Starch-based monascus pigment microcapsule as well as preparation method and application thereof

Abstract

The invention provides a starch-based monascus pigment microcapsule as well as a preparation method and application thereof, and belongs to the technical field of food. The starch-based monascus pigment microcapsule disclosed by the invention forms a stable embedding structure through hydrogen bonds, so that the thermal decomposition temperature is increased from 260 DEG C to over 296 DEG C, and after microencapsulation, the light stability and storage stability of the monascus pigment are remarkably enhanced; the raw materials adopted by the starch-based monascus pigment microcapsule are all natural sources and accord with the national food safety standard, the preparation process is a pure physical process, and no chemical reaction is introduced; the coloring agent adding mode is compatible with a traditional sausage production process, the preparation and application process is simple and controllable, the equipment requirement is low, and industrial popularization is easy. The starch-based monascus pigment microcapsule is applied to preparation of sausages, the redness value and sensory score of the sausages are remarkably improved, the peroxide value of the sausages is remarkably reduced, and the problem that the existing sausages fade and become yellow due to oxidative degradation of monascus pigments in the storage process is solved.

Description

Technical Field

[0001] This invention belongs to the field of food technology, specifically relating to a starch-based red yeast rice pigment microcapsule, its preparation method, and its application. Background Technology

[0002] Cantonese sausage is a traditional cured meat product from the Lingnan region of China, widely favored by consumers for its unique rose-red color and sweet flavor. Color is the primary sensory indicator for judging the quality of sausages and directly influences consumers' purchasing decisions. Currently, red yeast rice pigment is often added during production to give the sausages a natural red color. However, red yeast rice pigment is sensitive to light, heat, and oxygen environments, and is prone to structural degradation during storage, leading to fading and yellowing.

[0003] To address these issues, researchers have attempted to improve the stability of red yeast rice pigment through microencapsulation technology. For example, Northeast Agricultural University has disclosed a meat product colorant composed of microencapsulated saccharified nitrosohemoglobin pigment, red yeast rice, and sodium isoascorbate, which can replace nitrite in meat products. Wuhan University of Light Industry has disclosed a red yeast rice pigment microcapsule and its preparation method, using sodium alginate and calcium carbonate as wall materials. The red yeast rice pigment microcapsules are prepared through an emulsification-gel method, effectively solving the problems of unstable color value and easy decomposition and fading when red yeast rice pigment is used for food coloring. However, existing microencapsulation technologies mostly use protein, hydrophilic colloid, and other wall materials, which have problems such as high cost and insufficient compatibility with meat product matrices. Moreover, existing technologies mostly focus on improving pigment stability, and no systematic technical solution has been found that combines starch-encapsulated red yeast rice pigment with the specific application scenario of Cantonese sausage. Starch, as a natural polysaccharide, has good biocompatibility and film-forming properties, but the encapsulation effect and protection mechanism of different crystalline starches on red yeast rice pigment have not been systematically studied. Furthermore, existing technologies lack systematic optimization of microcapsule preparation processes, making it difficult to achieve a synergistic improvement in encapsulation efficiency and stability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a starch-based red yeast rice pigment microcapsule, its preparation method and application, and solving the problems of easy degradation and fading of existing red yeast rice pigments during storage and insufficient antioxidant capacity.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a starch-based red yeast rice pigment microcapsule, wherein the core material includes red yeast rice pigment and the wall material includes corn starch, potato starch, cassava starch or wheat starch; the mass ratio of the core material to the wall material is 1:6-1:14.

[0006] More preferably, the wall material is corn starch.

[0007] Through experiments, the inventors of this application investigated the screening of microcapsule wall materials and the relationship between crystal form and effect. They compared the encapsulation effects of type A and type B starch on red yeast rice pigment and found that type A starch has a compact structure and higher pigment stability after encapsulation. Moreover, corn starch has the best encapsulation effect due to its porous surface and suitable particle size, with an encapsulation rate of 71.18% and a retention rate of 78.36%.

[0008] In a preferred embodiment of the microcapsule of the present invention, the core material further includes an antioxidant.

[0009] In a preferred embodiment of the microcapsules of the present invention, the antioxidant includes sodium isoascorbate.

[0010] The present invention also provides a method for preparing the starch-based red yeast rice pigment microcapsules, comprising the following steps: (1) Dissolve red yeast rice pigment and antioxidant in water and sonicate to obtain a core material pigment solution; (2) Add the core material pigment solution to the starch to obtain a starch-pigment suspension. Stir the starch-pigment suspension in a water bath to obtain mixture A. (3) Centrifuge mixture A, discard the supernatant, and obtain pigment-starch wet precipitate; (4) Wash the pigment-starch wet precipitate with distilled water, take the precipitate, stir it evenly, and let it stand. (5) The precipitate from step (4) is dried, ground, and sieved to obtain the starch-based red yeast rice pigment microcapsules.

