A kumquat preservative and its preparation method
A kumquat preservative prepared by combining oxalis extract and soluble starch solves the shortcomings of low-temperature storage and chemical preservatives, achieving a safe and environmentally friendly fruit preservation effect, and is suitable for a variety of fruits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGXI TEACHERS EDUCATION UNIV
- Filing Date
- 2026-05-26
- Publication Date
- 2026-06-30
AI Technical Summary
Existing low-temperature storage technologies cause chilling injury to fruits, chemical preservatives have drug residues and environmental impacts, and the development of natural preservatives is insufficient.
A preservative was prepared by combining wood sorrel extract and soluble starch. It delays fruit decay through antibacterial and antioxidant effects and forms an edible protective film to reduce moisture loss and microbial infection.
It achieves safe and environmentally friendly fruit preservation, extends shelf life, reduces chemical residues, is suitable for a variety of fruits, is inexpensive, and is suitable for promotion at the grassroots level.
Smart Images
Figure CN122296360A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of preservative technology, specifically relating to a kumquat preservative and its preparation method. Background Technology
[0002] Currently, common fruit preservation technologies include low-temperature storage and chemical preservatives. Low-temperature storage inhibits fruit respiration, pathogen growth, and enzyme activity by lowering the temperature, thus delaying fruit aging and decay. However, long-term low-temperature storage may lead to chilling injury, causing the fruit peel to become sunken, brown, and lose flavor, affecting fruit quality. Chemical preservatives are widely used, with common examples including chlorpyrifos and thiamethoxam. They rapidly inhibit pathogen growth and extend the fruit's shelf life, but long-term use or insufficient fruit washing can easily lead to drug residues, harming human health; they may also cause pathogens to develop drug resistance, negatively impacting the ecological environment.
[0003] With increasing consumer awareness of food safety and the popularization of environmental protection concepts, the development of safe, efficient, and environmentally friendly natural preservatives has become a research hotspot in the fields of food science and agriculture. Natural preservatives, derived from plants, animals, or microorganisms, possess advantages such as being non-toxic, residue-free, and biodegradable, meeting the needs of green food development and showing broad application prospects in fruit and vegetable preservation. Summary of the Invention
[0004] This invention provides a kumquat preservative and its preparation method, which solves the above-mentioned technical problems.
[0005] To solve the above technical problems, the present invention adopts the following technical solution: A kumquat preservative includes the following ingredients: Oxalis extract, soluble starch, and appropriate amount of water; The preservative has a total phenol content of 250-310 mg / g and a total flavonoid content of 10-30 mg / g.
[0006] The mass concentration of oxalis extract prepared by adding water is 0.05-0.1 g / mL; The mass concentration of soluble starch prepared by adding water is 0.06-0.2 g / mL.
[0007] Furthermore, the total phenol content of the preservative is 172.86-302.58 mg / g, and the total flavonoid content is 12.15-24.72 mg / g.
[0008] Furthermore, the preservative has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
[0009] Furthermore, the method of using the preservative is as follows: immerse the kumquats in the preservative for 1-2 minutes, then remove them and let them air dry.
[0010] This application also provides a method for preparing a kumquat preservative, including: S1. Weigh out the oxalis extract as described in any one of 1-4 to prepare an oxalis extract solution; S2. Weigh out the soluble starch as described in any one of 1-4 and prepare a starch solution; S3. The volume ratio of oxalis extract to starch solution is 1:1-1.3. Mix and stir for 40-50 minutes. S4. Let it stand for another 5-10 minutes to obtain the preservative.
[0011] Furthermore, the preparation method of wood sorrel extract includes: S11. Take the weighed oxalis extract and water, mix them, stir well, and soak for 10-15 hours. The mass concentration of the oxalis extract is 0.05-0.1 g / mL. S12. After soaking, treat in a water bath at 70-90℃ 1-3 times, 1-2 hours each time; S13 and S11: The solutions after each treatment are filtered separately, and the filtrates are combined to obtain oxalis extract.
[0012] Further, step S2 involves dissolving the material in a water bath at 55-65°C for 10-20 minutes.
[0013] Furthermore, the preservative obtained in step S4 has a total phenol content of 172.86-302.58 mg / g and a total flavonoid content of 12.15-24.72 mg / g.
[0014] Furthermore, the preservative obtained in step S4 has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
[0015] Compared with the prior art, the present invention has the following beneficial effects: The preservative in this application is a compound of natural sage extract and food-grade soluble starch, with no chemical residue, safe and biodegradable, solving the safety hazards of traditional chemical preservatives.
[0016] After 15 days of use, the preservative in this application showed lower weight loss and disease rates compared to the control group and the chemical preservative group; furthermore, the total sugar, vitamin C, and acid content were all superior to the two groups mentioned above, demonstrating a better preservation effect. The preservative prepared in this application can be stored at room temperature away from light for 15 days, and its shelf life can reach 30 days under refrigeration at 4℃. It can be stirred evenly before use; it has the characteristics of long shelf life and easy use.
[0017] In addition to being suitable for preserving Rong'an kumquats, the preservative in this application can also be used for citrus fruits such as crispy-skinned kumquats, as well as fruits and vegetables such as tangerines, navel oranges, strawberries, grapes, and cherry tomatoes.
[0018] The preparation process of this application is simple, requires no complicated equipment, and has a cost that is only 40% of that of chemical preservatives, making it suitable for grassroots promotion. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 Line graphs showing the weight loss rate for each experimental group.
[0021] Figure 2 Line graph showing the lesion rate for each experimental group.
[0022] Figure 3 Line graphs showing the sugar content of each experimental group.
[0023] Figure 4 Line graph showing the vitamin C content of each experimental group.
[0024] Figure 5 Line graphs showing the acid content of each experimental group.
[0025] Figure 6 This is a comparison chart of the states of each experimental group on day 0.
[0026] Figure 7 This is a comparison chart of the conditions of each experimental group on day 3.
[0027] Figure 8 This is a comparison chart of the conditions of each experimental group on day 7.
[0028] Figure 9 This is a comparison chart of the status of each experimental group on day 15. Detailed Implementation
[0029] To facilitate a better understanding of the present invention, the following examples are provided in conjunction with the accompanying drawings. These examples fall within the scope of protection of the present invention, but do not limit the scope of protection of the present invention.
[0030] A kumquat preservative includes the following ingredients: Oxalis extract, soluble starch, and appropriate amount of water; The preservative contains 250-310 mg / g of total phenols and 10-30 mg / g of total flavonoids.
[0031] The mass concentration of oxalis extract prepared by adding water is 0.05-0.1 g / mL; The mass concentration of soluble starch prepared by adding water is 0.06-0.2 g / mL.
[0032] The total phenol content of the preservative is 172.86-302.58 mg / g, and the total flavonoid content is 12.15-24.72 mg / g.
[0033] The preservative has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
[0034] The method for using the preservative is as follows: Immerse the kumquats in the preservative for 1-2 minutes, then remove them and let them air dry.
[0035] A method for preparing a kumquat preservative, comprising: S1. Weigh the above oxalis extract and prepare oxalis extract solution; S2. Weigh the soluble starch above and prepare a starch solution; S3. The volume ratio of oxalis extract to starch solution is 1:1-1.3. Mix and stir for 40-50 minutes. S4. Let it stand for another 5-10 minutes to obtain the preservative.
[0036] Methods for preparing wood sorrel extract include: S11. Take the weighed oxalis extract and water, mix them, stir well, and soak for 10-15 hours. The mass concentration of the oxalis extract is 0.05-0.1 g / mL. S12. After soaking, treat in a water bath at 70-90℃ 1-3 times, 1-2 hours each time; S13 and S11: The solutions after each treatment are filtered separately, and the filtrates are combined to obtain oxalis extract.
[0037] Step S2 involves dissolving the material in a water bath at 55-65℃ for 10-20 minutes.
[0038] The preservative obtained in step S4 contains 172.86-302.58 mg / g of total phenols and 12.15-24.72 mg / g of total flavonoids.
[0039] The preservative obtained in step S4 has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
[0040] This invention uses oxalis powder as its core functional component. Its rich flavonoids and phenolic acids, after hot water extraction, exert broad-spectrum antibacterial and strong antioxidant effects: on the one hand, they inhibit the growth of pathogenic bacteria such as Penicillium and Alternaria, reducing fruit rot; on the other hand, they scavenge free radicals, inhibit polyphenol oxidase activity, and delay fruit browning and senescence. Furthermore, its organic acids, vitamins, alkaloids, and volatile oils also have antibacterial effects, reducing rot, blackening, and softening of kumquats. The food-grade soluble starch used serves as the film-forming substrate, forming a uniform, breathable, and edible protective film on the fruit surface, reducing moisture loss and blocking oxygen and microbial contamination. The combined use of these two ingredients achieves a dual synergistic preservation effect of "antibacterial and antioxidant effects + physical water retention."
[0041] Example 1 A kumquat preservative includes the following ingredients: Oxalis extract, soluble starch, and appropriate amount of water; The preservative has a total phenol content of 250 mg / g and a total flavonoid content of 10 mg / g.
[0042] The mass concentration of the oxalis extract prepared by adding water was 0.05 g / mL; The mass concentration of soluble starch prepared by adding water is 0.06 g / mL.
[0043] The preservative has a total phenol content of 172.86 mg / g and a total flavonoid content of 12.15 mg / g.
[0044] The method for using the preservative is as follows: immerse the kumquats in the preservative for 2 minutes, then remove them and let them air dry.
[0045] A method for preparing a kumquat preservative, comprising: S1. Weigh the above oxalis extract and prepare oxalis extract solution; S2. Weigh the soluble starch above and prepare a starch solution; S3. The volume ratio of oxalis extract to starch solution is 1:1.3. Mix and stir for 40 minutes. S4. Let it stand for another 10 minutes to obtain the preservative.
[0046] Methods for preparing wood sorrel extract include: S11. Take the weighed oxalis extract and water, mix them together, stir well and soak for 10 hours. The mass concentration of the oxalis extract is 0.05 g / mL. S12. After soaking, treat in a 70℃ water bath 3 times, 2 hours each time; S13 and S11: The solutions after each treatment are filtered separately, and the filtrates are combined to obtain oxalis extract.
[0047] Step S2 involves dissolving the material in a water bath at 55°C for 20 minutes.
[0048] The preservative prepared in step S4 has a total phenol content of 172.86 mg / g and a total flavonoid content of 12.15 mg / g.
[0049] In this group, the mass-to-volume ratio of soluble starch to water was 10:100 g / mL; the oxalis extract was commercially available oxalis powder, with a mass-to-volume ratio of 1:20 g / mL to water.
[0050] Example 2 A kumquat preservative includes the following ingredients: Oxalis extract, soluble starch, and appropriate amount of water; The preservative has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
[0051] The mass concentration of the oxalis extract prepared by adding water was 0.08 g / mL; The mass concentration of soluble starch prepared by adding water is 0.1 g / mL.
[0052] The method for using the preservative is as follows: immerse the kumquats in the preservative for 1 minute, then remove them and let them air dry.
[0053] A method for preparing a kumquat preservative, comprising: S1. Weigh the above oxalis extract and prepare oxalis extract solution; S2. Weigh the soluble starch above and prepare a starch solution; S3. The volume ratio of oxalis extract to starch solution is 1:1. Mix and stir for 45 minutes. S4. Let it stand for another 5 minutes to obtain the preservative.
[0054] Methods for preparing wood sorrel extract include: S11. Take the weighed oxalis extract and water, mix them together, stir well and soak for 12 hours. The mass concentration of the oxalis extract is 0.08 g / mL. S12. After soaking, treat twice in an 80℃ water bath, 1.5 hours each time; S13 and S11: The solutions after each treatment are filtered separately, and the filtrates are combined to obtain oxalis extract.
[0055] Step S2 involves dissolving the substance in a water bath at 60°C for 15 minutes.
[0056] The preservative obtained in step S4 has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
[0057] In this group, the mass-to-volume ratio of soluble starch to water was 10:100 g / mL; the oxalis extract was commercially available oxalis powder, with a mass-to-volume ratio of 1:12 g / mL to water.
[0058] Example 3 A kumquat preservative includes the following ingredients: Oxalis extract, soluble starch, and appropriate amount of water; The preservative has a total phenol content of 310 mg / g and a total flavonoid content of 30 mg / g.
[0059] The mass concentration of the oxalis extract prepared by adding water was 0.1 g / mL; The mass concentration of soluble starch prepared by adding water is 0.2 g / mL.
[0060] The preservative has a total phenol content of 302.58 mg / g and a total flavonoid content of 24.72 mg / g.
[0061] The method for using the preservative is as follows: immerse the kumquats in the preservative for 1 minute, then remove them and let them air dry.
[0062] A method for preparing a kumquat preservative, comprising: S1. Weigh the above oxalis extract and prepare oxalis extract solution; S2. Weigh the soluble starch above and prepare a starch solution; S3. The volume ratio of oxalis extract to starch solution is 1:1.2. Mix and stir for 50 minutes. S4. Let it stand for another 7 minutes to obtain the preservative.
[0063] Methods for preparing wood sorrel extract include: S11. Take the weighed oxalis extract and water, mix them, stir well, and soak for 15 hours. The mass concentration of the oxalis extract is 0.1 g / mL. S12. After soaking, treat twice in a 90℃ water bath, 1 hour each time; S13 and S11: The solutions after each treatment are filtered separately, and the filtrates are combined to obtain oxalis extract.
[0064] Step S2 involves dissolving the material in a water bath at 65°C for 10 minutes.
[0065] The preservative obtained in step S4 has a total phenol content of 302.58 mg / g and a total flavonoid content of 24.72 mg / g.
[0066] In this group, the mass-to-volume ratio of soluble starch to water was 10:100 g / mL; the oxalis extract was commercially available oxalis powder, and its mass-to-volume ratio with water was 1:10 g / mL.
[0067] Comparative experiments showed that Example 2 had a better preservation effect on kumquats than Examples 1 and 3. The mass-to-volume ratio of soluble starch to water in Example 2 was 10:100 g / mL; the oxalis extract was commercially available oxalis powder, and its mass-to-volume ratio with water was 1:12 g / mL. The following comparative experiments will use Example 2.
[0068] test 1. Test Description In February 2026, freshly harvested Rong'an kumquats were selected. Healthy, intact kumquats without damage and with relatively uniform fruit size were selected and divided into three groups: a control group (47 kumquats), a chemical preservative group (48 kumquats), and the present invention group (48 kumquats). The control group was not treated. The chemical preservative group used Shibaike, and the present invention group used the preservative prepared in the example. The control group was not preserved. The chemical preservative group and the present invention group were prepared into solutions according to the instructions. The corresponding kumquats were soaked in the solutions for 1 minute, then removed, dried, and stored in a room temperature and ventilated environment for 20 days.
[0069] 2. Detection indicators The decay rate, weight loss rate, vitamin C (Vc) content, sugar content (soluble solids), and titratable acid content were all measured according to the corresponding standard methods to ensure data accuracy.
[0070] Rot rate = (Number of rotten fruits / Total number of fruits) × 100% Weight loss rate = (Initial total fruit weight - Total fruit weight after storage) / Initial total fruit weight × 100%; The following indicators were determined using national standard methods: sugar content (soluble solids content) was determined using a handheld saccharimeter; vitamin C content was determined using the 2,6-dichlorophenolindophenol titration method; and titratable acid content was determined using the sodium hydroxide neutralization titration method.
[0071] Table 1 shows that the weight loss rate and decay rate of the present invention are significantly lower than those of the freshness preservation method using Spock and the blank control group, indicating that the preservative of the present application has a better preservation effect.
[0072] Table 1. Indicators of each group after 15 days of preservation.
[0073] Table 2 shows the test results of each indicator after 20 days of preservation for each group.
[0074] Table 2. Indicators of each group after 20 days of preservation.
[0075] The data in Table 2 shows that: 1) Anti-corrosion and antibacterial effect: The decay rate of the group of this invention was only 25.0%, which was much lower than that of the blank control group and significantly lower than that of the conventional chemical preservative Shibaike group, demonstrating outstanding antibacterial and anti-corrosion capabilities.
