Yes, obviously it can vary. I'm just looking for an approximate range, as a good place to start for my first time making a batch.
A good answer would be something along the lines of:
10 to 20 grams of salt per 100 grams of raw cabbage
Or something like that.
[EDIT: that was just the format of answer I wanted. That actual ratio would probably be about ten times too much salt.]
2% (20g per 1000g) would be my default recommendation based on sources local to me, but with care less salt may work if sanitation is extremely good (to minimize introduction of undesirable bacteria which the salt helps to supress.)
On the high end, I can say that 4% seems to slow things down, but work, and 8% seems to be simply too much. The pictured jars are 2%, 4% and 8% salt, using red cabbage, which acts as a pH indicator. The 8% jar (rightmost) has not turned pink (and is growing mold on the surface) while the other two are successfully acidifying (the 2% somewhat faster than the 4%) and mold-free. The lids are put on "fingertip-tight" as in canning, so they form a crude but effective airlock seal (they "burp" themselves as needed, just as in canning - they are not loosened manually to relieve pressure.)
Actually 75% red cabbage and 25% apples for these. And the stuff on top is some ceramic tile as improvised weights. Other than for pictures, they are kept in the dark.
I checked a few German Sources1 and found a range between
So anywhere between one and a generous two teaspoons per kilogram (two pounds) should be fine.
But what exactly is the salt doing in your cabbage/sauerkraut?
Well, in theory you could leave it out. The bacteria and yeasts necessary for the process will work just fine without it. Unfortunately, so will unwanted bacteria which may be present on your equipment, your cabbage or your environment. Should you choose to try this, work very cleanly, sterilize your gear and do not attempt the open jar method. Still the risk of failure is high.
Salt in your cabbage will hinder all microbiological activity, including your "friendly ones". But unwanted "guests" will be affected far more than your desired acetic and lactic acid bacteria in the range recommended above. Too much salt will stop all fermentation, salt is a preservative, after all.
There is another reason to add some salt, though: The addition of salt supports the release of liquid from your shredded cabbage (together with "kneading" or "pounding" the cabbage), effectively speeding up the formation of the brine.
1 I guess we are nicknamed Krauts for a reason...
This PDF from the University of Wisconsin says to use 2.25 - 2.5 % of non-iodized salt by weight.
Based on converting from the barbaric units from this source, I guess something like:
15 to 23 grams of salt per 1000 grams of cabbage
