ROTTERDAM, Netherlands (AP) – It’s not easy to keep a banana yellow.

To get it to market ripe but unblemished by brown sugar spots takes careful timing, a slight fiddling with nature’s rhythms and a delivery system that is increasingly computer-driven and technical.

The perfect banana used to be a rare and precious find, but technology is changing that. From the tree in the sweltering tropics to the grocery rack in the frigid north, scientists are seeking new ways to strengthen the food chain and extend the shelf life of perishables so they reach distant consumers as if freshly picked.

Commercially, the goal is to satisfy a demand for quality food anywhere, any time, and at maximum profit.

But the implications go further: As the world’s population expands by half to 9 billion by mid-century, food security will become critical. The wild rise in food prices that peaked last July, with staples doubling or tripling in cost over three years, underscored the consequences of shortages, whether real or perceived.

As cities grow and wealth expands, more people eat meat, dairy and fresh products. “That requires a totally different way of approaching agriculture. You have chains of total food systems,” said Rudy Rabbinge, chairman of the Science Council Consultative Group on International Agricultural Research, an alliance of agricultural bodies worldwide.

Suppliers need to move these foods longer distances, reduce spoilage and waste, and curb their climate-changing carbon emissions.

It is less challenging for dry goods like grains and rice – survival foods for much of the world’s poor.

But in developing countries with poor infrastructure, as much as half of harvested fruits and vegetables rot in transit before they can be eaten, says food scientist Henry Boerrigter.

Even in industrial countries, 10-20 percent is lost, much of it tossed away by restaurants, groceries or consumers, but the waste often starts close to the farm, and worsens as the produce travels.

Perfotec, a Dutch company, produces laser machines that make microscopic perforations in plastic wrapping film, allowing packaged food to breathe at a reduced rate. That slows ripening by up to five days.

It is just one technique for prolonging the shelf life long enough to open markets to farmers in Africa, Latin America or Asia.

Goods can move by sea rather than by air – in greater bulk, at lower costs and in more controlled conditions. Sea freight also produces 25 times less carbon emissions per box of fruit, according to Maersk Lines, the world’s largest container shipping operator.

As food becomes more mobile, the marketplace shifts. Mega-buyers like Wal-Mart look for the cheapest supplier of quality goods, says Boerrigter, a post-harvest technologist at Wageningen University and Research Center in the Netherlands.

“Where labor is cheap, high-scale production farms come up,” he said. As one example, Spain has begun importing Egyptian strawberries even though it also is a major producer.

Refrigerated transportation has been in use since the 1870s when Chicago’s stockyards began shipping meat to the East Coast by dripping ice through the roof of railway cars – with frequent stops to replenish the ice.

Today, 40-foot containers circulate cool air around pallets piled high with specially designed packing boxes. If necessary, nitrogen is pumped into the sealed container to lower the oxygen level.

“We used to think avocados were exotic. Now you can get them every day, everywhere,” says Henrik Lindhardt, a senior general manager of Maersk.

A U.S. innovation that won safety approval by the European Union in 2005 virtually puts fruit to sleep. Marketed as SmartFresh, the active ingredient 1-MCP inhibits the effect of ethylene, the chemical agent that causes ripening. A tablespoon of the white powder dissolved in tap water inside a storage room or sealed refrigerator can keep three million apples crisp and fresh for up to two weeks, says Yvonne Harz-Pitre, the European communications manager for AgroFresh Inc. which makes the product.

Dutch flower growers have begun shipping some hardy varieties by sea to New York, kept fresh in containers with “controlled atmosphere,” says Lindhardt. Shellfish are being shipped live in vats of water from Canada to Europe in 30 days rather than being frozen and airfreighted. Tuna and other sushi specialties are being sent to Japan in super-freezers reaching minus 75 Fahrenheit.

Lindhardt was watching bananas from the Dominican Republic being unloaded at a Rotterdam warehouse.

Cell-phone-sized monitoring units were clipped to some fruit boxes to record the conditions of the 15-day journey. The data was downloaded to a computer, and within an hour the fruit was moved into a cold storage room, where the temperature was adjusted according to the delivery schedule.

“These bananas are still alive,” said Lindhardt. They breathe, they generate heat and they mature. “What we do is slow the process, not stop it.”