to be the barrier to not cross.

It’s pretty easy to see how the basic vodka seltzer morphs into cocktails using different spirits, mixers, fruits, garnishes, sweeteners, bitters, and all of the other stuff that is used to stock a bar. Funny how quickly beer brewing pops into one’s mind when considering all of the excitement of the home-approach to hard seltzers.  Of course that means the addition of vodka is out of the question. So, how would a commercial brewer go about making a hard seltzer that can legally be sold using a brewer’s license?

Hard Seltzers Made in Breweries

While the logical approach described in the last section works great at home and in commercial facilities licensed for cocktail production, breweries must use a variant on the malternative theme. And thanks to the giant loophole in the legal definition of beer, breweries can ferment sugar water into what the tax collector defines as beer. The problem is that sugar water lacks the nutrients that make wort an ideal solution to ferment into beer. Sure, sugar water can be fermented by yeast to produce a crude mixture of water and alcohol, but the resulting flavor is not clean and is not the sort of product that can be enjoyably consumed without further processing. Distillation is the most common method to remove impurities from these rough washes, but breweries are not distilleries, so the old still in the back 40 is not the answer. Perhaps this is one of the reasons that Herr Rein H. Gebot penned his now-famous beer purity law back in 1516.

This is where yeast nutrients enter the picture as a crucial ingredient required for the production of any fermented beverage using a high proportion of simple sugars. Winemakers and meadmakers are much more familiar with the practical uses of different nutrients than brewers and taking lessons from their playbooks is a pretty handy start. The term yeast assimilable nitrogen, or YAN (where YAN = nitrogen from ammonia + nitrogen from amino acids), is used by winemakers and meadmakers to quantify the amount of nitrogen compounds in must — for example grape juice — that can be metabolized by yeast. Brewers use the term free amino nitrogen, or FAN, to describe amino compounds whose “free-amino” group reacts with ninhydrin stain (the same stain used in finger printing). YAN and FAN differ in the fact that not all FAN can be metabolized by yeast because proteins and polypeptides (not assimilable by yeast) have one free amino group. The takeaway message is that by knowing the YAN concentration of must, or sugar water in the case of hard seltzers, nutrient adjustments can be made by referring to tables relating nutrient addition scheme to YAN concentration.

Must containing less than 50 ppm of YAN is a high risk environment for yeast and a combination of organic nitrogen (amino acids), inorganic nitrogen (ammonia), and micronutrients, such as zinc, manganese, and B-vitamins, is recommended for healthy fermentations. The most common nutrient blends are proprietary and contain varying concentrations of lysed yeast cells and diammonium phosphate (DAP). Lysed yeast cells provide amino acids and micronutrients, and DAP is a ready source of ammonia. This all becomes quite the science project when brewers begin playing around with different yeast strains and nutrient combinations because of the vast number of combinations that can be used. Since the objective is to produce a neutral finished product and because yeast and nutrient blends can be purchased that have been specifically developed to cleanly ferment sugar solutions, many commercial producers of seltzers turn to these ready-made blends and skip the R&D project. A final thing to note about yeast nutrients is they will add a yellowish tinge to the sugar-fermented seltzer, which is one reason many brewers use carbon fining or carbon filtering.

The recipe and instructions provided to the right puts this information to use to produce the same basic hard seltzer described in the previous section, but this time the alcohol base will be produced by fermentation. Note the low starting gravity of the sugar solution. Sugar is completely fermentable by yeast, so this means that fully attenuated hard seltzer base will have little to no fermentables left at the end of fermentation. If you use brewing software or online apps to approximate alcohol in beer, be aware that these tools use regression models to predict alcohol based on large data sets collected from normal beer; these calculators do not work for sugar water mixtures.

Beyond the Basics and Into the Future

The easiest way to flavor a neutral hard seltzer base is by adding unfermentable flavorings and organic acids to the finished and carbonated base produced from the method described in the recipe on page 47. Another simple way to make variants from a single batch of neutral base is to add flavored syrups, a la Berliner weisse, immediately before serving. This is especially appealing for commercial brewers (as well as homebrewers) who don’t want to tie up multiple taps for seltzer.

Neutral hard seltzer bases can be envisioned as the base of a cocktail where sweetness, fruitiness, color, and body are layered onto the base. The challenge becomes product stability; brewers must consider methods to prevent re-fermentation when hard seltzers are packaged. The best method, unavailable to homebrewers and most craft brewers, is tunnel pasteurization following packaging. The addition of potassium sorbate or potassium metabisulfite and/or flash pasteurization prior to packaging are alternates to tunnel pasteurizers. These last points are being directed to any commercial brewers who are reading this article. Whatever is decided, just make sure that unstable product is not packaged and sold.

