An orange peel extract and a method for preparing the same

Abstract

This application relates to the field of natural plant extract technology, and particularly to an orange peel extract and its preparation method. The method includes: pulverizing orange peel raw material and mixing it with water; adding a compound enzyme preparation for enzymatic hydrolysis and cell wall breaking; subjecting the enzymatically hydrolyzed product to dual-frequency ultrasonic treatment, inactivating the enzyme, filtering, vacuum concentrating the filtrate, and collecting the aroma condensate; heating the concentrated solution and adding xanthan gum and sodium carboxymethyl cellulose, stirring and dispersing, and then adding back the aroma condensate to construct an aroma-preloaded colloidal composite system; then performing high-pressure homogenization, followed by gradient cooling to crystallize and solidify the surface of oil droplets; finally, sterilizing and filling to obtain the orange peel extract. This application not only significantly improves the extraction rate of flavonoids in orange peel and preserves the natural aroma, but also effectively solves the problem of floating oil and sedimentation in orange peel extract through a dual stabilization mechanism of "chemical encapsulation + physical solidification," ensuring that the product remains in a uniform and stable suspension state even after long-term standing at room temperature.

Description

Technical Field

[0001] This application relates to the field of natural plant extract technology, and in particular to an orange peel extract and its preparation method. Background Technology

[0002] Orange peel (also known as dried tangerine peel) is the dried, mature peel of the citrus fruit (Citrus reticulata) and its cultivated varieties, belonging to the Rutaceae family. It is a traditional Chinese medicine that is both food and medicine. Orange peel is rich in flavonoids (such as hesperidin, nosenoside, and tangeretin) and volatile components (such as d-limonene and γ-terpinene), which have various physiological activities such as anti-oxidation, anti-inflammation, and regulating qi and strengthening the spleen.

[0003] Currently, orange peel extraction mainly employs hot reflux, water decoction, or Soxhlet extraction. However, the cell walls of orange peel consist of a dense network structure formed by highly cross-linked cellulose, hemicellulose, and pectin, which encapsulates active ingredients such as flavonoids within the cells, resulting in significant mass transfer resistance during traditional extraction processes. To overcome this resistance, traditional processes typically require continuous extraction at temperatures above 90°C for 4–6 hours. This high-temperature, long-duration operation brings several problems: On the one hand, high temperatures cause heat-sensitive volatile components in orange peel (such as d-limonene and γ-terpinene) to oxidize, polymerize, or volatilize and escape, resulting in a serious loss of natural aroma. On the other hand, high-temperature hydrolysis causes the glycosidic bonds in the hesperidin structure to break, producing uncontrollable byproducts, which causes the extract to darken in color, develop caramelized off-flavors, and become more bitter.

[0004] On the other hand, orange peel contains a large amount of pectin, dietary fiber, and other substances, which dissolve in large quantities during high-temperature extraction, resulting in high viscosity of the extract, difficulty in filtration, and cumbersome subsequent refining processes. In addition, traditional processes often use organic solvents (such as ethanol) for extraction, which leads to problems such as high energy consumption, solvent residue, and significant environmental pressure.

[0005] Besides extraction efficiency, the stability of orange peel extract is also a significant bottleneck restricting its industrial application. Orange peel extract contains both fat-soluble components such as volatile oils and insoluble solid particles such as pectin, dietary fiber, and polyphenols. Due to the poor compatibility of volatile oils with the aqueous phase, oil-water separation easily occurs, with the oil rising to form an oil layer; while the fine solid particles such as pectin and dietary fiber, due to density differences, easily settle and aggregate, forming sediment. This stratification phenomenon, with an upper layer of oil and a lower layer of sediment, not only leads to uneven and cloudy product appearance, affecting sensory quality, but also causes uneven distribution of active ingredients, resulting in unstable flavor and active ingredient content between batches, and severely shortening the product's shelf life.

[0006] To address the aforementioned issues, while existing technologies have attempted methods such as single enzymatic hydrolysis, ultrasound-assisted extraction, or the addition of stabilizers, these approaches primarily focus on solving single problems—either solely on improving extraction rates or post-extraction stability—failing to provide a systematic process design encompassing the entire process from extraction to stabilization. Therefore, developing a method for preparing orange peel extract that balances extraction efficiency, activity retention, and system stability has significant application value. Summary of the Invention

[0007] In view of the above, the main purpose of this application is to provide an orange peel extract and a method for preparing the same, so as to solve the above-mentioned technical problems.

[0008] Firstly, the method for preparing orange peel extract provided in this application adopts the following technical solution: A method for preparing an orange peel extract, the method comprising the following steps: Step 1: Crush the orange peel raw material and mix it with water at a material-to-liquid ratio of 1:8 to 1:12. Add a compound enzyme preparation made of endo-cellulase, endo-hemi-cellulase and polygalacturonase in a mass ratio of (1.5 to 2.5):(0.8 to 1.5):(1.0 to 2.0). Stir and enzymatically hydrolyze the mixture at pH 4.5 to 5.2 and 45 to 55°C for 4 to 6 hours to obtain the enzymatic hydrolysate. Step 2: The enzymatic hydrolysate is subjected to dual-frequency ultrasonic treatment at 45~55℃ and a vacuum of -0.06~-0.095MPa, with an ultrasonic frequency combination of 28kHz and 40kHz and an energy density of 0.45~0.60W / cm³. 2 After processing for 20-40 minutes, an ultrasonic liquid was obtained. The ultrasonic liquid was then filtered through three stages of vibrating screens (80 mesh, 120 mesh, and 200 mesh) and then through a 600 mesh bag filter. The filtrate was then vacuum concentrated to a Brix of 25-30° Brix at a temperature of 45-55°C and a vacuum of -0.08 to -0.095 MPa. At the same time, the aroma condensate that escaped during the concentration process was collected to obtain the concentrated liquid and the aroma condensate. Step 3: After heating the concentrate to 75~80℃, add xanthan gum and sodium carboxymethyl cellulose, stir and disperse at a speed of 2500~3500r / min, and add the aroma condensate back to the concentrate during the stirring process, so that the three-dimensional gel network formed by xanthan gum and sodium carboxymethyl cellulose will embed the aroma components in the network pores during the construction process, and obtain the aroma preloaded colloidal composite system. Step 4: The aroma-preloaded colloidal composite system is subjected to high-pressure homogenization at 50~60℃, with a first-stage pressure of 3~8MPa and a second-stage pressure of 15~25MPa to obtain a homogenized liquid. The homogenized liquid is then cooled to 4~10℃ at a gradient rate of 0.5~2℃ / min to cause local crystallization on the surface of the refined oil droplets in the homogenized liquid to form a solid lipid shell, thus obtaining a phase-change stable liquid. Step 5: After ultra-high temperature instantaneous sterilization, the phase change stabilized liquid is filled to obtain orange peel extract.

