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Lychee quality preservation
Integrated postharvest decay control treatment

Lychee is an important tropical fruit that suffers greatly by postharvest decay, especially after current commercial application of sulphur treatment and acidification.

Researches have found that the major fungal genera associated with lychee in the marketing chain are Phomopsis, Pestalotiopsis, Penicillium, Trichoderma, Alternaria, Botryosphaeria and Fusarium spp.. Among them, Penicillium was reported as the major pathogen especially after sulphur treatment and under low temperature storage condition. Commercial SO2 fumigation stimulate lychee pericarp micro-cracking which results not only on speedy water loss, a major factor of lychee pericarp browning, but also provide an entry point for decay pathogens that colonize on the fruit surface.



Most tough fungus, including Penicillium species, are wound pathogens that are airborne and they reproduce very rapidly. They infect the fruit in the field, in the packing house, in cold storage, and along marketing chain. The reason that they are so tough to deal with is because their conidia in wounds would penetrate into the lychee membrane and cause infection even at low temperature and RH. And the nature of lychee pericarp micro-cracks makes the situation worse and more difficult to control than other fruits.

In the industry, synthetic chemical fungicides, such as imazalil (IZ), sodium ortho-phenyl phenate (SOPP), thiabendazole (TBZ) and prochloriz, were widely used to fight postharvest decay. Due to the toxicological effects on consumption and environment, the application using such chemicals, along with SO2, has been tightening up dramatically. (US FDA has totally banned SO2 use on fresh fruit in April, 2010.)

On top of regulatory restrictions, the wide and continuous use of these synthetic compounds has led to the build-up of fungal genera of high resistance in commercial packinghouses and seriously compromises the effectiveness of these chemicals. Thus an alternative fungicidal application is of immediate necessity.

The fungus inside wounds requires free water and nutrients, and is stimulated by volatiles emitted from the fruit tissue. Therefore, in-package condensation becomes a very critical issue especially when cold chain is broken at distribution and retail level. Thus fungicidal MAP packaging along is not always satisfactory as it is expected.

It is long found that stable and effective commercial application on postharvest decay control cannot be achieved by single mode of treatments. Postharvest decay control is a multiple-phase subject that has to be dealt with multiple approaches.
At Agrifresh Biotech, a practical postharvest decay control procedure is developed along a sulphur free lychee quality preservation treatment. It is focused on the following:
  • Immediate postharvest disinfection procedure to reduce inoculums’ levels of fungus on the fruit surface and in the atmosphere;
  • with compound formula of non hazardous antifungal substances to enhance the effectiveness of single substance,
  • with supplementation of trace substances together with rehydration to enhance fruit stamina and induce fruit resistance to pathogen postharvestly,
  • with non destructive auxiliaries to enhance fungicidal effectiveness,
  •  incorporation of fungicidal substances and edible coating to extend the effectiveness in storage and marketing chain.
This multi-phased treatment is relatively simple, gentle to fruit and environment, cost effective, and practical as a ready alternative to conventional chemical fungicides.

Contact:
Agritech Biotech Co.
Mr. Edward Jih, email: jihedward@gmail.com

Ms. Lynn Sun, email: lynnsun09@gmail.com


Publication date: 12/6/2010


 


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