In making fermented pickles, brine strength is critical. A too-salty pickle can be entirely unpalatable, although what’s too salty for one person can be just right for another, and what’s too salty for a person one day can be perfect for the same person a day later. If salt raises your blood pressure, though, fermented pickles aren’t for you at all, because you can’t make them without salt. By regulating the growth of various microbes that are naturally present on the vegetables in the pickle crock, salt minimizes the risk of spoilage and maximizes your chance of producing firm and delicious pickles with a complex, sour taste.
Salt varies in density depending on its coarseness, so in mixing brine you can correctly measure salt by volume only if your salt has the same density as the recipe writer’s. This is why, in The Joy of Pickling, I always call for pickling salt—fine, pure sodium chloride. If you’re using another kind of salt—for example, kosher (which is generally less dense than pickling salt, no matter what the package says)—you may need to measure it by weight rather than by volume. Tables for translating between volume and weight are on pages 38 and 39 of The Joy of Pickling, revised edition.
Now, what if you’ve made up some brine and then wondered whether you’ve done it right? Maybe the salt looks fine to you, but it isn’t labeled as pickling salt, and your kitchen scale is broken. Maybe you’re not sure that you counted cups or tablespoons correctly, or that your scale is accurate. Can you check the brine strength?
You can, indeed, and my Husband the Chemist wanted to be sure I had the tools to do so. So he bought me a refractometer and a hydrometer, and I used them recently while making up brine for beef tongue.
A hydrometer for measuring brine strength is also called, confusingly, a salinometer, a salimeter, a salometer, and a brinometer. My husband bought one at www.butcher-packer.com (search for “salinometer”). Priced at only $13.50, it’s a glass tube sealed at both ends. The swollen bottom end has a lump of lead enclosed at the tip, and the narrow top end has a precisely placed slip of paper printed with a scale. The hydrometer works by the same principle as the egg that picklers once floated to check brine strength, except that the hydrometer tells you not simply that your brine is quite strong but exactly how strong it is.
To use the hydrometer, float it in a tall container of brine. My hydrometer came in a thin, narrow plastic storage tube which is meant to double as a cylinder for floating the hydrometer, but my husband recommends buying a regular hydrometer cylinder, or “jar,” in the size of 500 milliliters. With your hydrometer floating in brine, look for the number at the top of the brine. What does the number mean? To find out, you need a table like the one at www.wedlinydomowe.com (an amazingly complete and authoritative source of information on meat curing); click on “Making Brine,” in the right column on the home page. In the Wedliny Domowe table, the column headed “Salometer Degrees” matches the scale on your hydrometer. Look down the column for your hydrometer reading, and then find the corresponding figure under “Pounds of Salt per Gallon of Water” or “Percent of Sodium Chloride (Salt) by Weight.” To adjust your brine, add salt or water until you get the hydrometer reading that matches the salt percentage or weight you’re aiming for.
Note that a salinity hydrometer is scaled for brine at a certain temperature—normally 60 degrees Fahrenheit. Fortunately, my hydrometer came with a table of adjustments in case the brine is warmer or colder.
Note also that you can accurately measure brine strength only before you’ve added sugar (as is generally done for meat curing, though not for fermenting vegetables). Once you’ve added sugar, the hydrometer will measure the density of the solution, not the salinity of the brine.
A refractometer is fancier and more expensive than a hydrometer. The same basic instrument that grape growers use to determine the sugar content of their grapes, a refractometer looks like a little telescope. You drop a little brine onto the plate at one end and then look into the eyepiece at the other end, aiming the device toward a lighted window or other light source. You see the brine strength clearly indicated on a scale before your eye.
My husband got my refractometer at www.coleparmer.com, where “low-cost” salinity hydrometers range from $105 to $258. One model measures salt content in parts per thousand; others measure the percentage of salt by weight of the solution. You can translate percentage of salt to either weight or volume by using the tables on pages 38 and 39 of my book.
Like a hydrometer, a refractometer is temperature-specific (in this case it’s the temperature of the air, not the brine, that matters), but you can calibrate the instrument before performing your test.
Do home picklers really need either of these instruments? Generally no, in my opinion, but either one can be useful at times, and a hydrometer costs so little that you may want to have one on hand just in case you need it, as well as for science lessons for the kids or grandkids. A refractometer, of course, is a bigger investment. You may want one if you go into pickling as a business.