Students operate robots to pick lychee. ZHENG ERQI/FOR CHINA DAILY

Earlier this year, Liang Qinru, deputy director of the Guangdong provincial department of science and technology, said the special freezing technique involves immediate pre-cooling, protective coloration and freezing, thus preserving the freshness of just-picked lychee.

"The core point is to quickly freeze the flesh cells of lychee below-35 C, without damaging the original structure of the flesh, just like animals' hibernating," Liang said.

"Frozen dormant lychees" have the same bright red color as fresh varieties and the outer skin remains crystal clear, which maintains the color and aroma of the fruit after thawing, Liang added.

He said his department had given strong support to scientists tackling the problem of lychee preservation over the past year, and scientists in Guangdong have now mastered the ultralow temperature freshness preservation technology.

He added that relevant departments will strive to expand production capacity and use the new methods to preserve more than 2,000 tons of the fruit this year.

Frozen dormant lychee will hit the market in the following months when demand rises.

"Meanwhile, the new lychee preservation technology will help solve the problem of growers' incomes being affected by low prices during good harvest years," he said.

Jiang Yueming, a researcher at South China Botanical Garden, said Chinese researchers have also developed a special composite preservative that can preserve the bright color and flavor of lychee for a long time, avoiding browning and maintaining good quality.

By soaking for 4-6 minutes, the long-term color retention effect of the outer skin is achieved, significantly extending the shelf life and meeting color retention technology requirements of developed countries, including the United States and Japan, for fresh lychee imports, Jiang said.

The preservative, which is safe, reliable, cost-effective and easy to use, has become a substitute for sulfur fumigation or sulfite based preservatives, as it meets the requirements of food regulations and quarantine requirements of developed countries and regions such as Europe, the US, Japan and South Korea for lychee imports, Jiang said.

"The preservative has been promoted and applied in many lychee production areas in Guangdong," he said, adding that the new preserving agent will also be used in preserving other fruits and vegetables in the following years.