How cool rooms and cold storage work to keep fruit fresh year-round
Australians can enjoy apple pies in winter and oranges in summer, and even indulge in berries all year round. But with seasonal fruits out of reach during those times, consumers unknowingly rely on science, significant investment, and an ancient technique.
Across Australia, specialized cool rooms and storage units are employed to keep fruits and vegetables fresh for up to a year at a time. This means an apple picked in February 2025 could be on your table in 2026.
Tim Riley, manager of the Orange Fruit Growers Co-Op for over three decades, explains their process. The organization, owned by growers from Central West NSW, utilizes a technology called "controlled atmosphere" to maintain fruit freshness year-round. "The fruit is picked at its optimal maturity, then dipped to prevent fungicides. It's placed in a cool room at around 2 degrees Celsius," Mr. Riley said.
"Next, we adjust the room to controlled atmosphere conditions, which consist of 2% oxygen and lower CO2 levels, effectively putting the fruit into a deep sleep state," he continued. The fruit remains sealed in these conditions for three months before the room is reopened. Growers then remove about a quarter of the produce and seal it back up for another few months, repeating this process for six to eight months annually.
"Supermarkets that stock fruit weekly only have a three-month window for harvesting," Mr. Riley noted. "If we excel in our work, the fruit remains in prime condition until Christmas, when most of it is sold out."
Australia's apple supply
According to Apple and Pear Australia, 99.7% of all apples in Australian supermarkets are sourced from local orchards. Jeremy Griffith, head of industry at the peak body representing Australian apple and pear growers, emphasizes the importance of year-round fruit availability from a food security perspective.
"We can provide fresh, nutritious food throughout the year, which is beneficial and significantly reduces food waste," he said. "Unfortunately, in other countries, up to 30% of fresh fruit and vegetables can be lost due to a lack of facilities for year-round supply."
Nutritional value of stored fruit
John Golding, a senior research scientist at the Department of Primary Industries and Regional Development, clarifies that the nutritional difference between freshly harvested fruit and stored fruit is minimal. He explains that fruits continue to ripen, albeit at a slower pace, even in cold storage.
"The ripening process may be slower, but that's the purpose of cold storage," Dr. Golding said. "It will still undergo its normal processes."
Stored fruit is considered an extension of fresh fruit, according to Dr. Golding. He encourages people to consume fresh fruits and vegetables, emphasizing their nutritional value and importance for public health.
"Even if fruit has been in the fridge for a while, it's still good to eat, nutritionally and for public health," Dr. Golding advised.
History of cold storage
In the absence of advanced technology during Roman times, they utilized underground limestone to preserve produce. Around the first century BC, Romans discovered that storing fruit in cool areas significantly extended its shelf life.
Research from Princeton University's Department of Classics reveals that various Mediterranean societies developed methods to prolong the shelf life of their foods by storing them in pots, ceramic vessels, and other containers. Caroline Cheung, the author of the university's research project "Managing food storage in the Roman Empire," highlights the impact of Roman technological innovations on storage practices.
"They stored larger quantities of food, maintained its quality, and streamlined the food supply system's logistics," Ms. Cheung wrote. "The practice of 'nesting' containers within rooms and structures designed for climate control provided multiple layers of protection and insulation while facilitating easy access, organized storage, and responses to local environmental conditions."
It was discovered that reducing temperature slowed the respiration rate, senescence, and the death of the fruit. However, the advent of electric refrigeration revolutionized the storage of fresh produce.
"Over a century ago, refrigeration was used to transport meat from Tasmania and NSW to England, and apples from Tasmania to the UK," Dr. Golding mentioned. "We were sending fruit over long distances and storage periods."
