Vegetables
Commodities Included:
Leafy & Succulent Vegetables:
Leaves and Associated Parts
Leaf & head lettuce, chard, endive, celery, rhubarb, cabbage, green onions, leeks, spinach,
brussels sprouts,
Stem Vegetables
Asparagus, kohlrabi
Floral Vegetables (immature flower parts).
Cauliflower, broccoli, artichoke
Underground Vegetables:
Potatoes, yams, sweet potatoes, cassava, beet, turnip, radish, jicama, carrots, onions, garlic, etc.
Fruit Vegetables (product of a ripening ovary and its associated tissue):
Monocots => Sweet corn
Dicots
Curcurbitaceae =>cucumber, zucchini, honeydew melon, muskmelon, winter squash, chayote,
watermelon.
Leguminosae => Lima bean, snap bean, pea, broad bean, mung bean.
Malvaceae => Okra.
Solanaceae => Bell pepper, chili pepper, tomato, eggplant, husk tomato.
Fruit vegetable can also be divided into:
Immature fruits - cucumbers, summer squash, sweet corn, eggplant, green pepper, chayote,
okra, snap beans, Lima beans, southern peas (cowpeas), peas, broad beans.
Mature fruits - tomatoes, winter squash, watermelon, red pepper, pumpkins, muskmelons,
dry peas, dry beans.
Ripening Pattern:
Leafy & Succulent Vegetables:
Non-climacteric vegetative tissues.
The have moderate to very high respirations rates.
Low ethylene production. All (except artichoke) are either sensitive or highly sensitive to the
negative effects of ethylene.
Underground Vegetables:
Non-climacteric vegetative tissue.
Low (8-12 mg CO2/kg-hr) to very low (2-8 mg CO2/kg-hr) rates of respiration. Respiration is
accelerated if the crop is marketed with the tops attached. Immature product
respires faster that mature product. Cured potato and sweet potatoes have lower
respiration rates that if not cured.
Low ethylene production.
Fruit Vegetables:
Fruit vegetable harvested immature are non-climacteric
Fruit vegetables mature can be climacteric or non-climacteric.
Compositional Characteristics:
219469559
1
7/11/2016
Leafy & Succulent Vegetables:
Most contain large amounts of chlorophyll.
High water content (succulent & tender).
Low acids.
Many are high in vitamin A. E.g. Kale = 8,900 I.U/100 g fr. wt.; Parsley = 8,500; Chard =
6,500; Broccoli = 2,500; Spinach = 8,100; Turnip greens = 7,600.
Many are high in vitamin C (Ascorbic acid). E.g. Parsley = 172 mg/100g fr. wt.; Turnip greens
= 139; Broccoli = 113; Collards = 92; Cauliflower = 78; Cabbage = 47; Asparagus
= 48; Brussels sprouts = 102. Oranges contain ~ 60 mg vit. C per 100 g fresh wt.
Good sources of minerals such as P, K, Fe, Na and Ca.
Underground Vegetables:
Water content is usually lower than other vegetables. E.g. sweet potato and garlic = ~61%;
radish = ~94%.
Carbohydrates are usually higher than other vegetables. E.g. potato = 21%; sweet potato = ~
33%; taro = ~ 23%; parsnip = ~ 18%; carrots and beets = ~ 10%.
Starch is converted to sugar when these commodities are held at temperatures of 32 to 41oF (0
to 5oC). This can be either desirable (e.g. parsnips) or undesirable (potatoes).
Many are high in vitamin A. E.g. Carrots = 11,000 IU/100 g fr. wt.; sweet potatoes = 8,000;
Many are good sources of vitamin C (ascorbic acid). E.g. potatoes = 18 mg/100 g fr. wt.;
radish = 25; turnip = 30; rutabaga = 35; sweet potato = 20.
Fruit Vegetables:
Good sources of vitamin C and A.
Legumes are a good source of protein, niacin, thiamine, and some minerals.
Maturity and Quality Standards:
Includes internal quality attributes (sugars, acids, ratio, etc.) and exterior attributes (color, shape,
size, freedom from defects, etc.).
Leafy & Succulent Vegetables:
Harvest indices. Different crops have different specific requirements. E.g.:
Head Lettuce = solidity of the head (e.g. soft, fairly firm, firm, hard & extra-hard).
Asparagus = spear length (5 to 8 inches).
Broccoli = compact flower heads, no open flowers.
Cabbage = solidity, color.
Cauliflower = head size and condition.
Celery = size.
Quality attributes (freshness and turgidity also apply to all). Different crops have different
specific requirements. E.g.:
Asparagus = straightness, diameter, percent green color, no defects.
Head Lettuce = color, solidity, no seedstems, no defects or decay.
Cabbage = solidity, no seedstems, color, no defects.
Cauliflower = cleanness, compactness, white color, size, no defects.
