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Asked by helmut ·August 28, 2018 ·15.9k readers

FPJ

I made some FPJ from hona hona grass. After six days of fermenting, there were many clear sugar crystals in my fermentation jar. I used brown sugar. Did I do something wrong?

Top answer

Drake Weinert L4 Instructor · provisional Foundation · Aug 30, 2018
Sounds like you may have added too much sugar? A plant like honohono grass has very little sugar content, and thus not much additional sugar is needed to create the osmotic pressure necessary to get the juice to come through the cell wall. Master Cho's book recommends using between 1/3-1/2 of the plants weight in sugar for making FPJ. So if I have 1 pound of honohono grass, I will typically add about a half pound of brown sugar to start the extraction. Though others say the sugar cap is necessary, the literature only suggests the cap on the Fermented Fruit Juice recipe, where also the sugar is 1:1 or greater. Adding additional sugar on the top does not make any measurable difference in practice.

From the KNF library

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

Six days is not too long. The manual says fermentation should happen in 2-3 days and no longer than 7 (Student's Manual, Basic Course, p. 36). Cho puts full fermentation at five to seven days when it is about 20 Celsius outside (Cho, Theory, p. 71).

Check the jar against Cho's signs. The fibers float. The color turns from green to yellow green. A sweet smell comes out (Cho, Theory, p. 71). If you see those, fermentation is done, and you can strain the juice.

Extra sugar is part of the plan after that. Drake's manual says to ferment once, then saturate the liquid with sugar to arrest the fermentation (Pure KNF Manual, p. 38). For long-term storage, combine the FPJ with equal parts brown sugar (Student's Manual, Basic Course, p. 36).

The library does not say what the crystals are or whether they signal a mistake. It says nothing about honohono grass in particular.

Sources

  • p. 36 Student's Manual, Basic Course · “Fermentation should happen in 2-3 days, no longer than 7 days”
  • p. 71 Cho, Theory · “when outside temperature is around 20 Celsius, full fermentation is completed after five or seven days”
  • p. 38 Pure KNF Manual · “we want fermentation to occur once, then we want to super saturate the liquid with sugar to arrest the fermentation.”

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