What Is Sourdough Starter Hooch? (It's Not What You Think)

Hooch is a thin, watery, grey-to-brown liquid that separates from your starter and collects on top when the starter hasn't been fed for a while. It forms because the heavier flour settles to the bottom while the liquid rises. The liquid turns darker over time as flour particles lighter than water and dead microorganism cells float to the surface and oxidise. It's primarily ethanol (alcohol) produced by the yeast as it runs out of simple sugars and starts metabolising its own fermentation products. It may also contain water and some dissolved acids. The name comes from bootleg alcohol — but sourdough hooch is not drinkable, not toxic, and not a problem. It's a hunger signal. There's even a small protective benefit: the liquid layer creates an anaerobic zone at the top of the jar, blocking aerobic mould from colonising your starter while you're not feeding it.

The starter goes through its peak — full of activity, all the available sugars consumed — and then continues fermenting in a starved state. As food becomes scarcer, the bacteria and yeast shift their metabolic balance toward more acid and alcohol production. The alcohol, being less dense than the starter paste, rises to the top and pools as liquid. Hooch usually appears 24-48h after the last feed on a counter starter, or after more than a week in the fridge. The earlier it appears, the hungrier your starter's metabolism and the more frequent your feeding schedule needs to be.

Both options are fine. Stirring it back in gives you a slightly more sour starter — the acids dissolved in the hooch get reincorporated. Pouring it off (or spooning it out) before feeding gives you a slightly milder starter. If your bread has been coming out too sour recently, pour the hooch off. If you like the sourness, stir it in. There's no wrong answer. After you decide, discard to your maintenance weight and feed as normal.

Hooch is a liquid — grey, brown, or yellowish. It has a sharp, alcoholic or vinegary smell. It is flat and sits on top of the starter. Mould is fuzzy, dry, and has colour: pink, orange, green, blue, or white with texture. If what you're looking at is clearly a liquid and smells like alcohol or vinegar, it's hooch. If it has any fuzz, any dry texture, any unusual colour beyond grey or brown — that's mould, and the starter needs to be discarded. When in doubt, smell it: hooch smells like a sharp, sour spirit; mould smells like rot.

Feed more frequently. On the counter, a 1:1:1 starter at 22°C should be fed every 12-24h before hooch appears. In the fridge, feed every 6-7 days. If hooch keeps appearing well before your expected feed window, your starter has a faster metabolism than your current schedule allows — either feed more often, use a larger ratio (1:2:2 or 1:5:5 to extend the window), or move the starter to a cooler spot to slow fermentation.