A tropical fruit preservation box and a method for preserving freshness of tropical fruits

Abstract

The application provides a tropical fruit preservation box and a fresh-keeping method for tropical fruits, and relates to the technical field of food preservation boxes. The preservation box comprises a box body for containing tropical fruits and having at least one opening, and the box body is provided with a matched cover body at the opening; a containing cavity is formed in the bottom of the box body, a through hole is opened in the side wall of the box body at the containing cavity, the containing cavity is communicated with the inside of the box body through the through hole, and a fresh-keeping gel is arranged in the containing cavity of the box body. The tropical fruits are stored in the preservation box, the volatile components generated by the fresh-keeping gel effectively inhibit the enzymatic browning of the epidermis of the tropical fruits in the box body, the quality deterioration of the tropical fruits in the storage and transportation process is inhibited, the shelf life of the tropical fruits is effectively prolonged, and the environmental protection and safety in the fresh-keeping process are improved by extracting components from agricultural and sideline products.

Description

Technical Field

[0001] This invention relates to the field of food preservation box technology, and in particular to a tropical fruit preservation box and a method for locking in the freshness of tropical fruits. Background Technology

[0002] As living standards continue to improve, people are paying more and more attention to the freshness and nutritional value of fruits. Tropical fruits, which are rich in nutrients and have unique flavors, are very popular. However, the ripening period of tropical fruits is concentrated in the hot and humid season. In addition, the fruits themselves have a high water content and vigorous metabolism. They are not resistant to storage and transportation after harvesting. If left at room temperature, they are very easy to grow mold, which not only destroys the nutritional components, but also causes the flesh to turn brown quickly. This seriously restricts the development of the tropical fruit industry.

[0003] Currently, the commonly used methods for preserving tropical fruits are mainly physical preservation and chemical preservation. Physical preservation mainly focuses on low-temperature storage, which inhibits the respiration and microbial activity of the fruit by controlling the ambient temperature and humidity. It also combines controlled atmosphere storage technology to extend the shelf life. Chemical preservation, on the other hand, uses preservatives to treat the surface of the fruit through coating, soaking, or fumigation to inhibit quality deterioration. For example, natural plant ingredients such as thyme essential oil and mustard essential oil are used as preservatives to extend the shelf life.

[0004] However, controlled atmosphere storage and low-temperature refrigeration equipment are mainly limited to the transportation process; once removed from the cold chain, they lose their preservation effect. When using chemical preservation methods for surface treatment, excessively high concentrations can alter the flavor of the fruit, while low concentrations fail to provide complete preservation. Therefore, there is an urgent need to provide a solution to address these issues. Summary of the Invention

[0005] The purpose of this invention is to provide a tropical fruit preservation box and a method for locking in the freshness of tropical fruits. By storing tropical fruits in the preservation box, the volatile components generated by the preservation gel effectively inhibit the enzymatic browning of the tropical fruit's skin within the box, thereby inhibiting the quality deterioration of tropical fruits during storage and transportation, effectively extending the shelf life of tropical fruits. At the same time, the use of agricultural by-products for component extraction improves the environmental friendliness and safety of the preservation process.

[0006] In a first aspect, the present invention provides a tropical fruit preservation box, comprising a box body for containing tropical fruit and having at least one opening, wherein the box body is provided with a suitable lid at the opening; a receiving cavity is formed at the bottom of the box body, and a through hole is opened on the side wall of the box body at the receiving cavity, the receiving cavity communicating with the interior of the box body through the through hole; a preservation gel is disposed in the receiving cavity of the box body, and the preparation method of the preservation gel includes: impregnating a biomass matrix in plant essential oil to obtain a composite matrix; modifying a polyphenol polymer layer on the surface of the composite matrix to obtain a composite carrier; dispersing the composite carrier in a preservation solution, gelling and shaping it under the action of calcium ions to obtain the preservation gel; wherein: the preservation solution contains rambutan peel extract and plant polysaccharides.

[0007] Optionally, the ratio of the preservation gel to the volume of the box is 3 mg / cm³. 3 -15mg / cm 3 ; and / or, the ratio of the projected area of ​​the preservation gel to that of the box body is 60%-90%; and / or, when the box body preserves tropical fruits, the box body is filled with an inert gas, the inert gas including nitrogen and argon; and / or, the box body is provided with a sealing film at the opening, the sealing film being heat-fused to the side wall of the opening; and / or, the tropical fruits include one of rambutan, lychee, longan, wax apple, passion fruit, custard apple, papaya, mango, mangosteen, and miracle fruit.

[0008] Optionally, the preparation method of the biomass matrix includes: dispersing biomass powder in sodium alginate solution and then gelling it to obtain a composite gel; freeze-drying the composite gel to obtain a biomass matrix; wherein: the biomass powder includes the extraction residue remaining after extracting the fruit peel extract; and / or, mixing and dispersing the biomass powder and sodium alginate solution at a mass ratio of (1-2):8; and / or, gelling under the action of calcium ions to obtain a composite gel.

