By Ronald Goldy, Michigan State University Extension
“A little knowledge goes a long way” is a common saying. According to University of Vermont’s Meredith Niles, the average person in the U.S. wastes approximately a pound of food a day. That is roughly 1,150 pounds a year for an average U.S. family. This is food purchased and brought home that you were not able to eat before it spoiled. Therefore, if knowing more about proper storage of fresh produce reduces any of this loss, it is worth gaining that knowledge.
The first thing to know is that not all produce like to be stored at the same temperature. Each produce item has an ideal temperature or temperature range that is best for maintaining quality. Higher temperatures cause them to mature or spoil quicker. Lower temperatures will cause “chilling injury,” and if low enough (below 32 degrees Fahrenheit) they may freeze. For some produce, chilling injury can happen at what might be considered not that cold. Chilling injury shows itself as off color (bananas skin turns brown), or the flavor goes bland (tomatoes). Items that have frozen will look like they have been cooked and will have what is called a “water soaked” appearance.
Table 1 shows common storage conditions required for common fruit and vegetables. Most in-home refrigerators are set at 35 to 40 F, a range covering most of what is on the list, but some things do best at higher temperatures. As shown in Table 1, tomatoes, potatoes, bananas, squash, pumpkins, etc. store longer at temperatures above 50 F. Some high-end refrigerators now have a special compartment for storage of these higher temperature items.
Fruit and vegetables are categorized as climacteric or non-climacteric. Climacteric fruit reach a certain developmental stage and once attaining that stage, continue to develop to full physiological maturity, even when removed from the plant. Climacteric fruit such as peaches, plums, cantaloupe, bananas, pears and tomatoes continue to gain flavor and get sweeter by changing starch into sugar. Many also go from firm to soft and juicy (peach and plum), or at least softer (avocado and cantaloupe). They are also sensitive to ethylene gas, which they self-generate, further aiding the ripening process.
Climacteric fruit can be left at room temperature until consumed or mature and then refrigerated. Since many climacteric fruit soften as they ripen, to minimize bruising during shipment and extend shelf life, they are harvested firm and physiologically immature. If not left to fully mature, this results in crunchy peaches, nectarines and plums; green, starchy bananas; and bland tasting cantaloupe. Many consumers are used to this condition and taste and think that is the way it is supposed to be. However, if left at room temperature for a few days, the fruit would develop more flavor and sweetness. Peaches, nectarines and plums reach optimum flavor when soft and juicy, bananas reach optimum when they are yellow and have brown speckling on the skin and cantaloupe when the fruit is somewhat soft.
Non-climacteric fruit are fruit that need to stay on the plant to reach full physiological maturity. Once removed, they will not continue to mature, gain flavor or sugar. Their highest eating quality is at harvest. Some examples of non-climacteric fruits, as shown in Table 2, are cherries, grapes, oranges and raspberries. For food safety, it is important that once all whole fruits and vegetables are cut-up, they need to be eaten or refrigerated within 2 hours.
Table 2 is a list of common climacteric and non-climacteric fruit. All climacteric fruit in Table 2 are labeled as ethylene sensitive in Table 1. Table 1 also has some fruit and non-fruit items as ethylene sensitive. As a gas, ethylene is hard to contain and many things respond in negative ways if stored with ethylene generating fruit. Cabbage and Brussels sprouts will turn yellow or crack and start to grow, carrots develop a bitter flavor due to ethylene-induced isocoumarin production and cucumbers deteriorate quicker. Other ethylene-sensitive items respond in different ways.
Knowing how to properly handle and store produce can make for a more nutritious and tasteful experience as well as decreasing your food waste and making your produce dollars go farther.
Go here for the Storage Conditions Tables.
This article was published by Michigan State University Extension. For more information, visit http://www.msue.msu.edu. To have a digest of information delivered straight to your email inbox, visit http://www.msue.msu.edu/newsletters. To contact an expert in your area, visit http://expert.msue.msu.edu, or call 888-MSUE4MI (888-678-3464).