[0009] By adopting the above technical solution, this application first uses a compound enzyme preparation composed of endo-cellulase, exo-hemicellulase, and polygalacturonase to perform targeted enzymatic hydrolysis of orange peel cell walls under conditions of pH 4.5-5.2 and 45-55℃. The three enzymes produce a synergistic effect: endo-cellulase cuts the β-1,4-glycosidic bonds in the amorphous region of cellulose, loosening the microfibril structure; exo-hemicellulase gradually degrades the hemicellulose molecular chain from the chain end; and polygalacturonase hydrolyzes the α-1,4-galacturonic acid glycosidic bonds in the pectin backbone to soften the mesoglea layer. This results in the layered and targeted deconstruction of the three-dimensional network framework of "cellulose-hemicellulose-pectin" in the orange peel cell wall, allowing the flavonoid components densely encapsulated inside the cells to be fully released. On this basis, dual-frequency ultrasound of 28kHz and 40kHz is used to further deconstruct the cell wall. Cavitation-induced secondary cell wall disruption is performed on softened cell fragments after enzymatic hydrolysis under vacuum conditions at 45-55℃, further promoting the convection and diffusion of intracellular active ingredients. The synergistic effect of combined enzymatic hydrolysis and dual-frequency ultrasound significantly improves the extraction rate of flavonoids such as hesperidin. Simultaneously, the low-temperature operation at 45-55℃ throughout the process effectively avoids the oxidative condensation and vaporization loss of heat-sensitive volatile components and the high-temperature hydrolysis and breakage of hesperidin glycosidic bonds during traditional high-temperature extraction, maximizing the preservation of the extract's natural aroma and bioactivity. Furthermore, this application further refines the natural aroma condensate collected during concentration by reacting xanthan gum with sodium carboxymethyl cellulose at 2500℃. During the construction of the three-dimensional gel network by stirring at 3500 r / min, aroma components are simultaneously added back. Utilizing the dynamic characteristics of colloidal molecular chains unfolding and rearranging during stirring and dispersion, aroma components are in situ embedded within the pores of the gel network, achieving chemical binding of the aroma components. Subsequently, high-pressure homogenization refines the oil droplets in the aroma-preloaded colloidal composite system to submicron size. Then, the temperature is gradually reduced to 4–10 °C at a rate of 0.5–2 °C / min, causing localized crystallization on the surface of the refined oil droplets to form a solid lipid shell, achieving physical solidification and locking of the oil droplets. This dual stabilization mechanism of "chemical embedding + physical solidification" simultaneously solves the long-term storage problem of orange peel extract. The two major stability defects of upper layer floating oil and lower layer sedimentation are eliminated, so that the final product remains in a uniform and stable suspension state even after long-term standing at room temperature, with no oil-water interface, no floating oil layer and no bottom sedimentation. In addition, the above-mentioned compound enzymatic hydrolysis steps simultaneously complete cell wall disruption and pectin degradation under low temperature conditions, which makes subsequent filtration smooth and the refining process simplified. Organic solvent extraction is not required, which significantly reduces energy consumption and solvent residue risks. At the same time, the sequential synergistic design of aroma condensation and addition and colloidal network construction, as well as the step connection of high pressure homogenization and gradient cooling phase change solidification, greatly shorten the entire production cycle. The steps form a tight functional coupling, and the overall effect is better than the simple sum of the effects of each step.

[0010] Preferably, the mass ratio of endo-cellulase, exo-cellulase and polygalacturonase in the compound enzyme preparation is 2:1:1.5, and the amount of compound enzyme preparation added is 0.5% to 2.0% of the mass of orange peel raw material.

[0011] Preferably, the enzymatic hydrolysis is performed at a temperature of 50°C, a time of 5 hours, and a pH of 4.8 to 5.0.

[0012] Preferably, the temperature of the dual-frequency ultrasonic treatment is 45°C and the treatment time is 30 min; the temperature of the vacuum concentration is 50°C.

[0013] By adopting the above technical solution, this application preferably controls the mass ratio of endo-cellulase, exo-hemicellulase, and polygalacturonase to 2:1:1.5. Under this specific ratio, the synergistic effect of the three enzymes is most significant—polygalacturonase fully hydrolyzes pectin to expose the cellulose skeleton, while endo-cellulase and exo-hemicellulase synergistically degrade cellulose and hemicellulose from the inside and the ends, respectively, so that the deconstruction efficiency of the cell wall reaches the optimal level. Further, the enzymatic hydrolysis temperature is preferred to be 50℃, the time to be 5h, and the pH to be 4.8~5.0, so that the compound enzyme preparation is under the optimal reaction conditions and the enzyme activity can be fully exerted. At the same time, the dual-frequency ultrasonic treatment temperature is preferred to be 45℃, the treatment time to be 30min, and the vacuum concentration temperature to be 50℃, so that the low-temperature operation conditions throughout the process are optimized, ensuring a high extraction rate while maximizing the retention of heat-sensitive aroma components, significantly improving the flavor quality and batch stability of the final product.

[0014] Preferably, the mass ratio of xanthan gum to sodium carboxymethyl cellulose is 1:1 to 3:1, and the total amount added is 0.1% to 0.5% of the mass of the concentrate.

[0015] Preferably, the mass ratio of xanthan gum to sodium carboxymethyl cellulose is 2:1.

[0016] Preferably, the first-stage pressure of the high-pressure homogenization is 5 MPa, the second-stage pressure is 20 MPa, and the homogenization temperature is 55°C; the gradient cooling rate is 1°C / min, and the final temperature is 4°C.

[0017] Preferably, the ultra-high temperature instantaneous sterilization temperature is 130~137℃ and the time is 4~6s, and the filling temperature is below 35℃.

[0018] By adopting the above technical solution, this application preferably controls the mass ratio of xanthan gum to sodium carboxymethyl cellulose to be 2:1. At this ratio, the synergistic effect between the two is most significant, forming the most complete and dense three-dimensional gel network structure in the concentrate, which has the best binding effect on aroma components and oil droplets, while avoiding excessive addition of colloids that would lead to excessively high system viscosity and affect taste and processing fluidity. Further, the high-pressure homogenization is preferably performed with a first-stage pressure of 5 MPa, a second-stage pressure of 20 MPa, and a homogenization temperature of 55°C. Under these conditions, the oil droplets are refined to the optimal particle size range, providing a uniform template for subsequent crystallization and solidification. Combined with a gradient cooling rate of 1°C / min to the endpoint of 4°C, a uniform and dense solid lipid shell is formed on the surface of the oil droplets, ensuring the crystallization and solidification effect while avoiding excessively thick lipid shells or system damage caused by excessively rapid cooling. The ultra-high temperature instantaneous sterilization temperature is preferably 130~137°C for 4~6s, and the filling temperature is below 35°C, minimizing the impact of heat treatment on product flavor and stability while ensuring microbial safety.

[0019] Secondly, the orange peel extract provided in this application adopts the following technical solution: An orange peel extract is prepared by the method described in the first aspect. The orange peel extract is a uniform and stable suspension system with no oil-water interface, no floating oil layer and no bottom sediment. It does not show any visible layering or precipitation after standing at room temperature for more than 6 months.

[0020] By adopting the above-mentioned technical solution, this application successfully prepared an orange peel extract with excellent stability through the preparation method of the first aspect. This orange peel extract not only completely retains the flavonoid active ingredients and natural volatile aroma components of orange peel, but also achieves uniform suspension of oil droplets and insoluble solid particles in the system through a dual stabilization mechanism of "chemical encapsulation + physical solidification." This results in a uniform suspension state without an oil-water interface, floating oil layer, or bottom sediment. Even after long-term standing at room temperature, no visible layering or precipitation occurs, thus fundamentally solving the long-standing stability defects of orange peel extract. Applying such an orange peel extract to beverages, health products, or condiments eliminates the need for additional emulsifiers or stabilizers, maintaining sensory uniformity and uniform distribution of active ingredients throughout the product's shelf life, significantly broadening the application scenarios of orange peel extract in the food industry.

