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Asked by cristthomas365 ·September 25, 2023 ·12.3k readers

Decreasing volume of Vinegar

Started a Grapefruit vinegar about 5 months ago with about 2/3rds of a gallon by volume with breathable lid. As time has passed the volume has decreased  to slightly more than 1/2 a gallon, wondering what going on? Ethanol evaporating before being converted to acetic acid?

vinegar

Top answer

From the KNF library

From the KNF library Drafted by Claude from Office Hours and the books · Sep 2026 · 5 sources

The library does not explain the volume loss. It says nothing about evaporation, ethanol or otherwise.

It does cover the method. Cho's banana vinegar uses a breathable lid and takes 3 to 6 months. (Cho's Solutions, p. 8) Drake's teaching is that air turns alcohol to vinegar, and alcohol only stays alcohol if sealed airtight. (Office Hours Ep. 17, 30:20) Master Cho's method is the same: leave it exposed so acetic acid bacteria turn it into vinegar. (Office Hours Ep. 66, 1:02:09)

The timelines differ across sources. The student manual says 3 months at room temperature. (Student's Manual, Basic Course, p. 40) A kombucha SCOBY start finishes in about two months, depending on temperature. (Office Hours Ep. 37, 8:08) At five months, your jar is inside the 3 to 6 month range. (Cho's Solutions, p. 8)

To speed a slow batch, Drake recommends adding a splash of living vinegar or a mother from an existing vinegar. (Cho's Solutions, p. 8)

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