[0011] In a preferred embodiment of the preparation method described in this invention, the ultrasonic time in step (1) is 10~50 min.

[0012] As a preferred embodiment of the preparation method of the present invention, the water bath temperature in step (2) is 40~80℃; the stirring time is 30~150 min.

[0013] As a preferred embodiment of the preparation method of the present invention, the centrifugation in step (3) is performed at 25°C and 4000 r / min for 10 min.

[0014] In a preferred embodiment of the preparation method of the present invention, the sieve aperture size in step (5) is 60 mesh.

[0015] In a preferred embodiment of the preparation method described in this invention, the drying in step (5) is vacuum freeze drying.

[0016] The present invention also provides the application of the starch-based red yeast rice pigment microcapsules in the preparation of sausages.

[0017] The starch-based red yeast rice pigment microcapsules of the present invention, when applied to the preparation of sausages, can significantly improve the quality of sausages. After storage at 27°C for 60 days, the redness value of the sausages increased by 22.2% compared with the single pigment group, the sensory score increased by 18.6%, and the peroxide value decreased by 27.9%. This indicates that the starch-based red yeast rice pigment microcapsules of the present invention can effectively delay the deterioration of sausage color and fat oxidation, and maintain the sensory quality of the product.

[0018] The beneficial effects of this invention are as follows: This invention provides a starch-based red yeast rice pigment microcapsule. By studying the relationship between wall material selection and crystal form-effect, and optimizing the preparation process parameters, a starch-based red yeast rice pigment microcapsule was prepared. This microcapsule exhibits a high encapsulation rate of red yeast rice pigment, successfully embedding the pigment into the crystalline region of the wall material and forming a stable encapsulation structure through hydrogen bonding. This increases the thermal decomposition temperature from 260°C to over 296°C. Furthermore, after microencapsulation, the photostability and storage stability of the red yeast rice pigment are significantly enhanced. The raw materials used in the starch-based red yeast rice pigment microcapsules of this invention are all of natural origin, complying with national food safety standards. The preparation process is purely physical, without introducing chemical reactions. The colorant addition method is compatible with traditional sausage production processes. The preparation and application processes are simple and controllable, with low equipment requirements, and are easy to industrialize. Applying the starch-based red yeast rice pigment microcapsules of this invention to the preparation of sausages significantly improves the redness value and sensory score of the sausages and significantly reduces the peroxide value, solving the problem of fading and yellowing of existing sausages due to the oxidative degradation of red yeast rice pigment during storage. Attached Figure Description

[0019] Figure 1 Fourier transform infrared spectroscopy of starch-based red yeast rice pigment microcapsules.

[0020] Figure 2 X-ray diffraction analysis of starch-based red yeast rice pigment microcapsules.

[0021] Figure 3 This is a TGA analysis chromatogram of starch-based red yeast rice pigment microcapsules.

[0022] Figure 4 The image shows the photostability results of starch-based red yeast rice pigment microcapsules.

[0023] Figure 5 The figure shows the storage stability results of starch-based red yeast rice pigment microcapsules.

[0024] Figure 6 The figure shows the effect of different starch wall materials on the encapsulation and retention rates of red yeast rice pigment.

[0025] Figure 7 The figure shows the effect of different core-to-wall ratios on the encapsulation and retention rates of red pigments in red yeast rice.

[0026] Figure 8The graph shows the effect of different ultrasound times on the embedding and retention rates of red pigments in red yeast rice.

[0027] Figure 9 The graph shows the effect of different adsorption temperatures on the encapsulation and retention rates of red yeast rice pigment.

[0028] Figure 10 The response surface and contour plots show the effect of pairwise interactions on the encapsulation efficiency of red yeast rice pigment microcapsules.