Celery = form, compactness, color, no seedstems, no defects.
Underground Vegetables:
Harvest indices. Different crops have different specific requirements. E.g.:
Carrot = root size.
Radish = days from planting.
219469559
2
7/11/2016
Potato = drying of foliage, setting of skins.
Taro = drying of leaves.
Garlic and Onion = dry tops, neck tissues begin to soften.
Sweet potato = senescence of vines.
Quality attributes include uniformity, firmness, color, shape, size, and freedom from defects.
Different crops have different specific requirements. E.g.:
Potato = maturity, firmness, cleanness, and freedom from sprouts, blackheart, greening, and
other defects.
Sweet potatoes = firmness, smoothness, cleanness, and freedom from growth cracks,
mechanical damage, internal breakdown, and other defects.
Carrots = turgidity, color, and freedom from growth cracks, pithiness, internal discoloration,
and other defects.
Onions = firmness, freedom from wet sunscald, doubles, bottlenecks, sprouting, and other
defects.
Fruit Vegetables:
Ripeness classes for fresh market tomatoes:
Mature green 1 - seeds cut by a sharp knife on slicing the fruit; no jellylike material in any of
the locules; fruit is more than 10 days from breaker stage.
Mature green 2 - seeds fully developed and not cut on slicing fruit; jellylike material in at
least one locule; fruit is 6 to 10 days from breaker stage; minimum harvest maturity.
Mature green 3 - jellylike material well developed in locules but fruit still completely green;
fruit is 2 to 5 days from breaker stage.
Mature green 4 - internal red coloration at the blossom end, but no external color change;
fruit is 1 to 2 days from breaker stage.
Breaker - first external pink or yellow color at the blossom end (USDA Color Stage 2).
Turning - more than 10 percent but not more than 30 percent of the surface, in the aggregate,
shows a definite change in color from green to tannish-yellow, pink, red, or a
combination (USDA Color Stage 3).
Pink - more than 30 percent but not more than 60 percent of the surface, in the aggregate,
shows pink or red color (USDA Color Stage 4).
Light red - more than 60 percent of the surface, in the aggregate, shows pinkish-red or red,
but less than 90% of the surface shows red color (USDA Color Stage 5).
Red - more than 90 percent of the surface shows, in the aggregate, shows red color (USDA
Color Stage 6).
Optimum Temperatures, Relative Humidity and Estimated Maximum Shelf Life (see
handout for specific storage information):
Leafy & Succulent Vegetables
Maintain temperature of about 33 oF (1oC) with relative humidity of 95-100%.
Underground Vegetables:
Exclude light from potato storage to prevent greening and production of a bitter and toxic
substance (solanin).
Many require special treatment to inhibit sprouting.
Because of the low value of many of these crops, alternatives to refrigerated storage are often
used such as field storage (delayed harvest) or storage in pits, trenches or clamps in
the field.
219469559
3
7/11/2016
Fruit Vegetables:
Most are sensitive to chilling injury. Exceptions are sweet corn and cool-season crops like
peas and broad beans.
Most are not adapted to long-term (>3 weeks) storage.
Water loss:
Immature fruit vegetables have thinner cuticles that are more easily damaged than mature
fruit vegetables and thus loose water more readily.
In mature fruit like tomatoes, a well developed cuticle limits water loss so that ~ 65% of the
water loss occurs through the stem scar.
Removal of trichomes (hairs) from fruit vegetables like zucchini greatly increases water loss.
Fruit vegetables tend to have low surface to volume ratios reducing water loss susceptibility.
Modified or Controlled Atmospheres:
Leafy & Succulent Vegetables
O2 levels between ~ 2 to 3% retards senescence (except asparagus which does not tolerate low
O2.
Tolerance to high CO2 varies. Lettuce, celery, endive are injured at CO2 > 2%. Asparagus and
broccoli benefit (reduced yellowing) from CO2 concentrations between 5 to 10%.
Underground Vegetables:
May be beneficial on carrots, beets, celeriac, horseradish and turnip. CA has not been
recommended on potato. Onions can tolerate low O2 (~1%), but not high CO2.
Ripening:
Leafy & Succulent Vegetables
None
Underground Vegetables:
None
Fruit Vegetables:
For fruit vegetables usually consumed ripe, quality is best when the fruit are ripened on the
plant. Harvesting when the fruit are immature will result in inferior quality after
ripening.
Physiological Disorders:
Leafy & Succulent Vegetables:
Freezing injury (preharvest & postharvest).
Solar injury (solar browning of cauliflower).
Bolting (seedstalks development). E.g. lettuce, leek.
Pithiness = senescence in celery.
Riciness = senescence in cauliflower.
Blackheart = Ca deficiency of celery, endive, escarole.
Yellowing = general senescence (enhanced by ethylene exposure).
