The science of nanotechnology - the study and application of tiny matter and the manipulation of individual molecules and atoms – is historically associated with engineering but has been emerging in agricultural research in recent years. But how exactly can nanotech help growers and exporters? Associate professor Jayasankar Subramanian at the University of Guelph in Canada is working with partners in India, Sri Lanka, Tanzania, Kenya and the Caribbean to improve the shelf-life of fruit and reduce post-harvest loses using this scientific technique.

"This is a fairly lengthy investigation that started with one of my colleagues who discovered that an enzyme called phospholipase D is responsible for breaking membranes during a fruit’s ripening process and also that hexanal, which is a naturally occurring compound in plants can inhibit this enzyme," Subramanian tells www.freshfruitportal.com.

"In basic terms this means shelf life can be extended because membranes remain intact and stable and ripening is slowly delayed so fruits remain fresh and firm for longer.

"Eventually we created a formulation that can be used as a spray on plants, fruits and trees. This spray can be used before the onset of ripening and it keeps the fruit a little bit longer on the tree and also very gradually slows down the ripening process."

Better control over the harvesting process

Maintaining fruits' freshness is a big deal in countries like India which is severely lacking in cold storage facilities and faces huge waste problems due to the poor cold chain supply. It's a regular occurrence for producers to be faced with a sudden glut of banana or mango crops that cannot be completely sold or fetch lower prices because of oversupply.

Subramanian says using nanotech and hexanal bypasses this problem, and so far field trials in Sri Lanka and India have significantly reduced post-harvest losses in mango and banana.

Aside from spraying mango trees, the nanotech formula can be used to coat, with the fruit being dipped before being exported.

"Let's say a mango farmer sprays half or one-third of the plant with the formulation, he gets that same mango production but spread out over a three to four-week window instead of just that one week window which causes a major rush and a glut in the market which then leads onto low prices.

Mangoes after 12 days at room temperature with Hexanal treatment.

"One of the objectives is that this doesn't just reach the elite and large growers of the world, but also the small grassroots level farmers so everyone can benefit from it.

"After extensive field trials with mango, it will now be extended to include other fruits like banana, citrus, papaya and some Canadian berry crops as well.”

Subramanian's Ontario-based research, which is funded by the International Development Research Centre (IDRC) and Foreign Affairs, Trade and Development Canada, includes collaboration with several countries, not just the Indian sub continent.

Thanks to $4.2 million worth of federal support awarded in January 2015, field trials can be extended in different countries including Kenya, Tanzania, and Trinidad and Tobago, and tested on a variety of crops such as papaya and citrus.

"We are also trying a method with papayas in Africa and the Caribbean. With papaya you don’t get the fruits ripening at the same time, you have a continuous ripening process. And this would require a sort of continuous spray which is not economically viable.

"So in those cases, you pick the fruits when they are at the very early stages of the ripening process, and you dip them in the solution which contains the hexanal as a nano formulation. The fruit is then washed thoroughly and packed out and it would then have a much longer shelf life compared to fruits without this treatment."

Mangoes kept under the same conditions but without hexanal treatment.

Commercialized within two years

Thanks to the extension in funding, the grand plan is to take the formula to market within 24 months and then potentially roll it out on a global scale. Subramanian says studies have shown that hexanal is safe for all normal orchard organisms and meets bio-safety standards.

"One exceptionally good thing we have found is that there is very little lingering. I’m sure it has a place in the market because it’s such a good product and comes without baggage as it were.

"It’s a very natural compound and even in our academic research we have found that if you spray or dip the fruit with this compound, within 48 hours it’s all gone and you can’t even find a tiny trace using a microscope.

"Hexanal is a compound approved by the FDA in the U.S. and is used as a food agent already. It’s also classified as one of those grass compounds which are generally regarded as safe. So it’s more like an organic product and definitely meets the criteria of an organic product for those in the organic business."

In addition to the spray and the dipping formula, the research project is also harnessing hexanal to be used in sachets that can be placed in fruit cartons or boxes to prolong shelf life.

"Imagine a sachet of silica gel like the ones you get in a box of new shoes, that’s the idea. We have created the nano particles from agricultural waste, like using banana waste as there are huge volumes of this in countries like India.

"The stem and other parts of the plants are thought to be useless, but they are not. We have extracted the fibers from banana waste and turned them into bio nano particles. These are like tiny pockets that you can see through a hypo electron microscope and we have successfully packaged hexanal molecules into these nano pores.

"We have, at the research stage, created a sachet and this could be placed in banana cartons and again all it needs is for hexanal to be triggered which would happen when fruits are packaged and allowed to breathe, that is enough to trigger the slow release of hexanal from the sachet."

Using nanotechnology, the University of Guelph’s research team will continue to develop hexanal-impregnated packaging and coatings to keep fruit fresh during handling and shipping.

Via a statement, interim vice president (research) John Livernois says this research project is a great example of why the institution is considered a world leader in agricultural research.

"We’re taking a local invention to the global level. With our current and new partners, we will be working in Asia, East Africa and the Caribbean, as well as in Canada.

"This confirms our commitment to improve agriculture in East Africa and around the world."

www.freshfruitportal.com