Fresh Vegetable Storage for Homeowners.pdf

Vegetables

Extension

SP 291-L

Fresh Vegetable Storage for the Homeowner

AlvinD.Rutledge,ProfessorEmeritus,PlantSciences

Many vegetables grown in home gardens can be stored

fresh, but they must be harvested at the proper maturity and

kept at the correct temperature and humidity. In addition,

proper ventilation and sanitation must be maintained during

storage. Basically, storage is placing harvested vegetables

in an environment where the life processes, respiration and

water loss, are kept at low levels.

the oxygen level. During respiration, oxygen is absorbed

and carbon dioxide is released. Consequently, an airtight

area will allow a decrease in oxygen and an increase in

carbon dioxide. As a result, the respiration rate gradually

decreases. However, if an area is completely airtight and

oxygen levels fall too low for the complete combustion of

sugars, undesirable compounds are produced that lower

vegetable edibility. Therefore, respiration should be held

at low levels rather than be stopped completely. For this

reason, vegetable and fruit items are often wrapped in

perforated plastic containers in supermarkets.

Respiration during Storage

During respiration, sugars and other compounds are

broken down within the cells. This releases energy, carbon

dioxide, water and heat. The energy is needed by the living

cells of the stored product. The carbon dioxide should be

removed by adequate ventilation.

Several factors regulate respiration. In general, the

higher the temperature, within normal ranges, the faster the

respiration rate. Thus, you can see the importance of refrig-

eration in prolonging the life of harvested vegetables. The

presence of soluble sugars in cells also inluences the rate

of respiration. At 70 degrees F, the respiration rate of sweet

corn is 3.6 times as fast as it is at 41 F. Thus, it needs to be

cooled immediately after harvest.

The rate of respiration also varies directly with

water content. At a given temperature, succulent plant

parts, such as head lettuce, respire more rapidly than

non-succulent products, such as sweet or Irish potatoes.

Immature vegetables respire more rapidly than mature

vegetables. Finally, the respiration rate is inluenced by

Water Loss during Storage

Water loss in fresh vegetables results in a wilted,

dull appearance that reduces eye appeal and freshness.

Preventing water loss improves shelf life, appearance and

desirability. Water loss in storage is prevented by storing

the product at as low a temperature and as high a relative

humidity as possible for the product. Proper humidity con-

ditions are discussed in Table 1.

The Refrigerator

Homeowners most commonly store vegetables in a re-

frigerator. Refrigerators usually maintain a temperature of

about 40 degrees F, but temperatures may vary within the

storage compartment. In single-door models with a frozen

food storage unit, temperatures are generally lowest just

beneath the storage unit. Cold air settles and forces warm

air near the vegetable tray upward

along the sides. The circulation air

is usually of lower humidity and

will dry out uncovered vegetables.

However, the humidity in the tray

can be maintained at a higher level

by using moist towels or by an

abundance of vegetables.

While many vegetables can

be stored well in the refrigerator

for a week or longer, you should

observe certain storage precau-

tions. For instance, many ripening

fruits should not be stored together

with vegetables. These fruits give

off ethylene gas, which causes yel-

lowing of green vegetables, russet

spotting on lettuce, toughening

of asparagus spears, sprouting of

potatoes and bitterness in carrots.

Some commonly used fruits that

are high ethylene producers are

pears, plums, apples, cantaloupes

and peaches.

Table 1. Grouping Fresh Vegetables According to Their

Storage Requirements

Group 1

Keep at 32 to 41 degrees F and 85 to 95 percent relative humidity. Store in the

refrigerator crisper and maintain high humidity by keeping the crisper more than

half full. Wash and drain well before storage.

Beet greens

Swiss chard

Collards

Green onions

Kale

Store the following vegetables in a crisper separate from the above vegetables,

in plastic bags or containers in the main compartment of the refrigerator.

Asparagus

Beets

Broccoli

Brussel sprouts

Cabbage

Carrots

Caulilower

Celery

Group 2

Ideally, the following vegetables keep best at 45 to 55 degrees F and 85 to 95

percent relative humidity, due to their sensitivity to chilling injury. Since this is

not always possible in most homes, store in the refrigerator no longer than about

seven days. Use soon after removing from refrigerator.

Bell peppers

Hot peppers

Cucumbers

Storage Requirements of

Speciic Vegetables

Now that we have outlined the

reasons for cool storage of fresh

vegetables, speciic requirements

for several crops are outlined in

Table 1. Notice that the ideal stor-

age requirements vary with the

speciic groups.

Ripe melons

Snapbeans

Summer squash (yellow, zucchini, scallop)

Group 3

Store vegetables in this group in a cool place (50 to 60 degrees F). Lower

temperatures may cause chilling injury. Pantries, basements or garages can

provide a cool place during most of the year. Non-insulated garages may be too

warm in summer and too cold in winter. If you do not have space, store eggplant

and okra as discussed for Group 2. Store ripe tomatoes, winter squash (hard rind)

and pumpkins, sweet potatoes and potatoes as recommended in Group 4.

Eggplant

Okra

Ripe tomatoes

Irish potatoes (store in subdued light to prevent greening)

Sweet potatoes

Group 4

Store the following vegetables at room temperature (65 to 70 degrees F) and

away from direct sunlight.

Dry garlic

Melons

SP291L-11/05(Rep) 05-0272

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Lettuce

Mustard greens

Spinach

Turnip greens

Lima beans

Mushrooms

Peas

Radishes

Rhubarb

Sweetcorn (if unhusked, keep close to the freezer compartment)

Turnips

Dry onions (in open mesh container)

Tomatoes (mature green, partly ripe and ripe)

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