Color protection liquid and low-temperature fresh-keeping technology thereof
By using a compound color-protecting liquid and low-temperature preservation technology, the problems of high cost and short preservation period of lychees have been solved, achieving a low-cost long-term preservation effect, expanding the sales scope and time of lychees, and improving economic benefits.
Patent Information
- Application Number
- CN202511914959.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-02-27
AI Technical Summary
Existing methods for preserving lychees are costly and have short preservation periods, making it difficult to meet the needs of large-scale production and long-distance transportation, thus limiting the sales scope and time of lychees.
The product employs a compound color-protecting solution and low-temperature preservation technology, including pretreatment, blanching for color protection, soaking for color protection, quick freezing, and storage. It uses low-cost raw materials such as sodium alginate and citric acid, combined with nitrogen filling and low-temperature quick freezing technology to inhibit browning and rotting of lychees.
It significantly extends the shelf life of lychees, reduces preservation costs, and improves the economic benefits for growers and distributors, making it suitable for large-scale industrial production.
Smart Images
Figure CN121569846A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fruit preservation technology, specifically to a color-protecting liquid and its low-temperature preservation technology. Background Technology
[0002] Lychee, a typical tropical and subtropical fruit, is widely loved by consumers for its tender flesh and sweet taste. However, lychee fruits undergo vigorous respiration and metabolism after harvesting, making them prone to dehydration, browning, microbial growth, and flesh rot, resulting in an extremely short shelf life. Traditional lychee preservation methods mostly rely on simple refrigeration or single color-protecting agents, which have drawbacks such as high preservation costs, short preservation periods, and difficulty in meeting the needs of large-scale production and long-distance transportation. This limits the sales scope and sales time of lychee, seriously affecting the marginal profits of growers and distributors.
[0003] Therefore, developing a low-cost, high-efficiency lychee preservation technology to achieve large-scale freshness preservation and extend the sales cycle has become a technical problem that needs to be solved in this field. Summary of the Invention
[0004] The purpose of this invention is to provide a color-protecting liquid and its low-temperature preservation technology to solve the problems of high cost, difficulty in large-scale production, and short sales cycle of existing lychee preservation, and to provide process guarantee for long-term preservation and increased profitability of lychee.
[0005] To achieve the above objectives, this invention discloses a composite color-protecting liquid and a low-temperature freshness-preserving technology based on the color-protecting liquid, the specific technical contents of which are as follows:
[0006] 1. Composite color-protecting liquid
[0007] The composite color-protecting liquid of this invention comprises two functional mixtures, used for color protection during bleaching and soaking respectively, with the specific formula as follows:
[0008] First color-protecting bleaching solution: It is prepared by mixing 0.2% to 0.5% sodium alginate and 0.1% citric acid. Sodium alginate can form a preliminary protective film on the surface of lychee, and citric acid can adjust the pH value of the system and inhibit the activity of polyphenol oxidase.
[0009] The second color-protecting soaking solution is composed of 0.01%–0.05% sodium hexametaphosphate, 0.05%–0.25% citric acid, and 0.01%–0.04% sodium isoascorbate. The three components work synergistically to effectively inhibit browning of lychees and delay the oxidative deterioration of the pulp.
[0010] 2. Low-temperature preservation technology
[0011] Based on the aforementioned composite color-protecting solution, the low-temperature freshness-preserving technology for lychees of the present invention includes five key steps: pretreatment, blanching for color protection, soaking for color protection, quick freezing, and storage. The process parameters for each step are precisely controlled as follows:
[0012] S1: Pretreatment: Select lychees that are 70-90% ripe, as these have plump flesh and the best storage resistance. Soak the lychees in a 1%-2% salt solution for 5-10 minutes, keeping the solution temperature between 0℃ and 20℃. Through the penetration and cooling effect of the salt solution, the lychees are cleaned, insect-repelled, and initially cooled, bringing the temperature of the lychees down to below 23℃, laying the foundation for subsequent color protection treatment.
