Response surface method optimized tarragon color protection treatment process

Abstract

The invention belongs to the field of food processing, and relates to a response surface method optimized tarragon color protection treatment process which comprises the following steps: S1, blanching fresh tarragon to be processed; s2, cooling the blanched artemisia dracunculata, and putting the cooled artemisia dracunculata into a color protection solution for soaking treatment; the color protection liquid comprises citric acid, ascorbic acid, calcium chloride and water. And S3, draining the artemisia dracunculata subjected to the soaking treatment. The blanching treatment can significantly inhibit the activity of polyphenol oxidase in the tarragon, further inhibits the leaf browning of the tarragon, and prolongs the green value of the tarragon. The green color of the tarragon can tend to be deepened by soaking the tarragon in the color protection liquid, the loss of chlorophyll in the tarragon can be reduced by the color protection liquid, and meanwhile, the activity of polyphenol oxidase is reduced.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to the optimization of the color-protecting process for pepper and artemisia using response surface methodology. Background Technology

[0002] Artemisia annua is a tenacious plant that can adapt to various types of soil, such as arid land, barren land, and even saline-alkali land. It is widely distributed in the northern temperate zone and subtropical semi-desert and grassland regions, specifically in grasslands, roadsides, fields, dry river valleys, and river terraces.

[0003] Spicy watercress is rich in various trace elements, such as calcium and zinc, as well as alkaloids, vitamin C, and carotene. It has certain immunomodulatory functions, enhancing immunity and preventing colds. There are also records of its use in treating edema and scurvy. Spicy watercress contains volatile oils and flavonoids and has a long history of use in cooking. It can be used not only as a spice in everyday dishes but also brewed into vinegar to enhance the flavor of various meat products, or added as a flavoring to beverages and wines.

[0004] Pre-cooked meals are finished or semi-finished dishes made primarily from agricultural or plant-based ingredients and pre-packaged. Compared to traditional vegetables, the main advantages of pre-cooked vegetables like pepper and water chestnut are their portability and immediacy.

[0005] However, when prepared as a ready-to-eat dish, *Artemisia annua* faces the problem of enzymatic browning. This phenomenon is particularly pronounced during processing; when exposed to air, the green leaves of *Artemisia annua* are easily browned by polyphenol oxidase, affecting its quality and color. This not only impacts the product's appearance but may also reduce consumer acceptance.

[0006] There is currently no research on color protection and freshness preservation of Artemisia annua. Therefore, it is necessary to inhibit browning of Artemisia annua, perform color protection treatment on Artemisia annua, and extend its shelf life. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the problem of browning easily occurring in pre-processed pepper wormwood in existing technologies, this invention provides a response surface methodology-optimized color-protecting treatment process for pepper wormwood.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0011] A response surface methodology-based optimization of the color-protecting treatment process for Artemisia annua includes the following steps:

[0012] S1: Blanch the fresh pepper shoots that need to be processed;

[0013] S2: Cool the blanched scallion greens and then soak them in a color-protecting solution; the color-protecting solution includes citric acid, ascorbic acid, calcium chloride and water;

[0014] S3: Drain the soaked artemisia.

[0015] In the above-described process for protecting the color of Artemisia annua, preferably, in step S1, the temperature of the blanching treatment is 90-100℃ and the blanching time is 4-5 minutes.

[0016] In the above-described process for protecting the color of Artemisia annua, preferably, in step S1, the temperature of the blanching treatment is 95°C and the blanching time is 5 minutes.

[0017] In the above-described color-protecting treatment process for Artemisia annua, preferably, in step S2, the optimal soaking data is obtained by the following method:

[0018] The optimal soaking data for Artemisia annua in the color-protecting solution was determined by using historical soaking data of Artemisia annua in the color-protecting solution;

[0019] The historical soaking data includes the mass concentration of citric acid, the mass concentration of ascorbic acid, the mass concentration of calcium chloride, the soaking time, and the green a* value of Artemisia annua after soaking.

[0020] The optimal soaking data includes the optimal soaking time, the optimal mass concentration of citric acid in the color-protecting solution, the optimal mass concentration of ascorbic acid, and the optimal mass concentration of calcium chloride.

[0021] The color-protecting treatment process for Artemisia annua described above, preferably, involves determining the optimal soaking data for Artemisia annua in the color-protecting solution based on historical soaking data of Artemisia annua in the solution, specifically including the following steps:

[0022] A1: Collect historical soaking data of Artemisia annua in color-protecting solution;

[0023] A2: A response surface regression equation was constructed using response surface methodology, with the mass concentrations of citric acid, ascorbic acid, and calcium chloride, and the soaking time as independent variables, and the green a* value of the pepper stalk after soaking as the green a* value of the response quantity.

