Blackberries at various stages of ripeness: unripe (green), ripening (pink and red), and ripe (black)

Ripening process of a date on a phoenix dactylifera.

This lemon is turning yellow as it ripens.

Ripe lemons.

Ripening is a process in fruits that causes them to become more edible. In general, a fruit becomes sweeter, less green, and softer as it ripens. However the acidity as well as sweetness rises during ripening, but the fruit still tastes sweeter regardless. The reason for this is the Brix-Acid Ratio.

[edit] Ripening agents

Ripening agents speed up the ripening process.

They allow many fruits to be picked prior to full ripening, which is useful since ripened fruits do not ship well. For example, bananas are picked when green and artificially ripened after shipment by being gassed with ethylene. A similar method used in parts of Asia was to cover a bed of slightly green-harvested mango and a few small open containers of clumps of calcium carbide with a plastic covering. The moisture in the air reacted with the calcium carbide to release the gas acetylene, which apparently has the same effect as ethylene.

Calcium carbide is used for ripening the fruit artificially in some countries. Industrial-grade calcium carbide may contain traces of arsenic and phosphorus and thus use of this chemical for this purpose is illegal in most countries. Calcium carbide once dissolved in water produces acetylene^[1] which acts as an artificial ripening agent. Acetylene is believed to affect the nervous system by reducing oxygen supply to brain, however in practice it is sufficiently reactive that this should not affect consumers^{[citation needed]}.

Covered fruit ripening bowls are commercially available to increase fruit ripening. ^[2] The manufacturers claim the bowls increase ethylene and carbon dioxide gasses around the fruit which promote ripening.

Climacteric fruits are able to continue ripening after being picked, a process accelerated by ethylene gas. Non-climacteric fruits can only ripen on the plant and thus typically suffer from short shelf-lives.

[edit] Ripening delaying

SmartFresh is a technology useful to maintain fresh-picked quality of whole fruits and vegetables. 1-Methylcyclopropene (1-MCP 0.14%) works with the ripening process to dramatically slow down ethylene production and prevent over-ripening and problems associated with ageing.

[edit] Ripening indicators

Iodine (I) can be used to check if the fruit is ripening or rotting by showing whether starch in the fruit has turned into sugar. For example, in an apple that has rotted (not bruised, just rotted) a drop of iodine on a slightly rotten part (not skin) will turn a dark blue ,or black color if there is starch there. If it stays yellow, then most of the starch did turn into sugar.