[0013] S2: Blanching and Color Protection: After pretreatment, blanch the lychees in a first color-protecting blanching solution at 88℃~95℃ for 5 to 20 seconds. The high temperature quickly deactivates the polyphenol oxidase and peroxidase activities in the lychees, inhibiting browning at its source. Simultaneously, sodium alginate rapidly forms a film at high temperature, coating the lychee surface. Immediately after blanching, rinse and cool with clean water at 0℃~20℃ to prevent the high temperature from affecting the taste of the lychee flesh.
[0014] S3: Soaking for Color Protection: Immerse the cooled lychees in the second color protection soaking solution for 10-25 minutes to allow the color-protecting agent to fully penetrate the surface of the fruit pulp, further enhancing the color protection effect. After soaking, remove the lychees, blow-dry the surface moisture to reduce the carriers of microbial growth, and manually select and remove any damaged or spoiled lychees.
[0015] S4: Quick-freezing and storage: Selected lychees are quickly frozen in a freezing tunnel at -18℃ to -25℃ to rapidly reduce the metabolic activity of lychee cells and minimize damage to cell structure from ice crystals. After quick-freezing, they are packaged in high-barrier plastic bags filled with nitrogen to replace the air inside the bags, preventing oxygen contact and further inhibiting oxidation and microbial growth. Each bag weighs between 20KG and 50KG to facilitate large-scale storage and transportation. Finally, they are stored in a low-temperature environment at -18℃ to -25℃.
[0016] The beneficial effects of this invention are:
[0017] Low preservation cost: The composite color-protecting liquid uses low-cost raw materials such as sodium alginate and citric acid. The process steps are simple and easy to operate, requiring no complicated equipment, making it suitable for large-scale industrial production.
[0018] Excellent freshness retention: Through a dual color protection mechanism of "blanching and soaking for color protection", combined with nitrogen filling and oxygen isolation and low temperature quick freezing technology, it can effectively inhibit browning and rotting of lychees and significantly extend the shelf life.
[0019] Significant economic benefits: Extending the sales period of lychees, expanding the sales scope, directly increasing the marginal income of growers and distributors, and possessing extremely high industrial application value.
[0020] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.
[0021] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation
[0023] The present invention is illustrated below with specific embodiments, which are not intended to limit the scope of the invention.
[0024] according to Figure 1 As shown:
[0025] Example 1
[0026] Pretreatment: Pick lychees that are 70% ripe and soak them in a 1% salt solution at 0℃ for 10 minutes. After taking them out, check that the temperature of the lychees has dropped to 20℃.
[0027] Blanching and color protection: Prepare a first color-protecting blanching and bleaching solution containing 0.2% sodium alginate and 0.1% citric acid, heat it to 88℃, put the lychees into it and blanch for 20 seconds, then immediately rinse and cool with 0℃ water.
[0028] Soaking for color protection: Prepare a second color protection soaking solution containing 0.01% sodium hexametaphosphate, 0.05% citric acid, and 0.01% sodium isoascorbate. Soak the lychees in the solution for 25 minutes, then remove them, blow dry, and select them.
[0029] Quick-freezing and storage: The lychees are quick-frozen in a -18℃ freezing tunnel, packaged in high-barrier plastic bags, each bag weighing 20KG, sealed with nitrogen, and stored in an environment of -18℃.
[0030] Tests showed that, in this example, the browning rate of the lychees was less than 5% after 60 days of storage, and the freshness of the fruit flesh remained good.
[0031] Example 2
[0032] Pretreatment: Pick lychees that are 80% ripe and soak them in a 1.5% salt solution at 10℃ for 8 minutes. After removing them, the temperature of the lychees should be reduced to 22℃.
[0033] Blanching and color protection: Prepare a first color protection blanching and bleaching solution containing 0.35% sodium alginate and 0.1% citric acid, heat it to 92℃, put the lychees into it and blanch for 12 seconds, then immediately rinse and cool with 10℃ water.