[0009] Optionally, the plant polysaccharide includes one of pectin, fucoidan, and purslane polysaccharide; and / or, the polyphenol includes tannic acid; and / or, the composite matrix is ​​dispersed in a polyphenol solution, and the composite carrier is obtained by adding Tris-HCl solution dropwise, stirring and reacting; and / or, the preservation solution also contains an antioxidant, which includes one of tea polyphenols, catechins, and phytic acid.

[0010] Optionally, the extraction method of the fruit peel extract includes: enzymatically hydrolyzing the rambutan fruit peel, inactivating the enzyme, and separating the enzymatic hydrolysate and the enzymatic product; extracting the enzymatic product with a eutectic solvent and separating the extract; mixing the enzyme-inactivated hydrolysate and the extract to obtain the fruit peel extract; wherein the eutectic solvent is a food-grade raw material, including one of the following: betaine and citric acid in a molar ratio of 1:1, citric acid and glucose in a molar ratio of 1:1, and citric acid and glycerol in a molar ratio of 1:2.

[0011] Optionally, the average particle size of the rambutan peel is 0.1 mm-1 mm; and / or, the moisture content of the rambutan peel is 5%-10%; and / or, the rambutan peel is enzymatically hydrolyzed using at least one of cellulase, hemicellulase, and pectinase; and / or, the hydrolysis is performed at 40℃-50℃; and / or, the hydrolysis is performed for 1 h-3 h; and / or, the hydrolysis is performed in a buffer solution with pH=4-6; and / or, the mass ratio of enzyme to rambutan peel during hydrolysis is 0.3%-0.8%; and / or, the solid-liquid ratio of the hydrolysate to the eutectic solvent is 0.03 g / mL-0.06 g / mL; and / or, the extraction is performed under ultrasonic and / or microwave conditions; and / or, the extraction is performed at 2 MPa-5 MPa; and / or, the extraction is performed for 3 h-5 h.

[0012] Secondly, the present invention also provides a method for preserving tropical fruits using any of the above-mentioned optional preservation boxes, comprising: cleaning the surface of the tropical fruits to be preserved, removing inferior fruits with mechanical damage on the surface, sterilizing them, transferring them into the box body of the preservation box, sealing the opening of the box body with a lid, and storing them in an environment of 4℃-25℃. Attached Figure Description

[0013] Figure 1 This invention provides a schematic diagram of the internal cross-sectional structure of a tropical fruit preservation box. Figure 2 This is a flowchart illustrating a method for extracting fruit peel extract according to some embodiments of the present invention.

[0014] Explanation of reference numerals in the attached diagram: 1. Box body; 2. Lid; 3. Preservative gel; 4. Receiving cavity; 5. Through hole; 6. Divider. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0016] See Figure 1 This invention provides a tropical fruit preservation box, comprising a box body 1 for containing tropical fruit and having at least one opening, with a fitted lid 2 disposed at the opening of the box body 1. In practice, the lid 2 can be used to adjust the state of the opening of the box body 1 (open or closed), thereby facilitating the placement and removal of the tropical fruit stored therein. Furthermore, by using the lid 2 to close the opening, a relatively sealed space is created within the preservation box, which helps to improve the protection of the tropical fruit stored in the box and prevents damage to the skin of the tropical fruit from external impacts.

[0017] In fact, a receiving cavity 4 is formed at the bottom of the box body 1, and a through hole 5 is opened on the side wall of the box body 1 at the receiving cavity 4. Thus, the receiving cavity 4 can be connected to the inside of the box body 1 through the through hole 5. In addition, a preservative gel 3 is provided in the receiving cavity 4 of the box body 1. When preserving tropical fruits, the preservative gel 3 in the receiving cavity 4 generates volatile components and enters the inside of the box body 1 containing tropical fruits through the through hole 5. Thus, the preservative gel 3 is used to preserve tropical fruits, improve the quality stability of tropical fruits during storage and transportation, and help extend the sales period of tropical fruits and the shelf life at the terminal sales.

[0018] Specifically, when tropical fruits are placed inside box 1 and the opening of box 1 is sealed with lid 2, the preservative gel 3 slowly releases volatile components with preservative properties. These components enter the space of box 1 containing the tropical fruits through the through-hole 5, creating a preservative atmosphere. This effectively inhibits enzymatic browning on the surface of the tropical fruits, helping to improve the quality stability of the tropical fruits when stored in box 1. Furthermore, as the temperature of the preservation box increases, the release rate of the preservative gel 3 also increases, thus helping to improve the quality stability of the tropical fruits at higher storage temperatures. More specifically, the tropical fruits include one of the following: rambutan, lychee, longan, wax apple, passion fruit, custard apple, papaya, mango, mangosteen, and miracle fruit.

