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Asked by welshbp ·November 15, 2020 ·17.1k readers

LAB gone bad

Hi everyone! Recently had two batches of LAB sit too long with dairy milk. Pretty sure I know the answer, but wanted to see if anyone had experience using LAB once dark mold presented itself on the separated curd on top? Thanks!

lab bad-mold

Top answer

From the KNF library

From the KNF library Drafted by Claude from Office Hours and the books · Sep 2026 · 3 sources

Cho's recipe says to remove the cheese once the culture has run 7 days. Left in place, it melts and goes through a secondary reaction. (Cho, Recipe, p. 55)

The Basic Course recipe pours off only the clear whey and strains if needed. (Student's Manual, Basic Course, p. 17) It also says the curd should be firm and smell sweet. (Student's Manual, Basic Course, p. 17)

An office hours answer gives the smell guide for LAB: sweet turning sour, then yogurt water, then a normal acetone smell on opening. Rotten eggs or vomit means it is bad. (Office Hours Ep. 44, 15:58)

Drake's sources point to this order: lift off the curd, pour off only the whey, then smell it. Rotten eggs or vomit means discard it. (Student's Manual, Basic Course, p. 17) (Office Hours Ep. 44, 15:58)

The library says nothing about dark mold, whether such whey is safe to use, or how long a batch can sit before it is too long.

Sources

1 more answer
suze · Jan 6, 2021
i've used batches that have developed a little pink or grey mold on top by removing it before straining. but if the whey doesn't taste right, bad, or cheesy it shouldn't be considered a good batch.

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