Small-Scale Postharvest Handling Practices PDF

CHAPTER 7: STORAGE OF HORTICULTURAL CROPS - 1 If produce is to be stored, it is important to begin with a high quality product. The lot of produce must not contain damaged or diseased units, and containers must be well ventilated and strong enough to withstand stacking. In general, proper storage p...

CHAPTER 7: STORAGE OF HORTICULTURAL CROPS - 1 If produce is to be stored, it is important to begin with a high quality product. The lot of produce must not contain damaged or diseased units, and containers must be well ventilated and strong enough to withstand stacking. In general, proper storage practices include temperature control, relative humidity control, air circulation and maintenance of space between containers for adequate ventilation, and avoiding incompatible product mixes. Commodities stored together should be capable of tolerating the same temperature, relative humidity and level of ethylene in the storage environment. High ethylene producers (such as ripe bananas, apples, cantaloupe) can stimulate physiological changes in ethylene sensitive commodities (such as lettuce, cucumbers, carrots, potatoes, sweet potatoes) leading to often undesirable color, flavor and texture changes. Temperature management during storage can be aided by constructing square rather than rectangular buildings. Rectangular buildings have more wall area per square feet of storage space, so more heat is conducted across the walls, making them more expensive to cool. Temperature management can also be aided by shading buildings, painting storehouses white to help reflect the sun's rays, or by using sprinkler systems on the roof of a building for evaporative cooling. The United Nations' Food and Agriculture Organization (FAO) recommends the use of ferro-cement for the construction of storage structures in tropical regions, with thick walls to provide insulation. Low cost cold rooms can be constructed using concrete for floors and polyurethane foam as insulation materials. Building the storeroom in the shape of a cube will reduce the surface area per unit volume of storage space, also reducing construction and refrigeration costs. All joints should be carefully caulked and the door should have a rubber seal around the edges. While cooling produce, the ventilation system should be set to create an air flow rate of 100 cfm/ton (5 l/sec/ton). Once cooling is completed, air flow rates should be decreased to the lowest speed that will keep produce cool (20 to 40 cfm/ton is usually sufficient, according to Thompson et al. 1998). The greater the refrigerator's evaporator coil area, the less of a temperature difference there will be between the coils and the target room temperature, and the less moisture will be lost from the product as it cools. (See Thompson et al in Kader, 2002 for more information). Facilities located at higher altitudes can be effective, since air temperature decreases as altitude increases. Increased altitude therefore can make evaporative cooling, night cooling and radiant cooling more feasible. Underground storage for citrus crops is common in Southern China , while in Northwest China , apples are stored in caves (Liu, 1988). This system was widely used in the U.S. during the early 1900s. Certain commodities, such as onions and garlic, store better in lower relative humidity environments. Curing these crops by allowing the external layers of tissue to dry out prior to handling and storage helps to protect them from decay and further water loss (see Chapter 2). Commercially constructed cold rooms can be quite expensive, but fortunately the small-scale operator has many choices. Cold rooms can be self-constructed, purchased as prefabricated units (new or used), or made from refrigerated transportation equipment such as railway cars, highway vans or marine containers. For more detailed information about determining the cold room