[0019] In some embodiments, a partition 6 with through holes 5 is provided at the bottom of the box body 1, and a receiving cavity 4 is formed between the partition 6 and the bottom of the box body 1. Thus, when tropical fruits are stored in the food storage box, the tropical fruits are placed on top of the partition 6 to avoid direct contact between the preservative gel 3 and the surface of the tropical fruits. Furthermore, the partition 6 in the box body 1 can be fixedly connected to the inner wall of the box body 1. In this case, the preservative gel 3 is locked in the receiving cavity 4. Alternatively, the box body 1 and the partition 6 can be separately configured. For example, an annular groove is pre-formed on the inner wall of the box body 1, and the partition 6 is then snapped into the annular groove to form the receiving cavity 4.

[0020] In some embodiments, when using a food storage container to preserve tropical fruits, the container 1 is filled with an inert gas under slight positive pressure. This inhibits the aerobic growth of bacteria during storage, thus improving the preservation effect. Specifically, during the sealing process of tropical fruits using the food storage container, a sealing film can be used to heat-seal the opening of the container 1 in an inert atmosphere, and then the lid 2 can be placed on top before storage at a low temperature of 4℃-25℃.

[0021] In some embodiments, the volume ratio of the preservative gel 3 in the food storage container to that in the container body 1 is 3 mg / cm³. 3 -15mg / cm 3 In practice, when the preservative gel 3 is placed inside the box 1 to preserve tropical fruits, the volatile components in the preservative gel 3 will evaporate and permeate the inside of the box 1, thereby preserving the tropical fruits and inhibiting browning and other deterioration of the fruit's skin, thus improving the quality stability of the tropical fruits during storage. Furthermore, when the preservative gel 3 is placed at the bottom of the box 1, the ratio of the projected area of ​​the preservative gel 3 to the bottom of the box 1 is 60%-90%, which helps the preservative gel 3 to fully release its volatile components within the box 1.

[0022] In fact, the method for preparing the food preservation gel in the food storage box provided in any of the above embodiments includes the following steps: Z1. A composite matrix is ​​obtained by impregnating a biomass matrix in plant essential oils; Z2. A composite carrier was prepared by modifying the surface of the composite matrix with a polyphenol polymer layer. Z3. The composite carrier is dispersed in the preservation solution, and gelled and shaped under the action of calcium ions to obtain tropical fruit preservation gel.

[0023] Specifically, by impregnating the biomass matrix with plant essential oils, the plant essential oils can be adsorbed into the biomass matrix. By modifying the surface with a polyphenol polymer layer to prevent the plant essential oils from leaking out quickly, the composite carrier is then gelled in a preservation solution. The preservation solution enters the composite carrier and forms an aqueous gel through the action of calcium ions. At this point, the composite matrix can serve as a supporting framework for the gel, improving the overall mechanical strength and structural stability of the preservation gel.

[0024] Specifically, the preservation solution contains fruit peel extract and plant polysaccharides. Through the gelation reaction of plant polysaccharides and calcium ions, an aqueous gel is formed in the composite matrix. In addition, by making the fruit peel extract into an aqueous gel, volatile active ingredients can be slowly released during use. At the same time, plant essential oils adsorbed in the biomass matrix skeleton are also slowly released, thereby creating a preservation atmosphere with plant essential oil components and fruit peel extract active ingredients in the preservation box, thus preserving the quality of tropical fruits.

[0025] In some embodiments, the preparation method of the biomass matrix used in step Z1 includes the following steps: dispersing biomass powder in a sodium alginate solution and then gelling it under the action of calcium ions to obtain a composite gel; freeze-drying the composite gel to obtain the biomass matrix. In fact, by gelling biomass powder in a sodium alginate solution and then freeze-drying it, a porous network with biomass powder as the main component can be formed, which helps to improve the wetting and adsorption capacity of essential oils, and increasing the specific surface area helps to modify the surface into a polyphenol polymer layer.

[0026] In some embodiments, biomass powder at a mass ratio of (1-2):8 can be ultrasonically mixed with sodium alginate solution to effectively improve dispersion uniformity and reduce air bubbles in the gel after gelation. In fact, during the gelation process, the biomass powder is uniformly dispersed and forms a framework, thereby avoiding structural collapse during freeze-drying and forming a biomass matrix with high specific surface area and high porosity.

[0027] In some embodiments, the plant essential oil used in step Z1 includes one of thyme essential oil, mustard essential oil, tea tree essential oil, clove essential oil, and lemon essential oil. In fact, plant essential oils have significant antibacterial, antifungal, and antifungal effects, effectively inhibiting the activity of mold on the surface of tropical fruits, reducing skin rot and spoilage caused by mold activity, while maintaining the original taste and nutritional components of the fruit. Furthermore, the plant essential oil used can be a commercially available product, or it can be extracted from the plant material in a laboratory using extraction methods known in the art.