[0024] ;

[0025] Wherein, k1, k2, k3, k4, k5, k6, k7, k8, k9, k 10 k 11 k 12 k 13 k 14k 15 Let A be a constant, B be the mass concentration of citric acid, C be the mass concentration of ascorbic acid, and D be the soaking time.

[0026] A3: Solve the green a* value response surface regression equation to obtain the initial soaking data;

[0027] A4: Correct the initial soaking data obtained in step A3 according to the actual process to obtain the optimal soaking data.

[0028] In the above-described color-protecting treatment process for Artemisia annua, preferably, in step A2, the green a* value response surface regression equation is:

[0029] .

[0030] In the above-described color-protecting treatment process for Artemisia annua, preferably, in step A4, the optimal soaking data are as follows: the optimal soaking time is 40 min, the optimal mass concentration of citric acid in the color-protecting solution is 0.06%, the optimal mass concentration of ascorbic acid is 0.04%, and the optimal mass concentration of calcium chloride is 0.75%.

[0031] In the above-described process for protecting the color of Artemisia annua, preferably, in step S2, the color-protecting solution contains 0.06% citric acid, 0.04% ascorbic acid, and 0.75% calcium chloride by weight percentage, and the soaking time is 40 minutes.

[0032] In the above-described process for color protection of Artemisia annua, preferably, in step S2, the soaking temperature is 25-30℃, and the mass ratio of Artemisia annua to color protection solution is 1:4-1:6.

[0033] In the above-described process for protecting the color of Artemisia annua, preferably, in step S2, the mass ratio of Artemisia annua to the color-protecting liquid is 1:5.

[0034] (III) Beneficial Effects

[0035] This invention first blanches the *Artemisia annua*, then soaks the blanched *Artemisia annua* in a color-protecting solution. Blanching significantly inhibits the activity of polyphenol oxidase in *Artemisia annua*, thereby suppressing leaf browning and prolonging the green color of the leaves.

[0036] When immersed in a color-protecting solution, air inside the *Artemisia annua* tissue is expelled, making the tissue more transparent. As the transparency increases, light refraction within the tissue decreases, resulting in a deeper, more saturated green color when light passes through. Furthermore, the color-protecting solution reduces chlorophyll loss from the *Artemisia annua* and simultaneously lowers the activity of polyphenol oxidase.

[0037] This invention provides a new technical strategy for improving the quality of pepper and wormwood shelves, and also has application value for the processing and storage of fruit and vegetable products. Attached Figure Description

[0038] Figure 1 This is a graph showing the effect of different amounts of citric acid added on the green a* value of Artemisia annua in this invention;

[0039] Figure 2 This is a graph showing the effect of different amounts of ascorbic acid added on the green a* value in Artemisia annua in this invention;

[0040] Figure 3 This is a graph showing the effect of different calcium chloride addition amounts on the green a* value of Artemisia annua in this invention;

[0041] Figure 4 This is a graph showing the effect of different soaking times on the green a* value in Artemisia annua in this invention;

[0042] Figure 5 A graph showing the effect of different citric acid addition amounts on the chlorophyll content in Artemisia annua;

[0043] Figure 6 A graph showing the effect of different ascorbic acid addition amounts on the chlorophyll content in Artemisia annua;

[0044] Figure 7 A graph showing the effect of different calcium chloride addition amounts on the chlorophyll content in Artemisia annua;

[0045] Figure 8 A graph showing the effect of different soaking times on the chlorophyll content in Artemisia annua;

[0046] Figure 9 The interaction diagram of soaking time and citric acid addition amount on the green a* value of pepper;

[0047] Figure 10 The interaction diagram of soaking time and ascorbic acid addition amount on the green a* value in Artemisia annua;

[0048] Figure 11 The interaction diagram of soaking time and calcium chloride addition amount on the green a* value of Artemisia annua;

[0049] Figure 12 The interaction diagram of the effects of ascorbic acid and citric acid addition on the green a* value in Artemisia annua;

[0050] Figure 13 The interaction diagram of the effects of calcium chloride addition and citric acid addition on the green a* value in Artemisia annua;

[0051] Figure 14 The interaction diagram of the effects of calcium chloride and ascorbic acid addition on the green a* value in Artemisia annua;

[0052] Figure 15 This is a graph showing the relationship between blanching temperature and polyphenol oxidase activity in this invention;

[0053] Figure 16 This is a graph showing the relationship between blanching time and polyphenol oxidase activity in this invention. Detailed Implementation

[0054] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0055] This invention provides a response surface methodology-optimized color-protecting treatment process for Artemisia annua, comprising the following steps:

[0056] S1: Blanch the fresh wormwood in hot water.