size best suited to your operation, evaluating choices when purchasing or building a cold room, refer to the source below. Thompson, J.F. and Spinoglio, M. 1994. Small-scale cold rooms for perishable commodities. Family Farm Series, Small Farm Center , University of California , Davis. The air composition in the storage environment can be manipulated by increasing or decreasing the rate of ventilation (introduction of fresh air) or by using gas absorbers such as potassium permanganate or activated charcoal. Large-scale controlled or modified atmosphere storage requires complex technology and management skills, however, some simple methods are available for handling small volumes of produce. Recommended storage temperatures Recommended Temperature and Relative Humidity, and Approximate Transit and Storage Life for Fruits and Vegetable Crops (see Hardenburg et al, 1986 for more complete information on individual crops). Product Temperature Relative Approximate storage life Humidity  °C °F (percent) Amaranth 0-2 32-36 95-100 10-14 days Anise 0-2 32-36 90-95 2-3 weeks Apples -1-4 30-40 90-95 1-12 months Apricots -0.5-0 31-32 90-95 1-3 weeks Artichokes, globe 0 32 95-100 2-3 weeks Asian pear 1 34 90-95 5-6 months Asparagus 0-2 32-35 95-100 2-3 weeks Atemoya 13 55 85-90 4-6 weeks Avocados, Fuerte, Hass 7 45 85-90 2 weeks Avocados, Lula, Booth-1 4 40 90-95 4-8 weeks Avocados, Fuchs, Pollock 13 55 85-90 2 weeks Babaco 7 45 85-90 1-3 weeks Bananas, green 13-14 56-58 90-95 14 weeks Barbados cherry 0 32 85-90 7-8 weeks Bean sprouts 0 32 95-100 7-9 days Beans, dry 4-10 40-50 40-50 6-10 months Beans, green or snap 4-7 40-45 95 7-10 days Beans, lima , in pods 5-6 41-43 95 5 days Beets, bunched 0 32 98-100 10-14 days Beets, topped 0 32 98-100 4-6 months Belgian endive 2-3 36-38 95-98 24 weeks Bitter melon 12-13 53-55 85-90 2-3 weeks Black sapote 13-15 55-60 85-90 2-3 weeks Blackberries -0.5-0 31-32 90-95 2-3 days Blood orange 4-7 40-44 90-95 3-8 weeks Blueberries -0.5-0 31-32 90-95 2 weeks Bok choy 0 32 95-100 3 weeks Boniato 13-15 55-60 85-90 4-5 months Breadfruit 13-15 55-60 85-90 2-6 weeks Broccoli 0 32 95-100 10-14 days Brussels sprouts 0 32 95-100 3-5 weeks Cabbage, early 0 32 98-100 3-6 weeks Cabbage, late 0 32 98-100 5-6 months Cactus Leaves 2-4 36-40 90-95 3 weeks Cactus Pear 2-4 36-40 90-95 3 weeks Caimito 3 38 90 3 weeks Calabaza 10-13 50-55 50-70 2-3 months Calamondin 9-10 48-50 90 2 weeks Canistel 13-15 55-60 85-90 3 weeks Cantaloupes (3/4-slip) 2-5 36-41 95 15 days Cantaloupes (full-slip) 0-2 32-36 95 5-14 days Carambola 9-10 48-50 85-90 3-4 weeks Carrots, bunched 0 32 95-100 2 weeks Carrots, mature 0 32 98-100 7-9 months Carrots, immature 0 32 98-100 4-6 weeks Cashew apple 0-2 32-36 85-90 5 weeks Cauliflower 0 32 95-98 34 weeks Celeriac 0 32 97-99 6-8 months Celery 0 32 98-100 2-3 months Chard 0 32 95-100 10-14 days Chayote squash 7 45 85-90 4-6 weeks Cherimoya 13 55 90-95 2-4 weeks Cherries, sour 0 32 90-95 3-7 days Cherries, sweet -1 to -0.5 30-31 90-95 2-3 weeks Chinese broccoli 0 32 95-100 10-14 days Chinese cabbage 0 32 95-100 2-3 months Chinese long bean 4-7 40-45 90-95 7-10 days Clementine 4 40 90-95 24 weeks Coconuts 0-1.5 32-35 80-85 1-2 months Collards 0 32 95-100 10-14 days Corn, sweet 0 32 95-98 5-8 days Cranberries 2-4 36-40 90-95 24 months Cucumbers 10-13 50-55 95 10-14 days Currants -0.5-0 31-32 90-95 1-4 weeks Custard apples 5-7 41-45 85-90 4-6 weeks Daikon 0-1 32-34 95-100 4 months Dates -18 or 0 0 or 32 75 6-12 months Dewberries -0.5-0 31-32 90-95 2-3 days Durian 4-6 39-42 85-90 6-8 weeks Eggplants 12 54 90-95 1 week Elderberries -0.5-0 31-32 90-95 1-2 weeks Endive and escarole 0 32 95-100 2-3 weeks Feijoa 5-10 41-50 90 2-3 weeks Figs fresh -0.5-0 31-32 85-90 7-10 days Garlic 0 32 65-70 6-7 months Ginger root 13 55 65 6 months Gooseberries -0.5-0 31-32 90-95 34 weeks Granadilla 10 50 85-90 3-4 weeks Grapefruit, Calif. & Ariz. 14-15 58-60 85-90 6-8 weeks