Freezing Sleep and Fresh Locking Technology Make Guangdong Litchi Edible All Seasons
2024-05-11
You can eat fresh lychees all year round! On May 7th, Liang Qinru, a member of the Party Group and Deputy Director of the Guangdong Provincial Department of Science and Technology, led a team to launch the "Guangdong Voice Hotline" program, showcasing lychees that had been "frozen dormant" for 10 months on site. Since last year, Guangdong has strongly supported scientific researchers in tackling the problem of lychee preservation. Now, the Guangdong Academy of Agricultural Sciences has successfully mastered the technology of ultra-low temperature preservation, freshness locking, and freezing and sleeping. After thawing, the nutritional quality of "frozen dormant lychee" can be maintained at over 80-90%, which can meet the needs of consumers to enjoy fresh lychees throughout the four seasons. Behind the "frozen dormant lychee" lies a vivid portrayal of the mutual promotion of industry and technology in Guangdong. The adjustable size of ice crystals is the technical core. "Riding on a horse in the mortal world, no one knows it's lychees." The poem by Tang Dynasty poet Du Mu vividly reflects the speed of transporting lychees. The reason for such a rapid acceleration is naturally related to the short shelf life of lychee. At room temperature, fresh lychees undergo color change, phase change, and taste change within one day, but after four or five days, their color, aroma, and flavor disappear. Even if placed in the refrigerator, lychees quickly turn black in color and soften in texture. How can we extend the shelf life of lychees? The lychee preservation and processing research team of the Institute of Sericulture and Agricultural Product Processing of Guangdong Academy of Agricultural Sciences has successfully broken through the ultra-low temperature freezing and dormancy locking technology, and has successfully transformed it into a new fresh lychee product - "frozen dormant lychee". "The freeze-thaw and freshness locking technology is a technological system that integrates the wisdom of multiple disciplines such as food, agricultural products, and physics. Its core technology lies in the adjustable size and distribution of ice crystals." Xu Yujuan, director of the Institute of Sericulture and Agricultural Product Processing, Guangdong Academy of Agricultural Sciences, introduced that by improving heat exchange efficiency at -35 ℃ or below, the path and distribution of ice crystal formation during lychee freezing are regulated, allowing lychees to form small, dense, and evenly distributed ice crystals, keeping cells in a dormant state. After harvesting fresh lychees, integrated technologies and means such as rapid pre cooling, precise packaging, quick freezing and preservation, and frozen storage are immediately applied, resulting in a shelf life of up to one year. "These technical processes are interrelated, and no link can be neglected." Associate researcher Cheng Lina, a team member, introduced that the team used new packaging materials to vacuum package lychees, achieving the effect of oxygen and moisture resistance, and delaying oxidation and discoloration. Cheng Lina stated that the soaking quick freezing technology used in "frozen dormant lychee" is a mature technology that has been used for many years both domestically and internationally. They have taken the lead in developing a lychee freezing dormant technology system based on the characteristics of lychee. "After thawing, the color of 'frozen dormant lychee' can still be as bright red as fresh lychee, and the flesh is still crystal clear and crispy, maintaining a nutritional quality of more than 80-90%. This technology solves the problem of cell damage and quality deterioration caused by the formation of large ice crystals in traditional freezing. To solve the problem of 'low fruit damage to farmers', it provides technological solutions such as Feizixiao, Guiwei, Jinggang Hongnuo... There are hundreds of lychee varieties, and can each one transform into' frozen dormant lychee '?"? "Each variety has its own uniqueness, and not all varieties are suitable for freezing. For the 'frozen dormant lychee' variety, consideration should be given to the shape, structure, flesh texture, and other aspects of the fruit shell." Cheng Lina said, "Due to the different freezing characteristics of different lychee varieties, different processes need to be matched."
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