[0057] S2: Cool the blanched scallion greens and then soak them in a color-protecting solution; the color-protecting solution includes citric acid, ascorbic acid, calcium chloride and water.

[0058] S3: Drain the soaked artemisia.

[0059] Preferably, in step S1 above, the blanching temperature can be 90-100℃, and the blanching time can be 4-5 minutes. The blanching time in this invention is relatively short, avoiding the loss of flavor substances in the artemisia annua. More preferably, research has found that when the blanching temperature in step S1 is 95℃ and the blanching time is 5 minutes, the inhibitory effect on polyphenol oxidase in artemisia annua is most significant. The principle of blanching is that blanching can significantly inhibit the activity of polyphenol oxidase in artemisia annua, thereby inhibiting leaf browning and prolonging the green value of artemisia annua. In addition, the artemisia annua can be simply washed before step S1.

[0060] Preferably, in step S2, the optimal soaking data is obtained by the following method:

[0061] The optimal soaking data for Artemisia annua in the color-protecting solution was determined by using historical soaking data of Artemisia annua in the color-protecting solution.

[0062] Historical soaking data includes the mass concentrations of citric acid, ascorbic acid, and calcium chloride, soaking time, and the green a* value of the pepper after soaking. Optimal soaking data includes the optimal soaking time, the optimal mass concentrations of citric acid, ascorbic acid, and calcium chloride in the color-protecting solution.

[0063] More preferably, determining the optimal soaking data for Artemisia annua in the color-protecting solution based on historical soaking data specifically includes the following steps:

[0064] A1: Collect historical soaking data of Artemisia annua in color-protecting solution.

[0065] A2: A response surface regression equation was constructed using response surface methodology, with the mass concentrations of citric acid, ascorbic acid, and calcium chloride, and the soaking time as independent variables, and the green a* value of the pepper stalk after soaking as the green a* value of the response quantity.

[0066] ;

[0067] Wherein, k1, k2, k3, k4, k5, k6, k7, k8, k9, k 10 k 11 k 12 k 13 k 14 k 15 Let A be a constant, B be the mass concentration of citric acid, C be the mass concentration of ascorbic acid, and D be the soaking time.

[0068] A3: Solve the green a* value response surface regression equation to obtain the initial soaking data.

[0069] A4: Correct the initial soaking data obtained in step A3 according to the actual process to obtain the optimal soaking data.

[0070] More preferably, the response surface regression equation for the green a* value in step A2 is:

[0071] .

[0072] After calculation, the optimal soaking data in step A4 are as follows: the optimal soaking time is 40 min, the optimal mass concentration of citric acid in the color-protecting solution is 0.06%, the optimal mass concentration of ascorbic acid is 0.04%, and the optimal mass concentration of calcium chloride is 0.75%.

[0073] Based on the above optimal soaking data, in step S2, the color-protecting solution contains 0.06% citric acid, 0.04% ascorbic acid, and 0.75% calcium chloride by weight percentage, and the soaking time is 40 minutes. This invention uses response surface methodology to optimize the concentration of each solute in the color-protecting solution and the soaking time, thereby achieving the best color-protecting effect.

[0074] In addition, the citric acid, ascorbic acid, and calcium chloride in the color-protecting solution can also reduce the activity of polyphenol oxidase.

[0075] Preferably, in step S2 above, the soaking temperature can be 25-30℃. The principle of the color-protecting solution's effect on color protection and preservation in this invention is as follows: When soaked in the color-protecting solution, the air inside the *Artemisia annua* tissue is expelled, making the tissue more transparent. As the transparency of the *Artemisia annua* tissue increases, the refraction of light inside the tissue decreases. Thus, when light passes through the tissue, the green color tends to deepen, appearing more saturated. Furthermore, the color-protecting solution can also reduce the loss of chlorophyll in the *Artemisia annua* and simultaneously reduce the activity of polyphenol oxidase.

[0076] Furthermore, in step S2 above, the mass ratio of artemisia to the color-protecting liquid is 1:4 to 1:6, preferably 1:5. If the mass ratio of artemisia to the color-protecting liquid is greater than 1:4, the amount of color-protecting liquid received per unit of artemisia will be reduced, resulting in poor color protection. Conversely, if the mass ratio of artemisia to the color-protecting liquid is less than 1:6, it will result in waste of the color-protecting liquid, and excessive color-protecting liquid may also negatively affect the taste or flavor of the artemisia.

