What "Discard" Actually Is

Discard is just unfed sourdough starter. It still has flavor, mild acidity, and some leavening power (just not enough on its own to lift a bread loaf reliably). Treat it as a flavor-and-texture ingredient, not a leavener.

Discard is roughly 50% flour and 50% water by weight (because that's the ratio you've been feeding). So when a recipe calls for "100 g discard," you're effectively adding 50 g flour + 50 g water + a tangy fermented kick.