[0034] Soaking for color protection: Prepare a second color protection soaking solution containing 0.03% sodium hexametaphosphate, 0.15% citric acid, and 0.025% sodium isoascorbate. Soak the lychees in the solution for 18 minutes, then remove them, blow dry, and select them.
[0035] Quick-freezing and storage: The lychees are quick-frozen in a -22℃ freezing tunnel, packaged in high-barrier plastic bags, each weighing 35KG, sealed with nitrogen, and stored in an environment of -22℃.
[0036] Tests showed that, in this example, the browning rate of the lychees after 75 days of storage was less than 3%, and the taste of the flesh was not significantly different from that of fresh lychees.
[0037] Example 3
[0038] Pretreatment: Pick lychees that are 90% ripe and soak them in a 2% salt solution at 20℃ for 5 minutes. After removing them, the temperature of the lychees should be reduced to 23℃.
[0039] Blanching and color protection: Prepare a first color protection blanching and bleaching solution containing 0.5% sodium alginate and 0.1% citric acid, heat it to 95℃, put the lychees into it and blanch for 5 seconds, then immediately rinse and cool with 20℃ water.
[0040] Soaking for color protection: Prepare a second color protection soaking solution containing 0.05% sodium hexametaphosphate, 0.25% citric acid, and 0.04% sodium isoascorbate. Soak the lychees in the solution for 10 minutes, then remove them, blow dry, and select them.
[0041] Quick-freezing and storage: The lychees are quick-frozen in a -25℃ freezing tunnel, packaged in high-barrier plastic bags, each bag weighing 50KG, sealed with nitrogen, and stored in an environment of -25℃.
[0042] Tests showed that, in this example, the browning rate of the lychees was less than 4% after 65 days of storage, and the flesh showed no obvious signs of rotting.
[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0044] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A compound color-protecting liquid for preserving lychees, characterized in that, It includes a first color-protecting bleaching solution and a second color-protecting soaking solution; the first color-protecting bleaching solution is composed of 0.2% to 0.5% sodium alginate and 0.1% citric acid; the second color-protecting soaking solution is composed of 0.01% to 0.05% sodium hexametaphosphate, 0.05% to 0.25% citric acid and 0.01% to 0.04% sodium isoascorbate.
2. A low-temperature preservation technology for lychees based on the composite color-protecting liquid of claim 1, characterized in that, Includes the following steps: S1: Pretreatment: Select lychees with a maturity of 70-90% for picking. Soak the picked lychees in a 1%-2% salt solution for 5-10 minutes. The temperature of the salt solution is 0℃-20℃. After soaking, let the temperature of the lychees drop to below 23℃, and then take them out for later use. S2: Blanching and color protection: Blanch the pre-treated lychees in the first color protection blanching solution at a temperature of 88℃~95℃ for 5 seconds to 20 seconds. After blanching, immediately rinse with clean water at 0℃~20℃ and cool. S3: Soaking for color protection: Immerse the cooled lychees in the second color protection soaking solution for 10-25 minutes. After soaking, remove them, dry the surface moisture, and sort them. S4: Quick-freezing and storage: Selected lychees are quick-frozen in a freezing tunnel at -18℃ to -25℃. After quick-freezing, they are packaged in high-barrier plastic bags. Nitrogen gas is introduced during the packaging process and the bags are sealed. Each bag weighs 20KG to 50KG. After sealing, the bags are stored in an environment at -18℃ to -25℃.
3. The low-temperature preservation technology for lychees according to claim 2, characterized in that, The purpose of the salt solution in step S1 is to cool, clean, and repel insects.
4. The low-temperature preservation technology for lychees according to claim 2, characterized in that, The high-barrier plastic bag described in step S4 has gas barrier properties, which can maintain the stability of the nitrogen atmosphere inside the packaging.