[0028] In some embodiments, in step Z1, the biomass matrix can be immersed in plant essential oils and impregnated under reduced pressure, which helps the plant essential oils to fully penetrate the biomass matrix and form a stable adsorption bond. Specifically, when the plant essential oil is a blend of two or more essential oils, the plant essential oils are pre-blended to form a blended essential oil before using the biomass matrix for impregnation and loading, and then the biomass matrix is ​​immersed in the blended essential oil. Furthermore, when the biomass matrix is ​​impregnated in the plant essential oils, ultrasonic treatment can be applied to effectively remove gas from the pores of the biomass matrix and improve impregnation efficiency.

[0029] In some embodiments, in step Z1, the biomass matrix can be preheated in an environment of 40°C-50°C before being immersed in plant essential oils that have been kept warm in a water bath at 40°C-50°C. In fact, immersing the biomass matrix in a heated environment helps reduce the viscosity of the essential oils, thereby promoting their penetration into the biomass matrix and increasing the loading capacity of the biomass matrix for plant essential oils. Specifically, the plant essential oil content in the composite matrix is ​​50%-80%.

[0030] In some embodiments, in step Z2, after the composite matrix is ​​mixed and dispersed in a tannic acid solution, Tris-HCl solution is added dropwise and stirred to react, followed by separation to obtain the composite carrier. This allows tannic acid to undergo in-situ polymerization on the surface of the composite matrix, forming a polytannic acid coating layer, which in turn protects the plant essential oils in the composite matrix. Specifically, the concentration of tannic acid in the tannic acid solution can be 0.03 mg / mL-0.08 mg / mL, and the mass ratio of the composite matrix to tannic acid can be 1:(0.005-0.02).

[0031] In some embodiments, see Figure 2 The extraction method for the peel extract used in step Z3 includes the following steps: S1. After enzymatic hydrolysis of rambutan peel, the enzyme is inactivated and the hydrolysate and hydrolysate are separated. S2. The enzyme hydrolysate is extracted using a eutectic solvent and then separated to obtain the extract. S3. Mix the enzyme hydrolysate after enzyme inactivation with the extract to obtain the peel extract.

[0032] In fact, enzymatic hydrolysis of rambutan peel in step S1 helps release the active ingredients bound to the cell wall in the rambutan peel cells into the hydrolysate. Simultaneously, it improves the porous microstructure of the hydrolysate, facilitating extraction with a eutectic solvent in step S2. This promotes rapid penetration of the eutectic solvent into the hydrolysate and fully releases the active ingredients. Then, in step S3, the enzyme-inactivated hydrolysate and the extraction solution are mixed to obtain the peel extract. In some embodiments, the mixture can be concentrated in step S3 to enrich the active ingredients in the rambutan peel.

[0033] In some further embodiments, the biomass powder used in preparing the biomass matrix includes the extraction residue remaining after extracting the fruit peel extract. In fact, after separating the extraction residue during fruit peel extraction, the residue is rinsed with purified water and dried to obtain biomass powder. This allows for the resource utilization of biomass materials and improves the utilization rate of rambutan fruit peel. Specifically, the biomass matrix can also be selected from other similar biomass residues remaining after extracting active ingredients, such as the residues of traditional Chinese medicine herbs remaining after extracting active ingredients.

[0034] In some embodiments, the rambutan peel used in step S1 can be freshly peeled rambutan peel, which is pre-dried to a moisture content of 5%-10% before being pulverized to obtain rambutan peel powder. This can increase the relative content of active ingredients in the rambutan peel, and drying helps to improve pulverization efficiency, thereby obtaining peel powder with a larger specific surface area, which helps to ensure sufficient enzymatic hydrolysis and improve the efficiency of enzymatic hydrolysis.

[0035] In some embodiments, one of cellulase, hemicellulase, and pectinase can be used to enzymatically hydrolyze the rambutan peel in step S1. In practice, a combination of cellulase and pectinase can be used for enzymatic hydrolysis of the rambutan peel. Cellulase specifically hydrolyzes the cellulose skeleton in the peel cell wall, helping to release the active ingredients encapsulated in the cell wall, while pectinase specifically hydrolyzes the pectin in the peel cells, thereby promoting the rapid dissolution of cell contents. Specifically, the mass ratio of the enzyme used to the rambutan peel during enzymatic hydrolysis is 0.3%-0.8%, and the mass ratio of cellulase to pectinase can be 2:1.

[0036] In some embodiments, in step S1, the rambutan peel powder can be dispersed in a buffer solution with a pH of 4-6 and then enzymatically hydrolyzed at 40℃-50℃ for 1-3 hours. In fact, enzymatic hydrolysis in a weakly acidic environment helps to increase the activity of cellulase and pectinase, thereby improving hydrolysis efficiency and inhibiting the activity of oxidases in the peel cells, thus increasing the yield of active ingredients and preventing their inactivation. Specifically, the buffer solution used can be a citrate-sodium citrate buffer solution.