Russet spotting on lettuce = caused by exposure to ethylene (>0.1 ppm).
Brown stain = CO2 (>2%) injury in lettuce held at 0 to 5 oC.
Pink rib = general senescence of lettuce.
Etc.
Underground Vegetables:
219469559
4
7/11/2016
Greening (solanin production).
Blackheart of potatoes (anaerobic respiration).
Internal Black Spot of potatoes (K deficiency and other unknown factors).
Sprouting.
Chilling injury of tropical root crops.
Freezing injury.
Heat injury (sunburn and sunscald).
Etc.
Fruit Vegetables:
Chilling injury.
Freezing injury.
Solar injury (sunburn, sunscald).
Blotchy ripening of tomatoes.
Blossom-end rot of tomatoes and peppers – related to water stress and calcium deficiency.
Growth cracks.
Puffiness of tomatoes (air spaces).
Internal rind spot on watermelons.
Yellowing of cucumbers (ethylene related).
Etc.
Decay:
Leafy & Succulent Vegetables:
Bacterial soft rot – Chard, celery, lettuce, spinach
Gray mold rot – Artichoke, celery, lettuce, rhubarb
Watery soft rot – Celery, lettuce, cabbage
Downy mildew – Lettuce, spinach
Big vein – Lettuce
Rhizoctonia - Cabbage
Etc.
Underground Vegetables:
Bacterial soft rot - Onion, carrot, parsnip, potato.
Fusarium rot - Garlic, onion, potato, cassava.
Gray mold rot - Garlic, onion, carrot, parsnip.
Rhizopus soft rot - Carrot, sweet potato, cassava.
Blue mold rot - Garlic, cassava.
Black mold rot - Onion, cassava.
Etc.
Fruit Vegetables:
Anthracnose – Snap beans, cucumber, watermelon.
Bacterial soft rot – Cucurbits, tomatoes, peppers, melons.
Gray mold rot – Peas, peppers, tomatoes.
Rhizopus rot – Peppers, melons, tomatoes, pumpkins.
Fusarium rot – Melons, tomatoes, pumpkins.
Phytophthora rot – Tomato, watermelon.
Etc.
219469559
5
7/11/2016
Other Special Features/Factors to Consider:
Leafy & Succulent Vegetables:
High to very high surface to volume ratios = very susceptible to water loss.
Underground Vegetables:
Develop in a dark, physically restraining environments with high humidity and slower gas
exchange (easier to develop anaerobic conditions). The epidermis only develops
into an effect moisture barrier when the crop is mature, or after a postharvest
“curing” period.
Often represent dormant storage organs = low respiration rates and are well suited for storage.
If dormancy breaks, sprouting (growth) can greatly reduce quality and increase
water loss.
Low surface to volume ratio (bulky) = ~3:1 to 6:1 = reduced water loss. Water loss is also
influenced by periderm formation and number and distribution of lenticels.
Curing = for 2 to 3 weeks, expose product to higher temperatures and relative humidities (to
reduce water loss) than are optimum for normal storage. Actual temperature and
relative humidity depends on the commodity. After harvest, onions and garlic are
cured in the filed for 5 to 10 days before topping. Under lower temperatures or
modified or controlled atmospheres (low O2 or high CO2), wound healing is slowed.
Postharvest curing allows anatomical (periderm formation) and physiological (e.g.
production of compounds that inhibit pathogen growth and suberin to inhibit water
loss) changes to occur which prolong the storage life of some root crops. It
facilitates the healing of wounds incurred during harvest and handling.
Curing reduces water loss and decay of onions, garlic, potato, and sweet potato and some
tropical root vegetables.
Fruit Vegetables:
Immature fruit vegetables are especially susceptible to mechanical injury (thin cuticle and
epidermis). Partially-ripe or ripe fruit vegetables are also susceptible to bruising
and deformation because they are often softer than unripe fruit.
Postharvest Handling Systems – Selected Points:
Leafy & Succulent Vegetables
Usually, all are harvested by hand. Mechanical systems have been developed for some (e.g.
lettuce, cabbage, Brussels sprouts, asparagus) but they are generally not used
commercially.
Avoid ethylene exposure.
Underground Vegetables:
Most are harvest mechanically and handled in bulk to the packinghouse or processing plant.
Mechanical damage during harvest can be significant. Postharvest curing is often
used to help the crop recover from harvest injuries.
Sweet potato is still mostly harvested by hand.
Flooding prior to harvest can have severe detrimental effects on underground vegetables.
Major cause of loss results from mechanical injury and water loss. Water loss increases if
sprouting occurs.
Fruit Vegetables:
Though most are harvested for the fresh market, a large percentage of some fruit vegetables are
processed. E.g. most legumes and over half of the U.S. tomato crop.
219469559
6
7/11/2016