[0021] In summary, this application includes at least one of the following beneficial technical effects: 1. This application utilizes a compound enzyme preparation consisting of endo-cellulase, exo-cellulase, and polygalacturonase in a specific ratio to perform targeted enzymatic hydrolysis of orange peel cell walls. This is combined with secondary cell wall disruption via dual-frequency ultrasonic cavitation at a low temperature of 45°C. Under mild conditions, this approach achieves thorough cell wall deconstruction and efficient release of intracellular active ingredients, significantly improving the extraction rate of flavonoids such as hesperidin. At the same time, it effectively avoids the oxidative loss of heat-sensitive volatile components and the thermal breakage of hesperidin glycosidic bonds during traditional high-temperature extraction, thus maximizing the preservation of natural aroma and bioactivity. 2. This application achieves chemical binding of aroma components by simultaneously adding aroma condensate during the construction of a three-dimensional gel network using xanthan gum and sodium carboxymethyl cellulose. This allows aroma components to be in situ embedded in the pores of the colloidal network during its formation. Furthermore, by combining high-pressure homogenization to refine oil droplets to submicron level and then using gradient cooling to locally crystallize the surface of the oil droplets to form a solid lipid shell, this achieves physical locking of the oil droplets. Through the above dual stabilization mechanism of "chemical embedding + physical solidification", the industry problem of upper layer floating oil and lower layer sedimentation that has long existed in orange peel extract is fundamentally solved. This allows the product to maintain a uniform and stable suspension state even after long-term standing at room temperature, with no visible layering or precipitation. 3. This application integrates steps such as compound enzymatic hydrolysis to break cell walls, dual-frequency ultrasonic cavitation for secondary cell wall breaking, colloidal network construction and aroma preloading, high-pressure homogenization and gradient cooling phase change solidification into a complete process chain with synergistic effects. Each step forms a tight functional coupling: enzymatic hydrolysis opens the cell wall at the molecular level to provide softened cell fragments for ultrasound; the physical bombardment of ultrasound further releases intracellular substances and provides a sufficient source of aroma for subsequent colloidal encapsulation; and the submicron-sized oil droplet template created by homogenization provides a structural basis for the crystallization and solidification of gradient cooling. The synergistic effect of each step significantly improves the extraction rate, aroma retention rate and system stability, and the overall effect far exceeds the simple sum of the effects of each step. Detailed Implementation

[0022] The present application will be further described in detail below with reference to the embodiments. The following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the application. Unless otherwise specified, specific conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the methods used are conventional methods known in the art, and the consumables and reagents used are commercially available. Unless otherwise stated, the technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be applied to this application. Example

[0023] This embodiment provides a method for preparing orange peel extract, which includes the following steps: Step 1: After crushing the orange peel raw material, mix it with water at a material-to-liquid ratio of 1:10. Add a compound enzyme preparation composed of endo-cellulase, exo-cellulase and polygalacturonase in a mass ratio of 2:1:1.5. The amount of compound enzyme preparation added is 1.0% of the mass of the orange peel raw material. Stir and hydrolyze for 5 hours at pH 4.9 and 50℃ to obtain the enzymatic hydrolysate.

[0024] Step 2: The enzymatic hydrolysate is subjected to dual-frequency ultrasonic treatment at 45℃ and a vacuum of -0.08MPa, with a combination of ultrasonic frequencies of 28kHz and 40kHz and an energy density of 0.50W / cm³. 2 After processing for 30 minutes, an ultrasonic solution was obtained. The ultrasonic solution was heated to 80°C to inactivate enzymes for 30 minutes, and then filtered through three stages of vibrating screens (80 mesh, 120 mesh, and 200 mesh) and then through a 600-mesh bag filter. The resulting filtrate was vacuum concentrated to a Brix of 28° Brix at a temperature of 50°C and a vacuum of -0.09 MPa. At the same time, the aroma condensate that escaped during the concentration process was collected to obtain the concentrated solution and the aroma condensate.

[0025] Step 3: After heating the concentrate to 78°C, add xanthan gum and sodium carboxymethyl cellulose (the mass ratio of xanthan gum to sodium carboxymethyl cellulose is 2:1, and the total amount added is 0.3% of the mass of the concentrate). Stir and disperse at 3000 r / min, and add the aroma condensate back to the concentrate during the stirring process. This allows the three-dimensional gel network formed by xanthan gum and sodium carboxymethyl cellulose to embed the aroma components in the network pores during the construction process, resulting in an aroma-preloaded colloidal composite system.

[0026] Step 4: The aroma-preloaded colloidal composite system is subjected to high-pressure homogenization at 55°C, with a first-stage pressure of 5MPa and a second-stage pressure of 20MPa, to obtain a homogenized liquid. The homogenized liquid is then gradually cooled to 4°C at a rate of 1°C / min, causing local crystallization on the surface of the refined oil droplets in the homogenized liquid to form a solid lipid shell, thus obtaining a phase-change stable liquid.

[0027] Step 5: After the phase change stabilized liquid is sterilized at 135℃ for 5 seconds, it is filled at a temperature below 35℃ to obtain orange peel extract. Example

[0028] This embodiment provides a method for preparing orange peel extract, which includes the following steps: Step 1: After crushing the orange peel raw material, mix it with water at a material-to-liquid ratio of 1:8. Add a compound enzyme preparation composed of endo-cellulase, exo-cellulase and polygalacturonase in a mass ratio of 2:1:1.5. The amount of compound enzyme preparation added is 0.5% of the mass of the orange peel raw material. Stir and hydrolyze for 5 hours at pH 4.8 and 50℃ to obtain the enzymatic hydrolysate.

[0029] Step 2: The enzymatic hydrolysate was subjected to dual-frequency ultrasonic treatment at 45℃ and a vacuum of -0.06MPa, with a combination of ultrasonic frequencies of 28kHz and 40kHz and an energy density of 0.45W / cm³. 2 After processing for 20 minutes, an ultrasonic solution was obtained. The ultrasonic solution was heated to 80°C to inactivate enzymes for 30 minutes, and then filtered through three stages of vibrating screens (80 mesh, 120 mesh, and 200 mesh) and then through a 600-mesh bag filter. The resulting filtrate was vacuum concentrated to a Brix of 28° Brix at 50°C and a vacuum of -0.08 MPa. At the same time, the aroma condensate that escaped during the concentration process was collected to obtain the concentrated solution and the aroma condensate.

[0030] Step 3: After heating the concentrate to 75°C, add xanthan gum and sodium carboxymethyl cellulose (the mass ratio of xanthan gum to sodium carboxymethyl cellulose is 2:1, and the total amount added is 0.1% of the mass of the concentrate). Stir and disperse at 2500 r / min, and add the aroma condensate back to the concentrate during the stirring process. This allows the three-dimensional gel network formed by xanthan gum and sodium carboxymethyl cellulose to embed the aroma components in the network pores during the construction process, resulting in an aroma-preloaded colloidal composite system.

[0031] Step 4: The aroma-preloaded colloidal composite system is subjected to high-pressure homogenization at 55°C, with a first-stage pressure of 5MPa and a second-stage pressure of 20MPa, to obtain a homogenized liquid. The homogenized liquid is then gradually cooled to 4°C at a rate of 1°C / min, causing local crystallization on the surface of the refined oil droplets in the homogenized liquid to form a solid lipid shell, thus obtaining a phase-change stable liquid.

[0032] Step 5: After the phase change stabilized liquid is sterilized at 130℃ for 4 seconds, it is filled at a temperature below 35℃ to obtain orange peel extract. Example

[0033] This embodiment provides a method for preparing orange peel extract, which includes the following steps: Step 1: After crushing the orange peel raw material, mix it with water at a material-to-liquid ratio of 1:12. Add a compound enzyme preparation composed of endo-cellulase, exo-cellulase and polygalacturonase in a mass ratio of 2:1:1.5. The amount of compound enzyme preparation added is 2.0% of the mass of orange peel raw material. Stir and hydrolyze for 5 hours at pH 5.0 and 50℃ to obtain the enzymatic hydrolysate.

