Tupperware has sold Americans plastic storage containers for decades. Its plastic containers have a patented “burp," which signals that air has been removed from the container, helping the food inside stay fresh longer. Tupperware's FridgeSmart containers have an airflow valve that lets air circulate in the container. This airflow, or venting, helps some fruits and vegetables to stay fresh longer. Tupperware's newer containers feature instructions printed on the side of the containers, but the older products came with printed instructions. If you lost these, you might not remember how the containers have to be used for them to work properly.

Choose a container that's larger than the fruits or vegetables you want to store. The line's largest Medium Deep size should be large enough to store a head of lettuce.

Fill the container with fruits or vegetables, using items that are the same or similar. Tupperware divides fruits and vegetables into different categories: "high breathers," "medium breathers" and "low breathers." If you have several fruits listed as "low breathers," sore those together in one container.

Open both vents on the container if you’re storing "high breathers" inside. "High breathers" include spinach, endive, artichokes, Brussels sprouts, sweet corn, broccoli and peas of all varieties. Move the container into the refrigerator as soon as you fill it and open the vents.

Press one valve on the container to ensure it’s closed and then open the opposite vent for "medium breathers." Tupperware considers string beans, snap beans, any type of fresh beans, cauliflower, herbs, shallots, cabbage and green onions to be "medium breathers." Lettuce, fresh greens and leeks are also "medium breathers." Medium-breather fruits include pears, peppers oranges, lemons, limes and apples.

Close both vents for any "low-breather" foods, such as beets, mushrooms, celery, radishes, turnips and okra. Zucchini, rutabaga, celery, carrots, cucumbers and asparagus are also "low breathers." Tupperware also suggests storing berries, ripe fruits and chopped or cut fruits in containers with the vents closed.