Research reveals how to extend the lifespan of mangoes

How to keep your juicy mangoes as fresh as possible for as long as possible?

Conventional wisdom says to keep unripe mangoes in a bowl or a paper bag on the counter - away from direct sunlight. They'll ripen naturally over two to four days.

Once they are ripe, tuck them into the fridge. This puts the ripening process on pause and gives you a few more days of good eating.

But new research from Edith Cowan University (ECU) in Australia has identified a way to extend the storage life of the popular tropical fruit.

The study, led by ECU School of Science Lecturer Dr Mekhala Vithana has found that dipping mangoes in ozonated water (aqueous ozonation) for 10 minutes before cold storage can extended the cold storage life of the fruit by up to two weeks, with significantly lowered occurrence of chilling injury.

“Increasing storage life of mangoes is incredibly important for both growers and traders, as it reduces food loss during storage and offers a longer market window,” Dr Vithana said.

With a global rise in the consumption of fruit and vegetables in recent years, there has been a subsequent increase in the production of mangoes.

A significant proportion of the fruit is, however, lost along the supply chain due to rapid ripening and excessive perishability.

“It is estimated that about 20% of the total Australian mango production is lost or wasted, and horticultural produce is responsible for about 50% of the total food waste in Australia,” Dr Vithana said.

“Therefore, it is important to explore eco-friendly and cost-effective technologies to minimise post-harvest losses of mangoes.”

Typically, mangoes are picked at the mature green stage and stored at 13 degrees Celsius for up to 14 days. This, however, is not cold enough for extended storage.

“Being a tropical fruit, unripe mangoes should not be stored below 12.5 degrees due to their high sensitivity to cold temperatures,” Dr Vithana said. “Prolonged storage of mango below this temperature causes a physiological disorder known as chilling injury, which damages the fruit skin and leads to decreased marketability and significant food waste.

“Therefore, susceptibility to chilling injury is the key limitation for exploiting cold storage technology to its maximum capacity for lengthening the storage life of mangoes.”

The study - carried out on Australia’s most widely produced variety of mango Kensington Pride - tested aqueous ozonation technology to improve chilling tolerance during cold storage.

By dipping the mango in the ozonated water for 10 minutes prior to cold storage at 5 degrees Celsius, researchers found that they could keep the mangoes for longer with much less chilling injury.

“Generally, Kensington Pride mango can only be stored for about two weeks without ripening at 13 degrees. However, aqueous ozonation extends the storage and shelf life of these mangoes up to 28 days, with 40% less chilling injury than untreated mangoes,” Dr Vithana said.

Ozonation can be controlled on-site, is cost-effective and considered safe for workers at a threshold level due to its faster break down into oxygen.

“Aqueous ozonation is bubbling ozone into water through an ozone generator,” she said. “Ozone is a compound widely used to sanitise fruits and vegetables on a commercial scale.

“The ozonation can be combined with the hydrocooling step after quarantine heat treatment in export mangoes or separately as a sanitisation step just after harvesting, depending upon the convenience of the grower, but this needs further optimisation under commercial settings.”

Dr Vithana said ECU researchers are hoping to do further research on other varieties of mangoes to test their responsiveness and to achieve further reduction in chilling injury for extended cold storage.

Image: Suparerg Suksai, scop.io

Cherry Christmas? Not for everbody

Australia's cherry industry is in a positive growth phase, but current wet weather threatens the upcoming harvest and may limit Christmas supply.

Growing consumer appetite for the fruit locally and in export markets is a huge positive, Rabobank says in a new industry report.

But three consecutive La Nina weather events have taken their toll on Australia’s cherry production, with continuing wet conditions expected to impact the outlook for the coming harvest.

This will not only weigh on grower returns, but could also affect the availability, quality and price of this summer and festive fruit favourite for Australian consumers, the specialist agribusiness bank says.

In the report Southern Hemisphere Cherries, Growing Exports and Challenges, Rabobank says Australia’s sweet cherry sector has been in a growth phase for the past four years, with more than 450,000 additional cherry trees reaching bearing age since 2018.

Despite this growth in plantings, sweet cherry production and export volumes “continue to be affected by three consecutive La Nina weather events,” the bank says.

This impact was evident last season, says report co-author RaboResearch associate analyst Pia Piggott, with the industry estimating that Australia’s total cherry production for 2021-22 was down 15% on the previous year, at 17,000 tonnes.

Total Australian cherry volumes to export markets - which require the highest-quality premium fruit - decreased 20% on the previous year.

Piggott said export markets are particularly important for Australia’s cherry industry, due to “higher unit value” obtainable for exported fruit.

“Exports account for approximately 25% of the Australian cherry industry’s sales volumes, but almost 40% of sale value,” she said.

“So lower volumes of high-quality cherries suitable for export markets - along with outbound airfreight rates remaining high - means margins will be challenged for the sector this coming season.”

Piggott said longer-term demand for high-quality cherries as prized fruit in Asia, and in the domestic Australian market - together with healthy lifestyle trends - will support growth opportunities in the Australian cherry industry.

“Australian cherries remain competitive in the export market, although production risks, elevated input cost and labour challenges persist for growers,” she said.