[0029] Figure 11 This graph shows the change in peroxide value of sausages during storage. Detailed Implementation

[0030] To more concisely and clearly demonstrate the technical solution, purpose, and advantages of the present invention, the technical solution of the present invention is described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0031] Example 1 This embodiment provides a method for preparing starch-based red yeast rice pigment microcapsules, including the following steps: (1) Preparation of core material solution: Red yeast rice pigment and sodium isoascorbate were dissolved in distilled water at a mass ratio of 6:1 and sonicated for 30 min to obtain core material pigment solution; (2) Adsorption and embedding: The core material pigment solution is slowly added to corn starch and mixed to prepare a starch-red yeast rice pigment suspension. The mixed suspension is placed in a water bath at 60°C and magnetically stirred for 15 min. The mass ratio of red yeast rice pigment to corn starch is 1:10. (3) Centrifugal separation: After adsorption is complete, centrifuge (4000 r / min, 25℃, 10 min), discard the supernatant to obtain pigment-starch wet precipitate; (4) Washing: Wash the pigment-starch wet precipitate repeatedly with distilled water to remove free red yeast rice pigment that is not bound to starch; (5) Standing: Take out the pigment-starch wet precipitate obtained in step (4), stir and mix it thoroughly, and then place it in the refrigerator to stand for 24 hours; (6) Drying: The pigment-starch wet precipitate obtained in step (5) is subjected to vacuum freeze drying. The dried microcapsule powder is collected, ground in a mortar and passed through a 60-mesh sieve to obtain corn starch-based red yeast rice pigment microcapsules (CS-CMP).

[0032] Example 2 This embodiment provides a method for preparing starch-based red yeast rice pigment microcapsules, including the following steps: (1) Preparation of core material solution: Red yeast rice pigment and sodium isoascorbate were dissolved in distilled water at a mass ratio of 6:1 and sonicated for 30 min to obtain core material pigment solution; (2) Adsorption and embedding: The core material pigment solution was slowly added to potato starch and mixed to prepare a starch-red yeast rice pigment suspension. The mixed suspension was placed in a water bath at 60°C and magnetically stirred for 15 min. The mass ratio of red yeast rice pigment to potato starch was 1:10. (3) Centrifugal separation: After adsorption is complete, centrifuge (4000 r / min, 25℃, 10 min), discard the supernatant to obtain pigment-starch wet precipitate; (4) Washing: Wash the pigment-starch wet precipitate repeatedly with distilled water to remove free red yeast rice pigment that is not bound to starch; (5) Standing: Take out the pigment-starch wet precipitate obtained in step (4), stir and mix it thoroughly, and then place it in the refrigerator to stand for 24 hours; (6) Drying: The pigment-starch wet precipitate obtained in step (5) is subjected to vacuum freeze drying. The dried microcapsule powder is collected, ground in a mortar and passed through a 60-mesh sieve to obtain potato starch-based red yeast rice pigment microcapsules (PS-CMP).

[0033] Example 3 This embodiment provides a method for preparing starch-based red yeast rice pigment microcapsules, including the following steps: (1) Preparation of core material solution: Red yeast rice pigment and sodium isoascorbate were dissolved in distilled water at a mass ratio of 6:1 and sonicated for 30 min to obtain core material pigment solution; (2) Adsorption and embedding: The pigment solution of the core material is slowly added to the cassava starch and mixed to prepare a starch-red yeast rice pigment suspension. The mixed suspension is placed in a water bath at 60°C and magnetically stirred for 15 min. The mass ratio of red yeast rice pigment to cassava starch is 1:10. (3) Centrifugal separation: After adsorption is complete, centrifuge (4000 r / min, 25℃, 10 min), discard the supernatant to obtain pigment-starch wet precipitate; (4) Washing: Wash the pigment-starch wet precipitate repeatedly with distilled water to remove free red yeast rice pigment that is not bound to starch; (5) Standing: Take out the pigment-starch wet precipitate obtained in step (4), stir and mix it thoroughly, and then place it in the refrigerator to stand for 24 hours; (6) Drying: The pigment-starch wet precipitate obtained in step (5) is subjected to vacuum freeze drying. The dried microcapsule powder is collected, ground in a mortar and passed through a 60-mesh sieve to obtain cassava starch-based red yeast rice pigment microcapsules (TS-CMP).

[0034] Example 4 This embodiment provides a method for preparing starch-based red yeast rice pigment microcapsules, including the following steps: (1) Preparation of core material solution: Red yeast rice pigment and sodium isoascorbate were dissolved in distilled water at a mass ratio of 6:1 and sonicated for 30 min to obtain core material pigment solution; (2) Adsorption and embedding: The core material pigment solution was slowly added to wheat starch and mixed to prepare a starch-red yeast rice pigment suspension. The mixed suspension was placed in a water bath at 60°C and magnetically stirred for 15 min. The mass ratio of red yeast rice pigment to wheat starch was 1:10. (3) Centrifugal separation: After adsorption is complete, centrifuge (4000 r / min, 25℃, 10 min), discard the supernatant to obtain pigment-starch wet precipitate; (4) Washing: Wash the pigment-starch wet precipitate repeatedly with distilled water to remove free red yeast rice pigment that is not bound to starch; (5) Standing: Take out the pigment-starch wet precipitate obtained in step (4), stir and mix it thoroughly, and then place it in the refrigerator to stand for 24 hours; (6) Drying: The pigment-starch wet precipitate obtained in step (5) is subjected to vacuum freeze drying. The dried microcapsule powder is collected, ground in a mortar and passed through a 60-mesh sieve to obtain wheat starch-based red yeast rice pigment microcapsules (WS-CMP).

