Fermentation

How to tell it is going right

• Held somewhere with a steady temperature it can actually work at, chosen on purpose rather than wherever there happened to be room.
• There is visible activity before it is called started: bubbles, rise, or movement in the liquid. A ferment showing nothing after its first hours is not slow, it is not going.
• It smells clean: sour, yeasty, or alcoholic, with nothing putrid, and with nothing fuzzy or coloured growing where air meets it.
• Everything is under the liquid or under a cover, as the method requires: nothing solid left sitting dry in the air to spoil while the rest works.
• Judged by taste and behaviour and then STOPPED: chilled, baked, or refrigerated at the point wanted, rather than left running because the stated hours had not elapsed.

Where it goes wrong It was run on the clock in a kitchen colder or warmer than the recipe assumed. Fermentation is a rate and not a duration, so the same number of hours gives an under-developed ferment in a cold room and a slack, over-soured one in a warm one, and only tasting it would have said which.