[0037] In fact, the eutectic solvent used in step S2 is a food-grade raw material, including one of the following: betaine and citric acid in a molar ratio of 1:1, citric acid and glucose in a molar ratio of 1:1, and citric acid and glycerol in a molar ratio of 1:2. In practice, using a eutectic solvent to extract the enzymatic residue helps to fully dissolve the active ingredients in the alcohol extract residue. Simultaneously, when the fruit peel extract forms a preservation solution, the eutectic solvent can fully dissolve and disperse within the preservation solution, eliminating the need for concentration and separation of the fruit peel-derived active ingredients obtained from the extract.

[0038] In some embodiments, after mixing the enzymatic hydrolysate with a eutectic solvent at a solid-liquid ratio of 0.03 g / mL to 0.06 g / mL in step S2, extraction is carried out under ultrasonic and / or microwave conditions at 2 MPa to 5 MPa for 3 to 5 hours. In fact, extraction under high-pressure ultrasonic or microwave conditions helps transfer the active ingredients in the enzymatic hydrolysate to the eutectic solvent, thus improving extraction efficiency and the amount of active ingredients extracted from the extract. Further, in step S3, after ultrasonically mixing the enzyme-inactivated hydrolysate with the extract, vacuum filtration is performed through a 0.45 μm filter membrane to obtain the peel extract.

[0039] In practice, during the preparation of the preservation gel, the mass ratio of the plant essential oil loaded in the composite matrix to the rambutan peel extract in the preservation solution is (1-5):100. For example, when the composite matrix is ​​impregnated with 2 parts by mass of plant essential oil, the peel extract in the preservation solution used in step Z3 can be either the stock extract obtained from 100 parts of rambutan peel or an extract that has been appropriately concentrated. Specifically, during the preservation of tropical fruits by the preservation box, the peel extract in the preservation gel releases volatile components, thus playing a major role in preservation. Meanwhile, the plant essential oil in the composite matrix, after being released, can also preserve the fruit itself and work synergistically with the peel extract, thereby effectively improving the preservation effect.

[0040] In some embodiments, the plant polysaccharides in the preservation solution in step S3 include one of pectin, fucoidan, and purslane polysaccharide. Furthermore, an antioxidant is dissolved in the preservation solution, and the antioxidant includes one of tea polyphenols, catechins, and phytic acid. In fact, the antioxidants in the preservation solution can enhance the antioxidant properties of the fruit peel extract after gelation, thereby improving the durability of the preservation gel during use. Specifically, the antioxidants used include one of tea polyphenols, catechins, and phytic acid, and the mass ratio of rambutan fruit peel from which the fruit peel extract is derived to the antioxidant is 1:(0.01-0.015).

[0041] Preparation Example 1: A method for extracting a fruit peel extract, comprising the following steps: S1. Rambutan peel powder (Rambutan Hongguo Baoyan No. 7) with a water content of 8% and an average particle size of 0.5 mm was ultrasonically mixed with a citric acid-sodium citrate buffer solution at pH=5 at a solid-liquid ratio of 0.05 g / mL to obtain a mixed suspension. The mixed suspension, cellulase and pectinase were mixed and dispersed. The mass ratio of rambutan peel powder, cellulase and pectinase was controlled at 100:0.4:0.2. The mixture was stirred and enzymatically hydrolyzed at 45℃ and 300 rpm for 2 h. The supernatant was collected by centrifugation to obtain the enzymatic hydrolysate. The remaining bottom precipitate was washed and dried to obtain the enzymatic hydrolysate. S2. After mixing citric acid and glucose in a molar ratio of 1:1 and heating to obtain a eutectic solvent, the enzymatic hydrolysate is mixed with the eutectic solvent at a solid-liquid ratio of 0.05 g / mL. After ultrasonic soaking at room temperature of 25°C for 1 h, ultrasonic extraction is carried out at 3 MPa and 60°C for 3 h and centrifuged. The supernatant is collected as the extract, and the remaining bottom precipitate is washed and dried to obtain the extraction residue. S3. After ultrasonically mixing the enzyme-inactivated hydrolysate and the extract at 50°C for 30 min, the extract is obtained by vacuum filtration using a 0.45 μm filter membrane.

[0042] Preparation Example 2: A method for extracting rambutan peel extract, which differs from Preparation Example 1 in that steps S2 and S3 are not performed. The enzyme hydrolysate obtained in step S1 is obtained as rambutan peel extract after enzyme inactivation.

[0043] Preparation Example 3: A method for extracting a fruit peel extract, which differs from Preparation Example 1 in that steps S1 and S3 are not performed. In step S2, rambutan fruit peel powder with a water content of 8% and an average particle size of 0.5 mm is mixed with a eutectic solvent at a solid-liquid ratio of 0.05 g / mL at a solid-liquid ratio of 0.05 g / mL. After ultrasonic soaking at room temperature of 25°C for 1 h, ultrasonic extraction is performed at 3 MPa and 60°C for 3 h, followed by centrifugation. The supernatant is collected as the fruit peel extract.