[0035] Comparative Example 1 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as in Example 1, except that the mass ratio of red yeast rice pigment to corn starch is different in step (2). The mass ratio of the core material pigment solution to corn starch in this comparative example is 1:6.

[0036] Comparative Example 2 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as in Example 1, except that the mass ratio of red yeast rice pigment to corn starch is different in step (2). The mass ratio of the core material pigment solution to corn starch in this comparative example is 1:8.

[0037] Comparative Example 3 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as in Example 1, except that the mass ratio of red yeast rice pigment to corn starch is different in step (2). The mass ratio of the core material pigment solution to corn starch in this comparative example is 1:12.

[0038] Comparative Example 4 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as in Example 1, except that the mass ratio of red yeast rice pigment to corn starch is different in step (2). The mass ratio of the core material pigment solution to corn starch in this comparative example is 1:14.

[0039] Comparative Example 5 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as those in Example 1, except that the ultrasonic time of the core material pigment solution in step (1) is different. In this comparative example, the ultrasonic time of the core material pigment solution in step (1) is 10 min.

[0040] Comparative Example 6 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as those in Example 1, except that the ultrasonic time of the core material pigment solution in step (1) is different. In this comparative example, the ultrasonic time of the core material pigment solution in step (1) is 20 min.

[0041] Comparative Example 7 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as those in Example 1, except that the ultrasonic time of the core material pigment solution in step (1) is different. In this comparative example, the ultrasonic time of the core material pigment solution in step (1) is 40 min.

[0042] Comparative Example 8 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules. The steps are the same as those in Example 1, except that the ultrasonic time of the core material pigment solution in step (1) is different. In this comparative example, the ultrasonic time of the core material pigment solution in step (1) is 50 min.

[0043] Comparative Example 9 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules, the steps of which are the same as those in Example 1, the only difference being the adsorption and embedding temperature in step (2), which is 40°C.

[0044] Comparative Example 10 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules, the steps of which are the same as those in Example 1, the only difference being the adsorption and embedding temperature in step (2), which is 50°C in step (2) of this comparative example.

[0045] Comparative Example 11 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules, the steps of which are the same as those in Example 1, the only difference being the adsorption and embedding temperature in step (2), which is 70°C in step (2) of this comparative example.

[0046] Comparative Example 12 This comparative example provides a method for preparing starch-based red yeast rice pigment microcapsules, the steps of which are the same as those in Example 1, the only difference being the adsorption and embedding temperature in step (2), which is 80°C.

[0047] Example of effect 1. This example demonstrates Fourier transform infrared spectroscopy (FTIR) detection of the starch-based red yeast rice pigment microcapsules prepared in Examples 1-4. The specific steps are as follows: Red yeast rice pigment, native starch, and the starch-based red yeast rice pigment microcapsules prepared in Examples 1-4 were respectively prepared into tablets using KBr compression. Specifically, 1 mg of sample and 200 mg of dried KBr were accurately weighed into an agate mortar, rapidly ground and mixed evenly, poured into a mold, and compressed into tablets using a tablet press. The tablets were then analyzed using a Fourier transform infrared spectroscopy spectrometer at 4 cm⁻¹. -1 Measuring 400~4000 cm at a resolution -1 The spectral region was defined to obtain the FT-IR spectra of each sample, and the changes in the characteristic peaks of the infrared spectra of each substance and the peaks before and after embedding were compared.

[0048] The results are as follows Figure 1 As shown, each sample exhibited a stretching vibration peak of -OH near 3411 cm⁻¹, originating from the hydroxyl groups in starch molecules and red yeast rice pigment. The CH peak near 2921 cm⁻¹ originates from the vibration of the saturated CH₂ / CH group in starch. The broadening of the -OH peak in the microencapsulated samples indicates that the starch -OH groups form hydrogen bonds with the pigment molecules. Simultaneously, the characteristic carbonyl peak of red yeast rice pigment at 1627 cm⁻¹ weakened and shifted, attributed to the entry of red yeast rice pigment into the starch structure. This demonstrates that starch and red yeast rice pigment are bound together by hydrogen bonds, forming a stable encapsulated structure.