Grapefruit, Fla. & Texas 10-15 50-60 85-90 6-8 weeks Grapes, Vinifera -1 to -0.5 30-31 90-95 1-6 months Grapes, American -0.5-0 31-32 85 2-8 weeks Greens, leafy 0 32 95-100 10-14 days Guavas 5-10 41-50 90 2-3 weeks Haricot vert (fine beans) 4-7 40-45 95 7-10 days Horseradish -1-0 30-32 98-100 10-12 months Jaboticaba 13-15 55-60 90-95 2-3 days Jackfruit 13 55 85-90 2-6 weeks Jaffa orange 8-10 46-50 85-90 8-12 weeks Japanese eggplant 8-12 46-54 90-95 1 week Jerusalem Artichoke -0.5-0 31-32 90-95 +5 months Jicama 13-18 55-65 65-70 1-2 months Kale 0 32 95-100 2-3 weeks Kiwano 10-15 50-60 90 6 months Kiwifruit 0 32 90-95 3-5 months Kohlrabi 0 32 98-100 2-3 months Kumquats 4 40 90-95 2-4 weeks Langsat 11-14 52-58 85-90 2 weeks Leeks 0 32 95-100 2-3 months Lemons 10-13 50-55 85-90 1-6 months Lettuce 0 32 98-100 2-3 weeks Limes 9-10 48-50 85-90 6-8 weeks Lo bok 0-1.5 32-35 95-100 24 months Loganberries -0.5-0 31-32 90-95 2-3 days Longan 1.5 35 90-95 3-5 weeks Loquats 0 32 90 3 weeks Lychees 1.5 35 90-95 3-5 weeks Malanga 7 45 70-80 3 months Mamey 13-15 55-60 90-95 2-6 weeks Mangoes 13 55 85-90 2-3 weeks Mangosteen 13 55 85-90 2-4 weeks Melons: Casaba 10 50 90-95 3 weeks Crenshaw 7 45 90-95 2 weeks Honeydew 7 45 90-95 3 weeks Persian 7 45 90-95 2 weeks Mushrooms 0 32 95 34 days Nectarines -0.5-0 31-32 90-95 2-4 weeks Okra 7-10 45-50 90-95 7-10 days Olives, fresh 5-10 41-50 85-90 +6 weeks Onions, green 0 32 95-100 34 weeks Onions, dry 0 32 65-70 1-8 months Onion sets 0 32 65-70 6-8 months Oranges , Calif. & Ariz. 3-9 38-48 85-90 3-8 weeks Oranges , Fla. & Texas 0-1 32-34 85-90 8-12 weeks Papayas 7-13 45-55 85-90 1-3 weeks Passionfruit 7-10 45-50 85-90 3-5 weeks Parsley 0 32 95-100 2-2.5 months Parsnips 0 32 95-100 +6 months Peaches -0.5-0 31-32 90-95 2-4 weeks Pears -1.5 to -0.5 29-31 90-95 2-7 months Peas, green 0 32 95-98 1-2 weeks Peas, southern 4-5 40-41 95 6-8 days Pepino 4 40 85-90 1 month Peppers, Chili (dry) 0-10 32-50 60-70 6 months Peppers, sweet 7-13 45-55 90-95 2-3 weeks Persimmons, Japanese -1 30 90 34 months Pineapples 7-13 45-55 85-90 24 weeks Plantain 13-14 55-58 90-95 1-5 weeks Plums and prunes -0.5-0 31-32 90-95 2-5 weeks Pomegranates 5 41 90-95 2-3 months Potatoes, early crop 10-16 50-60 90-95 10-14 days Potatoes, late crop 4.5-13 40-55 90-95 5-10 months Pummelo 7-9 45-48 85-90 12 weeks Pumpkins 10-13 50-55 50-70 2-3 months Quinces -0.5-0 31-32 90 2-3 months Raddichio 0-1 32-34 95-100 2-3 weeks Radishes, spring 0 32 95-100 34 weeks Radishes, winter 0 32 95-100 24 months Rambutan 12 54 90-95 1-3 weeks Raspberries -0.5-0 31-32 90-95 2-3 days Rhubarb 0 32 95-100 24 weeks Rutabagas 0 32 98-100 +6 months Salsify 0 32 95-98 2-4 months Santol 7-9 45-48 85-90 3 weeks Sapodilla 16-20 60-68 85-90 2-3 weeks Scorzonera 0-1 32-34 95-98 6 months Seedless cucumbers 10-13 50-55 85-90 10-14 days Snow peas 0-1 32-34 90-95 1-2 weeks Soursop 13 55 85-90 1-2 weeks Spinach 0 32 95-100 10-14 days Squashes, summer 5-10 41-50 95 1-2 weeks Squashes, winter 10 50 50-70 2-3 months Strawberries 0 32 90-95 5-7 days Sugar apples 7 45 85-90 4 weeks Sweetpotatoes 13-15 55-60 85-90 4-7 months Tamarillos 3-4 37-40 85-95 10 weeks Tamarinds 7 45 90-95 3-4 weeks Tangerines, mandarins, and 4 40 90-95 24 weeks related citrus fruits Taro root 7-10 45-50 85-90 4-5 months Tomatillos 13-15 55-60 85-90 3 weeks Tomatoes, mature-green 18-22 65-72 90-95 1-3 weeks Tomatoes, firm-ripe 13-15 55-60 90-95 4-7 days Turnips 0 32 95 4-5 months Turnip greens 0 32 95-100 10-14 days Ugli fruit 4 40 90-95 2-3 weeks Waterchestnuts 0-2 32-36 98-100 1-2 months Watercress 0 32 95-100 2-3 weeks Watermelons 10-15 50-60 90 2-3 weeks White sapote 19-21 67-70 85-90 2-3 weeks White asparagus 0-2 32-36 95-100 2-3 weeks Winged bean 10 50 90 4 weeks Yams 16 61 70-80 6-7 months Yucca root 0-5 32-41 85-90 1-2 months Source: McGregor, B.M. 1989. Tropical Products Transport Handbook. USDA Office of Transportation, Agricultural Handbook 668.