[edit] Ethylene Sensitivity Chart

source: www.mindfully.org/Plastic/Ethylene-Gas.htm

 N=None   H=High   L=Low    M=Medium   VH=Very High    VL=Very Low      Perishable              Temperature    Ethylene     Ethylene     Commodities                C / F      Production   Sensitivity   Fruits & Vegetables  Apple (non-chilled)         1.1 / 30        VH            H  Apple (chilled)             4.4 / 40        VH            H  Apricot                    -0.5 / 31         H            H  Artichoke                     0 / 32        VL            L  Asian Pear                  1.1 / 34         H            H  Asparagus                   2.2 / 36        VL            M (Toughness)  Avocado (California)        3.3 / 38         H            H  Avocado (Tropical)         10.0 / 50         H            H  Banana                     14.4 / 58         M            H  Beans (Lima)                  0 / 32         L            M  Beans (Snap/Green)          7.2 / 45         L            M  Belgian Endive              2.2 / 36        VL            M  Berries (Blackberry)       -0.5 / 31         L            L (Mold)  Berries (Blueberry)        -0.5 / 31         L            L (Mold)  Berries (Cranberry)         2.2 / 36         L            L (Mold)  Berries (Currants)         -0.5 / 31         L            L (Mold)  Berries (Dewberry)         -0.5 / 31         L            L (Mold)  Berries (Elderberry)       -0.5 / 31         L            L (Mold)  Berries (Gooseberry)       -0.5 / 31         L            L (Mold)  Berries (Loganberry)       -0.5 / 31         L            L (Mold)  Berries (Raspberry)        -0.5 / 31         L            L (Mold)  Berries (Strawberry)       -0.5 / 31         L            L (Mold)  Breadfruit                 13.3 / 56         M            M  Broccoli                      0 / 32        VL            H (Yellowing)  Brussel Sprouts               0 / 32        VL            H  Cabbage                       0 / 32        VL            H  Cantalope                   4.4 / 40         H            M  Cape Gooseberry            12.2 / 54         L            L  Carrots (Topped)              0 / 32        VL            L (Bitterness)  Casaba Melon               10.0 / 50         L            L  Cauliflower                   0 / 32        VL            H  Celery                        0 / 32        VL            M  Chard                         0 / 32        VL            H  Cherimoya                  12.8 / 55        VH            H  Cherry (Sour)              -0.5 / 31        VL            L (Softening)  Cherry (Sweet)             -1.1 / 30        VL            L (Softening)  Chicory                       0 / 32        VL            H  Chinese Gooseberry            0 / 32         L            H  Collards                      0 / 32        VL            M  Crenshaw Melon             10.0 / 50         M            H  Cucumbers                  10.0 / 50         L            H (Yellowing)  Eggplant                   10.0 / 50         L            L  Endive (Escarole)             0 / 32        VL            M  Feijoa                      5.0 / 41         M            L  Figs                          0 / 32         M            L  Garlic                        0 / 32        VL            L (Odor)  Ginger                     13.3 / 56        VL            L  Grapefruit (AZ,CA,FL,TX)   13.3 / 56        VL            M (Mold)  Grapes                     -1.1 / 30        VL            L (Mold)  Greens (Leafy)                0 / 32        VL            H (Russet Spotting)  Guava                        10 / 50         L            M  Honeydew                     10 / 50         M            H  Horseradish                   0 / 32        VL            L  Jack Fruit                 13.3 / 56         M            M  Kale                          0 / 32        VL            M  Kiwi Fruit                    0 / 32         L            H  Kohlrabi                      0 / 32        VL            L  Leeks                         0 / 32        VL            M  Lemons                     12.2 / 54        VL            M (Mold)  Lettuce (Butterhead)          0 / 32         L            M (Russet Spotting)  Lettuce (Head/Iceberg)        0 / 32        VL            H (Russet Spotting)  Lime                       12.2 / 54        VL            M (Mold Degreen)  Lychee                      1.7 /35          M            M  Mandarine                   7.2 / 45        VL            M  Mango                      13.3 / 56         M            H  Mangosteen                 13.3 / 56         M            H  Mineola                     3.3 / 38         L            L  Mushrooms                     0 / 32         L            M  Nectarine                  -0.5 / 31         H            H  Okra                       10.0 / 50         L            M  Olive                       7.2 / 45         L            M  Onions (Dry)                  0 / 32        VL            L (Odor)  Onions (Green)                0 / 32        VL            M  Orange (CA,AZ)              7.2 / 45        VL            M  Orange (FL,TX)              2.2 / 36        VL            M  Papaya                     12.2 / 54         H            H  Paprika                    10.0 / 50         L            L  Parsnip                       0 / 32        VL            L  Parsley                       0 / 32        VL            H  Passion Fruit              12.2 / 54        VH            H  Peach                      -0.5 / 31         H            H  Pear (Anjou,Bartlett/Bosc)  1.1 / 30         H            H  Pear (Prickley)             5.0 / 41         N            L  Peas                         0 / 32         VL            M  Pepper (Bell)             10.0 / 50          L            L  Pepper (Chile)            10.0 / 50          L            L  Persian Melon             10.0 / 50          M            H  Persimmon (Fuyu)          10.0 / 50          L            H  Persimmon (Hachiya)        0.5 / 41          L            H  Pineapple                 10.0 / 50          L            L  Pineapple (Guava)          5.0 / 41          M            L  Plantain                  14.4 / 58          L            H  Plum/Prune                -0.5 / 31          M            H  Pomegranate                5.0 / 41          L            L  Potato (Processing)       10.0 / 50         VL            M (Sprouting)  Potato (Seed)              4.4 / 40         VL            M  Potato (Table)             7.2 / 45         VL            M  Pumpkin                   12.2 / 54          L            L  Quince                    -0.5 / 31          L            H  Radishes                     0 / 32         VL            L  Red Beet                   2.8 / 37         VL            L  Rambutan                  12.2 / 54          H            H  Rhubard                      0 / 32         VL            L  Rutabaga                     0 / 32         VL            L  Sapota                    12.2 / 54         VH            H  Spinach                      0 / 32         VL            H  Squash (Hard Skin)        12.2 / 54          L            L  Squash (Soft Skin)        10.0 / 50          L            M  Squash (Summer)            7.2 / 45          L            M  Squash (Zucchini)          7.2 / 45          N            N  Star Fruit                 8.9 / 48          L            L  Swede (Rhutabaga)            0 / 32         VL            L  Sweet Corn                   0 / 32         VL            L  Sweet Potato              13.3 / 56         VL            L  Tamarillo                    0 / 32          L            M  Tangerine                  7.2 / 45         VL            M  Taro Root                  7.2 / 45          N            N  Tomato (Mature/Green)     13.3 / 56         VL            H  Tomato (Brkr/Lt Pink)     10.0 / 50          M            H  Tree-Tomato                3.9 / 39          H            M  Turnip (Roots)               0 / 32         VL            L  Turnip (Greens)              0 / 32         VL            H  Watercress                   0 / 32         VL            H  Watermelon                10,0 / 50          L            H  Yam                       13.3 / 56         VL            L   Live Plants              Cut Flowers (Carnations)     0 / 32         VL            H (Sleepiness)  Cut Flowers (Chrysanthemums) 0 / 32         VL            H  Cut Flowers (Gladioli)     2.2 / 36         VL            H  Cut Flowers (Roses)          0 / 32         VL            H (Open Sooner)  Potted Plants        -2.8-18.3 / 27-65      VL            H  Nursery Stock         -1.1-4.4 / 30-40      VL            H (Slower Start)  Christmas Trees              0 / 32          N            N  Flowers Bulbs (Bulbs/   7.2-15 / 45-59      VL            H  Corms/Rhizomes/Tubers) 

[edit] References

[edit] Notes

[edit] Bibliography

[edit] External links

• http://plantphys.info/plants_human/fruitgrowripe.html
• http://www.actahort.org/books/398/398_17.htm
• Burg SP, Burg EA (March 1962). "Role of Ethylene in Fruit Ripening". Plant Physiol. 37 (2): 179–89. PMID 16655629.