Cucumbers can be made sour by giving sugar to lactic acid bacteria (I do not like vinegar).
Do you really need salt and can it be avoided, or what is the minimum if you do need it as preservative?
Example: "You want to make a very salty solution of at least 5 percent".
Why?
Yes, you need salt. Salt selectively inhibits mold and bacteria which would otherwise out-compete the lactic acid bacteria. I'm sure you've seen vegetables rot; that's fermented cucumbers without salt.
There's no absolute minimum salt concentration. The less salt you add, the funkier and slimier the final product will be, and the more likely you'll be to end up with rotted vegetables. If you're using less salt, you'll also need to be more careful about fermentation temperature, and you may need to directly inoculate the pickles with a selected strain of lactic acid bacteria to help them compete.
Salt is necessary for lactic fermentation of vegetables. It is one of several components to creating a successful lactic acid ferment. Lactic acid lowers the pH of its environment rapidly, and to the point where competing, problematic organisms can't grow. You will probably need 2% salt at a minimum, but slightly higher amounts of salt will give you more wiggle room on safety. The temperature also matters, as this will impact the speed of fermentation. Further, you want to keep your ferment in an anaerobic environment (no oxygen exposure, such as submerged under a brine). So, there are a few variables to consider. To be more confident, and if you are a novice, you might want to measure the pH of your finished product, aiming for 4.6 or lower. There is a ton of information on the internets about the lactic fermentation of vegetables. It is not difficult to do, but before you start playing around with minimum amounts of salt, you should be absolutely sure about the mechanisms of the process so that you don't get yourself, or someone else, sick.