[0034] Step 2: The enzymatic hydrolysate was subjected to dual-frequency ultrasonic treatment at 45℃ and a vacuum of -0.095MPa, with a combination of ultrasonic frequencies of 28kHz and 40kHz and an energy density of 0.60W / cm³. 2After processing for 40 minutes, an ultrasonic solution was obtained. The ultrasonic solution was heated to 80℃ to inactivate enzymes for 30 minutes, and then filtered through three stages of vibrating screens (80 mesh, 120 mesh, and 200 mesh) and then through a 600-mesh bag filter. The resulting filtrate was vacuum concentrated to a Brix of 28° Brix at a temperature of 50℃ and a vacuum degree of -0.095MPa. At the same time, the aroma condensate that escaped during the concentration process was collected to obtain the concentrated solution and the aroma condensate.

[0035] Step 3: After heating the concentrate to 80°C, add xanthan gum and sodium carboxymethyl cellulose (the mass ratio of xanthan gum to sodium carboxymethyl cellulose is 2:1, and the total amount added is 0.3% of the mass of the concentrate). Stir and disperse at 3500 r / min, and add the aroma condensate back to the concentrate during the stirring process. This allows the three-dimensional gel network formed by xanthan gum and sodium carboxymethyl cellulose to embed the aroma components in the network pores during the construction process, resulting in an aroma-preloaded colloidal composite system.

[0036] Step 4: The aroma-preloaded colloidal composite system is subjected to high-pressure homogenization at 55°C, with a first-stage pressure of 5MPa and a second-stage pressure of 20MPa, to obtain a homogenized liquid. The homogenized liquid is then gradually cooled to 4°C at a rate of 1°C / min, causing local crystallization on the surface of the refined oil droplets in the homogenized liquid to form a solid lipid shell, thus obtaining a phase-change stable liquid.

[0037] Step 5: After the phase change stabilized liquid is sterilized at 137℃ for 6 seconds, it is filled at a temperature below 35℃ to obtain orange peel extract.

[0038] Comparative Example 1 (Traditional Hot Reflux Extraction Method) Following the method described in the literature: Orange peel raw material was pulverized and then 75% ethanol (by volume) was added at a material-to-liquid ratio of 1:35 (g / mL). Extraction was carried out under reflux at 85°C for 2.5 h. After extraction, the mixture was filtered, and the filtrate was concentrated under vacuum at 50°C to a Brix value of 28°. The concentrate was diluted with water to the same volume as in Example 1 and then bottled to obtain the orange peel extract.

[0039] Comparative Example 2 (Cellulase pretreatment combined with hot reflux extraction) Following the method described in the literature: Orange peel raw material was pulverized, pretreated with cellulase, and then extracted using a hot reflux extraction method at 85℃ for 3 hours, with 70% ethanol (v / v) and a solid-liquid ratio of 1:25 (g / mL). After extraction, the mixture was filtered, and the filtrate was concentrated under vacuum at 50℃ to a Brix level of 28°. The concentrate was diluted with water to the same volume as in Example 1 and then bottled to obtain the orange peel extract.

[0040] Comparative Example 3 (single enzymatic hydrolysis + homogenization, no ultrasound, no aroma restoration, no gradient cooling) The difference between this comparative example and Example 1 is as follows: in step 2, dual-frequency ultrasonic treatment is not performed; the enzymatic hydrolysate is directly inactivated by enzyme inactivation, followed by filtration and concentration. In step 3, the aroma condensate is not added back to the concentrate (the aroma condensate is discarded); only xanthan gum and sodium carboxymethyl cellulose are added, stirred, dispersed, and then homogenized. In step 4, after homogenization, gradient cooling is not performed; the mixture is directly sterilized and filled. The remaining steps and parameters are the same as in Example 1.

[0041] Comparative Example 4 (enzymatic hydrolysis + sonication + homogenization, no aroma re-addition, no gradient cooling) The difference between this comparative example and Example 1 is that: in step 3, the aroma condensate is not added back to the concentrate (the aroma condensate is discarded), and only xanthan gum and sodium carboxymethyl cellulose are added, stirred and dispersed, and then homogenized; in step 4, after homogenization, no gradient cooling treatment is performed, and sterilization and filling are carried out directly. The remaining steps and parameters (including dual-frequency ultrasonic treatment) are the same as in Example 1.

[0042] Comparative Example 5 (enzymatic hydrolysis + sonication + aroma restoration + homogenization, without gradient cooling) The difference between this comparative example and Example 1 is that in step 4, after homogenization, no gradient cooling treatment is performed; sterilization and filling are carried out directly. The remaining steps and parameters (including dual-frequency ultrasonic treatment and aroma condensate refilling) are the same as in Example 1.

[0043] Comparative Example 6 (Fragrance added after the colloidal network was fully formed) The difference between this comparative example and Example 1 is as follows: In step 3, the concentrated liquid is first heated to 78°C, xanthan gum and sodium carboxymethyl cellulose are added, and the mixture is stirred and dispersed at 3000 rpm. After the three-dimensional gel network formed by xanthan gum and sodium carboxymethyl cellulose is fully formed (and allowed to stand for 30 min after stirring and dispersion), the aroma condensate is added to the colloidal system, and the mixture is stirred at 3000 rpm for 10 min to disperse the aroma components in the colloidal network, thus obtaining a colloidal composite system. The remaining steps and parameters are the same as in Example 1.

[0044] Comparative Example 7 (Final blending stage with added aroma) The difference between this comparative example and Example 1 is as follows: In step 3, the concentrate is heated to 78°C, xanthan gum and sodium carboxymethyl cellulose are added, and the mixture is stirred and dispersed at 3000 r / min (without adding aroma condensate) to obtain a colloidal composite system; in step 4, only high-pressure homogenization and gradient cooling are performed (without aroma re-addition); in step 5, the aroma condensate is added to the phase change stabilizing liquid before ultra-high temperature instantaneous sterilization, stirred evenly, and then filled. The remaining steps and parameters are the same as in Example 1.

[0045] Comparative Example 8 (Rapid Cooling) The difference between this comparative example and Example 1 is that in step 4, after high-pressure homogenization, the homogenized liquid is directly placed in a 4°C environment for rapid cooling (without gradient cooling). After cooling to 4°C, a phase-change stable liquid is obtained. The remaining steps and parameters are the same as in Example 1.

[0046] Comparative Example 9 (Natural Cooling) The difference between this comparative example and Example 1 is that in step 4, after high-pressure homogenization, the homogenized liquid is allowed to cool naturally at room temperature (without gradient cooling). Once the liquid has cooled to room temperature (approximately 25°C), a phase-change stable liquid is obtained. The remaining steps and parameters are the same as in Example 1.

[0047] Comparative Example 10 (enzymatic hydrolysis + sonication, no colloid, no cooling) The difference between this comparative example and Example 1 is as follows: Xanthan gum and sodium carboxymethyl cellulose are not added in step 3, and the aroma condensate is not refilled (the aroma condensate is discarded). The concentrate is directly introduced into step 4 without colloidal compounding. In step 4, the concentrate is only subjected to high-pressure homogenization at 55°C (first stage pressure 5 MPa, second stage pressure 20 MPa). After homogenization, no gradient cooling treatment is performed; it is directly sterilized and filled. The remaining steps and parameters (including compound enzymatic hydrolysis and dual-frequency ultrasonic treatment) are the same as in Example 1.

[0048] Comparative Example 11 (enzymatic hydrolysis + colloid, no sonication, no cooling) The difference between this comparative example and Example 1 is as follows: In step 2, dual-frequency ultrasonic treatment is not performed; the enzyme-inactivated hydrolysate is directly filtered and concentrated. In step 3, xanthan gum and sodium carboxymethyl cellulose are added in the same manner as in Example 1, and the aroma condensate is added back to the concentrate during stirring to obtain an aroma-preloaded colloidal composite system. In step 4, the colloidal composite system is only subjected to high-pressure homogenization; after homogenization, no gradient cooling treatment is performed, and it is directly sterilized and filled. The remaining steps and parameters are the same as in Example 1.