[0049] 2. This example demonstrates X-ray diffraction analysis of the starch-based red yeast rice pigment microcapsules prepared in Examples 1-4. The specific steps are as follows: The crystallinity of the sample was determined using an X-ray diffractometer, generating monochromatic Cu-Kα radiation at a voltage of 40 kV and a current of 40 mA. The powdered sample was placed in a rectangular aluminum electrolytic cell, flattened and compacted. The sample was measured in an X-ray beam with a diffraction angle of 2θ, ranging from 5 to 60°, at a scanning rate of 4° / min.

[0050] The results are as follows Figure 2As shown, the red yeast rice pigment is in an amorphous state (crystallinity 0). Among the four native starches, corn starch, cassava starch, and wheat starch have type A crystalline structures with crystallinities of 15.1%, 24.3%, and 18.43%, respectively; potato starch has a type B crystalline structure with a crystallinity of 24.0%. After microencapsulation, the crystallinity of corn starch decreased to 14.3% (a decrease of 5.3%), wheat starch to 14.9% (a decrease of 19.2%), cassava starch to 19.92% (a decrease of 18.1%), and potato starch plummeted to 11.2% (a decrease of 53.3%). The results indicate that the red yeast rice pigment successfully intercalates into the crystalline regions of the starch. The loose structure of type B potato starch is more conducive to pigment intercalation.

[0051] 3. This example demonstrates thermogravimetric analysis of the starch-based red yeast rice pigment microcapsules prepared in Examples 1-4. The specific steps are as follows: Thermogravimetric analysis was used to analyze the mass changes of the four types of starch-based microcapsule powders with temperature. 5-10 mg of powder sample was placed in an aluminum crucible, which was then placed in a furnace with high-purity nitrogen as the carrier gas at a flow rate of 100 mL / min. The temperature was increased from 30°C to 600°C at a heating rate of 10°C / min.

[0052] result Figure 3 As shown, free red yeast rice pigments undergo significant decomposition at 262.4℃; after microencapsulation, the thermal decomposition temperature increases to above 296℃, and the thermal stability is significantly enhanced. The order of protection of the thermal stability of red yeast rice pigments by the four starches is: corn starch > wheat starch > tapioca starch > potato starch.

[0053] 4. This example tests the photostability of the starch-based red yeast rice pigment microcapsules prepared in Examples 1-4. The specific steps are as follows: The microcapsule samples and unencapsulated red yeast rice pigment were dissolved in PBS buffer solution (pH 7.0) at a concentration of 1 mg / mL. Each sample solution was placed in an artificial climate chamber with a light intensity of 10000 lux, a temperature of 27℃, and a humidity of 50% for 6 hours. Samples were taken every 1 hour to measure the absorbance, and the retention rate of red yeast rice pigment in the solution was calculated. The calculation formula is as follows: Retention rate (%) = Red yeast rice pigment content in the treated solution / Red yeast rice pigment content in the initial solution × 100%.

[0054] The results are as follows Figure 4The figure shows the change in the pigment retention rate of red yeast rice after 6 h (10000 lx) of strong light treatment. The microcapsules prepared from corn starch (CS-MPS) had the highest pigment retention rate (75.41%), which was 1.23 times that of unencapsulated MPS. The pigment retention rates of microcapsules prepared from PS-MPS, WS-MPS, and TS-MPS were 70.49%, 69.1%, and 63.55%, respectively, which were 1.14, 1.12, and 1.03 times higher than that of MPS. This indicates that the photostability of MPS is enhanced after microencapsulation, and all wall materials have a good protective effect on MPS.

[0055] 5. This example tests the storage stability of the starch-based red yeast rice pigment microcapsules prepared in Examples 1-4. The specific steps are as follows: The microcapsule samples and unencapsulated red yeast rice pigment were dissolved in PBS buffer solution (pH 7.0) at a concentration of 1 mg / mL and stored in a constant temperature incubator at 27℃. The absorbance was measured periodically, and the pigment retention rate was calculated.

[0056] The results are as follows Figure 5 As shown, the retention rates of each microcapsule after 60 days of storage at room temperature were 40.6% (CS-MPS), 38.21% (PS-MPS), 33.76% (WS-MPS), and 35.11% (TS-MPS), respectively, all of which were higher than the retention rate of unencapsulated MPS (24.43%).

[0057] 6. This study tested the encapsulation and retention rates of red yeast rice pigment in the starch-based red yeast rice pigment microcapsules of Examples 1-4 and Comparative Examples 1-12, and investigated the effects of various factors in the preparation method of starch-based red yeast rice pigment microcapsules on the encapsulation and retention rates of red yeast rice pigment. The results are as follows: Figure 6-9 As shown.

