Mango is beloved by many for its sweetness and flavor, but this tropical fruit is prone to “chilling injury” when stored in cold temperatures, causing black spots on the skin and mushy flesh that affect its quality and taste. Australian scientists have developed a low-cost, non-toxic technology that not only effectively combats chilling injury but also doubles the refrigerated shelf life of mangoes.
As global demand for fruits and vegetables continues to rise, mango production has also increased accordingly. However, extreme weather conditions worldwide make fruits and vegetables susceptible to rapid decay during long-distance transportation, even when cold storage techniques are utilized, leading to the occurrence of “Chilling Injury” (CI) in some cold-sensitive fruits.
Tropical fruits like mangoes and bananas are particularly sensitive to low temperatures and are also prone to damage from pests and mechanical injuries. Mangoes are typically harvested at the green ripening stage and can be stored for about 14 days at 13°C, but storing them below 12.5°C can trigger chilling injury, causing black spots on the skin and flesh to become mushy.
To address the issues caused by chilling injury in mangoes, the Edith Cowan University in Australia, with over 100 years of history, has developed a low-cost and non-toxic technology called “Phenolic Acid Ozonated” (PAO). By immersing mangoes in ozone-infused water, they have been able to extend the refrigerated shelf life of mangoes to 28 days and significantly reduce the incidence of chilling injury.
This research focused on the widely produced “Kensington Pride” mangoes in Australia and conducted tests using the “Phenolic Acid Ozonated” technology to enhance their cold tolerance during refrigeration. The results were published in the International Journal of Plant Growth and Development in early July.
Researchers divided ripe, green Kensington Pride mangoes into two groups for experimentation. One group was soaked in ozone water with a concentration of 1mg/liter for 10 minutes, while the other was the control group that was not soaked in ozone water. Both groups of mangoes were then refrigerated at 5°C and 80% humidity for 21 and 28 days, followed by 6 days on shelves at room temperature (around 20°C) to simulate a retail environment.
The results showed that the mangoes treated with ozone water performed remarkably well in resisting chilling injury. The incidence of chilling injury decreased significantly by 62.5% and 42.9% after refrigeration for 21 and 28 days, respectively, with an overall reduction of 40.4% in the chilling injury index. Additionally, weight loss decreased by 18.4% and 21.8%, demonstrating better maintenance of fruit quality.
The chilling injury index is categorized into no surface damage, extremely slight surface damage (less than 5%), slight surface damage (5%–10%), moderate surface damage (10%–25%), and severe surface damage (more than 25%).
Furthermore, researchers also soaked mangoes in ozone water for 10, 20, and 30 minutes before refrigeration to observe changes in the flesh and skin of the mangoes. The results indicated that mangoes soaked in ozone water for 10 minutes exhibited the best performance, but longer soaking times also improved the chilling injury situation.
Researchers also found that mangoes treated with “Phenolic Acid Ozonated” showed a significant increase in the activity of various antioxidant enzymes inside the mango, such as ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR). The enhanced activity of these enzymes helps maintain the fundamental quality and cold resistance of the fruit.
Researchers stated that these results suggest that “Phenolic Acid Ozonated” seems to be a feasible technology, and they hope to conduct tests on other mango varieties in the future to study their responsiveness while reducing the chilling injury issues that arise from prolonged refrigeration.
Dr. Mekhala Dinushi Kananke Vithana, a lecturer at the School of Science at Edith Cowan University, expressed to the university’s press office, “It is estimated that 20% of Australia’s total mango production is lost or wasted before reaching consumers. Among them, horticultural agricultural products account for about 50% of Australia’s total food waste. Therefore, extending the storage life of mangoes has become crucial for mango growers and traders.”
Dr. Vithana further explained, “Phenolic Acid Ozonated is a technique that involves dissolving ozone in water through an ozone generator, a compound widely used in commercial fruit and vegetable disinfection. Not only is it cost-effective and efficient, it can be performed on-site, and low concentrations of ozone rapidly decompose into oxygen, making it relatively safe for workers.”
She elaborated, “This technology can be integrated with the existing water cooling process for mangoes or used as a separate disinfection procedure after harvesting. However, further optimization of the treatment is needed before it can be truly implemented for commercial applications.”