[0049] Comparative Example 12 (ultrasound + colloid, no enzymatic hydrolysis, no cooling) The difference between this comparative example and Example 1 is as follows: In step 1, no compound enzyme preparation is added. The orange peel raw material is directly mixed with water after being crushed and heated to 50°C and stirred for 5 hours (without enzymatic hydrolysis) to obtain a liquid. In step 2, the liquid is directly subjected to dual-frequency ultrasonic treatment to inactivate the enzyme (no enzyme inactivation is required, but the temperature is raised to 80°C and held for 30 minutes to maintain the same heat treatment history as in Example 1), followed by filtration and concentration. In step 3, xanthan gum and sodium carboxymethyl cellulose are added in the same manner as in Example 1, and the aroma condensate is added back to the concentrate during stirring to obtain an aroma-preloaded colloidal compound system. In step 4, the colloidal compound system is only subjected to high-pressure homogenization. After homogenization, no gradient cooling treatment is performed, and the system is directly sterilized and filled. The remaining steps and parameters (including dual-frequency ultrasonic treatment) are the same as in Example 1.

[0050] Performance testing 1. Determination of hesperidin extraction rate Orange peel extracts were prepared according to the methods of Examples 1-3 and Comparative Examples 1-12, respectively. The content of hesperidin in each extract was determined by high-performance liquid chromatography (HPLC), and the hesperidin extraction rate was calculated using the following formula: Hesperidin extraction rate (%) = (mass of hesperidin in the extract / mass of orange peel raw material) × 100%.

[0051] 2. Aroma Retention Rate Determination The contents of the main volatile components (d-limonene and γ-terpinene) in each extract were determined by gas chromatography-mass spectrometry (GC-MS). The aroma retention rate was calculated based on the total amount of the corresponding components in the orange peel raw material (100%).

[0052] 3. System stability evaluation The orange peel extracts prepared in each example and comparative example were placed in transparent glass bottles and stored at room temperature (25±2℃). The stratification of the system was observed and recorded on day 1, day 7, day 30, day 90 and day 180, including whether there was a floating oil layer on the upper layer, whether there was a precipitate at the bottom, and whether an oil-water interface appeared in the system.

[0053] 4. Test Results The test results for each embodiment and comparative example are shown in Table 1.

[0054] Table 1 Test results for each embodiment and comparative example Example 1 6.2 93.5 Uniform suspension, free of floating oil, sediment, and oil-water interface. Example 2 5.9 91.2 Uniform suspension, free of floating oil, sediment, and oil-water interface. Example 3 6.0 92.8 Uniform suspension, free of floating oil, sediment, and oil-water interface. Comparative Example 1 3.28 Approximately 38 Severe stratification, with a large amount of floating oil on the top layer and a large amount of sediment at the bottom. Comparative Example 2 5.99 Approximately 42 Severe stratification, with oil floating on top and a large amount of sediment at the bottom. Comparative Example 3 4.1 52.3 There is a clear stratification, with a thicker upper layer of floating oil and sediment at the bottom. Comparative Example 4 5.6 56.8 There is obvious stratification, with oil floating on top and sediment at the bottom. Comparative Example 5 5.8 89.6 Slight stratification, with a small amount of floating oil on the top layer and no sediment at the bottom. Comparative Example 6 6.1 72.4 Uniform suspension, free of floating oil, sediment, and oil-water interface. Comparative Example 7 6.1 68.7 Uniform suspension, free of floating oil, sediment, and oil-water interface. Comparative Example 8 6.1 92.8 There is obvious stratification, with a large amount of floating oil on the top layer and no sediment at the bottom. Comparative Example 9 6.1 92.1 There is obvious stratification, with a large amount of floating oil on the top layer and a small amount of sediment at the bottom. Comparative Example 10 5.6 56.8 Severe stratification, with a large amount of floating oil on the top layer and a large amount of sediment at the bottom. Comparative Example 11 4.3 90.5 There is obvious stratification, with a large amount of floating oil on the top layer and no sediment at the bottom. Comparative Example 12 3.9 62.5 Severe stratification, with a large amount of floating oil on the top layer and a large amount of sediment at the bottom. It should be noted that: the hesperidin extraction rate of Comparative Example 1 was based on the results of ethanol hot reflux extraction (3.28%±0.1%) reported in the 24th issue of "Food Industry Technology" in 2012; the hesperidin extraction rate of Comparative Example 2 was based on the results of cellulase pretreatment combined with hot reflux extraction (5.99%) reported in the 8th issue of "Food Industry" in 2021; the aroma retention rate was calculated based on the total amount of d-limonene and γ-terpinene in fresh orange peel raw material (100%).

[0055] Results Analysis 1. Extraction rate and aroma retention As shown in Table 1: Comparative Example 1 used the traditional ethanol hot reflux extraction method, and the hesperidin extraction rate was only 3.28%, and the aroma retention rate was only about 38%. This indicates that the traditional high-temperature extraction not only has low extraction efficiency, but also suffers from serious loss of heat-sensitive volatile components.

[0056] Comparative Example 2 used cellulase pretreatment combined with hot reflux extraction, which increased the hesperidin extraction rate to 5.99%, but the aroma retention rate was still only about 42%. This indicates that although cellulase pretreatment improved the extraction rate to some extent, the subsequent 85℃ high-temperature hot reflux operation still resulted in the loss of a large number of volatile aroma components.

[0057] The extraction rate of hesperidin in Comparative Example 3 (single enzymatic hydrolysis + homogenization, without ultrasound, aroma re-addition, or gradient cooling) was 4.1%, and the aroma retention rate was 52.3%, which was improved compared to Comparative Example 1, but the extraction rate was still significantly lower than that in Examples 1-3. This indicates that without dual-frequency ultrasound for secondary cell wall disruption, single enzymatic hydrolysis alone cannot fully break down the cell wall, resulting in incomplete release of intracellular active ingredients.

[0058] The hesperidin extraction rate of Comparative Example 4 (enzymatic hydrolysis + ultrasound + homogenization, no aroma re-addition, no gradient cooling) was 5.6%, and the aroma retention rate was 56.8%, which was improved compared to Comparative Example 3, but still lower than Examples 1-3. This indicates that the secondary cell disruption by dual-frequency ultrasound helps to further improve the extraction rate. However, due to the lack of an aroma condensate re-addition step, a large amount of aroma components that escaped during the concentration process were not recovered and utilized, resulting in a significantly lower aroma retention rate than Examples 1-3.

[0059] The hesperidin extraction rate of Comparative Example 5 (enzymatic hydrolysis + ultrasound + aroma re-addition + homogenization, without gradient cooling) was 5.8%, and the aroma retention rate was 89.6%, which is close to the level of Examples 1-3. This indicates that the re-addition of aroma condensate during the colloidal network construction process can indeed effectively encapsulate aroma components and improve aroma retention. However, its system stability (slight stratification after standing for 180 days, with a small amount of floating oil on the upper layer) was significantly worse than that of Examples 1-3, indicating that without the gradient cooling phase change solidification step, the physical locking of oil droplets cannot be achieved, resulting in insufficient long-term system stability.

[0060] In comparison, the hesperidin extraction rate of Examples 1-3 reached 5.9%~6.2%, and the aroma retention rate reached 91.2%~93.5%, both significantly better than the comparative examples. This indicates that this application utilizes a three-in-one complex enzyme preparation of "endo-cellulase + exo-hemicellulase + polygalacturonase" to perform layered and directional deconstruction of the cell wall, combined with dual-frequency ultrasonic cavitation for secondary cell wall disruption. Under mild conditions, this achieves thorough cell wall deconstruction and efficient release of intracellular active ingredients, while the low-temperature operation throughout the process effectively avoids the loss of heat-sensitive aroma components.

