The exact microbial composition varies, but the key to sourdough is the cooperation between bacteria and fungi. “In addition to yeasts, naturally occurring lactic and acetic acid-producing bacteria are an integral part of the starter,” Shallcross explains. “These contribute to the characteristic textures and flavors of sourdough.”
To set the sponge—which is a starter that can be fed and used again—bakers take a half-cup of starter and add equal parts flour and water to feed the yeast. After being left for six to eight hours, the sponge will have gained half its bulk.
While old-timers added flour to the starter to shape into a ball for easier carrying, today’s sponges can be stored in a refrigerator or cool place for future use.
“You need to leave plenty of room in the container for it to expand,” says Shallcross, “and you don’t want to put it in a metal container because it could react with the acid. If you really don’t want to refrigerate it, you can dry your starter and then reconstitute it with water.”
According to Emilie Raffa—a cook, baker, and author of bestselling book Artisan Sourdough Made Simple and the blog The Clever Carrot—the overall feeding process for a starter typically takes seven days if the temperature is warm enough. However, it can take up to two weeks or more for a strong starter to become established. She advises those making a starter to find a warm spot for the starter to rise and to use warm water in the feedings (if necessary) to give the fermentation a boost.
She notes that, as part of the feeding process, most bakers discard some of their sourdough starter before adding fresh flour and water to the jar. This is done to refresh the acidity levels and to manage its overall growth in size.
Making a Business of Sourdough
Once a starter starts, it’s a living thing, practically immortal if treated with care. The Bake Shop, a bakery in Girdwood, has a 100-year-old starter that has earned a widespread reputation.
“People come from all over, very excited about our starter,” says Isha Kari, who owns The Bake Shop with her husband, Brian. “They’ve heard lots of things about it, and our bread and our pancakes are widely coveted.”
Whether a starter is 100 years old or 2 weeks old, Kari says it must be cared for. “You must either feed it regularly or put it into a dormant state, which we do by refrigerating it,” she says. “In November, we close our shop for a month, and we refrigerate it until about a week before we reopen. Then we take our time feeding it daily to get it back to a happy state.”
While there are rumors as to where the starter originally came from, Kari says she doesn’t have the answer. “I think an old miner may have brought the starter with him, but that is a bit of an old wives’ tale. Who really knows for sure?” she says. “But Alyeska sourdough is unique because it has lived and thrived in this valley for all these years.”
The pragmatic reason for pioneers to carry sourdough recurred during the COVID-19 pandemic. Home baking became instantly popular, which emptied store shelves of baker’s yeast within a matter of weeks. Luckily, wild yeast leavens just as well (if more slowly) and can be harvested anywhere.
“During the pandemic, many have started baking it at home and, on social media, sourdough reached a massive peak as a sign of consumer engagement,” said Karl De Smedt, the curator of the world’s only sourdough library, in an interview with The Fermentation Association, a group founded in 2017 to support food, beverage, and supplement producers. “No wonder because it truly has a unique, rich taste.”
Located in the Belgian village of St. Vith, 87 miles southeast of Brussels, the Sourdough Library houses the world’s most extensive collection of sourdough starters. It was established in 2013 by Puratos, a company that serves the bakery, patisserie, and chocolate industry worldwide. According to the company, 52 percent of today’s consumers know of sourdough, and approximately 45 percent of consumers associate sourdough with better taste. Nearly 30 percent associate sourdough with the terms “rustic,” “healthier,” and “more natural.” Indeed, some studies have shown the bacterial action makes sourdough more digestible than other breads.
The first printed mention of sourdough in Alaska comes from 1887, referring not to bread or prospectors but to fermented liquor. That tradition lives on west of Fairbanks.
Ursa Major Distilling produced Alaska’s first rum using a 60-year-old sourdough starter. The company, originally established in a “tiny little shack” on Chena Ridge in 2012, now sells this rum—which it markets as “an honest rum with no added sweeteners, spices, or flavorings”—out of its larger location in Ester, which opened in 2014.
“There weren’t a lot of folks distilling alcohol up here, so we pretty much learned to hand make everything. We’re good at making something out of nothing,” Ursa Major owner and distiller Rob Borland says with a laugh. “We started making vodka and then gin at some point, and when we decided to make a new product, we thought it would be fun to make some rum.”
Borland researched Jamaican rum fermented in dunder pits where all-natural yeasts are combined with molasses and sugarcane. “The bacteria from the sugarcane is what gives it its funkiness,” says Borland.
This led to his experimenting with sourdough. “Every Sunday morning, I make sourdough pancakes, and I started to wonder what would happen if I threw sourdough in the rum. I figured it would make a unique Alaskan product,” he says.
Borland’s 60-year-old sourdough originally came from Lake Clark, where he notes it was “fairly famous.” He bought a bag of it at a school fundraiser for $1 and has used it ever since to make pancakes.
“It turns out that it gives the rum funk—what I call the sweeter notes,” he says. “The bacteria makes more esters, or fruity flavors, and it has a bready sourdough taste on the tail end. It gets even better with age; the barrel-aged product we make turns out really well.”
Ursa Major Distillery makes a white rum called Fairbanks Sourdough, and its Tanana Gold brand is the same rum aged for a year in an oak barrel. “Aging smooths it out a little bit,” says Borland, adding that the next rum batch will be aged for two years, with the long-term goal of creating a three-year aged rum.
