On April 7, Yangcheng Evening News reported that Liang Qinru, a member of the party group and deputy director of the Guangdong Provincial Department of Science and Technology, revealed that the lychee that had been preserved for 10 months using the "freeze sleep" technology was bright in color, good in taste, and maintained the original color and aroma when thawed and eaten. "Lychee of Frozen Sleep" has become a hot search keyword on the Internet for a while.
While netizens generally cheered that delicious lychees can be eaten all year round, in the south and in the north, they are also asking what kind of high-tech "frozen sleep" is? What is the technical principle of keeping lychees fresh for a year?
In response to the above-mentioned hot issues of public concern, a reporter from Yangcheng Evening News interviewed Cheng Lina, an associate researcher at the Institute of Sericulture and Agricultural Products Processing of the Guangdong Academy of Agricultural Sciences, to answer.
"Freeze-sleeping" lychees taken out of cold storage
Dipping and quick-freezing technology is mainly used
Cheng Lina explained the principle of the "freeze sleep" technology that allows lychees to be stored for 10 months, and said that the dipping and quick-freezing technology is mainly used. The core point of this technology is that the freshly picked lychees are immediately subjected to a series of treatments such as rapid pre-cooling, sterilization reduction, precise packaging, quick-freezing and fresh-locking, and freeze-storage and preservation, so as to protect the cells and tissues to the greatest extent and enable them to achieve annual storage.
She said that in fact, the quick-freezing technology has been studied for many years, and has been applied to all kinds of fruits, such as common berries, mangoes, durians, etc., all of which are preserved by quick-freezing methods, but the lychee freeze-dormancy technology belongs to an innovative technology system, which is developed for the unique attributes of lychee, such as variety, husk, pulp and other characteristics, and needs to maintain the color, flavor, taste, and nutrition of lychee. "With the long-term support of the Provincial Department of Science and Technology, the Provincial Department of Agriculture and Rural Affairs and other departments, we have continued to carry out technical research, and since last year, we have carried out technology transformation in response to the application needs of the lychee industry." Cheng Lina said that practice has proved that the lychee freeze sleep preservation technology is very feasible.
"Freeze-sleeping" lychees taken out of cold storage
No additional chemical additives and food additives are added
Cheng Lina responded and emphasized: "There is no need to use preservatives, no additional chemical additives, food additives, and the main thing is to use physical means to lock in freshness." She said that lychees stored with the "freeze-sleep" technology can have a shelf life of up to one year, and when thawed and eaten, they can still "burst juice" like when they are freshly picked, and they are not like traditional freezing methods, "after thawing, they will melt into a pool of water".
After testing, when the "freeze-sleeping" lychee is thawed and eaten, the color and flavor can maintain the original eighty or ninety-percent, and the merchant will have obvious "freeze-sleep" food identification when selling, and the production and listing date will be marked on the packaging bag, and the current shelf life of "freeze-sleeping" lychee is generally marked as one year.
Not all lychees can "freeze sleep"
"The original intention of technology research and development is to extend the preservation time of lychees, and then extend the lychee industry chain to meet market demand, so that lychees with a shelf life of only three to five days can be preserved longer and reach users farther. If there is demand in the industry and demand in the market, there will be application. Cheng Lina said.
Cheng Lina said that "Frozen Sleeping Lychee" also has certain requirements for lychee varieties, and the "Frozen Sleeping" lychee product on the market this time is Conghua Jinggang Red Glutinous Lychee. "There are hundreds of varieties of lychee, and different varieties have different frost characteristics. Some varieties can be frozen, and some varieties are not suitable (frozen). ”
The frozen sleeping lychee displayed at the Guangdong Provincial High-quality Development Conference Photo courtesy of the correspondent
Source: Yangcheng Evening News