[0077] In step S3, the drained pepper wormwood can be weighed, bagged, vacuum-packed or nitrogen-filled, and sealed to obtain the finished product.

[0078] In this invention, the process of constructing a response surface regression equation using response surface methodology with the mass concentrations of citric acid, ascorbic acid, calcium chloride, and soaking time as independent variables, and the green a* value of Artemisia annua after soaking as the response quantity, is as follows:

[0079] I. Effects of color protection conditions on the green a* value of Artemisia annua (single-factor experiment on color protection):

[0080] ① Effect of citric acid concentration on the green a* value of Artemisia annua

[0081] Accurately weigh 20g of blanched artemisia (blanched at 95℃ for 5min; blanching conditions are the same for all artemisia below) and soak them in a color-protecting solution with a material-to-liquid ratio of 1:5. Using color difference change as an indicator, design citric acid concentrations of 0.02%, 0.04%, 0.06%, 0.08%, and 0.10% (m / m) and soaking times of 40min. After treatment, record the green value a* (red / green value) of the artemisia and take the average value to obtain the result. Figure 1 .

[0082] ② Effect of ascorbic acid concentration on the green a* value of Artemisia annua

[0083] Accurately weigh 20g of blanched artemisia annua and soak it in a color-protecting solution with a material-to-liquid ratio of 1:5. Using color difference change as an indicator, the ascorbic acid addition amounts were designed to be 0.02%, 0.04%, 0.06%, 0.08%, and 0.10% (m / m), with a soaking time of 40 minutes. After treatment, the green value a* (red / green value) of the artemisia annua was recorded, and the average value was taken to obtain the result. Figure 2 .

[0084] ③ Effect of calcium chloride concentration on the green a* value of Artemisia annua

[0085] Accurately weigh 20g of blanched artemisia annua and soak it in a color-protecting solution with a material-to-liquid ratio of 1:5. Using color difference change as an indicator, design calcium chloride addition amounts of 0.60%, 0.65%, 0.70%, 0.75%, and 0.80% (m / m) for 40 minutes each. Record the green value a* (red / green value) of the artemisia annua after treatment and take the average value to obtain the result. Figure 3 .

[0086] ④ Effect of soaking time on the green a* value of Artemisia annua

[0087] Accurately weigh 20g of blanched artemisia annua and soak it in a color-protecting solution with a material-to-liquid ratio of 1:5. Use color difference change as an indicator. The addition amounts of citric acid, ascorbic acid, and calcium chloride were 0.06%, 0.06%, and 0.70% (m / m), respectively. The designed soaking times were 10min, 20min, 40min, 60min, and 80min. After treatment, the green value a* (red / green value) of the artemisia annua was recorded, and the average value was taken to obtain the result. Figure 4 .

[0088] pass Figures 1-4 It can be seen that when the mass concentration of citric acid is 0.06%, the average green a* value is -14.75, indicating a more significant color effect; when the mass concentration of ascorbic acid is 0.04%, the green a* value is -14.27, indicating a more significant color effect; when the mass concentration of calcium chloride is 0.65%, the green a* value is -12.09, indicating a more significant color effect; and the effect is more significant when the soaking time is 40 minutes.

[0089] In addition, the chlorophyll content of Artemisia annua after the above single-factor experimental treatment was measured, and the results were obtained respectively. Figure 5-8 Chlorophyll content was measured using a spectrophotometer, specifically referring to the national standard "NY / T 3082-2017 Determination of chlorophyll content in fruits, vegetables and their products by spectrophotometry".

[0090] pass Figure 5-8It can be seen that when the citric acid content is 0.06%, the chlorophyll content is 0.017; when the ascorbic acid content is 0.04%, the chlorophyll content is 0.009; when the calcium chloride content is 0.65%, the chlorophyll content is 0.01; and when the soaking time is 40 minutes, the chlorophyll content is 0.022, showing a more obvious green effect.

[0091] This invention uses Excel, Origin 2021, and IBM SPSS 26.0 software for statistical analysis and graphing of data. Design-Expert 8.0.6 software is used to perform response surface methodology on the single-factor experimental results and optimize process parameters.

[0092] II. Color Protection Response Surface Experiment:

[0093] Based on the central combination of Box-Behnken and the results of the single-factor experiments above, a four-factor, three-level experimental design was adopted with the green a* value of Artemisia annua as the response value. Regression analysis and optimization were performed on the results. The Box-Behnken experimental factors and levels are shown in Table 1.