[0058] (1) By Figure 6 It was found that the four starches exhibited different adsorption capacities for pigments, with the adsorption capacity ranking as follows: corn starch > wheat starch > potato starch > tapioca starch. This indicates that corn starch has a stronger adsorption capacity for pigments and a higher pigment encapsulation rate. The retention rates of the red yeast rice pigment microcapsules after storage also varied among the different starch-based pigment samples. The pigment retention rates of the four starch-based pigment microcapsules ranked as follows: corn starch > wheat starch > potato starch > tapioca starch. Corn starch showed the highest pigment retention capacity. Considering both factors, the corn starch-based pigment microcapsules exhibited the highest pigment encapsulation rate and pigment retention rate.

[0059] (2) By Figure 7It can be seen that the encapsulation efficiency of the microcapsules increases with the increase of the wall material addition, reaching a peak (73.07%) when the core-to-wall ratio is 1:10. At core-to-wall ratios of 1:12 and 1:14, the encapsulation efficiency decreases significantly (P < 0.05), indicating insufficient core material and vacant adsorption sites on the starch wall material, leading to a decrease in encapsulation efficiency. The optimal core-to-wall ratio for starch-based red yeast rice pigment microcapsules is 1:10: at this ratio, the adsorption capacities of the core material and the starch wall material are matched, and both the encapsulation efficiency and retention rate reach their optimal levels.

[0060] (3) By Figure 8 It was found that the encapsulation efficiency significantly increased with the extension of the ultrasonic treatment time for the red yeast rice pigment solution, reaching a peak and then slightly decreasing. When the ultrasonic treatment time was less than 30 min, the encapsulation efficiency and retention rate were low. Under short-term ultrasonication, the pigment molecules in the red yeast rice pigment aqueous solution aggregated, making it difficult for the hydrophobic cavities of the starch wall material to fully contact and bind the pigment aggregates during subsequent encapsulation, resulting in low adsorption efficiency and a decreased encapsulation efficiency. As the ultrasonic treatment time increased, the pigment dispersed into smaller particles, increasing the contact area with the starch wall material, improving adsorption and binding efficiency, and thus increasing the encapsulation efficiency. Excessive ultrasonic treatment time slightly reduced the encapsulation efficiency. Therefore, the appropriate ultrasonic treatment time for the red yeast rice pigment aqueous solution is 30 min.

[0061] (4) By Figure 9 It can be seen that the encapsulation efficiency first increases and then decreases with increasing adsorption temperature. The encapsulation efficiency is lowest at 40℃; it increases significantly at 50℃; it reaches its peak at 60℃, with an encapsulation efficiency of 72.18% and a retention rate of 78.36%; it begins to decrease at 70℃, and returns to a level comparable to that at 50℃ at 80℃. In summary, the suitable adsorption temperature for microcapsules is 60℃: this temperature matches the gelatinization initiation characteristics of corn starch, which can both fully expose the adsorption sites of starch to achieve a high encapsulation efficiency and maintain a dense network structure to ensure pigment stability under strong light.

[0062] 7. Based on the single-factor experimental results of Example 6, this effect example further optimizes the encapsulation efficiency of red yeast rice pigment microcapsules through response surface methodology. The specific experiments are as follows: (1) Response surface methodology and results: Based on the results of the single-factor experiments, the core-to-wall ratio, ultrasonic time and adsorption temperature, which have a greater impact on the encapsulation rate, were selected as independent variables. Using Design-Expert 13 software and the Box-Behnken method, a total of 17 three-factor, three-level experiments were designed, with the encapsulation rate of red yeast rice pigment microcapsules as the response value. The variable conditions and experimental results are shown in Table 1.

[0063] Table 1. Box-Behnken Optimization Experimental Design and Results (2) Model Establishment and Significance Test: Analysis of variance was performed on the response surface experimental data in Table 2 using Design Expert 13 software. The results showed that the microcapsule encapsulation rate response value fit the quadratic polynomial model. The obtained microcapsule encapsulation rate (Y) regression equation model with respect to core-wall ratio, ultrasonic time, and adsorption temperature is as follows: Y=72.89+2.23A+1.06B-1.1C+0.28AB+0.6875AC-0.3BC-4.81A 2 -3.16B 2 -4.05C 2 .

[0064] Table 2. Significance test and variance analysis of the coefficients of the quadratic regression equation. Note: * indicates a significant difference (P<0.05); ** indicates an extremely significant difference (P<0.01).