[0061] 2. System stability As shown in Table 1: The extracts of Comparative Example 1 and Comparative Example 2 showed severe stratification after standing—a large amount of floating oil on the upper layer and a large amount of sediment at the bottom, which is a typical stability defect of orange peel extract.

[0062] Although the extracts of Comparative Examples 3-4 showed some improvement compared to Comparative Examples 1-2 after standing, they still exhibited obvious stratification, indicating that simply relying on colloid thickening and homogenization cannot fundamentally solve the problems of oil floating and sedimentation.

[0063] The extract of Comparative Example 5 showed slight stratification and a small amount of floating oil on the upper layer after standing for 180 days, indicating that although aroma re-addition improved the aroma retention rate, the long-term suspension stability of oil droplets has not been fundamentally resolved.

[0064] In contrast, the extracts of Examples 1-3 remained in a uniform and stable suspension after standing at room temperature for 180 days, with no oil-water interface, no floating oil layer, and no bottom sediment. This indicates that this application achieves chemical binding of aroma components (aroma preloading) through "in-situ re-addition of aroma condensate during colloidal network construction," and then achieves physical locking of oil droplets through "high-pressure homogenization + gradient cooling phase change solidification"—the synergistic effect of the dual stabilization mechanism of "chemical encapsulation + physical solidification" fundamentally solves the long-standing stability defects of upper floating oil and lower sediment in orange peel extract.

[0065] Based on the above results, the following conclusions can be drawn: First, the synergy between enzymatic hydrolysis and ultrasound: the extraction rate of Comparative Example 3 (without ultrasound) was 4.1%, while that of Comparative Example 4 (with ultrasound) was 5.6%, representing an increase of 36.6%. This indicates that dual-frequency ultrasound can effectively compensate for the incomplete cell wall disruption caused by single enzymatic hydrolysis by cavitation secondary disruption of softened cell fragments. The two processes work together in a synergistic effect of "enzymatic hydrolysis at the molecular level → ultrasound at the physical level."

[0066] Second, the temporal synergy between aroma re-addition and colloidal network construction: the aroma retention rate of Comparative Example 4 (without aroma re-addition) was 56.8%, while that of Comparative Example 5 (with aroma re-addition) was 89.6%, representing an improvement of 57.7%. However, it is noteworthy that in Comparative Example 5, the aroma condensate was added after the colloidal network was formed (this application refers to it as "simultaneous re-addition during stirring"), and its aroma retention rate was still lower than that of Example 1 (93.5%). This indicates that re-adding aroma during the colloidal network construction process, utilizing the dynamic process of colloidal molecular chain unfolding and rearrangement to in-situ embed the aroma within the network pores, has a significantly higher embedding efficiency than passive adsorption after network formation.

[0067] Third, the key role of gradient cooling phase change solidification: The only difference between Comparative Example 5 (without gradient cooling) and Example 1 (with gradient cooling) is whether or not gradient cooling treatment is performed, but there is a fundamental difference in the stability of their systems—Comparative Example 5 showed slight stratification and floating oil after standing for 180 days, while Example 1 maintained a completely homogeneous and stable suspension. This indicates that after high-pressure homogenization refines the oil droplets, gradient cooling is necessary to induce local crystallization on the surface of the oil droplets to form a solid lipid shell, thus achieving permanent physical locking of the oil droplets. The two constitute a causal relationship in time: "homogenization creates a crystallization template → cooling completes template solidification." This technique crosses boundaries from the crystallization principle of oil fractionation to the stability control of plant extracts, and its application changes from "separation" to "stabilization," exhibiting a clear non-obviousness.

[0068] Fourth, the comprehensive effect of the four-step synergy: The hesperidin extraction rate (6.2%), aroma retention rate (93.5%), and system stability (no stratification after 180 days) of Example 1 are significantly better than those of Comparative Examples 3-5, which only possess some technical features. This indicates that a tight functional coupling is formed among the four steps of "compound enzymatic hydrolysis → dual-frequency ultrasonic secondary cell disruption → colloidal network construction and aroma preloading → high-pressure homogenization and gradient cooling phase transition solidification"—enzymatic hydrolysis opens the cell wall at the molecular level, providing softened cell fragments for ultrasound; the physical bombardment of ultrasound further releases intracellular substances and provides a sufficient aroma source for subsequent colloidal encapsulation; and the submicron-sized oil droplet template created by homogenization provides a structural basis for the crystallization solidification of gradient cooling.

[0069] The results of Example 1 and Comparative Examples 6-12 are analyzed in conjunction with Table 1: The aroma retention rate of Comparative Example 6 (aroma added after complete colloidal network formation) was 72.4%, the aroma retention rate of Comparative Example 7 (aroma added during the final blending stage) was 68.7%, and the aroma retention rate of Example 1 (aroma added simultaneously during colloidal network construction) was 93.5%. Example 1 showed an improvement of approximately 29.1% compared to Comparative Example 6 and approximately 36.1% compared to Comparative Example 7.

[0070] The above results indicate that the timing of aroma re-addition has a decisive impact on aroma retention. When aroma condensate is added simultaneously during the construction of the three-dimensional gel network using xanthan gum and CMC-Na, the colloidal molecular chains are in a dynamic state of unfolding and rearrangement. Aroma components can be in situ embedded within the pores of the gel network during network formation, achieving efficient physical confinement. In contrast, when aroma condensate is added after the gel network is fully formed, the network pore structure is fixed, and aroma components can only be passively adsorbed onto the network surface or pore entrances, making it difficult for them to penetrate deep into the network, significantly reducing the encapsulation efficiency. When aroma condensate is added only in the final blending stage, the binding effect of the colloidal network is no longer present in the system, and the aroma components mainly exist in a free state, making them highly susceptible to loss during subsequent sterilization and storage.

[0071] This result demonstrates that the timing design of "adding aroma back during the construction of colloidal networks" is not a conventional choice for those skilled in the art, and that the technical approach of using the dynamic characteristics of the colloidal network formation process to achieve in-situ aroma encapsulation is non-obvious.

[0072] Although the aroma retention rates of Comparative Examples 8 (rapid cooling) and 9 (natural cooling) (92.8% and 92.1%, respectively) were close to those of Example 1 (93.5%), their system stability differed significantly. Both Comparative Examples 8 and 9 showed obvious stratification after 180 days of standing—a large amount of floating oil on the upper layer, indicating that the oil droplets were not effectively locked and significantly floated and aggregated. In contrast, Example 1 remained in a completely homogeneous and stable suspension after 180 days of standing, with no oil-water interface and no floating oil layer.

[0073] The above results indicate that after high-pressure homogenization refines the oil droplets, the choice of cooling method has a decisive impact on the solidification effect of the oil droplets and the long-term stability of the system. Example 1 used gradient cooling (1℃ / min) to induce controllable local crystallization on the surface of the oil droplets, forming a uniform and dense solid grease shell, physically locking the oil droplets within the system. Comparative Example 8 used rapid cooling (directly placed in a 4℃ environment), resulting in an excessively large temperature difference between the inside and outside of the oil droplets, leading to excessively fast crystallization, uneven grease shells, and even cracking, failing to form a complete protective shell. Comparative Example 9 used natural cooling (static cooling at room temperature), but the cooling rate was too slow and uncontrollable, allowing sufficient time for the oil droplets to migrate, collide, and aggregate during the slow cooling process, resulting in equally poor crystallization and solidification.

