How to Preserve Fruits and Vegetables

Clean out your refrigerator.

By Kevin RR Williams

HEALTH From the moment a fruit or vegetable is picked, it begins dying. Initially, residual juices provide a reasonable shelf life. As foods begin to decompose, they give off gases until they rot.

There is a reason why refrigerators have separate fruit and vegetable bins — also why some produce should be kept out of the refrigerator. As some fruits and vegetables ripen, they release ethylene, a gas that can cause other produce to become spotted, soft, or mealy. To prevent this, keep ethylene-sensitive fresh fruits separate from vegetables that emit the gas. Generally, the ethylene producers are mostly fruits and the ethylene sensitive produce is mostly vegetable. The exceptions are watermelon and unripe bananas.

Ethylene-Sensitive

Refrigerated Vegetable Bin

  • Asparagus
  • Broccoli
  • Brussels sprouts
  • Carrots
  • Cucumbers
  • Eggplants
  • Green beans
  • Lettuce and other greens
  • Peas
  • Summer squash
  • Watermelons

Outside Refrigerator

  • Apples*
  • Bananas (unripe)*
  • Potatoes

Ethylene-Producing

Refrigerated Fruit Bin

  • Apricots
  • Cantaloupes
  • Honeydew melons
  • Kiwis
  • Mangoes
  • Nectarines
  • Papayas
  • Passion fruit
  • Peaches
  • Pears
  • Plums
  • Prunes

Outside Refrigerator

  • Avocados*
  • Bananas (ripe)*
  • Tomatoes*

* Apples, avocados, and tomatoes are both high producing and sensitive so they should be separated from other produce and left out of the refrigerator — on the countertop or place root vegetables in a potato bin. Using this knowledge to your advantage, you can hasten ripening of produce by paring it with an ethylene producer. For example hard unripe avocados might be placed in a brown paper bag with an apple for a day or two. Likewise, a quick way to hasten green banana ripening is to store with an apple.

Related: Secrets to Sensational Salads

Freshly picked tomatoes release huge amounts of ethylene, experiencing what is known as “ethylene shock,” whereas the closely related chili peppers show no such effect. Because of the amount of ethylene, tomatoes should not be refrigerated but kept on the countertop. Shop for tomatoes on the vine at farmers’ markets when possible for long-lasting results.

Making a soup, salad or sandwich may result in some residual pieces of vegetables. It may seem efficient to place the extra pieces in a plastic bag together or add them to an existing bag of vegetables in the refrigerator. Because of varying rates of decay (ethylene production), the cross-contamination can reduce the shelf life. It is better in my opinion to bag everything separately (especially cut tomatoes).

It perhaps goes without saying that separately packaged frozen fruits and vegetables have no ethylene interaction in the freezer. As mentioned in a prior article, extra pieces of herbs and vegetables may be kept together in a freezer bag in order to boil, strain and make soup broth.

How To Distinguish Fruits From Vegetables

To a botanist, a fruit is an entity that develops from the fertilized ovary of a flower. This means that tomatoes, squash, pumpkins, cucumbers, peppers, eggplants, corn kernels, and bean and pea pods are all fruits; so are apples, pears, peaches, apricots, melons and mangos. A vegetable, botanically speaking, is any edible part of a plant that doesn’t happen to be a fruit, as in leaves (spinach, lettuce, cabbage), roots (carrots, beets, turnips), stems (asparagus), tubers (potatoes), bulbs (onions), and flowers (cauliflower and broccoli).

Are tomatoes fruit or vegetables? Botanical and polical produce definitions differ. In 1886, importer John Nix and colleagues landed a load of West Indian tomatoes at the Port of New York where the resident customs official—one Edward Hedden—demanded payment of a ten percent tax in accordance with the Tariff Act of 1883, which levied an import duty on “foreign vegetables.” Nix, who knew his botany, objected, on the grounds that the tomato — a fruit — should be tax-exempt. The case eventually made its way to the Supreme Court where, in 1893, Justice Horace Gray ruled in favor of vegetable.

“Botanically speaking,” said Justice Gray, “tomatoes are the fruit of the vine, just as are cucumbers, squashes, beans and peas. But in the common language of the people…all these vegetables…are usually served at dinner in, with, or after the soup, fish, or meat, which constitute the principal part of the repast, and not, like fruits, generally as dessert.”

Cambria Bold offers the following tips for storing fruits and vegetables:

For Fruits: Non-cherry stone fruits, avocados, tomatoes, mangoes, melons, apples, and pears will continue to ripen if left sitting out on a countertop, while items like bell peppers, grapes, all citrus, and berries will only deteriorate and should be refrigerated. Bananas in particular ripen very quickly, and will also speed the ripening of any nearby fruits.

For Vegetables: Before storing, remove ties and rubber bands and trim any leafy ends. Leave an inch to keep the vegetable from drying out. Make sure the bag you store the veggies in has some holes punctured to allow for good air flow. Pack vegetables loosely in the refrigerator. The closer they are, the quicker they will rot. Leafy greens can be washed before storing by soaking them in a sink full of water, while soft herbs and mushrooms should not be washed until right before they are used.

Considerations for Nightshade Foods

Among the nightshade plants most commonly enjoyed as foods, the alkaloids in tomatoes, potatoes, and eggplant are best studied. Below is a chart showing key alkaloids in these three nightshade foods.

Nightshade FoodScientific NameKey Alkaloids
TomatoLycopersicon esculentumtomatine, deyhdro­toma­tine
PotatoSolanum tuberosumalpha-solanine, chaconine
EggplantSolanum melongenasolasonine, solar­margine

Along with the potential health benefits associated with food alkaloids, however, are also potential problems with excessive intake. Based on a study of potatoes from Mexico, 65-70% of the alkaloids were removed by skinning the potatoes prior to cooking. For persons wanting to lower the alkaloid content of potatoes, it would also make sense to cut out any sprouting spots prior to cooking. Exposure to light can increase the alkaloid content of potatoes so storing them in a dark place is recommended.

Some individuals who have been diagnosed with varying forms of arthritis or other musculoskeletal health problems in which elimination of nightshades vegetables resulted in a feeling of improvement. A large-scale human research study that suppots this theory is lacking.

Related: End Carbohydrate Cravings

Do not place too much confidence in pre-washed leafy greens. These are residuals from various whole lettuces, spinach and other greens. They have different rates of decomposition due to age and variety. In your refrigerator, some turn brown and give off odors faster than others in the same bag. (A whiff of the contents can resemble the smell of flatulence.) Isolating the good, bad and ugly requires rinsing and separating even though they were pre-washed. When possible, purchase (or grow) whole vegetables to stay A Bit More Healthy.

Tags: decay, preservatives

References
  1. Avoid Premature Spoiling of Fruits and Vegetables. realsimple.com
  2. List of sensitive produce. eris-filter.com
  3. Why You Should Store Some Fruits and Vegetables Separately. thekitchn.com
  4. Ethylene of no effect: Why peppers do not mature after picking. phys.org
  5. Is a Tomato a Fruit? It Depends on How You Slice It. nationalgeographic.com
  6. The Kitchn's Guide to Storing Fruits and Vegetables. thekitchn.com
  7. Which foods are classified as "nightshades," and is it true that foods from this group can potentially contain problematic substances? whfoods.org