Skip to main content

← All questions

Asked by 21joshmatthew ·February 9, 2025 ·1.62k readers

Papaya Fermented Fruit Juice

Hello! I did the Papaya Ferment Fruit Juice  and at the end some black or brown and white mold appeared on top of it

This is good or bad ? the FFJ still smells like papaya and sorry for the newbie question, if you care to elaborate more it will help a lot.

fermented-fruit-juice papaya

Top answer

From the KNF library

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

The library says nothing about black or brown mold, and nothing on whether this batch is safe.

Cho's notes on plant juice say white mold can appear when material soaks too long. Fermentation then runs abnormally fast. (Cho, Recipe, p. 36) That note covers bamboo shoots, not papaya. (Cho, Recipe, p. 36)

Smell is the other check. Drake says finished fermented fruit juice should not smell or taste like alcohol or vinegar. (Office Hours Ep. 14, 35:45) That line is about year-old stored juice. It differs from the human answer, which treats a slight alcohol smell as a sign the ferment is done. (Office Hours Ep. 14, 35:45)

Cho's method puts enough black sugar on the top surface and covers the pot with paper. Compare your top layer to that. (Cho, Theory, p. 77)

Sources

Also discussed on Office Hours

Know the answer? Members answer, ask, and get their questions onto the Sunday show.

Sign in Become a member