A doubt on how to ferment for FPJ
Hi Eric, I'd like to clarify a doubt if you'll be so kind to help: in the second video of your classes on lev.1 knf, at 1h:26' or thereabouts, you state that a sugar cap on the comfrey fpj is a wrong practice, that is made for ripe fruit extracts but not for leafy material fpj (or fpj in general).
Why is that? I'm trying to understand the dynamics of the method and I came to understand what enormous difference a seemingly small detail can make.
I mean: the compaction of the material in the fermenting vessel, well enough ensures an anaerobic environment in which the Lacto bacilli can operate and as well the yeasts, given that lab do not care about oxigen presence for they lack respiratory organs, yet the yeasts are hindered by its presence, wouldn't you ensure a more correct fermentation of the top layer with a sugar cap rather than without it?
Besides, some older texts, like Cho's recipe book, does include a sugar cap in fpj making.
Would you please elaborate on this sugar cap detail please?
Top answer
The sugar cap is not necessary for fermenting plant juice to make KNF Food. The sugar cap is used when fermenting fruit juice because fruit tends to have a higher concentration of sugars and moisture, so it needs the additional sugars to create osmotic pressure to pull the liquid out of the cells before fermenting.
The recommended sugar to plant material weight is 1:1/3-1/2, so 1 kilo of plant material would be mixed with between a third to a half kilo of brown sugar. When making from fruit, the recommended sugar ratio is 1:1, so one kilo of fruit to one kilo of sugar, with a portion of the sugar reserved to make a sugar cap.
Adding a sugar cap to less sweet plant material increases the osmotic pressure too much and retards fermentation.
From the KNF library
From the KNF library
Drafted by Claude from Office Hours and the books
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Sep 2026
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4 sources
Drake's recipes mix the sugar with the leaves, then pack the mixture tight, two-thirds full. (KNF Demystified, p. 33) The stated aim of packing is to keep the air out. (Student's Manual, Basic Course, p. 36)
Sugar's job in FPJ is osmotic pressure on the plant material. (Pure KNF Manual, p. 38) The library gives two amounts. One recipe adds roughly equal parts sugar by weight. (KNF Demystified, p. 33) Another says to use less sugar up front, just enough for extraction, then add more afterward to preserve the juice. (Office Hours Ep. 64, 52:33)
The library does not cover yeast and oxygen in the top layer. It does not explain why Cho's recipe caps FPJ with sugar.
Sources
- 52:33 Office Hours Ep. 64 (Feb 2023) — Desert IMO Collection, Pasture Regeneration, FPJ Sugar Ratios · “Use less sugar up front, just enough for osmotic extraction, then add more sugar afterward to supersaturate and preserve it.”
- p. 38 Pure KNF Manual · “Sugar exerts osmotic pressure when put in close proximity to plant material.”
- p. 33 KNF Demystified · “Tightly pack fermentation vessel 2/3 full with plant/sugar mixture”
- p. 36 Student's Manual, Basic Course · “The idea is to keep the air out.”
2 more answers
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Jul 5, 2018
I have not tried a fpj without a sugar cap yet.
From my understanding the sugar cap is in place to inhibit mold growth because it acts as a preservative.
I have checked out Master Cho's book and he writes of using a sugar cap for FFJ ("put enough sugar on the uppermost surface") and writes of using a sugar cap for FPJ ("cover the uppermost part with black sugar"). He illustrates the sugar cap for the FFJ, however, he DOESN'T include a sugar cap in the illustration for the FPJ. There is a discrepancy here.
Making FFJ is done by layering the material and sugar like a sandwich, making FPJ is not. It would make sense to end with sugar as the sweet material needs the sugar for the osmotic pressure to draw the essence out. FPJ doesn't need the sugar cap and in fact it makes the FPJ unnecessarily sweet, diluting the essence further.
When I have made FPJ, I have at times had some mold but it looks like IMO- it is fermented at that stage. It smelled fine- slightly fermented and sweet. Just as we make IMO and culture what appears to be mold, it doesn't mean the mold is bad. I have poured the FPJ off, added the stabilizing additional brown sugar and have never had a mold issue or had my FPJ go "bad".
I vote to keep the essence of the FPJ as concentrated as possible and avoid using the sugar cap, following the illustration in the book. This is also the way Drake has taught me and it works.
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