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A Safer Way to Keep Greens Fresh with Carbon Dioxide

By Cook's Illustrated Published September 2012

Is there a way to prolong the shelf life of a bag of greens without resorting to unsanitary methods like exhaling into the bag? What about combining baking soda and vinegar to create a mini generator of carbon dioxide?

Intrigued by this question, we came up with a “time-release” version of this method that would slightly delay gas production until we placed the “generator” in the bag of greens, preserving the maximum amount of CO2: Freeze 1 teaspoon of white vinegar in a 2- to 4-ounce container (such as a spice bottle) and then sprinkle 1 teaspoon of baking soda over the vinegar’s surface. Next, cut a small, three-layer-thick square of paper towels and secure it over the container’s opening with a rubber band. Place the container in a zipper-lock bag full of salad greens and seal it immediately. As the acidic vinegar melts, it combines with the alkaline baking soda to produce carbon dioxide. The paper towels let the gas seep into the bag while preventing any melting vinegar from leaking out.

We admit that it’s a little wacky, but this far more sanitary method works just as well as blowing into the bag, extending the life of the greens by up to five days (as long as the bag is kept sealed).

MAKE IT: Create a mini CO2 generator by freezing a little vinegar in a small container, sprinkling it with baking soda, and covering the container with paper towels.

USE IT: Seal the container in a zipper-lock bag with greens and refrigerate. As the vinegar melts, it will interact with the baking soda, providing up to five extra days of freshness.