After I sliced and served my last Kosher style pickle, I was left with a jar filled with wonderful brine. Rather than just throw it out, I got some more cucumbers from the garden and plunged them into this brine, to see if I could make even better pickles by reusing it. About five days later, the cukes had transformed themselves into rather bland pickles and there were white curds (different from the scum that had formed with the original batch) floating on the top.
Knowing from my bread making experience how often wild yeasties invade a casually tended sourdough, I should have expected this. My pickle brine was a giant petri dish, and the chance of getting the same product two times running was probably about the same as life forming from carbon molecules in the early days of our planet. So the answer is: drink the stuff, or experiment with it in potato salad or maybe a Bloody Mary (both these uses are mentioned on various websites). But don’t expect that your pickle juice will ever get better than the day you crunch into that perfect half-sour. Start fresh the next time around, with everything thoroughly cleaned.
Speaking of the internets, in the course of my research I found there is quite a culture (sic) of people who re-use the pickle liquid from commercial pickle jars. They soak vegetables in it, or spray it on potato chips. So in the interest of science, I brined some chicken thighs in liquid from a gallon jar of Vlasic pickles and blanched some garden green beans and plunged them into the same liquid (though not with the raw chicken) along with a couple garlic cloves and a few flakes of red pepper.
Note that this is a completely different substance than my pickle brine, though it’s interesting that people on boards like chowhound seem to talk about the two liquids interchangeably. A commercial pickle jar liquid is vinegar based and it’s also going to have preservatives and stabilizers in it. Thus it would seem unlikely any chemical reaction is going to take place. More likely the pickling is done with another process, then the pickles are transferred to the jars for preservation and distribution.
And indeed my chicken thighs (after 8 hours) had a mild tang, but none of the moistness and tight texture of meat that had ben brined. The beans (after 24 hours) were also pleasant, but tasted like beans flavored with pickle jar liquid. No chemical transformation had taken place.
So, no. Other than the exceptions and adaptions above, I would say you can’t reuse pickle juice. It’s like a soufflé. Enjoy, then move on.