[0074] Comparative Example 10 (enzymatic hydrolysis + ultrasound, no colloids, no cooling) showed a hesperidin extraction rate of 5.6% and an aroma retention rate of 56.8%, but severe stratification occurred after standing for 180 days. Although the extraction rate of Comparative Example 14 was better than that of Comparative Example 3 (4.1%), its aroma retention rate was significantly lower than that of Example 1 (93.5%), and the system stability was extremely poor. This indicates that without the colloidal network construction and aroma preloading steps, the extract cannot effectively confine aroma components and achieve long-term system stability.

[0075] Comparative Example 11 (enzymatic hydrolysis + colloid, no ultrasound, no cooling) showed a hesperidin extraction rate of 4.3% and an aroma retention rate of 90.5%. After standing for 180 days, significant stratification occurred, with a large amount of oil floating on the upper layer. Although the aroma retention rate of Comparative Example 15 was close to that of Example 1, its extraction rate was significantly lower than that of Example 1 (4.3% vs 6.2%), and the system stability was still insufficient. This indicates that the lack of a dual-frequency ultrasound secondary cell disruption step resulted in insufficient cell wall disintegration and incomplete release of intracellular active ingredients. Furthermore, the lack of a gradient cooling phase transition solidification step prevented the physical locking of oil droplets. Even though the colloidal network could bind some aroma components, it could not solve the problem of oil droplet floating.

[0076] Comparative Example 12 (ultrasound + colloid, no enzymatic hydrolysis, no cooling) showed a hesperidin extraction rate of 3.9% and an aroma retention rate of 62.5%, but severe stratification occurred after standing for 180 days. Comparative Example 16 had the lowest extraction rate, indicating that the lack of a combined enzymatic hydrolysis step meant that the intact cell wall structure was not chemically softened, and the dual-frequency ultrasonic cavitation energy was insufficient to effectively break down the dense cell wall, resulting in the lowest release of intracellular active ingredients.

[0077] A comparison of Comparative Examples 10-12 with Example 1 shows that the absence of any one of the four steps prevents the simultaneous achievement of high extraction rate, high aroma retention rate, and excellent system stability. Specifically: Enzymatic hydrolysis (step 1) is a prerequisite for ultrasound to work: enzymatic hydrolysis softens the cell wall at the molecular level, providing softened cell fragments for ultrasound (comparative example 16 lacked enzymatic hydrolysis and had the lowest extraction rate of 3.9%). Ultrasound (step 2) is key to further release of intracellular substances: ultrasound physically bombards the cell debris after enzymatic hydrolysis, further promoting the convection and diffusion of intracellular active ingredients (comparative example 15 lacked ultrasound, and the extraction rate was only 4.3%). Colloidal network construction and aroma preloading (step 3) are fundamental to aroma retention: aroma is added back simultaneously during colloidal network construction to achieve in-situ physical encapsulation of aroma components (Comparative Example 14 lacks colloidal encapsulation, and the aroma retention rate is only 56.8%). High-pressure homogenization and gradient cooling phase change solidification (step 4) are the guarantee for achieving long-term stability of the system: homogenization creates a crystallization template, and gradient cooling completes the template solidification. The two constitute a causal relationship in time (comparative examples 14-16 all lack the cooling step and all show severe stratification).

[0078] To further clarify the synergistic mechanism between the various steps of this application, the core technical principles of this application are analyzed from the molecular and physical levels below: I. Molecular Mechanism of Complex Enzymatic Hydrolysis for Cell Wall Disruption The cell wall of orange peel is mainly composed of a three-dimensional network framework formed by highly cross-linked cellulose, hemicellulose, and pectin. Among them, cellulose microfibers form the "steel" framework of the cell wall, hemicellulose acts as "connectors" to cross-link the cellulose microfibers, and pectin acts as a "filling matrix" to fill the spaces between the cellulose-hemicellulose network, densely encapsulating active ingredients such as flavonoids inside the protoplasts and vacuoles.

[0079] The endo-cellulase, exo-cellulase, and polygalacturonase used in this application are compounded in a specific ratio. These three enzymes exhibit a synergistic effect of layered, directional deconstruction under conditions of pH 4.8–5.0 and 45°C. Polygalacturonase first hydrolyzes the α-1,4-galacturonic acid bonds in the pectin backbone, degrading the pectin matrix and exposing the cellulose-hemicellulose backbone, while reducing the pectin content in the subsequent extract and lowering the viscosity of the system. Endo-cellulase randomly cleaves β-1,4-glycosidic bonds in the amorphous region of cellulose, loosening the cellulose microfibril structure and generating a large number of new chain ends. Exocellulases progressively degrade hemicellulose from the non-reducing ends of the hemicellulose molecular chain, further breaking down the cross-linking network between cellulose and hemicellulose.

[0080] The three-stage enzymatic hydrolysis sequence of "pectin degradation first → cellulose internal breakage → hemicellulose end degradation" causes the three-dimensional framework of the cell wall, "cellulose-hemicellulose-pectin", to be disintegrated layer by layer from the inside out, and the mass transfer resistance of the active ingredients is eliminated from the source.

[0081] II. Physical Mechanism of Secondary Cell Disruption by Dual-Frequency Ultrasonic Cavitation After enzymatic hydrolysis, the cell wall skeleton has been chemically broken down into micron-sized cell fragments, but some intracellular active ingredients are still partially encapsulated within the fragments. This application employs dual-frequency ultrasound (28 kHz and 40 kHz) under vacuum conditions at 45°C to perform secondary cavitation disruption on the enzymatically hydrolyzed cell fragments.

[0082] Dual-frequency ultrasound exhibits a significantly superior cavitation effect compared to single-frequency ultrasound: the large cavitation bubbles generated by 28kHz low-frequency ultrasound produce a stronger mechanical impact upon collapse, making it suitable for breaking up larger cell fragments; the smaller cavitation bubbles generated by 40kHz high-frequency ultrasound are more numerous and more uniformly distributed, making it suitable for finely breaking up tiny fragments. The dual-frequency combination achieves a synergistic enhancement effect of "powerful low-frequency fragmentation + uniform high-frequency refinement"—low-frequency cavitation breaks up large fragments, while high-frequency cavitation further refines small fragments, resulting in a more thorough release of intracellular active components. Simultaneously, the vacuum condition lowers the cavitation threshold, allowing the cavitation effect to occur effectively at a low temperature of 45℃, avoiding the damage to heat-sensitive components caused by high temperatures.

[0083] III. Spatiotemporal Coordination Mechanism of Aroma Preloading and Colloidal Network Construction One of the core innovations of this application is that the natural aroma condensate collected during the concentration process is simultaneously added back during the construction of a three-dimensional gel network with xanthan gum and sodium carboxymethyl cellulose.

[0084] Xanthan gum molecules contain negatively charged side chains and exhibit a random coil conformation in water; sodium carboxymethyl cellulose molecules have a rigid rod-like structure. During stirring and dispersion, the molecular chains gradually unfold, extend, and entangle from their random coil state, forming a three-dimensional network structure through hydrogen bonds and hydrophobic interactions. Simultaneously, aroma condensate is added during this dynamic process. Due to their hydrophobicity, aroma molecules (mainly terpenes such as d-limonene and γ-terpinene) can interact hydrophobically with the hydrophobic regions of xanthan gum and the hydrophobic framework of sodium carboxymethyl cellulose, becoming in-situ embedded within the network as pores form.

[0085] In contrast, if the aroma condensate is added after the gel network has fully formed (Comparative Example 6), the network pore size is already fixed, and aroma molecules can only passively adsorb onto the network surface or diffuse into the formed pores, significantly reducing the encapsulation efficiency. If the aroma condensate is added only in the final blending stage (Comparative Example 7), there is no binding effect of the colloidal network in the system, and the aroma molecules are in a free state, making them extremely easy to escape during subsequent sterilization and storage.

