How small brewers build a flavor

Reading a can that says blueberry ginger, you might assume the flavor was decided when the blueberries went in. Most of the decisions came much earlier, and a brewer has several places to shape the result. Working through them in order gives you a way to read a kombucha. It also gives you better questions for whoever made it.

Two choices made before anything ferments

Culture is the least visible decision. Oregon State researchers found four main types of SCOBY among the 103 they sequenced. They also said more research is needed to tie each type to acidity, flavor and aroma. So nobody can yet read a bottle and name the culture behind it. A later study in Frontiers in Microbiology found microbial makeup was the strongest factor in how the drink smelled to a trained panel. It beat the type of tea. Yesfolk Tonics lists its own house kombucha culture on its FAQ, right beside its tea and sugar.

Tea and sugar come next, and the sourcing can get quite specific. Yesfolk uses single-origin tea. Zak's Kombucha buys oolong from small farmers in the mountains of northern Thailand. It pairs that with organic cane and panela sugars in its Sparkling Oolong. The Kombucha Code of Practice, from Kombucha Brewers International, allows a range of sugar sources. It also names a style called jun, where raw honey is the only sweetener allowed. Zak's goes further on the plant side, with herbal brews like its lavender that use no added tea.

Time and the vessel

Fermentation length may be the simplest dial a brewer has. The Code says the taste moves from pleasantly fruity and tangy after a few days to vinegary after a longer time. The Harrison and Curtin paper notes that producers set their end points by the sweet and acid balance they want. Published timelines vary widely. Baba's Brew ran seven days in its first ferment when PA Eats visited. Brew Dr. reports around 2 to 4 weeks.

Container choice can change the drink as well, and oak is the clearest case. Yesfolk says on its FAQ that it ferments in oak barrels made in the Adirondacks. A 2021 roundup of small brewers on Yahoo Lifestyle credited that oak with rounding out the usual acidity. The same piece described Yesfolk's roasted oolong as creamy, with notes of cacao and tamarind skin.

Flavor before fermentation, or after

Timing separates two approaches to added ingredients. The Code allows botanicals, fruit and other ingredients to go in during the steep, so the microbes ferment them along with the tea. Brew Dr. does this for its base, blending tea and botanicals in the brew tank by recipe. Its page on craft brewing says it avoids brewing plain tea and flavoring it as an afterthought. It does still add some fruit juice or ginger extract near the end for its bolder flavors.

The other route is a plain first ferment followed by a flavor infusion. Under the Code, this step counts as a secondary fermentation when the flavorings contain fermentable sugars. The founder of Contraband Ferments explained the approach to Edible Brooklyn in 2017. A finished ferment moves to a new vessel with fresh fruit, dried fruit, whole spices, herbs or juices. It stays there anywhere from two days to several weeks or months. The founder plans combinations and amounts first, tastes daily, and finds frozen berries work best. Favorites in that roundup included blueberry peach basil and sage with tart cherry.

Local and seasonal sourcing gives small brewers a lot of their range. Baba's Brew used local strawberries for a strawberry-basil version. It also built a play on root beer from wintergreen, sarsaparilla, molasses and ginger. Zak's gathers magnolia flowers from a garden near Sevenoaks each spring. Its Citrus Hops combines oolong with three varieties of Kent-grown hops. Brew Dr. makes a related point on its craft page, saying small batches leave more freedom for seasonal ingredients.

Limits exist too, at least for brewers following the trade standard. The Code caps optional ingredients, flavorings and juices among them, at 20 percent of the finished product by volume. Above that level, it requires a dilution percentage on the label for products not made from kombucha base.

Aging, blending and leaving things out

Some of the most distinctive decisions come at the end, or involve adding nothing at all. The Code recognizes a tertiary fermentation, where kombucha stays in the bottle for a while to change its flavor or fizz. It also allows filtering at any stage to remove excess yeast. Unified Ferments says on its FAQ that it uses blending, aging and clarity to set its drinks apart. The result can taste quite different from the kombucha on store shelves.

Bon Appétit reported that Unified Ferments lets the tea do the talking, with no added fruits or flavorings. It sells in 750 milliliter bottles and names each one after its single-origin tea.

All of this gives you better questions for any brewer. You can ask which tea went in, how long it fermented, in what vessel, and whether the flavor went in before or after. You can ask the same things about any flavor on a shelf, from ginger to jasmine. The sealed carbonation stage may matter less than you would expect, at least without fruit. The Frontiers researchers found it had less effect on how samples smelled and tasted than the microbes did.