[0065] The analysis of variance results of the regression model show that the F-value of the embedding rate (Y) model is 104.92, and the P-value is <0.0001, indicating that the model is highly significant; the F-value of the lack-of-fit term is 3.39, and the P-value is 0.1345 >0.05, indicating that the lack-of-fit term is not significant, the influence of unknown factors on the experiment is small, and the equation fits well; the coefficient of determination R... 2 =0.9926, R 2 An Adj = 0.9832 indicates a high correlation between the actual and predicted values, suggesting that the model can explain 98.32% of the variations in red yeast rice pigment microcapsules. Therefore, this model can effectively reflect the relationship between various factors and encapsulation efficiency during microcapsule preparation and predict the optimal preparation process. All linear and quadratic terms have extremely significant effects on the microcapsule encapsulation efficiency (P < 0.01), indicating that the influence of each factor on the red yeast rice pigment microcapsule encapsulation efficiency is complex, not a simple linear relationship. The F-value shows that the order of influence of the three factors on the microcapsule encapsulation efficiency is: A > C > B, i.e., core-wall material ratio > adsorption temperature > ultrasonic time.

[0066] (3) Response Surface and Contour Analysis: To more intuitively observe the interaction among the three factors and determine the optimal value of the response index, Design-expert software was used to draw the pairwise interaction response surface analysis surface and its contour lines based on the regression equation and the analysis of variance table of the regression model. The three-dimensional surface plots and contour lines can more intuitively analyze the impact of each factor and their interaction on the response value. Each response surface represents the effect of the interaction between the other two independent variables on the encapsulation rate of red yeast rice pigment microcapsules while maintaining one variable as optimal. Figure 10As can be seen, the contour plots are all elliptical, indicating that the interaction among the three factors has a significant impact on the microcapsule encapsulation rate, and the effect of the core-to-wall ratio is greater than that of adsorption temperature, and the effect of adsorption temperature is greater than that of ultrasonic time. The three-dimensional surface plots show that the significance of the interaction between the two factors on the encapsulation rate of red yeast rice pigment microcapsules is consistent with the significance analysis in Table 2.

[0067] (4) Optimal parameter combination and verification: The first-order partial derivative of the fitting equation (Y) for the encapsulation rate was obtained using Design Expert 13 software. When the encapsulation rate reached its maximum value, the optimal process conditions were: core-to-wall ratio 1:11.74, ultrasonic time 32.10 min, and adsorption temperature 59.30°C. The theoretical maximum value of the predicted encapsulation rate was 71.35%. To verify the accuracy of the response surface analysis, the process parameters optimized by the above model were appropriately adjusted to: core-to-wall ratio 1:12, ultrasonic time 32 min, and adsorption temperature 59°C. Under these conditions, the encapsulation rate of red yeast rice pigment microcapsules was (71.18±0.23)%, which was close to the predicted value and the difference was not significant (P>0.05). That is, the response surface method basically matched the experimental value and the predicted value of the regression equation, indicating that the established response surface regression model is scientific and reliable.

[0068] Application examples 1. Application Example of the Invention: The starch-based red yeast rice pigment microcapsules prepared in Example 1 are applied to the preparation of Cantonese sausage. The specific preparation method is as follows: (1) Raw material pretreatment: Cut the lean meat into 5mm cubes and the fat into 3mm cubes, and refrigerate at 0-4℃ for later use. (2) Preparation of pickling sauce: Mix white sugar and salt evenly, add high-proof liquor and ice water, and stir until the sugar and salt are completely dissolved to obtain the pickling sauce; (3) Mixed marinating: Put the lean meat cubes and fatty meat cubes into a marinating bowl, pour in the marinade, and stir for 10 minutes. After the diced meat is fully in contact with the marinade, add the starch-based red yeast rice pigment microcapsules prepared in Example 1 (addition amount is 0.05 g / kg), continue vacuum stirring for 5 min to ensure that the oil evenly coats the diced meat, and then place it in 0-4℃ for refrigeration and marinating for 12 h; (4) Sausage filling and shaping: Stuff the marinated minced meat into natural sausage casings, tie the sections every 10 cm with cotton thread, and poke small holes in the surface of the casings with a needle to release air; (5) Baking and drying: Place the sausage in an oven and bake at 50°C for 2 hours, then raise the temperature to 65°C and bake for 4 hours; (6) Cooling and packaging: Cool the baked sausage to room temperature and vacuum package it to obtain sausage CS-MPS.

[0069] 2. Using sausage MPS as a control, the sausage CS-MPS was stored at 27℃ for 60 days, and the various indicators of the prepared sausage CS-MPS were measured. The preparation method of sausage MPS is the same as that of sausage CS-MPS. The only difference is that red yeast rice pigment is directly added in step (3) of the preparation method of sausage MPS, and the amount added is 0.05 g / kg.