[0086] The "construction and encapsulation" sequential design utilizes the dynamic characteristics of the colloidal network formation process—molecular chain unfolding → network cross-linking → pore formation → simultaneous encapsulation of aroma—achieving efficient in-situ locking of aroma components, increasing the aroma retention rate from 68.7%~72.4% (Comparative Examples 6-7) to 93.5% (Example 1).

[0087] IV. The causal synergistic mechanism of high-pressure homogenization and gradient cooling phase change solidification Another core innovation of this application is that it establishes a causal link between high-pressure homogenization and gradient cooling in terms of time sequence.

[0088] The first stage of high-pressure homogenization (5 MPa) initially breaks down the oil droplets in the colloidal composite system. The second stage of homogenization (20 MPa) refines the oil droplets to the submicron level (approximately 0.2~0.5 μm in diameter) under high shear force. The purpose of this refinement is not only to ensure uniform dispersion of the oil droplets, but more importantly, to create a "template" for subsequent crystallization and solidification—the submicron-sized oil droplets have a very large specific surface area, providing uniform nucleation sites for crystallization.

[0089] The gradient cooling (1℃ / min) plays a crucial role here: as the temperature slowly decreases to 4℃, the surface of the oil droplets first reaches the crystallization temperature of its high-melting-point components (mainly saturated fatty acid glycerides). These high-melting-point components preferentially crystallize and precipitate on the oil droplet surface, forming a uniform and dense solid lipid shell. This lipid shell completely encapsulates the liquid oil at the core of the droplet, making the density of the droplet more compatible with the continuous phase. At the same time, the solid structure of the lipid shell provides a physical barrier, preventing the oil droplet from floating and agglomerating.

[0090] Without high-pressure homogenization (i.e., the oil droplets are not refined to the submicron level), large oil droplets have a small specific surface area, uneven crystallization, and an incomplete grease shell, making effective locking impossible. Without gradient cooling (such as the rapid cooling or natural cooling in Comparative Examples 8-9), the crystallization process is uncontrollable—rapid cooling leads to excessive temperature differences between the inside and outside of the oil droplets, causing crystallization to be too fast, resulting in an uneven grease shell or even cracking; natural cooling is too slow and uncontrollable, allowing sufficient time for oil droplets to migrate and collide during cooling, forming large droplet aggregations before recrystallization, similarly failing to form a uniform grease shell. The sequence of "homogenization creating a crystallization template → gradient cooling completing template solidification" is causally related and neither can be omitted.

[0091] V. The complete logical chain of four-step collaboration Based on the above mechanistic analysis, the synergistic relationship between the steps in this application can be summarized as the following causal chain: Enzymatic hydrolysis (step 1) softens the cell wall at the molecular level → Ultrasonication (step 2) performs secondary bombardment at the physical level → Intracellular active ingredients (including flavonoids and volatile aroma components) are fully released → Colloidal network construction and aroma preloading (step 3) embeds the released aroma components in situ into the gel network at the chemical level to achieve chemical confinement → High-pressure homogenization (first half of step 4) refines oil droplets to the submicron level at the dispersion level, creating a uniform template for crystallization and solidification → Gradient cooling phase change solidification (second half of step 4) enables the oil droplet surface to crystallize controllably to form a solid lipid shell at the physical level, achieving physical locking.

[0092] The aforementioned four-layer mechanism of "molecular deconstruction → physical bombardment → chemical confinement → physical locking" is progressive and interconnected, forming a complete process chain with a closed causal loop.

[0093] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing an orange peel extract, characterized in that, The method includes the following steps: Step 1: Crush the orange peel raw material and mix it with water at a material-to-liquid ratio of 1:8 to 1:

12. Add a compound enzyme preparation made of endo-cellulase, endo-hemi-cellulase and polygalacturonase in a mass ratio of (1.5 to 2.5):(0.8 to 1.5):(1.0 to 2.0). Stir and enzymatically hydrolyze the mixture at pH 4.5 to 5.2 and 45 to 55°C for 4 to 6 hours to obtain the enzymatic hydrolysate. Step 2: The enzymatic hydrolysate is subjected to dual-frequency ultrasonic treatment at 45~55℃ and a vacuum of -0.06~-0.095MPa, with an ultrasonic frequency combination of 28kHz and 40kHz and an energy density of 0.45~0.60W / cm³. 2 After processing for 20-40 minutes, an ultrasonic liquid was obtained. The ultrasonic liquid was then filtered through three stages of vibrating screens (80 mesh, 120 mesh, and 200 mesh) and then through a 600 mesh bag filter. The filtrate was then vacuum concentrated to a Brix of 25-30° Brix at a temperature of 45-55°C and a vacuum of -0.08 to -0.095 MPa. At the same time, the aroma condensate that escaped during the concentration process was collected to obtain the concentrated liquid and the aroma condensate. Step 3: After heating the concentrate to 75~80℃, add xanthan gum and sodium carboxymethyl cellulose, stir and disperse at a speed of 2500~3500r / min, and add the aroma condensate back to the concentrate during the stirring process, so that the three-dimensional gel network formed by xanthan gum and sodium carboxymethyl cellulose will embed the aroma components in the network pores during the construction process, and obtain the aroma preloaded colloidal composite system. Step 4: The aroma-preloaded colloidal composite system is subjected to high-pressure homogenization at 50~60℃, with a first-stage pressure of 3~8MPa and a second-stage pressure of 15~25MPa to obtain a homogenized liquid. The homogenized liquid is then cooled to 4~10℃ at a gradient rate of 0.5~2℃ / min to cause local crystallization on the surface of the refined oil droplets in the homogenized liquid to form a solid lipid shell, thus obtaining a phase-change stable liquid. Step 5: After ultra-high temperature instantaneous sterilization, the phase change stabilized liquid is filled to obtain orange peel extract.

2. The method for preparing orange peel extract according to claim 1, characterized in that, In step 1, the mass ratio of endo-cellulase, exo-cellulase and polygalacturonase in the compound enzyme preparation is 2:1:1.5, and the amount of compound enzyme preparation added is 0.5% to 2.0% of the mass of orange peel raw material.

3. The method for preparing orange peel extract according to claim 1, characterized in that, In step 1, the enzymatic hydrolysis is performed at a temperature of 50°C for 5 hours and at a pH of 4.8 to 5.

0.

4. The method for preparing orange peel extract according to claim 1, characterized in that, In step 2, the temperature of the dual-frequency ultrasonic treatment is 45°C and the treatment time is 30 min; the temperature of the vacuum concentration is 50°C.

5. The method for preparing orange peel extract according to claim 1, characterized in that, In step 3, the mass ratio of xanthan gum to sodium carboxymethyl cellulose is 1:1 to 3:1, and the total amount added is 0.1% to 0.5% of the mass of the concentrate.

6. The method for preparing orange peel extract according to claim 5, characterized in that, The mass ratio of xanthan gum to sodium carboxymethyl cellulose is 2:

1.

7. The method for preparing orange peel extract according to claim 1, characterized in that, In step 4, the first-stage pressure of the high-pressure homogenization is 5 MPa, the second-stage pressure is 20 MPa, and the homogenization temperature is 55°C; the gradient cooling rate is 1°C / min, and the final temperature is 4°C.

8. The method for preparing orange peel extract according to claim 1, characterized in that, In step 5, the ultra-high temperature instantaneous sterilization temperature is 130~137℃ and the time is 4~6s, and the filling temperature is below 35℃.

9. An orange peel extract, characterized in that, The orange peel extract is prepared by the method described in any one of claims 1-8. The orange peel extract is a uniform and stable suspension system with no oil-water interface, no floating oil layer and no bottom sediment. It does not show any visible layering or precipitation after standing at room temperature for more than 6 months.