This isn't a rhetorical question. I'm embarrassed to admit it, but I actually don't know.
During the early days of gloved boxing, it was standard to soak one's face and hands in brine after a workout. Most fighters used only a simple solution of salt and water, but Jack Dempsey reportedly favored beef brine. His ruddy complexion was attributed to it. The brine supposedly toughened the skin and made a boxer less susceptible to cuts.
I have this vision of a boxer walking into a kosher deli and soaking his head in a barrel of pickles. Pass this suggestion along to Chris Algieri.