Q: How do you extend the life of spinach or other greens? They seem to go bad SO quickly.
The two things that make leafy greens spoil quickly are moisture and air – they work in tandem with bacteria to break down the cell walls and create the “slime” that coats greens after a few days in the fridge. When vegetables look fresh from the store (or better yet, the garden) the cells are full of water and push out against their cell walls (this is, honestly, known as “turgid”). As soon as a plant is cut off from it’s water source, the cells start to very slowly lose water via evaporation. When this happens, the cell walls start to collapse in on themselves and the leaves begin to wilt.
Eventually, the cells have lost enough water that the cell walls start to break down and create that “slime” that shows up after a few days in the fridge.
The first instinct most people have is to seal up leafy greens in an airtight container in order to prevent evaporation. However, this usually leads to them spoiling even more quickly. This is because the water still evaporates from the cells, but with nowhere to go, it hangs out in the air near the leaves and adds more moisture and “weight” to the air, which encourages the cells to break down even more quickly.
The best way to store leafy greens in the short-term (up to a week or so) is to wash them in cold water, pat them mostly-dry, and wrap them in paper towels (no more than one or two layers of greens – if you have more, layer them with more paper towels). Then put this paper-towel-greens layering into a plastic grocery sack, and store it in your fridge (the “veggie” drawer if you have one.) The slightly damp paper towels get a degree or two colder than the fridge and help slow down how fast water evaporates from the cells. The grocery sack protects the greens from the breezes in your fridge while still allowing what moisture does seep out to actually evaporate.
If you want to freeze your leafy greens, however, you’ll need to treat them a bit more harshly. If you just throw the leaves in the freezer, then the water inside the cells will freeze, expand, and burst. Burst cells equals plant mush. It’s easiest to process leafy greens for freezing in medium to large batches, because you’ll need to get a few things set up.
First, get a large bowl and fill it with half water, half ice.
Second, wash your greens. Don’t worry about drying them.
Third, in a large, wide-mouth pot, boil some salt water (about 1 tablespoon salt for every 2-3 cups water)
Using tongs, take a bunch of the greens and dunk them in the boiling salt water for about a minute. Pull them out and immediately dunk them in the ice water. The boiling water kills bacteria and softens the plant fibers. The cold water stops the cooking process, so you don’t have fully cooked (and therefore mushy) greens on your hands. Once the greens are nice and chilled, either 1- wrap them in paper towel, seal in an airtight zip lock (evaporation isn’t an issue in the freezer) and freeze; or 2- chop them into small bits, seal in a small zip lock bag, and freeze. You won’t want to use these frozen greens for salads, but in dips, baked dinners, or soups, they are amazing.
However you choose to store, process, and use your leafy greens, they’re worth enjoying. Thanks to Laurie, my beloved plant geek, for making sure I remembered my basic cell biology correctly!