The summer of 2019 may or may not go down in brewing history as the summer of the one hit wonder known as hard seltzer. In my opinion, I think this style is just getting started and that creative brewers will find interesting and exciting ways to push the envelope. Sugars with flavor, such as honey, agave nectar, brown sugar, Belgian candi sugars, and fruit juices, are the tip of the iceberg. Forrest Gump is my inspiration for the future of seltzer with his monologue about shrimp variants. There will surely be cloudy seltzer, kettle-soured seltzer, barrel-aged seltzer, nitro coffee seltzer, imperial seltzer, triple-double seltzer, PB&J seltzer, zero IBU seltzer, CBD seltzer, herbal seltzer, herbed seltzer (TTB got nothin’ on homebrewing), spiced seltzer, high-calorie, gluten-unfriendly, pastry seltzer, and even peach-mint, orange-hued seltzer. The sky is the limit and homebrewers will certainly be searching for the outer limits. Have fun with this style and don’t take things too seriously.

Hard seltzer

5.25 gallons/20 L
OG = ~1.031  FG = ~1.000
ABV = ~ 5%

Neutral Base Ingredients
21 L reverse osmosis (RO) or distilled water 
4.5 g gypsum (adjusts calcium concentration to 50 ppm)
1.65 kg cane sugar
11.5 g packet SafAle US-05 or other neutral yeast strain
2.5 g Yeastex 82 yeast nutrient added with yeast pitch
2.5 g diammonium phosphate (DAP) added with yeast pitch
2.5 g Yeastex 82 yeast nutrient added 36–48 hours after yeast pitch
2.5 g diammonium phosphate (DAP) added 36–48 hours after yeast pitch

Flavorings
2.8 mL lime extract added after CO2 bubbling (if used) and carbonation
2.8 mL lemon extract after CO2 bubbling (if used) and carbonation
420 mL pulp-free orange juice (single-strength, not from concentrate) after CO2 bubbling (if used) and carbonation
14 g citric acid powder after CO2 bubbling (if used) and carbonation

Step by step
Add water and sugar to kettle, turn on heat, and stir to dissolve sugar. Check solution strength and adjust as necessary; the pre-boil gravity should be ~1.031 OG (7.6 °Plato). Continue heating until solution is boiling and boil for 20 minutes. Check solution strength and dilute as necessary with RO or distilled water. Cool to 64 °F (18 °C) and transfer to fermenter. Add yeast and first addition of nutrients. Aeration is not required for first use of most dried yeast strains, including US-05, due to high glycogen content related to propagation conditions (https://fermentis.com/en/tips-n-tricks/questions-and-answers/). Feel free to aerate as normal if this suggestion seems too unusual. Other common yeasts that are popular for seltzer production are Champagne yeast and distillers yeast.

Fermentation should begin within about 12 hours. The second nutrient addition is added once fermentation has really kicked off and the gravity has dropped by about 0.008 OG; this should be about 36–48 hours after yeast pitching. When fermentation is complete (5–7 days after yeast pitch — FG will depend on yeast and nutrients but should be around 1.000), cool to 32 °F (0 °C) (or as cold as possible at home) and hold cold to permit yeast sedimentation.

Commercially-produced seltzers are clarified by filtration and/or centrifugation, but most homebrewers do not have filters. Part of the seltzer appeal is clarity, therefore, filtration is recommended when going for a facsimile of the real McCoy. The good news is that hard seltzer is easy to clarify using a cartridge filter. But you could also go the Cloudy Claw route and skip this step. Whatever you decide with respect to filtration, transfer the seltzer into a keg and carbonate to 2.8–3.0 volumes. Bottle or keg conditioning is not typical for hard seltzer. Taste the seltzer base to determine if aroma stripping is needed.

Sulfur off-flavors are fairly common with hard seltzers. Carbon dioxide bubbling can be used to strip these unpleasant rotten-egg and burnt-match aromas from hard seltzer. Just make sure to vent the keg during bubbling to allow these volatiles to escape. Nutrient adjustments and/or yeast strain selection on future batches can be made to help dial in the process. The trial and error nature of this process is the primary reason that many commercial seltzer producers select a yeast/nutrient blend designed for these intentionally bland bases.

The last step is to add the flavor additions. Dissolve the citric acid powder in the orange juice and add it along with the lemon and lime aromas. Slowly release the pressure on the keg, open the top while flushing the headspace with CO2, and add the flavorings. Quickly closing the lid and re-pressurizing the headspace will minimize loss of carbonation. The orange juice in this recipe is intended to provide a slight haze, so if you choose not to filter, the juice will complement the haze of the seltzer.