Melatonin Is More Than a Sleep Aid — It Can Help Keep Fruits and Vegetables Fresh

The naturally occurring hormone melatonin, known to help with sleep, has been found to have another unrelated benefit: It can extend the freshness of fruits and vegetables.

Melatonin is produced by the brain, and is also present in many plants, including bananas, cherries, tomatoes, rice, wheat and olive oil.

When fruits and vegetables are transported in refrigerated trucks or stored at temperatures that are too cold, they can get “chilling injury,” reported Food Ingredients First. Researchers have recently found that melatonin can prevent this common postharvest issue.

Horticultural scientists from Edith Cowan University (ECU) have spent the past year compiling research from across the globe on melatonin’s benefits for keeping fruits and vegetables fresher for longer, a press release from ECU said.

“You will often see abnormal ripening, sunken spots, pitting, hardening of flesh and browning of peel and pulp in cold-stored fruits, while browning of tissues, translucency and water-soaked lesions in the vegetables, that is what we call chilling injury,” said Zora Singh, Foundation Professor of Horticultural Science in ECU’s School of Science and lead researcher of the study, in the press release.

The study, “Insight into the Role of Melatonin in Mitigating Chilling Injury and Maintaining the Quality of Cold-Stored Fruits and Vegetables,” was published in the journal Food Reviews International.

According to Singh, 44 percent of fresh produce goes bad between harvest and consumption, with chilling injury a major cause.

Berries can be kept fresh in the refrigerator for a week to 12 days, while fruits like apples can stay fresh in storage for as long as nine months. Fruits that grow in tropical and subtropical climates are most at risk for chilling injury.

“The average storage temperature for subtropical fruits and vegetables usually range[s] from 4–8°C while 10–20°C is optimum temperature to avoid chilling injury in tropical horticultural produce,” Singh said.

Singh and the research team said melatonin has been shown to reduce or prevent chilling injury’s effects on fruits and vegetables, and that it can be used instead of chemicals.

“Melatonin is a natural sleeping hormone in living organisms, and it is also helpful in reducing chilling injury symptoms and membrane leakage by maintaining higher levels of antioxidants and freshness of horticultural produce,” explained researcher and Ph.D. student Shoaib Shah in the press release. “Melatonin is a safe alternative to hazardous chemical treatments, without any adverse effects on consumer health.”

As annual food losses mount worldwide, preserving more produce without the use of dangerous chemicals could help with global food security.

Each year, an estimated $400 billion worth of food, that’s 13.2 percent, is lost from harvest to market, while 17 percent of food is wasted by the food service industry, retail and households. Food waste and loss are responsible for an estimated eight to 10 percent of greenhouse gas emissions worldwide.

Fresh produce production is declining due to several factors, like reduced water supplies, soil degradation, climate change and chilling injury.

“When it comes to grains and other produce for harvest, they are more resilient than fresh horticultural produce,” Singh said in the press release. “Fruit and vegetables are not only challenging to grow, preserving them is immensely difficult and this is a crisis affecting nations all over the world, so we need to find the solution to keep producing food from the earth in a sustainable way.”