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Asked by agnese.federica ·October 22, 2021 ·16.1k readers

FPJ supersaturation

Hi there! My question is about the addition of brown sugar during the preparation of the fermented plant juice. I have seen it done by adding sugar for double the amount in weight of the plant before the fermentation, and I have seen it done by adding half of the amount in weight and saturating the solution after the fermentation. Is there any difference, and if so, what? Thank you!

fermentation fpj supersaturation

Top answer

Drake Weinert L4 Instructor · provisional Foundation · Oct 31, 2021
There is a huge difference in terms of the fermentation that takes place. Adding too much sugar before fermentation retards (slows) it down. This can be a benefit when fermenting fruits, which are very high in moisture, because the extra water may make the fermentation happen too quickly, but this can be not so beneficial when doing plant material such as growth tips, because the excess sugar does not complete. The recipe recommends about 1/3 to 1/2 the weight of plant matter, or in the case of fruits equal parts to 1.3x more sugar than weight. So in example, if I have 3 lbs of plant tips, I should add 1 lb of sugar, or if I have 3 lbs of fruit, I should add 3 lbs of sugar. This will ensure great fermentation. To super saturate, which is the preservation method, this should be done after fermentation. Details can be found here.

From the KNF library

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

Drake's aim is to let fermentation happen once, then saturate the liquid with sugar to stop it. (Pure KNF Manual, p. 38)

The library treats the second sugar addition as a storage step:

  • The UH–CTAHR guide says to add an equal weight of brown sugar to the FPJ after fermentation.
  • The Pure KNF Manual says to add equal volume to be safe. To save sugar, add it slowly and stir thoroughly. (Pure KNF Manual, p. 80)
  • Master Cho says the extra sugar concentrates the juice, so it does not oxidize or turn to alcohol. (Cho, Theory, p. 71)

The two sources differ on the unit: weight in one, volume in the other. (Pure KNF Manual, p. 80)

The library does not compare the double-sugar-first method with the half-sugar method directly.

Sources

  • p. 71 Cho, Theory · “When storing it, put more black sugar to make it more densely concentrated so that it may not oxidize or turn to alcohol”
  • p. 80 Pure KNF Manual · “add equal volume as with PurePolice, but to be economical and not to waste sugar, add the sugar slowly and stir thoroughly.”
  • p. 38 Pure KNF Manual · “In our case, we want fermentation to occur once, then we want to super saturate the liquid with sugar to arrest the fermentation.”

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