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Flash Pickling

Science Snack
Flash Pickling
Take the pressure off pickling.
Flash Pickling
Take the pressure off pickling.

Infuse vegetables with a tasty brine—instantly—using a syringe.

Tools and Materials
  • Seasoned rice vinegar (the “brine”)
  • Raw vegetables cut into small pieces—cucumbers, bell peppers, carrots, radishes, or your own favorite
  • Clean plastic syringe; larger ones (60 mL or more) work best
  • Cup or bowl for the brine
Assembly

None needed.

To Do and Notice

Remove the plunger from the syringe and fill the barrel with chunks of chopped veggies.

Replace the plunger and squeeze out as much air as you can without crushing the veggies.

Pour some brine into a cup or bowl and draw enough into the syringe to submerge all the veggie pieces.

Point the syringe upward and push out all the air. (You may also want to tap on the outside of the barrel to dislodge any air bubbles.)

Place your thumb at the opening of the syringe to seal it and pull back on the plunger as hard as you can (see photo below). Hold it for a few seconds.

Release the plunger and allow it to snap back into place. Remove your thumb and push out any air that may have appeared in the syringe. Replace your thumb and pull back on the plunger again, as hard as you can. Hold for a few seconds before releasing.

Push down on the plunger to eject the brine from the syringe back into the cup. Remove the plunger, shake the veggies onto your plate, and enjoy your tasty treat.

What's Going On?

Pickles in a flash—not too bad, right? Officially, these aren’t true pickles, a term reserved for foods that are fermented with acid-producing bacteria.

What you’ve really done here would be more properly called flash marinating: rapidly infusing brine into food with the help of a pressure drop. As you might suspect, the secret to the trick lies in extracting the gases that are hiding within the veggies.

Like us, plants must exchange gases with the environment to survive: carbon dioxide in and oxygen out for photosynthesis; oxygen in and carbon dioxide out for cellular respiration. Unlike us, however, plants don’t have lungs or any other fancy gas transport systems. Instead, they “breathe” mainly via passive diffusion of gasses through a network of nooks, crannies, and tiny tubules found in the spaces between cells.

It’s these hidden pockets of “plant breath” that form the bubbles that appear in the syringe when you pull hard on the plunger. The extreme low pressure you create causes the gas pockets in and between the cells in the veggies to expand—courtesy of Boyle’s Law—and burst free from their membranes. When you release the syringe and the pressure increases around the submerged vegetables, liquid gets pushed back into the spaces where the air had been, infusing the vegetables with brine.

Going Further

When pulling on the plunger, you may have noticed tiny bubbles forming in the brine. Believe it or not, this is actually the brine boiling. As the pressure drops, the temperature at which the liquid boils drops, too. The fact that you see tiny bubbles in the brine suggests that the pressure is at or below 0.03 atmospheres, the pressure below which water will boil at room temperature (77°F; 25°C).

For a more personalized pickle, make your own brine by mixing water, vinegar, salt, sugar, and other seasonings to suit your taste.