The Dead Starter: Pathogen Takeover in Neglected Jars
There is a point of no return. A moment when a neglected starter stops being a culture of beneficial microbes and becomes a Petri dish for pathogens. This transition is chemical. It is driven by a single variable: pH.
Water Activity (Aw): The Secret to Sourdough's Shelf Life
If you leave a slice of supermarket white bread on the counter, it will turn into a brick in 24 hours. If you leave it in a bag, it will grow blue fuzz in 3 days. But a loaf of sourdough, sitting cut-side down on a wooden board, behaves differently. It doesn't mould. It doesn't dry out instantly. It simply... ages.
The Starter Invaders: Mold, Kahm, and Pink Streaks
When you open your jar to find fuzzy islands, wrinkled skins, or neon streaks, it is a sign that the pact has been broken. The acid was not strong enough, or the invader was too resilient.