Use of nanotubes to prevent grey mould in fruit

Grey mould (Botrytis cinerea) is responsible for the loss of tomatoes, grapes, strawberries and other plant species, causing serious economic damage to agricultural producers and those working in the sector.

At the Potosino Institute of Scientific and Technological Research (Ipicyt), there is a team of researchers who, using photoactive nanotubes, have been pursuing the task of eliminating this disease, which affects many crops and causes significant losses before and after the harvest, as well as in storage and distribution.

Vicente Rodríguez González, PhD in materials engineering and high technology and member of the research group that seeks to combat grey mould, outlined some of the most important points of the project in an interview with the Conacyt Information Agency.

The products' infection occurs in moist conditions. The fungus penetrates through wounds or cracks in the fruits or leaves, deteriorating their quality and even affecting the plant's green organs.

"This fungus is a microorganism that is present in the environment, and when it finds a humid environment, suitable for its growth, it begins to infect the crops. It is not specialised in a single one, but is usually found in tomatoes, grapes, strawberries and plums, from where it can feed and damage the plants."

The nanotubes that are used to fight the fungus are made of titanium dioxide (TiO2). This nanomaterial has a diameter of approximately 12 nanometres and is able to act against the fungus through three ways. It should be noted that this chemical is not toxic to humans.

Photochemical way
The structure has semi conductive properties, so it is possible to generate oxidising reactions when exposed to light radiation by means of halogen lamps, light-emitting diode (led) lamps, and even sunlight.

Microcide way 
It is possible to incorporate nanoparticles of silver or copper of less than five nanometres on the surface of the nanotubes. These nanoparticles have antifungal properties and inhibit the growth of fungal colonies.

Physical way
Given the nanometric size of the structures, it can puncture and damage the cell wall of the fungus, thus facilitating its annihilation.

One of the main advantages of three-way action is that it ensures that micro-organisms can not evolve and therefore are unable to develop immunity to these nanomaterials, contrary to what happens with fungicidal or chemical agents, in addition to This method is sustainable and respectful of the environment, as it does not generate waste, unlike the methods used by farmers.

To address this problem, agricultural producers use calcium oxide (CaO) and ozone (O3) in the nurseries, as well as different fungicides to control the fungus, but these are expensive and toxic for human consumption. Some transnationals have created transgenic crops, incorporating unidentified risks.

So far, laboratory test results have shown that these nanostructures have the ability to inhibit grey mould infection in as little as 20 minutes. The practical application that is being studied to prevent infections consists of transparent coatings that will be tested in greenhouse crops of the Potosi Institute and in the packaging.

"The idea is to manufacture thin, transparent films that can be placed on the fruit to prevent infection, and which may be reused. What is pursued is to prevent, rather than to eliminate the infection," pointed out the the Level III member of the National System of Researchers (SNI).


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