How to make a gluten-free sourdough starter

Which method for which flour

King Arthur explains why one routine does not fit every bag: gluten-free flour is thirstier than all-purpose, so its Gluten-Free Bread Flour starter takes roughly two parts water to one part flour by weight, where a wheat starter usually takes equal parts. A different blend can need a different ratio. So use the amounts written for your flour rather than borrowing another blend's, and judge the texture: King Arthur aims for thick pancake batter.

Gluten-free does not always mean wheat-free. King Arthur's Gluten-Free Bread Flour contains gluten-free wheat starch, which it says gives the starter the smell and taste of a wheat one; check the label if wheat itself is the problem for someone you bake for.

With King Arthur Gluten-Free Bread Flour

This is King Arthur's method, fed once a day rather than the twice a day many wheat starters get. Use a clear, straight-sided jar from day 3 so you can see how far it grows; a rubber band at the level after each feed makes the rise easy to read.

With King Arthur Measure for Measure flour

Measure for Measure is King Arthur's other gluten-free flour, and its starter takes far less water than the bread flour one: roughly equal weights of flour and water. King Arthur's own amounts are 120 g of flour to start and 121 g in each feed; the difference is in its recipe, not a typo.

With a dried brown rice culture

Cultures for Health sells a dried gluten-free starter that you wake up with brown rice flour. This is not a starter from scratch: the culture comes in the packet, and the method is measured by spoon and cup. Use a clean 1 quart glass jar, a breathable cover such as a coffee filter and a rubber band, room-temperature water free of chlorine and fluoride (bottled spring water, for example), and keep the jar at 70 to 80°F (21 to 27°C).

We give no grams here: rice flour and water weigh differently cup for cup, and the maker asks you to adjust toward a pancake-batter texture, so the exact amounts are yours. If you want to use the feeding calculator later, weigh your own half cups of flour and water once and write them on the jar.

Feeding and keeping it once it works

On the counter, a gluten-free starter is fed once a day; in the fridge, at least once a week. King Arthur's routine for its bread flour starter in the fridge is small: about 11 g of starter, 40 g flour and 80 g water, the rest discarded. Before you bake from the fridge, take it out a few days ahead and give it a couple of daily feeds at room temperature until it bubbles and doubles again (King Arthur).

King Arthur notes that a starter on its Gluten-Free Bread Flour hardly forms hooch, the liquid layer a wheat starter makes when it is hungry, because the blend's gums and fibres hold the water. A brown rice starter can: Cultures for Health says grey liquid on top means it is hungry; stir it in or pour it off and feed.

The night-before build, sized for your recipe

King Arthur's build of 22 g starter, 80 g flour and 160 g water makes 262 g. When your recipe asks for more or less, keep the same proportions: about 1 part starter to 3.6 parts flour and 7.3 parts water. The rows below are that ratio worked out by us and rounded to the gram. The feeding calculator, opened on this build, gives the same 22 g + 80 g + 160 g and splits the 262 g into 240 g for your recipe and 22 g kept back for the next feed; change the amounts there for any other recipe. Its starter hydration is set to 200%, where a starter fed two parts water to one of flour settles.

For same-day baking, King Arthur gives a faster build with more starter in it: about 125 g starter, 44 g flour and 88 g water, which peaks in about 4 to 6 hours.

Healthy, hungry or spoiled

A gluten-free starter that is working is bubbly, smells pleasantly tangy and has a batter-like texture. Do not taste it raw to check: flour is a raw food, and Colorado State University Extension advises judging by bubbles, smell, texture, growth and your notes instead. A strong sour or nail-polish-remover smell usually means it needs food (Cultures for Health).

Slow is the main risk. King Arthur explains that gluten-free starters often ferment so slowly that mold sets in before the starter is acidic enough to keep it out, which is one reason a warm spot matters. Any colored or fuzzy growth means throw the whole starter out, clean the jar thoroughly and start again (Colorado State University Extension, Cultures for Health). More in mold on sourdough starter, or answer a few questions in what is wrong with my starter.

Why not switch your wheat starter over

Feeding a wheat starter gluten-free flour only dilutes the wheat already in it; every feed carries some of the old starter forward. For a starter that is gluten-free from the first day, begin with gluten-free flour or a gluten-free culture in a clean jar with clean tools. To move a wheat starter between white, whole wheat and rye instead, see changing your starter's flour.