[0044] Preparation Example 4: A method for extracting fruit peel extract, which differs from Preparation Example 1 in that, in step S2, the enzymatic hydrolysate is mixed with purified water at a solid-liquid ratio of 0.05 g / mL, ultrasonically soaked at room temperature of 25°C for 1 h, ultrasonically extracted at 3 MPa and 60°C for 3 h, and then centrifuged to collect the supernatant as the extract.

[0045] Preparation Example 5: A method for extracting fruit peel extract, which differs from Preparation Example 1 in that, in step S2, the enzymatic hydrolysate is mixed with anhydrous ethanol at a solid-liquid ratio of 0.05 g / mL, ultrasonically soaked at room temperature of 25°C for 1 h, ultrasonically extracted at 3 MPa and 60°C for 3 h, and then centrifuged to collect the supernatant as the extract.

[0046] 1. Preservative properties test of fruit peel extract and plant essential oil: The rambutan peel extracts obtained in Preparation Examples 1 to 5 were diluted with purified water to obtain a peel extract dilution with a concentration of 10 mg / mL relative to the rambutan peel powder. Thyme essential oil and mustard essential oil were added to the dilution, followed by the addition of 0.3 wt% Tween-80 and 1 wt% chitosan, and then sheared and emulsified to obtain a preservation emulsion. The mass ratio of thyme essential oil, mustard essential oil and rambutan peel powder was controlled to be 1:1:50. Equal amounts of thyme essential oil and mustard essential oil were dispersed in deionized water, and 0.3% Tween-80 and 1 wt% chitosan were added and sheared and emulsified to obtain a mixed essential oil emulsion. The peel extract dilution with a concentration of 10 mg / mL relative to the rambutan peel powder (Preparation Example 1) was mixed with 1 wt% chitosan to obtain a preservation solution. Freshly picked rambutans with undamaged skin, uniform size, and similar maturity were collected and surface-washed. Then, at room temperature, the rambutans were immersed in the preservation emulsions corresponding to Preparation Examples 1 to 5, the mixed essential oil emulsion without added peel extract, and the preservation solution without added plant essential oils, respectively, for 90 seconds. After filtration, they were stored at 25°C for 10 days. The quality changes of the preserved rambutans compared to the unpreserved rambutans were observed. The skin browning rate, weight loss rate, and flavor changes of the preserved rambutans compared to the unpreserved rambutans were calculated. The results are shown in Table 2.

[0047]

[0048] In the formula: The browning rate of rambutan skin after preservation treatment. The browning rate of the skin of unpreserved rambutan; The weight loss rate of rambutan after preservation treatment and storage. The weight loss rate of rambutan after storage without preservation treatment.

[0049] To determine the flavor changes of rambutan, 10 college students with normal taste (male-female ratio 3:2, age 20 to 25 years old) were randomly selected to score the rambutan pulp according to the scoring criteria shown in Table 1.

[0050] Table 1 Sensory evaluation criteria for rambutan pulp

[0051] Table 2. Results of Preservative Effects of Peel Extract and Plant Essential Oil on Rambutan

[0052] As shown in Table 2, rambutan without any preservation treatment rapidly loses water during storage, leading to increased weight loss and severe browning of the peel. The pulp inside the peel is essentially rotten and inedible. However, after intervention with the rambutan peel extract prepared in Example 1 mixed with plant essential oils, the rambutan peel did not exhibit large-scale browning or dehydration during storage, and the pulp maintained stable flavor. This significantly improved the preservation performance of rambutan and helped extend its shelf life.

[0053] As shown in Table 2, when rambutan peel extract prepared in Preparation Example 1 was used directly to treat rambutan, the preservation performance of rambutan was reduced when the peel extract was used alone compared to the combined use of peel extract and plant essential oils. This indicates that the plant essential oil components help improve the preservation effect of the preservation solution on tropical fruits such as rambutan. Furthermore, when mixed plant emulsions were used directly to treat rambutan, the mixed plant emulsions showed a significant preservation effect compared to untreated rambutan, but its preservation effect was significantly weaker than that of the peel extract derived from rambutan.

[0054] As can be seen from Table 2, in Preparation Example 2, only the rambutan peel was enzymatically hydrolyzed to obtain the hydrolysate. The hydrolysate after enzyme inactivation was then mixed with plant essential oils and emulsified before being used to treat the rambutan. This resulted in an increase in the surface browning rate and weight loss rate of the rambutan during storage. This indicates that the lack of extraction of the hydrolysate leads to a decrease in the extraction amount of active ingredients, making it difficult for the preservation emulsion to effectively inhibit the enzymatic browning and moisture loss of the peel. Furthermore, the pulp is affected by the dehydration and browning of the peel, resulting in severe flavor deterioration.

[0055] As can be seen from Table 2, in Preparation Example 3, direct extraction of rambutan peel powder using a eutectic solvent was insufficient to fully release the active ingredients in the rambutan peel, resulting in a decrease in the preservation performance of rambutan. Meanwhile, as can be seen from Preparation Examples 4 and 5, pre-enzymatic hydrolysis of the peel powder can greatly improve the extraction efficiency of active ingredients in rambutan peel during the extraction process, which helps to improve the preservation effect of rambutan.

