Three identical jars, three feeding ratios, three weeks on the same 4 °C shelf, then one bake-off. This entry is the result. It is the only test in the ledger I ran deliberately rather than as a side effect of baking, and it settled a question I had been guessing at for years: how long a starter can actually sit before it stops being usable, and which feeding ratio buys the most time.
The setup
Three 250 ml jars with loose lids, all filled with the same culture on the same morning. Jar A fed 1:2:2, jar B fed 1:5:5, jar C fed 1:10:10. All three went into the fridge at 4 °C immediately after feeding and were not touched for three weeks.
| Jar | Feed | Week 1 | Week 2 | Week 3 | Bake result |
|---|---|---|---|---|---|
| A | 1:2:2 | Risen, mild | Grey liquid, sharp | Acetone, separated | Flat, pale, 12% rise |
| B | 1:5:5 | Risen, sweet | Thin liquid, sour | Sharp, some acetone | Good, 55% rise |
| C | 1:10:10 | Barely risen | No liquid, mild | Sour but clean | Best, 70% rise |
Why the weakest feed lasted longest
A 1:2:2 feed leaves a lot of sugar in the jar, and the culture exhausts it in the first week; the rest of the three weeks is starvation, which produces acetone. A 1:10:10 feed starts the culture with enough food that it is still finishing the last of it at week three. The trade-off is that jar C was barely risen at week one and would have been useless for baking then.
What to do with a three-week-old jar
Take 20 g, feed 1:5:5 at 24 °C, and give it two refreshes before you bake — one to wake it, one to build strength. The first refresh will take 10-12 hours to dome; the second, 7 hours. Do not bake with the first refresh. A culture coming out of three weeks of cold storage has a shifted population: more acetic acid bacteria, fewer yeasts, and it needs a cycle to rebalance.
- If the liquid on top is dark and the smell is acetone, refresh twice before judging.
- Pink or orange growth is not recoverable. Discard the jar and start over.
- A 1:10:10 maintenance feed once a week (per South Dakota State University Extension) keeps a starter alive indefinitely with no baking at all.
Cold storage does not kill a starter, it slows it and shifts its balance. The jar in this test that smelled worst at week three still made the best loaf after two refreshes.
Sources / 参考来源
Published reference works consulted for this log: