A method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil and its application in chili preservation.

Abstract

This invention belongs to the field of preservation technology, and specifically relates to a method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper oil, and its application in chili pepper preservation. This invention solves the technical problems of low water solubility and poor bioavailability of hypericin alone, and high volatility and poor stability of Sichuan pepper oil alone, making it difficult to achieve long-lasting antibacterial effects, and the fact that the two have never been used in synergistic antibacterial applications. This invention uses Tween 80 as an emulsifier, dissolving it in deionized water to obtain an aqueous phase containing Tween 80; Sichuan pepper oil and Tween 80 are ultrasonically mixed, and hypericin is added and ultrasonically mixed to obtain an oil phase; the oil phase is then added dropwise to the aqueous phase and stirred, and homogenized using a high-speed homogenizer to obtain a crude emulsion; the crude emulsion is then treated in an ultrasonic cell disruptor to obtain a hypericin-Sichuan pepper oil nanoemulsion containing 5%~7% of both Tween 80 and Sichuan pepper oil by volume. The emulsion exhibits excellent stability, effectively inhibiting pathogens, delaying fruit and vegetable spoilage, and improving preservation effects.

Description

Technical Field

[0001] This invention relates to the field of preservation technology, and in particular to a method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil and its application in the preservation of chili peppers. Background Technology

[0002] Postharvest spoilage of fruits and vegetables severely restricts their commercial value and circulation cycle. Developing green, safe, and efficient antibacterial and preservative agents is an important research direction in the food preservation field. Natural plant-derived antibacterial components, due to their advantages such as no chemical residues, high biosafety, and environmental friendliness, have become the preferred alternative to traditional synthetic chemical bactericides. Hypericin (Hy) and Sichuan pepper essential oil (SPEO) are two natural antibacterial components with great application potential. Hy, as a natural photosensitizer, can generate reactive oxygen species under light conditions, effectively destroying microbial structures through photodynamic inactivation. SPEO, rich in monoterpenoids such as linalool and limonene, can disrupt the cell membrane integrity of pathogens through membrane penetration, exhibiting broad-spectrum chemical antibacterial activity.

[0003] However, in existing technologies, Hy and SPEO are both applied separately as single components in antibacterial and preservation research. There is no relevant technical solution to co-encapsulate the two in the same delivery system. Moreover, each component has obvious physicochemical defects, which makes it difficult to fully exert their antibacterial efficacy and meet the actual application needs of postharvest preservation of fruits and vegetables. Hy has extremely low water solubility, and its molecules are prone to π-π stacking to form large-sized aggregates. It has low bioavailability and is unstable, and its photodynamic antibacterial activity cannot be maintained for a long time. SPEO has the problems of high volatility and poor chemical stability. It is easy to decompose and volatilize under natural conditions, making it difficult to maintain a long-term antibacterial effect. Summary of the Invention

[0004] In order to overcome the technical defects of existing natural plant-derived antibacterial and preservative agents, this invention provides a method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil and its application in chili preservation, specifically solving the following technical problems.

[0005] When Hy is used alone for fruit and vegetable preservation, its low water solubility and easy molecular aggregation lead to low bioavailability, resulting in the inability to exert its photodynamic antibacterial activity for a long time.

[0006] When SPEO is used alone for fruit and vegetable preservation, it is difficult to achieve long-lasting antibacterial effects due to its high volatility, poor chemical stability, and easy loss and decomposition.

[0007] There is a technological gap in the current technology that lacks the ability to co-encapsulate SPEO and Hy in the same delivery system, thus failing to achieve the synergistic effect of their antibacterial mechanisms.

[0008] This invention provides a method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil, and its application in chili preservation. The co-encapsulated emulsion uses natural plant-derived components Hy and SPEO as the core, and is constructed through a specific nanoemulsion delivery system to achieve stable encapsulation. The method is specifically completed according to the following steps: 1. Dissolve Tween 80 in deionized water to obtain an aqueous phase containing Tween 80; mix SPEO and Tween 80 ultrasonically, then add Hy and sonicate to obtain an oil phase; 2. After adding the oil phase to the aqueous phase and stirring, homogenize using a high-speed homogenizer to obtain a crude emulsion; place the crude emulsion into an ultrasonic cell disruptor for processing to obtain a Hypericin Sichuan pepper essential oil nanoemulsion (Hy@SPEO-NE) containing Tween 80 (6% by volume) and SPEO (6% by volume), i.e., a co-encapsulated emulsion.

[0009] An application of a co-encapsulated emulsion in food preservation.

[0010] A co-encapsulated emulsion for photocatalytic antibacterial use.

[0011] A co-encapsulated emulsion is used to prepare a nanoemulsion system with highly efficient antibacterial and objectively verifiable preservation effects.

[0012] Compared with the prior art, the advantages of the present invention are as follows.

[0013] I. Safe and Environmentally Friendly Raw Materials: SPEO is a natural volatile oil extracted from Sichuan pepper, a traditional spice, and has long been widely used in the food flavoring industry; its safety has been fully verified. Hy is a natural photosensitive active ingredient extracted from Hypericum plants, with broad application potential. Tween 80, as a food-grade nonionic surfactant, has been approved as a food additive, and its impact on human health and the environment has been extensively studied. All ingredients are derived from natural extracts or food-grade raw materials and contain no metal components, ensuring the safety and environmental friendliness of this co-encapsulated emulsion.

[0014] II. Simple and efficient preparation process: The uniform dispersion and stable emulsification of each component can be achieved through simple stirring, homogenization and ultrasonic technology. The preparation process does not require complex equipment or harsh reaction conditions. The process flow is simple and easy to scale up production.

[0015] III. Significant Photocatalytic Synergistic Antibacterial Efficacy: Under light irradiation, Hy, as a highly efficient photosensitizer, can generate reactive oxygen species, which significantly synergistically interact with the antibacterial components in SPEO, rapidly disrupting the cell membrane structure of microorganisms such as Staphylococcus aureus, leading to leakage of cell contents and cell death. Experiments show that after 60 minutes of light treatment, the initial concentration of 10... 8 The bactericidal efficiency of Staphylococcus aureus at CFU / mL can reach 99.99%.

[0016] IV. Excellent Emulsion Stability: Hy@SPEO-NE exhibits small particle size, low polydispersity index (PDI), and high absolute Zeta potential, demonstrating good uniformity and stability. Centrifugation and dilution stability experiments prove that this co-encapsulated emulsion is not prone to stratification or aggregation during storage, making it suitable for long-term storage and practical applications.

[0017] V. Significant Preservation Effect: In the application of chili preservation, this co-encapsulated emulsion can effectively inhibit microbial growth, delay the increase in water loss and decay rate, maintain the appearance quality and nutritional components of fruits and vegetables, significantly extend shelf life, and demonstrate excellent preservation performance.

[0018] VI. Wide applicability: All components of this system are green and environmentally friendly, with no burden on the environment. It is not only suitable for post-harvest preservation of fresh fruits and vegetables, but can also be extended to the preservation of other fresh foods such as meat and aquatic products, with broad market application prospects and promotional value. Attached Figure Description

[0019] Figure 1 Comparison of appearance and color of Hy aqueous solution, SPEO, SPEO nanoemulsion (SPEO-NE), and Hy@SPEO-NE prepared in this invention.

[0020] Figure 2 The particle size distribution diagram is shown for Hy@SPEO-NE prepared in Example 1 of this invention.

[0021] Figure 3 The particle size distribution diagram is shown for SPEO-NE prepared in Comparative Example 1 of this invention.

[0022] Figure 4 This is a particle size distribution diagram of the Hy aqueous solution prepared in Comparative Example 2 of the present invention.

[0023] Figure 5 The PDI diagrams are for the aqueous solutions of Hy@SPEO-NE, SPEO-NE, and Hy prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0024] Figure 6 The Zeta potential diagrams are for the aqueous solutions of Hy@SPEO-NE, SPEO-NE, and Hy prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0025] Figure 7 The figure shows the experimental results of the dyeing dye Hy@SPEO-NE prepared in Example 1 of this invention.

[0026] Figure 8 The image shows the field emission scanning electron microscope (SEM) result of Hy@SPEO-NE prepared in Example 1 of this invention.

[0027] Figure 9 The diagram shows the bactericidal efficiency of the aqueous solutions of Hy@SPEO-NE, SPEO-NE, and Hy prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0028] Figure 10 The image shows the SEM bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of this invention under light irradiation for 0 min.

[0029] Figure 11 The image shows the SEM bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of this invention after 20 min of light irradiation.

[0030] Figure 12 The image shows the SEM bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of this invention after 40 min of light irradiation.

[0031] Figure 13 The image shows the SEM bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of this invention after 60 min of light irradiation.

[0032] Figure 14 The image shows the appearance of the Hy@SPEO-NE chili pepper prepared in Example 1 of this invention.

[0033] Figure 15 The image shows the weight loss rate of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention during preservation.

[0034] Figure 16 The image shows the preservation and spoilage rate of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention.

[0035] Figure 17 The image shows the Hy@SPEO-NE pepper preservation soluble solids (TSS) prepared in Example 1 of this invention.

[0036] Figure 18 The image shows the ascorbic acid content of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention.

[0037] Figure 19 The image shows the preservation firmness of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention. Detailed Implementation

[0038] Specific Implementation Method 1: This implementation method describes a method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil, and its application in chili pepper preservation. The method is specifically completed according to the following steps: 1. Dissolve Tween 80 in deionized water to obtain an aqueous phase containing Tween 80; mix SPEO and Tween 80 ultrasonically, then add Hy and sonicate to obtain an oil phase; 2. After adding the oil phase to the aqueous phase and stirring, homogenize using a high-speed homogenizer to obtain a crude emulsion; process the crude emulsion in an ultrasonic cell disruptor to obtain a Hypericin Sichuan pepper essential oil nanoemulsion (Hy@SPEO-NE) containing Tween 80 (5%~7% by volume) and SPEO (5%~7% by volume), which is the co-encapsulated emulsion.

[0039] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the concentration of Tween 80 in the aqueous phase in step one is 2.0%~4.0% (v / v). The other steps are the same as in Specific Implementation Method One.

[0040] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the volume ratio of SPEO to Tween 80 in the oil phase in step one is 1:(0.4~0.6). The other steps are the same as in Specific Implementation Method One or Two.

[0041] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the amount of Hy added to the oil phase in step one is 0.5 mg / mL to 2.5 mg / mL. The other steps are the same as in Specific Implementation Methods One to Three.

[0042] Specific Implementation Method Five: The difference between this implementation method and Specific Implementation Methods One to Four is that, after mixing the oil phase and the water phase in step two, the total volume percentage of Tween 80 in the final emulsion is 5% to 7%. The other steps are the same as in Specific Implementation Methods One to Four.

[0043] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that the stirring time after adding the ingredients in step two is 5 to 15 minutes. The other steps are the same as in Specific Implementation Methods One to Five.

[0044] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the high-speed homogenization speed in step two is 8000 r / min to 12000 r / min. The other steps are the same as in Specific Implementation Methods One to Six.

[0045] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that the high-speed homogenization time in step two is 3 min to 10 min. The other steps are the same as in Specific Implementation Methods One to Seven.

[0046] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the power of the ultrasonic cell disruptor in step two is 30%~35%, and the time is 20 min~40 min. The other steps are the same as in Specific Implementation Methods One to Eight.

[0047] Specific Implementation Method 10: This implementation method is an application of a co-encapsulated emulsion prepared according to one of the methods described in Specific Implementation Methods 1 to 9 in antibacterial preservation.

[0048] The co-encapsulated emulsion of the present invention uses an oil-in-water nanoemulsion as a carrier to stably encapsulate Hy and SPEO within the system. On the one hand, SPEO acts as an oil phase core to dissolve and load hydrophobic Hy, effectively inhibiting its intermolecular π-π stacking and solving the problems of poor water solubility and easy aggregation and inactivation. At the same time, it reduces the volatility of SPEO itself and reduces its oxidative decomposition. On the other hand, the fine particle size and uniform dispersion structure formed by nanoemulsification simultaneously improve the dispersibility, storage stability and bioavailability of the two active ingredients. When this co-encapsulated emulsion is applied to the surface of fruits and vegetables, it forms a dense protective barrier film, reducing water loss and gas penetration, and initially inhibiting microbial infection. At the same time, terpenoid components in SPEO, such as linalool and limonene, can directly penetrate and destroy the cell membrane structure of pathogens, interfering with their energy metabolism and reducing their environmental resistance, thus providing a basis for subsequent effects. Under light conditions, well-dispersed Hy is excited and efficiently generates highly oxidizing reactive oxygen species through its conjugated π-electron structure, further aggravating oxidative damage to the cell membrane and destruction of intracellular components. Ultimately, this achieves a synergistic effect of the two antibacterial mechanisms, effectively inhibiting the growth and reproduction of pathogens, delaying the spoilage process of fruits and vegetables, and achieving a highly efficient and stable preservation effect.

[0049] The beneficial effects of the present invention are verified using the following embodiments: Example

[0050] A method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil and its application in chili preservation, characterized in that the preparation method of the co-encapsulated emulsion is specifically carried out according to the following steps.

[0051] 1. Dissolve Tween 80 in deionized water to obtain an aqueous phase containing Tween 80; after ultrasonically mixing SPEO and Tween 80, add Hy and ultrasonically obtain an oil phase.

[0052] The concentration of Tween 80 in the aqueous phase described in step one is 3.3% (v / v).

[0053] In step one, the volume ratio of SPEO to Tween 80 in the oil phase is 1:0.5, and the amount of Hy added is 0.89 mg / mL.

[0054] 2. After adding the oil phase to the aqueous phase and stirring, homogenize using a high-speed homogenizer to obtain a crude emulsion; process the crude emulsion in an ultrasonic cell disruptor to obtain Hy@SPEO-NE containing Tween 80 and SPEO, which is the co-encapsulated emulsion.

[0055] In step two, the total volume percentage of Tween 80 in the final emulsion after mixing the oil phase and the water phase is 6%. Compare with Example 1

[0056] The preparation method of SPEO-NE is carried out according to the following steps.

[0057] Tween 80 was dissolved in deionized water to obtain an aqueous phase containing Tween 80; SPEO and Tween 80 were ultrasonically mixed to obtain an oil phase. The oil phase was added dropwise to the aqueous phase and stirred, then homogenized using a high-speed homogenizer to obtain a crude emulsion; the crude emulsion was then processed in an ultrasonic cell disruptor to obtain SPEO-NE. Compare with Example 2

[0058] The preparation method of Hy aqueous solution is carried out according to the following steps.

[0059] Hy is dissolved in deionized water to obtain an aqueous solution of Hy.

[0060] Figure 1 Comparison of appearance and color of Hy aqueous solution, SPEO, SPEO-NE, and Hy@SPEO-NE prepared in this invention.

[0061] from Figure 1 It can be seen that the prepared Hy@SPEO-NE is pink, and SPEO-NE is milky white, and they are evenly distributed without oil-water separation. Due to the low water solubility of Hy, it disperses in water in particulate form to form a Hy aqueous dispersion solution.

[0062] Figure 2 The particle size distribution diagram of Hy@SPEO-NE prepared in Example 1 of this invention; Figure 3 The particle size distribution diagram of SPEO-NE prepared in Comparative Example 1 of this invention is shown. Figure 4 This is a particle size distribution diagram of the Hy aqueous solution prepared in Comparative Example 2 of the present invention.

[0063] from Figure 2 , Figure 3 and Figure 4 It can be seen that the average particle size distribution of SPEO-NE and Hy@SPEO-NE is similar to that of a normal distribution, and the particle size distribution is narrow, indicating that the nanoemulsion has good consistency and uniform particle size distribution. Hy does not show a normal distribution in water and has a large average particle size, mainly because Hy has low water solubility.

[0064] Figure 5 The PDI diagrams are for the aqueous solutions of Hy@SPEO-NE, SPEO-NE, and Hy prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0065] from Figure 5It can be seen that the smaller the PDI value, the better the emulsion dispersibility. The PDI value of Hy is 0.68±0.097, indicating poor dispersibility. The PDI value of SPEO-NE is 0.37±0.034, and the PDI value of Hy@SPEO-NE is 0.28±0.002, indicating that the prepared Hy@SPEO-NE has good dispersibility.

[0066] Figure 6 The Zeta potential diagrams are for the aqueous solutions of Hy@SPEO-NE, SPEO-NE, and Hy prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0067] from Figure 6 It can be seen that the Zeta potential reflects the electrostatic interaction between particles, and the higher the absolute value of the Zeta potential, the better the stability of the system. Aqueous dispersions of Hy alone exhibit a relatively high negative potential (-21.97±0.65 mV), and SPEO-NE also shows a negative potential (-21.63±2.44 mV). However, Hy@SPEO-NE has an even higher negative potential (-26.53±3.25 mV), indicating that Hy@SPEO-NE possesses high stability. Test Example 1

[0068] The type of Hy@SPEO-NE emulsion was determined using a staining dye method. 4 mL of Hy@SPEO-NE was placed in a 10 mL centrifuge tube, and oil-soluble dye Sudan III (red) and water-soluble dye methylene blue (blue) were added separately. The dispersion and diffusion rate of the two dyes in the emulsion were observed. The staining results are shown below. Figure 7 As shown.

[0069] Figure 7 The figure shows the experimental results of the dyeing dye Hy@SPEO-NE prepared in Example 1 of this invention.

[0070] from Figure 7 It can be seen that the Hy@SPEO-NE prepared in Example 1 of this invention is pink. To avoid the color affecting the judgment, Hy@SPEO-NE was diluted to a suitable concentration. The emulsion was easily diluted after adding water, indicating that the external phase was aqueous. After adding methylene blue, it diffused rapidly, while Sudan III remained in particulate form and did not diffuse, and no oil-water separation was observed. Therefore, it can be determined that Hy@SPEO-NE is an oil-in-water emulsion. Test Example 2

[0071] The microstructure of Hy@SPEO-NE was observed using SEM.

[0072] Figure 8 The image shows the SEM results of Hy@SPEO-NE prepared in Example 1 of this invention.

[0073] from Figure 8 It can be seen that the prepared Hy@SPEO-NE droplets exhibit a regular spherical structure and a relatively uniform size distribution, thus successfully constructing a nanoemulsion system. Test Example 3

[0074] Staphylococcus aureus ( S. aureus ) was selected as the indicator bacterium. All instruments and culture media were sterilized by high temperature before use. Add 1 mL of material solution (160 μg / mL Hy@SPEO-NE, 160 μg / mL Hy, SPEO-NE) and approximately 10 8 CFU / mL S. aureus After mixing the bacterial suspension, it was placed 25 cm away from a xenon lamp light source (intensity approximately equal to sunlight). After 0, 20, 40, and 60 min of light treatment, 100 μL of the bacterial suspension was serially diluted and plated onto LB agar plates. After incubation at 37°C for 15 h, colonies were counted. To investigate the effect of light, a dark control experiment was set up: 1 mL of 160 μg / mL Hy@SPEO-NE and the bacterial suspension were added to a centrifuge tube and mixed thoroughly. No light treatment was performed, while all other conditions remained the same. The antibacterial results are as follows: Figure 9 As shown.

[0075] Figure 9 The diagram shows the bactericidal efficiency of the aqueous solutions of Hy@SPEO-NE, SPEO-NE, and Hy prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0076] from Figure 9 It can be seen that as the light exposure time increases, the effects of light exposure on each group... S. aureus The concentrations decreased to varying degrees, and the bactericidal efficiency was Hy > Hy@SPEO-NE > SPEO-NE > Hy@SPEO-NE (dark control). After 60 min of light exposure, 80 μg / mL Hy@SPEO-NE could kill 10 8 The bactericidal effect of Hy@SPEO-NE at CFU / mL was close to 100%, attributed to the free diffusion of the photosensitizer and the generation of barrier-free reactive oxygen species. However, due to the encapsulation effect of the nanoemulsion, the release of Hy in Hy@SPEO-NE was regulated, exhibiting sustained-release characteristics. Therefore, its bactericidal rate within 60 min was slightly lower than that of Hy aqueous solution, but this provides a basis for its long-term effect and stability in complex environments. This also indicates that Hy is the main antibacterial component of Hy@SPEO-NE. Comparing the Hy@SPEO-NE (dark control group) and the Hy@SPEO-NE group, it was shown that light irradiation significantly improved the antibacterial efficiency of Hy@SPEO-NE, and the longer the irradiation time, the better the bactericidal effect, indicating that the Hy@SPEO-NE prepared in this invention has good photocatalytic bactericidal effect. Test Example 4

[0077] Observation via SEM S. aureus Changes in cell membrane integrity and morphology over time.