[0056] 2. Suitability tests of fruit peel extracts and plant essential oils on tropical fruits: Freshly picked lychees, longans, mangosteens, and mangoes with undamaged skin, uniform size, and similar maturity were selected. After surface washing, the lychees and longans were immersed in the preservation emulsion corresponding to Preparation Example 1 for 90 seconds at room temperature, then filtered out and stored in a nitrogen atmosphere at 25°C for 10 days. The quality changes of the preserved lychees and longans compared with those without preservation were observed. The skin browning rate, weight loss rate, and flavor changes of the preserved fruits compared with those without preservation were calculated. The results are shown in Table 3.

[0057] Table 3. Test results of the preservation performance of fruit peel extracts and plant essential oils on lychee, longan, mangosteen, and mango.

[0058] As can be seen from Table 3, the preservation solution provided by this invention has excellent preservation performance for tropical fruits such as lychee, longan, mangosteen, and mango. It can improve the quality stability of tropical fruits during storage, effectively inhibit peel browning and dehydration, and thus improve the flavor consistency of the pulp during storage, thereby improving the shelf life and quality of tropical fruits during transportation. In addition, as can be seen from Tables 2 and 3, the preservation solution has a better preservation effect on rambutan, because the peel extract in the preservation solution is derived from rambutan peel.

[0059] Example 1: A method for preparing a tropical fruit preservation gel, comprising the following steps: S0. After thoroughly drying the extract residue obtained in Preparation Example 1, it is thoroughly mixed in a saturated sodium alginate solution at a mass ratio of 1:8. After ultrasonic dispersion, calcium chloride solution is added and stirred and mixed. The mixture is then allowed to stand and gel to obtain a composite gel. The composite gel is frozen at -80°C and then vacuum dried to obtain a biomass matrix. S1. Thyme essential oil and mustard essential oil are ultrasonically mixed in a mass ratio of 1:1 to obtain a mixed essential oil. The biomass matrix is ​​soaked in the mixed essential oil and then ultrasonically degassed. After soaking in a reduced pressure environment for 3 hours to promote the full absorption of the mixed essential oil by the biomass matrix, it is taken out to obtain a composite matrix. S2. The composite matrix was immersed in a tannic acid solution with a concentration of 0.05 mg / mL at a mass ratio of 0.08 g / mL. Tris-HCl solution with pH=7 was added dropwise, and the reaction was continuously stirred during the addition process. The addition time was controlled to be 1 h. After the reaction was completed, the composite carrier was removed, rinsed with deionized water, and dried. S3. The peel extract obtained in Preparation Example 1 was diluted with a pectin aqueous solution. The mass ratio of rambutan peel to pectin in the peel extract was controlled to be 1:0.01 to obtain a diluted solution. The composite carrier was immersed in the diluted solution under reduced pressure and then calcium chloride solution was added and stirred to mix. The mixture was allowed to stand to gel and then shaped to obtain a tropical fruit preservation gel.

[0060] Example 2: A method for preparing a tropical fruit preservation gel, which differs from Example 1 in that tea polyphenols are also dissolved in the diluent in step S3, and the mass ratio of the extract to tea polyphenols is 1:0.12.

[0061] Comparative Example 1: A method for preparing a tropical fruit preservation gel, differing from Example 1 in that step S0 is omitted, and the biomass matrix used in step S1 is replaced with a matrix having a specific surface area of ​​600 m². 2 / g of activated carbon was pre-soaked in KH-550 silane solution (mass ratio of activated carbon to KH-550 is 1:0.2) at a solid-liquid ratio of 0.05g / mL. After ultrasonic treatment with an external power of 20kw for 20min, it was allowed to stand at room temperature for 10min, filtered and separated, and the resulting solid was dried.

[0062] Preservation performance test of the preservative gel: The preservative gels prepared in Examples 1, 2 and Comparative Example 1 were shaped into gel blocks with a length × width × height of 10cm × 5cm × 0.8cm. The gel blocks were transferred into the body of a transparent plastic food storage box. After separating the gel blocks with a transparent partition with through holes, freshly picked rambutans with no mechanical damage on the surface were placed on top of the transparent partition and the following preservation performance test was conducted. An equal amount of rambutans was placed in a blank food storage box without gel blocks as a blank control. 1. Low-temperature preservation performance test: After the food storage box was transferred to a low-temperature environment of 14℃ and stored for 10 days, 20 days and 30 days, the flavor change of the rambutan after preservation treatment compared with the unpreserved rambutan (blank food storage box) was calculated (under the same preservation period). The results are shown in Table 4 below. 2. High-temperature preservation performance test: After the food storage container was transferred to a high-temperature environment of 36℃ for 5 days, 10 days and 15 days, the flavor change of the rambutan after preservation treatment was calculated (under the same preservation period) compared with the untreated rambutan (blank food storage container). The results are shown in Table 4 below.