[0070] (1) Color Measurement: The apparent color of the sausage was measured using a colorimeter. The specific operating steps were as follows: The lens of the colorimeter was placed vertically on the sausage, ensuring close contact between the lens and the sausage. The brightness value (L*), redness value (a*), and yellowness value (b*) of the lean and fat surfaces were measured respectively. The colorimeter was calibrated before measurement. Five representative areas were selected for measurement, and each point was measured three times in parallel. The results were expressed as the average value. The total color difference (∆E) was calculated according to the following formula. L* reflects the brightness of the sample. The higher the value, the brighter the sausage. a* reflects the redness and greenness of the sample. The higher the positive value, the redder the color. The lower the negative value, the greener the color. b* reflects the yellowness and blueness of the sample. The higher the positive value, the yellower the color. The lower the negative value, the bluer the color.

[0071] In the formula: ∆L*, ∆a* and ∆b* are the differences between the corresponding indicators of each sample and the blank plate.

[0072] (2) Sensory evaluation: The sensory evaluation of sausages was based on the sensory requirements specified in GB / T 22210-2008 "Sensory Evaluation Standard for Meat and Meat Products" and SB / T 10003-92 "Cantonese Sausages", with appropriate modifications. The evaluation criteria are shown in Table 3. The sausages were placed in a white porcelain plate and observed for color and state under natural light. Their aroma was also smelled. A sensory evaluation group of 10 people (5 men and 5 women) evaluated the sensory attributes of the sausages from 0 to 20 points, including color, texture, aroma, and acceptability.

[0073] Table 3 Sensory Evaluation Table for Sausage (3) The peroxide value was determined in accordance with the determination method of GB 5009.227-2016 "National Food Safety Standard for Determination of Peroxide Value in Food".

[0074] The results are shown in Table 4. Figure 11As shown in the figure. During storage, the brightness (L*) and redness (a*) values ​​of both groups of sausages showed a decreasing trend, while the yellowness (b*) value first increased and then decreased. All color indicators of the CS-MPS group were superior to those of the MPS group. After 60 days of storage, the redness (a*) value of the CS-MPS group was 8.30, significantly higher than the 6.79 of the MPS group (P<0.05). In terms of sensory scores, the CS-MPS group consistently scored higher than the MPS group. After 60 days of storage, the sensory score of the CS-MPS group was 44.67, an increase of 18.6% compared to the MPS group (37.67). The peroxide value of both groups of sausages increased with prolonged storage time. The peroxide value of the CS-MPS group remained lower than that of the MPS group. After 60 days of storage, the peroxide value of the CS-MPS group was 0.049 g / 100g, a decrease of 27.9% compared to the MPS group (0.068 g / 100g).

[0075] Table 4. Changes in color difference and sensory scores of Cantonese sausage during storage. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A starch-based red yeast rice pigment microcapsule, characterized in that, The core material includes red yeast rice pigment, and the wall material includes corn starch, potato starch, cassava starch, or wheat starch; the mass ratio of the core material to the wall material is 1:6 to 1:

14.

2. The microcapsule according to claim 1, characterized in that, The core material also includes antioxidants.

3. The microcapsule according to claim 2, characterized in that, The antioxidant includes sodium isoascorbate.

4. The method for preparing starch-based red yeast rice pigment microcapsules according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Dissolve red yeast rice pigment and antioxidant in water and sonicate to obtain a core material pigment solution; (2) Add the core material pigment solution to the starch to obtain a starch-pigment suspension. Stir the starch-pigment suspension in a water bath to obtain mixture A. (3) Centrifuge mixture A, discard the supernatant, and obtain pigment-starch wet precipitate; (4) Wash the pigment-starch wet precipitate with distilled water, take the precipitate, stir it evenly, and let it stand. (5) The precipitate from step (4) is dried, ground, and sieved to obtain the starch-based red yeast rice pigment microcapsules.

5. The preparation method according to claim 4, characterized in that, The ultrasound time in step (1) is 10~50 min.

6. The preparation method according to claim 4, characterized in that, The water bath temperature in step (2) is 40~80℃; the stirring time is 30~150 min.

7. The preparation method according to claim 4, characterized in that, The centrifugation in step (3) is performed at 25°C and 4000 r / min for 10 min.

8. The preparation method according to claim 4, characterized in that, The sieve aperture size in step (5) is 60 mesh.

9. The preparation method according to claim 4, characterized in that, The drying in step (5) is vacuum freeze drying.

10. The use of the starch-based red yeast rice pigment microcapsules according to any one of claims 1-3 in the preparation of sausages.

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