Ethylene gas

Ethylene gas (C2H4) is an odorless, colorless gas that exists in nature and is also created by man-made sources. Not easily detectable, it exists where produce is stored. In nature, the largest producers are plant and plant products (ie. fruits, vegetables and floral products) which produce ethylene within their tissues and release it into the surrounding atmosphere. It is also a by-product of man-made processes, such as combustion.
Ethylene, also known as the 'death' or 'ripening hormone' plays a regulatory role in many processes of plant growth, development and eventually death. Fruits, vegetables and flowers contain receptors which serve as bonding sites to absorb free atmospheric ethylene molecules. The common practice of placing a tomato, avocado or banana in a paper bag to hasten ripening is an example of the action of ethylene on produce. Increased levels of ethylene contained within the bag, released by the produce itself, serves as a stimulant after reabsorption to initiate the production of more ethylene. The overall effect is to hasten ripening, aging and eventually spoilage. A refrigerator acts in much the same way. Kept closed to retain the desired temperature, it also enables an increased concentration of ethylene to accumulate. Any closed environment, such as a truck trailer, shipping container or warehouse, will have a similar effect.
Ethylene is a plant hormone that differs from other plant hormones in being a gas. It has the molecular structure:  H2C=CH2   When fruits approach maturity, they release ethylene. Ethylene promotes the ripening of fruit. Among the many changes that ethylene causes is the destruction of chlorophyll. With the breakdown of chlorophyll, the red and/or yellow pigments in the cells of the fruit are unmasked and the fruit assumes its ripened color. The presence of ethylene is probably detected by transmembrane receptors (protein that passes one or more times through the lipid bilayer of a cell membrane) in the surface of the plasma membrane of the cells.

Fruit Ripening
Abscission; leaf flower fruits (thinning, harvesting)
Triple Resonses
Hook Closure Maintenance
Initiates Germination in Grains
Activates dormant buds (potatoes in storage)
Stem elongation in deep-water rice
Induces Flowering in Pineapple
Promotes Female Expression in Flowers
Flower and Leaf Senescence: Ag preventative (vase life)
While ethylene is invaluable due to its ability to initiate the ripening process in several fruits, it can also be very harmful to many fruits, vegetables, flowers, and plants by accelerating the aging process and decreasing the product quality and shelf life. The degree of damage depends upon the concentration of ethylene, length of exposure time, and product temperature. One of the following methods should be used to ensure that ethylene-sensitive produce is not exposed: a) Ethylene producing items (such as apples, avocados, bananas, melons, peaches, pears, and tomatoes) should be stored separately from ethylene-sensitive ones (broccoli, cabbage, cauliflower, leafy greens, lettuce, etc.). Also, ethylene is emitted by engines. Propane, diesel, and gasoline powered engines all produce ethylene in amounts large enough to cause damage to the ethylene-sensitive produce items mentioned; b) Ventilate the storage area, preferably to the outside of the warehouse, on a continuous or regular basis to purge the air of any ethylene; c) Remove ethylene with ethylene absorbing filters. These have been proven in reducing and maintaining low ethylene levels. If ethylene damage is suspected, a quick and easy way to detect ethylene levels is with hand held sensor tubes. This will indicate if the above steps should be followed.
ethylene gas is effective at 0.1 to 1 ppm. One part of ethylene per million parts of air that's one cupful of ethylene gas in 62,000 gallons of air - is enough to promote the ripening process in fruits.
 why the fruit is ripe containing ethylene gas??
 if the fruit is not ripe d mixed with fruit that is ripe, it is not yet ripe fruit will cook faster. why did that happen?

experienced during the ripening of fruit, then the existing network in the fruit increased ethylene gas production ...
ethylene gas is able to solve the chlorophyll in the young fruit until the fruit has only resulted in xantofil and xarotein or substance that makes skin becomes red or orange fruit. because chlorophyll has been reduced by ethylene gas ....
only that the function of ethylene in ripening fruit, if problems flavors, from sour to sweet when the fruit is ripe, it depends on whether or not split sel2 perfect cork on the fruit or it could be caused by genetic factors.
stimulated fruit ripening by ethylene gas that diffuses into the intercellular spaces of the fruit. Gas can also diffuse through the air from one fruit to another fruit, fruit will mature more quickly if the fruit is stored in a plastic bag which resulted in accumulated ethylene gas.

posted by 
NIM : RSA1C110020
Angkatan : 2010
Nama Blog :

0 komentar:

Poskan Komentar

Write here, about you and your blog.
Copyright 2009 Chemistry All rights reserved.
Free Blogger Templates by
Wordpress Theme by EZwpthemes