[0063] Table 4. Test results of the preservation performance of the preservation gel

[0064] As can be seen from Table 4, making the preservation solution into a preservation gel helps to extend the preservation period. At the same time, when storing at low temperatures, the combination of low temperature environment can effectively improve the preservation performance of rambutan, thus maintaining good fruit texture and edibility after 10, 20 and 30 days of storage. At high temperatures, the high temperature environment can promote the release of volatile components in the preservation gel, thereby increasing the preservation time under high temperature environment. In addition, in Comparative Example 1, the direct use of porous carbon to load plant essential oils and other components resulted in poor slow release properties of the preservation gel.

[0065] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A tropical fruit preservation box, characterized in that, The invention includes a box for containing tropical fruit and having at least one opening, the box having a suitable lid at the opening; a receiving cavity is formed at the bottom of the box, and a through hole is opened on the side wall of the box at the receiving cavity, the receiving cavity communicating with the interior of the box through the through hole; a preservative gel is disposed in the receiving cavity of the box, the preparation method of the preservative gel including: impregnating a biomass matrix in plant essential oil to obtain a composite matrix; modifying a polyphenol polymer layer on the surface of the composite matrix to obtain a composite carrier; dispersing the composite carrier in a preservative solution, gelling and shaping it under the action of calcium ions to obtain the preservative gel; wherein: the preservative solution contains fruit peel extract and plant polysaccharides.

2. The food storage container according to claim 1, characterized in that: The ratio of the preservation gel to the volume of the box is 3 mg / cm³. 3 -15mg / cm 3 ; and / or, the ratio of the projected area of ​​the preservation gel to that of the box body is 60%-90%; and / or, when the box body preserves tropical fruits, the box body is filled with an inert gas, the inert gas including nitrogen and argon; and / or, the box body is provided with a sealing film at the opening, the sealing film being heat-fused to the side wall of the opening; and / or, the tropical fruits include one of rambutan, lychee, longan, wax apple, passion fruit, custard apple, papaya, mango, mangosteen, and miracle fruit.

3. The food storage container according to claim 1, characterized in that: The method for preparing the biomass matrix includes: dispersing biomass powder in sodium alginate solution and then gelling it to obtain a composite gel; freeze-drying the composite gel to obtain the biomass matrix; wherein: the biomass powder includes the extraction residue remaining after extracting the fruit peel extract; and / or, mixing and dispersing the biomass powder and sodium alginate solution at a mass ratio of (1-2):8; and / or, gelling under the action of calcium ions to obtain the composite gel.

4. The food storage container according to claim 1, characterized in that: The plant polysaccharide includes one of pectin, fucoidan, and purslane polysaccharide; and / or, the polyphenol includes tannic acid; and / or, the composite matrix is ​​dispersed in a polyphenol solution, and the composite carrier is obtained by adding Tris-HCl solution dropwise, stirring and reacting; and / or, the preservation solution also contains an antioxidant, which includes one of tea polyphenols, catechins, and phytic acid.

5. The food storage container according to claim 1, characterized in that: The extraction method of the fruit peel extract includes: enzymatically hydrolyzing the rambutan fruit peel, inactivating the enzyme, and separating the enzymatic hydrolysate and the enzymatic hydrolysate; extracting the enzymatic hydrolysate with a eutectic solvent and separating the extract; mixing the enzyme-inactivated enzymatic hydrolysate and the extract to obtain the fruit peel extract; wherein the eutectic solvent is a food-grade raw material, including one of the following: betaine and citric acid in a molar ratio of 1:1, citric acid and glucose in a molar ratio of 1:1, and citric acid and glycerol in a molar ratio of 1:

2.

6. The food storage container according to claim 5, characterized in that: The average particle size of the rambutan peel is 0.1 mm-1 mm; and / or, the moisture content of the rambutan peel is 5%-10%; and / or, the rambutan peel is enzymatically hydrolyzed using at least one of cellulase, hemicellulase, and pectinase; and / or, enzymatic hydrolysis is performed at 40℃-50℃; and / or, enzymatic hydrolysis is performed for 1 h-3 h; and / or, enzymatic hydrolysis is performed in a buffer solution with pH=4-6; and / or, the mass ratio of enzyme to rambutan peel during enzymatic hydrolysis is 0.3%-0.8%; and / or, the solid-liquid ratio of the hydrolysate to the eutectic solvent is 0.03 g / mL-0.06 g / mL; and / or, extraction is performed under ultrasonic and / or microwave conditions; and / or, extraction is performed at 2 MPa-5 MPa; and / or, extraction is performed for 3 h-5 h.

7. A method for preserving the freshness of tropical fruits using a preservation box as described in any one of claims 1 to 6, characterized in that, include: After cleaning the surface of tropical fruits to be preserved, remove inferior fruits with mechanical damage, sterilize them, transfer them into the container of the preservation box, seal the opening of the container with the lid, and store them in an environment of 4℃-25℃.

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