For Minimal Moisture and Petal Loss
By utilising a number of synergistic technologies, Convex Plastics has designed a modified atmosphere liner which increases the cut stem life of hydrangea by minimising moisture and petal loss.
Known as re~fresh, these liners have been successfully used over several seasons in New Zealand for export hydrangeas going to Asia and both the East and West coasts of the USA.
Although hydrangeas are relatively hardy compared to many other varieties of fresh cut flowers, they still suffer from moisture loss and ethylene induced abscission (loss) of flower petals. Moisture loss causes shrivelling and wilting of the stem and petals, and excessive moisture loss causes leaf and petal loss. Ethylene, a natural plant ripening hormone, also causes petal loss. Although hydrangeas produce only low-levels of ethylene, most environments where they are stored and distributed are high in ethylene and consequently adversely affect the storage life of the cut flowers. This is because, as a by-product of combustion, high levels of ethylene are often emitted by transport vehicles, forklifts, airplanes and cool stores.
Enhancing the cut stem life of hydrangea can be achieved in three ways: firstly by increasing the relative humidity (RH) inside the pack, secondly by reducing the amount of ethylene produced by the stem, and lastly by reducing the amount of external environmental ethylene coming into contact with the cut stems. The first and last factors can be achieved simply by using a plastic liner which reduces both the amount of moisture permeating out of the pack, and the amount of ethylene permeating in to the flowers from the external environment. However, dealing with the internal environment is more difficult as cut flowers continue to produce ethylene and traditional liners are not permeable enough to vent this ethylene out of the package.
Convex Plastics has overcome this difficulty by utilising a number of synergistic technologies which allow the flowers to create a passive modified atmosphere within the re~fresh liners.
As with all cut flowers, hydrangea continue to respire after harvesting and utilise O2 while giving off CO2. Through the correct design of the film structure, the rate of gas transfer by the cut stems can be matched with the film transpiration rate of the re~fresh liners, which thereby produces a more advantageous atmosphere within the sealed pack. The resulting reduced O2 concentration and increased CO2 concentration reduces the stems' respiration rate which in turn reduces the ethylene production rate. At the same time the increased CO2 levels also have an added advantageous effect because CO2 is a competitive inhibitor of ethylene action (i.e. CO2 blocks the receptor sites on the enzymes that are catalysed by ethylene, preventing the ethylene binding). By creating an effective passive modified atmosphere Convex Plastics' re~fresh liners not only reduce the amount of ethylene being produced, but also greatly reduce the effectiveness of the ethylene that is already present.
Along with the modified atmosphere technology, Convex Plastics also incorporates a resin into the inside layer of the re~fresh film structure which helps remove excess ethylene from within the package.
Because re~fresh liners minimise moisture loss, the use of vials or floss is no longer required. New Zealand hydrangea exporters have claimed this has saved them a considerable amount of time and money.