[0076] 2) Water retention and water locking effect: The weight loss rate of the group of the present invention was 8.96%, which is the lowest value among the three groups. It can effectively reduce the water loss of kumquats by evaporation and delay the shrinkage of the fruit.
[0077] 3) Nutritional retention effect: The VC content of the present invention group was significantly higher than that of the blank group and the Shibaike group, which can effectively inhibit the oxidative degradation of VC and retain the fruit nutrients to the greatest extent.
[0078] 4) Sugar content maintenance effect: The sugar content of the group of this invention reached 26.2%, which was significantly higher than the other two groups. It can effectively inhibit fruit respiration and sugar metabolism, and fully preserve the original sweet and sour flavor of kumquat.
[0079] 5) Acidity stabilization effect: The titratable acid content of the present invention is stabilized at 0.627%, the sugar-acid ratio is balanced, effectively delaying the degradation of organic acids in the fruit and avoiding flavor deterioration.
[0080] In summary, the preservative prepared in Example 2 of this application is significantly better than the blank control group and the conventional chemical preservative group (Sciboc). It performs well in antibacterial and antiseptic properties, water retention, nutrient preservation and flavor maintenance, and fully meets the requirements of food-grade preservation. It can be regarded as the preferred solution for post-harvest preservation of Rong'an kumquats.
[0081] The following is an explanation with accompanying images.
[0082] Figure 1 The graph shows the weight loss rate of each experimental group. The data indicates that in the early stages of storage, the difference in weight loss between groups was not significant. The group of this invention exhibited the least amount of decay and the latest onset of disease, confirming that the effective components of this invention, such as flavonoids and phenolic acids, have a significant inhibitory effect on pathogens, and its preservative and freshness-preserving efficacy is superior to that of the chemical preservative, Silvax.
[0083] Figure 2 The graph shows the disease incidence rate of each experimental group. The data indicates that the disease incidence rate of Rong'an kumquats continuously increased with prolonged storage time. In the early stages of storage, the disease incidence rates of all treatment groups showed a similar upward trend. However, by day 16, the disease incidence rate of the blank control group began to rise sharply, and its value was significantly higher than that of the fruit treated with the coating solution from Shibaike and the present invention.
[0084] Figure 3Line graphs showing the sugar content of each experimental group are provided. Total sugar content, as a key physicochemical indicator determining the flavor and quality of Rong'an kumquats, directly affects the sensory evaluation of the fruit. During storage, sugar content gradually accumulates along with the post-harvest physiological maturation and metabolic activities of the fruit, thereby optimizing the fruit's flavor and quality. During this period, the total sugar content of kumquats treated with the coating solution of this invention and with Shibo Ke was significantly better than that of the blank control group, indicating that both treatments help maintain a high level of nutrition and flavor in the fruit.
[0085] Figure 4 Line graphs showing the vitamin C content of each experimental group are provided. Vitamin C is a key nutritional indicator of fruit freshness, and Rong'an kumquats are rich in vitamin C. However, vitamin C content may vary depending on the variety and origin. During the later stages of storage, the vitamin C content in the control group of Rong'an kumquats decreased significantly, while the vitamin C content in Rong'an kumquats treated with the preservative Shibaike and the coating solution of this invention decreased relatively more gradually.
[0086] Figure 5 The graph shows the acid content of each experimental group. During fruit storage, some organic acids are consumed as respiration substrates, while others are converted into sugars within the fruit. The results show that the acid content of the control group continuously increased, indicating abnormal fruit respiration and a gradual deterioration in flavor; the acidity of the Schbaker group fluctuated significantly, indicating insufficient flavor stability; while the acidity of the group presented in this invention changed relatively smoothly, maintaining a suitable sugar-acid ratio and exhibiting the most harmonious flavor.
[0087] Figure 6 The image shows a comparison of the initial state of kumquats in different treatment groups on day 0 of the experiment: the left is the control group, the middle is the Shibok treatment group, and the right is the group of this invention. All three groups of kumquats were plump, brightly colored, and showed no signs of rot, mold, or dehydration, indicating a consistent state and no significant differences in the initial experimental conditions.
