Asked by jennifer ·February 4, 2021 ·23k readers

LAB smelly after separation

I just made the Police (LAB) in Denver (68 degrees average in the house) and it separated beautifully. I poured it off after @64 hours and it smelled more sour than I'm accustomed to. I usually detect a sweeter smell. I tasted the whey and it's slightly sour. Is it OK to keep going and supersaturate?

lab police separtion smell

The answer

suze · Feb 5, 2021 ✓ Marked as the answer

Different collections of LAB can certainly taste very different. From sweet-ish to bitter to sour to very mild and neutral tasting. "Sour" for me seems to be the most frequent flavor I end up with. As long as it's not a bad sour I think you're fine. Especially if it separated well and you poured it off in a reasonable time frame. Your nose and taste buds know. You don't have to like the taste but as long as your body knows it's not going to make you sick is the important part.

From the KNF library

From the KNF library Drafted by Claude from Office Hours and the books · Sep 2026 · 4 sources

The library does not say whether sour whey is fine to sugar. It does give some reference points.

The Student's Manual says the curd should be firm and smell sweet at pour-off. (Student's Manual, Basic Course, p. 17) Cho describes a sour smell as unique to lactic acid bacteria, though he means the rice-wash stage. (Cho, Recipe, p. 54) So the sources differ on what to expect.

Your 68°F house is below the range where LAB grows best. Cooler temperatures slow separation. (Office Hours Feb 2025, 19:29) The manual says to wait 48 hours or until you see clear separation. (Student's Manual, Basic Course, p. 17)

Pour off only the clear whey and strain if needed. (Student's Manual, Basic Course, p. 17)
Supersaturate with an equal volume of unrefined sugar. (Pure KNF Manual, p. 57)
Record the taste of the final product, as the Pure KNF certification asks. (Pure KNF Manual, p. 57)

Sources

19:29 Office Hours (Feb 2025) — LAB Temperature Fixes, Slug-Eating Nematodes, Worm Bin Slugs · “LAB grows optimally around 75-82°F, and cooler temps just slow separation.”
p. 17 Student's Manual, Basic Course · “Curd should be firm and it should smell sweet Pour off just the clear whey into a glass bowl- strain if needed”
p. 54 Cho, Recipe · “It starts to emit a sour smell unique to lactic acid bacteria.”
p. 57 Pure KNF Manual · “Supersaturate with equal volume of unrefined sugar”