by Tom Cucuzza – The Sourdough Journey
Can You Use and Unfed Starter Directly from the Refrigerator?
Can you use an unfed sourdough starter directly from the refrigerator?
You can, but it has about 25% less rising power than a recently fed starter.
In this experiment, I measured the CO2 generated by two sourdough starters:
1) A recently fed starter, at room temperature, fed 3.5 hours prior and just peaking in volume.
2) The same source starter fed 7 days prior, and refrigerated (3.5 hours after feeding, at peak). In fridge, unfed for 7 days.
Both samples were brought to the same starting temperature and mixed with the same 1:1:1 feeding (10g starter, 10g flour 50/50 bread/WW, 10g filtered water).
The fed starter outpaced the unfed starter throughout the test. It began generating CO2 earlier and peaked in volume (height) about 2 hours earlier than the fridge starter.
The refrigerated starter eventually “caught up” with the fed starter and created the same amount of CO2 by the 18-hour mark.
The recently fed starter had a higher starting pH (lower acidity), but after 12 hours, the pH of the fed starter dropped below the refrigerated starter. Refrigeration impacts the microbial makeup of the starter.
The refrigerated starter loses about 25% of its rising power during that 7-day period in the refrigerator, as compared to the recently fed starter.
Testing Method
I use specialized pressure vessels to measure the CO2 generation (Don’t try this at home! High pressure can be dangerous). I also measure the pH, temperature, time-to-peak, and volume change (height) of the samples in a highly controlled test environment.
I’ve been fine-tuning this equipment and method for about 6 months, and I believe the results are quite accurate, but I have not replicated this particular test multiple times yet.
Multiple pH testers are used for continuous monitoring. The testers are calibrated before each test but there can be some measurement variations (+/- .10) between the different pH testers.
Tom Cucuzza
Is a refrigerated starter as strong as a freshly fed starter?
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