[0078] Figure 10 This is a SEM image of the sterilization mechanism of Hy@SPEO-NE prepared in Example 1 of the present invention under light irradiation for 0 min; Figure 11 This is a SEM image of the bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of the present invention after 20 min of light irradiation; Figure 12 This is a SEM image of the bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of the present invention after 40 min of light irradiation; Figure 13 The image shows the SEM bactericidal mechanism of Hy@SPEO-NE prepared in Example 1 of this invention after 60 min of light irradiation.

[0079] from Figure 10 , Figure 11 , Figure 12 and Figure 13 It can be concluded that: those that have not been exposed to light S. aureus The surface is relatively smooth, the cell membrane is intact, and the cells are normally spherical or ellipsoidal; after photocatalytic treatment for 20 minutes, a small portion S. aureus Slight shrinkage or indentation initially appeared, gradually leading to deformation; after 40 minutes of photocatalytic treatment, S. aureus The bacteria no longer exhibit a plump spherical shape; after 60 minutes of photocatalytic treatment, the vast majority... S. aureus The bacterial cell surface showed obvious small pits and severe invagination, with significant changes in cell morphology and structure, and some cells even ruptured. This indicates that the Hy@SPEO-NE prepared in this invention can alter... S. aureus Cell morphology, causing it to gradually shrink and rupture, thereby inhibiting S. aureus The growth of [organisms] is effectively killed. S. aureus . Test Example 5

[0080] Using Xiangyan No. 95 chili peppers as test materials, fresh chili peppers with good appearance and uniform size were selected, rinsed with clean water, and air-dried naturally. Then, they were treated in the following three ways: (1) 80 μg / mL Hy@SPEO-NE treatment group (HS); (2) positive control group (PC), food-grade chlorine dioxide disinfectant; (3) negative control group (NC), sterile water. 2 mL of the treatment solution was taken and evenly spread on the surface of the chili peppers. After the surface was free of moisture, 5 chili peppers were placed in each bag in a polyethylene (PE) breathable bag and exposed to light for 5 min. All samples were stored at room temperature after treatment. Each treatment was repeated 3 times and stored for 20 days. Various indicators were measured and morphological changes were recorded on days 0, 4, 8, 12, 16, and 20.

[0081] Figure 14 The image shows the appearance of the Hy@SPEO-NE chili pepper prepared in Example 1 of this invention.

[0082] from Figure 14 It was found that after 20 days of storage, the peppers in each group showed varying degrees of spoilage, including mold, discoloration, and softening. Overall, around day 16 of storage, all groups gradually entered the ripening stage. Observation of the NC group showed that, with the passage of time, the fruit tips gradually lost water and shrank, later developing black spots on the surface, some with white centers, and the spots gradually expanding outwards. In the HS group, the fruit tips showed water loss and shrivelding around day 20 of storage, while in the PC group, the stem and tip showed water loss and discoloration. The Hy@SPEO-NE prepared in this invention can better maintain the appearance quality of peppers. Test Example 6

[0083] On day 0 of the experiment, the mass of the chili peppers was recorded as Z. On days 0, 4, 8, 12, 16, and 20, the mass of the chili peppers on the day of the experiment was Z1. The weight loss rate was calculated as follows: Weight loss rate (%) = ×100%(1) In Formula 1: Z is the mass of the chili peppers weighed on day 0; Z1 is the mass of the chili peppers weighed on the day of weighing.

[0084] Figure 15 The image shows the weight loss rate of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention during preservation.

[0085] from Figure 15 It can be seen that the weight loss rate of chili peppers in each experimental group increased with the extension of storage time. The weight loss rate of chili peppers in the HS group was lower than that in the PC and NC groups, which may be due to the formation of an isolation layer on the surface of the chili peppers by Hy@SPEO-NE, which inhibits moisture evaporation. Test Example 7

[0086] Observe the appearance of the chili peppers during the storage period. The presence of mold, discoloration, or softening on the surface indicates rot. The rot rate is the ratio of the number of rotten chili peppers (N1) to the initial number of chili peppers (N). The rot rate is calculated using the following formula: Rot rate (%) = ×100 %(2) In Equation 2: N1 is the number of rotten peppers; N is the initial number of peppers.