[0088] Figure 7 The following is a comparison of the preservation status of kumquats in different treatment groups on the third day of the experiment: The left is the control group, where the fruit has shown slight dehydration and darkening of the peel; the middle is the Shiboke treatment group, where the fruit has bright color and no obvious mold; the right is the invention group, where only one case of local mold appeared (marked in red), and the overall condition is better than the control group but slightly worse than the Shiboke treatment group.
[0089] Figure 8 The following is a comparison of the preservation status of kumquats in different treatment groups on day 7 of the experiment: The left is the control group, where 4 fruits showed severe mold and rot (marked with red boxes), with large areas of the peel darkened and wrinkled, and obvious water loss; the middle is the Shibok treatment group, where the overall condition of the fruits was good, with only 3 cases of slight mold (marked with red boxes) and no large-scale rot; the right is the invention group, with only 1 case of local mold (marked with red boxes), the fruit color was well maintained, and the mold rate was the lowest among the three groups.
[0090] Figure 9 The following is a comparison of the preservation status of kumquats in different treatment groups on day 15 of the experiment: The left is the control group, where the fruit was severely dehydrated and shrunken, with 6 cases of rot and mold (marked in red), the overall color was dull, and the commercial value was greatly reduced; The middle is the Shibok treatment group, where the overall condition of the fruit was acceptable, with only 4 cases of mold and rot (marked in red), and the mold rate was lower than that of the control group; The right is the invention group, with only 2 cases of local mold (marked in red), the fruit fullness and color were best maintained, and the preservation effect was the best among the three groups.
[0091] It should be noted that, in this document, relational terms such as "first" and "second" are used merely 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 a process, method, article, or apparatus. Without further limitation, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0092] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A kumquat preservative, characterized in that, Including the following raw materials: Oxalis extract, soluble starch, and appropriate amount of water; The preservative has a total phenol content of 250-310 mg / g and a total flavonoid content of 10-30 mg / g.
2. The kumquat preservative according to claim 1, characterized in that, The mass concentration of oxalis extract prepared by adding water is 0.05-0.1 g / mL; The mass concentration of soluble starch prepared by adding water is 0.06-0.2 g / mL.
3. The kumquat preservative according to claim 2, characterized in that, The preservative has a total phenol content of 172.86-302.58 mg / g and a total flavonoid content of 12.15-24.72 mg / g.
4. The kumquat preservative according to claim 3, characterized in that, The preservative has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.
5. The kumquat preservative according to claim 2, characterized in that, The method of using the preservative is as follows: Immerse the kumquats in the preservative for 1-2 minutes, then remove and air dry.
6. A method for preparing a kumquat preservative, characterized in that, include: S1. Weigh out the oxalis extract as described in any one of 1-4 to prepare an oxalis extract solution; S2. Weigh out the soluble starch as described in any one of 1-4 and prepare a starch solution; S3. The volume ratio of oxalis extract to starch solution is 1:1-1.
3. Mix and stir for 40-50 minutes. S4. Let it stand for another 5-10 minutes to obtain the preservative.
7. The method for preparing a kumquat preservative according to claim 6, characterized in that, Methods for preparing wood sorrel extract include: S11. Take the weighed oxalis extract and water, mix them, stir well, and soak for 10-15 hours. The mass concentration of the oxalis extract is 0.05-0.1 g / mL. S12. After soaking, treat in a water bath at 70-90℃ 1-3 times, 1-2 hours each time; S13 and S11: The solutions after each treatment are filtered separately, and the filtrates are combined to obtain oxalis extract.
8. The method for preparing a kumquat preservative according to claim 7, characterized in that, Step S2 involves dissolving the material in a water bath at 55-65℃ for 10-20 minutes.
9. The method for preparing a kumquat preservative according to claim 8, characterized in that, The preservative obtained in step S4 has a total phenol content of 172.86-302.58 mg / g and a total flavonoid content of 12.15-24.72 mg / g.
10. A method for preparing a kumquat preservative according to claim 9, characterized in that, The preservative has a total phenol content of 289.73 mg / g and a total flavonoid content of 22.2 mg / g.