If you were to crack open a can of hard seltzer and pour it into a glass, there isn’t a lot to look at, and that’s the point. Clear, robustly fizzy and a modest amount of flavoring are what drinkers have come to expect from the popular beverage category.
The ingredients of hard seltzer are simple: water, sugar, yeast and flavoring. Putting them together correctly is the challenge.
“There are so many variables that need to be considered to make the ingredients taste like nothing, in a sense, before adding in flavors and creating something that people are willing to drink,” says Dave Colt, cofounder and brewer at Sun King Brewery in Indianapolis. “Making it well is not for the faint of heart.”
What’s in Hard Seltzer?
Water used for hard seltzer should be as close to neutral as possible, with no real discernable flavor. Some breweries achieve this by using a reverse osmosis system, which removes contaminants and microbes from water. Other producers are lucky enough to have a suitable natural water source.
Hard seltzers are categorized as a flavored malt beverage, or FMB, according to the Alcohol and Tobacco Tax Trade Bureau (TTB). But the main fermentable source is usually sugar. Topo Chico Hard Seltzer doesn’t feature actual tequila, for example, but rather an alcoholic sugar base. Producers often use cane sugar or dextrose and mix it with warm water to create a sugar wash. Honey may also be used. The base is then pitched with yeast to begin fermentation.
A neutral yeast, one that does not release a lot of esters or phenols, is best as it helps producers to achieve a clean beverage. This is where things can get a little tricky.
The Fermentation and the Scrub
When a brewer makes beer, the grains used often provide ample nutrients for yeast to thrive during fermentation. Sugars alone provide little sustenance for yeast, so hard seltzer makers need to add nutrients to the wash to keep the yeast happy, flourishing and creating alcohol. The developing beverage may also have a slight discoloration at this point and be either vaguely yellow or partly cloudy.
“You can ferment a seltzer in two to five days, but it tastes horrible, and it smells like sulfur,” says Hopper Seeley, president of Grind City Brewing Co. in Memphis. “At this point you really need to clean the seltzer, scrub it.”
This is achieved through several different filtration methods. Producers might use a centrifuge, plate filters or even charcoal filters, which turns the seltzer black but removes unwanted flavors and aromas. It’s then scrubbed again to produce a clear liquid.
Getting the Right ABV
There are a number of reasons why hard seltzer appeals to so many people. Among them are a low carb and calorie count—100 calories or fewer is ideal—and an alcohol by volume (abv) that’s often around 5%, lower than many other canned alcoholic drinks.