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CO2
Benefits for Produce
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What Factors Affect Produce?
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Temperature:
Temperature is the major factor affecting the storage and shelf
life of produce. This is true for the grower, the shipper, the
wholesaler and the retailer. The sooner the grower can remove
the field heat from the fruits and vegetables, the longer will
be their storage potential. Every effort should be made not to
break the cold chain. |
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Temperature
is the single most important factor in maintaining quality after
harvest. Refrigerated storage retards the following elements
of deterioration in perishable crops:
• Aging due to ripening, softening, and textural and color changes;
• Undesirable metabolic changes and respiratory heat production;
• Moisture loss and the wilting that results;
• Spoilage due to invasion by bacteria, fungi, and yeasts;
• Undesirable growth, such as sprouting of potatoes (Hardenburg).
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Respiration:
Respiration generates heat as sugars, fats, and proteins in the
cells of the crop are oxidized. The loss of these stored food
reserves through respiration means decreased food value, loss
of flavor, loss of saleable weight, and more rapid deterioration
(Wilson).
Ethylene:
Ethylene gas reduces the longevity of fruits and vegetables. Low
temperatures can reduce the rate of ethylene production. When plants
are growing, ethylene helps fruits and vegetables become more colorful
and tasty. However, after harvest, ethylene becomes the plant's
worst enemy. Ethylene gas is to plant life what carbon monoxide
is to human life: A colorless, odorless, tasteless gas that kills.
Controlling ethylene is critical in the fresh produce industry.
Dehydration and Hydration:
As a function of photosynthesis, which happens even after harvest,
plants pull water through their bodies and to their surface. When
this water comes in contact with air, evaporation takes place,
causing plants to continually lose moisture. Rapidly moving air
in a refrigerated storage environment accelerates that process.
Water loss can severely degrade quality—for instance, wilted
greens may require excessive trimming, and grapes may shatter loose
from clusters if their stems dry out. Water loss means saleable
weight loss and reduced profit (Wilson).
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How Does CO2 help? |
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Temperature:
To optimize the effects of CO2 technology, it
must be matched with the proper atmospheric
storage conditions for fruits and vegetables.
CO2 is a refrigerant gas that can help you
obtain lower temperatures in your cooler and
save energy.
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Respiration:
CO2 gas slows the respiration rate of the fruit and vegetables
by modifying the
atmosphere with moist CO2, perishables will be surrounded with
heavier, more moist
air.
Ethylene:
CO2 gas is twice as dense as ethylene gas; therefore it displaces
the ethylene away
from the produce and dramatically slows the adverse affects
associated with it.
Dehydration and Hydration:
This heavier air will blanket the product, slowing the evaporation
of moisture and the
dehydration process. CO2-laden air is attracted to moisture.
This heavier air will hold
more moisture and keep it in contact with the product and reduce
dehydration.
Other Observed Benefits:
Most fruit and vegetable crops retain better quality at high
relative humidity (80 to
95%), but at this humidity, disease growth is encouraged. The
CO2 will help retard the
growth of the bacteria, mold and mildew.
A Note About Ozone:
Fruit and vegetable growers have begun using ozone in chill water
dump tanks, where it
can be thousands of times more effective than chlorine. Ozone
not only kills whatever
food borne pathogens might be present, it also destroys microbes
responsible for
spoilage (Gooch).
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References:
Gooch, Jamie. 1998. Getting into the ‘o’zone. Fruit
Grower. January. p. 10–11.
Hardenburg, Robert, et al. 1986. The Commercial Storage of Fruits,
Vegetables, and
Florist and Nursery Stocks. USDA Handbook No. 66. United States
Department of
Agriculture, Agricultural Research Service. 136 p.
Wilson, L.G., M.D. Boyette, and E.A. Estes. 1995. Postharvest
Handling and Cooling of
Fresh Fruits, Vegetables and Flowers for Small Farms. Leaflets
800–804. North Carolina
Cooperative Extension Service. 17 p. Accessed on-line at: http://www.foodsafety.org/nc/nc1055.htm
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