[0087] Figure 16 The image shows the preservation and spoilage rate of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention.

[0088] from Figure 16It can be seen that the decay rate of peppers in each treatment group increased with the extension of storage time, and the decay rate of the Hy@SPEO-NE group (50.0%) was lower than that of the NC group (100.0%). This indicates that the Hy@SPEO-NE prepared in this invention can effectively inhibit bacterial growth and delay decay. Test Example 8

[0089] After juicing the chili peppers, take about 0.2 mL of the juice and drop it onto a handheld saccharimeter for measurement. The result is expressed as a percentage (%).

[0090] Figure 17 The image shows the TSS (Total Sedimentation System) of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention.

[0091] from Figure 17 It can be seen that the TSS content of chili peppers in each treatment group generally showed a trend of first increasing and then decreasing. On day 20, the content in the Hy@SPEO-NE group (1.6%) was higher than that in the PC group and the NC group (both 1.5%). This indicates that the Hy@SPEO-NE prepared in this invention can delay the loss of TSS. Test Example 9

[0092] The sample was determined by the 2,6-dichlorophenolindophenol titration method (GB 5009.86-2016) and expressed as mg / 100 g.

[0093] Figure 18 The image shows the ascorbic acid content of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention.

[0094] from Figure 18 It was found that the ascorbic acid content of peppers in each treatment group gradually decreased with increasing storage days. On day 20, the ascorbic acid content of the Hy@SPEO-NE group (34.50 mg / 100 g) > PC group (31.75 mg / 100 g) > NC group (24.00 mg / 100 g). This indicates that the Hy@SPEO-NE prepared in this invention can effectively delay the decrease in ascorbic acid content. Test Case 10

[0095] The hardness of the middle part of the pepper fruit was measured using a texture analyzer in TPA mode, and the result was repeated three times.

[0096] Figure 19 The image shows the preservation firmness of Hy@SPEO-NE chili peppers prepared in Example 1 of this invention.

[0097] from Figure 19 It can be seen that the hardness of chili peppers decreases with increasing storage time. The rate of decrease in hardness of chili peppers in the Hy@SPEO-NE group is lower than that in the PC and NC groups, indicating that the Hy@SPEO-NE prepared in this invention can effectively slow down moisture loss and microbial growth, and maintain the mechanical strength of chili peppers.

Claims

1. A method for preparing an emulsion co-encapsulating hypericin and Sichuan pepper essential oil and its application in chili preservation, characterized in that... The preparation method of the co-encapsulated emulsion is specifically carried out according to the following steps:

1. Dissolve Tween 80 in deionized water to obtain an aqueous phase containing Tween 80; mix Sichuan pepper essential oil (SPEO) and Tween 80 by ultrasonication, then add hypericin (Hy) and ultrasonicate to obtain an oil phase; 2. After adding the oil phase to the aqueous phase and stirring, homogenize using a high-speed homogenizer to obtain a crude emulsion. Then, process the crude emulsion in an ultrasonic cell disruptor to obtain a hypericin-containing Sichuan pepper essential oil nanoemulsion containing Tween 80 (5%~7% by volume) and SPEO (5%~7% by volume), which is the co-encapsulated emulsion.

2. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... The concentration of Tween 80 in the aqueous phase in step one is 2.0%~4.0% (v / v).

3. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... In step one, the volume ratio of SPEO to Tween 80 in the oil phase is 1:(0.4~0.6).

4. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... The amount of Hy added to the oil phase in step one is 0.5 mg / mL to 2.5 mg / mL.

5. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... In step two, the total volume percentage of Tween 80 in the final emulsion after mixing the oil phase and the water phase is 5% to 7%.

6. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... The stirring time after the droplet is added in step two is 5 min to 15 min.

7. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... The high-speed homogenization speed in step two is 8000 r / min to 12000 r / min.

8. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... The high-speed homogenization time in step two is 3 min to 10 min.

9. The method for preparing a co-encapsulated emulsion according to claim 1, characterized in that... In step two, the ultrasonic cell disruptor is used at a power of 30% to 35% for a time of 20 to 40 minutes.

10. The method for preparing a co-encapsulated emulsion as described in claim 1, characterized in that... An application of a co-encapsulated emulsion in antibacterial preservation.

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