[0094] Table 1. Factors and Levels in the Box-Behnken Experiment

[0095]

[0096] Specifically, based on the results of the single-factor experiment, the factors that affect the color difference a* value of Artemisia annua were selected as influencing factors: the mass concentration of citric acid (A), the mass concentration of ascorbic acid (B), the mass concentration of calcium chloride (C), and the soaking time (D). Response surface methodology was conducted using the color difference a* value (Y). The experimental results are shown in Table 2.

[0097] Table 2. Response surface methodology and results statistics for Artemisia annua.

[0098]

[0099]

[0100] The data in Table 2 were fitted using the response surface methodology software Design-Expert 8.0.6 to obtain the regression model equation for the response surface color difference a* value (Y):

[0101] .

[0102] The regression model equations were analyzed, and Table 3 was obtained.

[0103] Table 3. Regression Model Analysis of Artemisia annua

[0104]

[0105] Note: In Table 3, "**" indicates an extremely significant effect (P<0.01); "*" indicates a significant effect (P<0.05).

[0106] Table 3 shows that the model is highly significant (P<0.0001), and the lack-of-fit term is not significant (P>0.05), indicating that the model is accurate, and the coefficient of determination R0.05 is [value missing]. 2 The corrected coefficient of determination R is 0.9917. 2 Adj The value of 0.9552 indicates that the equation has a small error, the experiment is highly accurate, and it can predict the effect of various factors on the color difference 'a' of Artemisia annua. * The influence of each factor on the value. The F-test can be used to determine the effect of each factor on the color difference a of Artemisia annua. * The order of influence of values ​​is: citric acid addition > calcium chloride addition > ascorbic acid addition > soaking time; among which A, C, AB, AC, BC, BD and A 2 B 2 C 2 D 2 Color difference of Artemisia a * The value has a highly significant impact; the interaction term AD has a significant effect on the green a. * The value has a significant impact.

[0107] III. Interactions in Box-Behnken Response Surface Analysis:

[0108] To more vividly illustrate the influence of the interaction among the four factors on the green a* value response of Artemisia annua, this invention also utilizes Design-Expert 8.0.6 software to plot the interaction of the other three factors while keeping one factor constant, analyzing their impact on the green a* value of Artemisia annua. The response surface is shown below. Figure 9-14 The steep response surface plot indicates that this variable has a significant impact on the green a* value. The analysis of the response surface plot and contour plot provides a strong basis for subsequent optimization of the pepper artemisia process and product improvement.

[0109] IV. Optimization and Verification Experiment:

[0110] The optimal conditions predicted using Design-Expert 8.0.6 software were 0.06% citric acid, 0.03% ascorbic acid, 0.77% calcium chloride, and a soaking time of 40.10 min, with a color difference a* value of -9.45. Considering the feasibility of actual operation and experimental conditions, the conditions were modified to 0.06% citric acid, 0.04% ascorbic acid, 0.75% calcium chloride, and a soaking time of 40 min. Three parallel experiments were conducted, and the average color difference a* value was taken as -10.47, which is not significantly different from the predicted value.

[0111] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.

[0112] Example 1

[0113] This embodiment provides a color-protecting treatment process for Artemisia annua, including the following steps:

[0114] S1: Blanch the fresh scallion greens that need to be processed in hot water at 95℃ for 5 minutes.

[0115] S2: Cool the blanched scallion greens, then immerse them in a color-protecting solution at 30°C for 40 minutes. The mass ratio of scallion greens to color-protecting solution is 1:5.

[0116] S3: Drain the soaked artemisia.

[0117] According to mass percentage, the color-protecting solution used in this embodiment includes 0.06% citric acid, 0.04% ascorbic acid, 0.75% calcium chloride, and the balance is water.

[0118] This embodiment is the best embodiment. Under this embodiment, the chlorophyll content of Artemisia annua was measured to be 0.021 mg / g, and the green a* value was -10.47.

[0119] Example 2-Example 3

[0120] Example 2 and Example 3 respectively provide a color-protecting treatment process for Artemisia annua. The difference between Example 1 and Example 2 is that the blanching temperature in step S1 is 90℃ and 100℃ respectively.

[0121] Comparative Example 1 - Comparative Example 2

[0122] Comparative Examples 1 and 2 respectively provide a color-protecting treatment process for Artemisia annua. The difference between Comparative Examples 1 and Example 2 is that the blanching temperature in step S1 is 80°C and 85°C, respectively.

[0123] Example 4

[0124] This embodiment provides a color-protecting treatment process for Artemisia annua. The difference from Embodiment 1 is that the blanching time in step S1 is 4 minutes.

[0125] Comparative Examples 3-5

[0126] Comparative Examples 3, 4, and 5 each provide a color-protecting treatment process for Artemisia annua. The difference between Comparative Examples 3 and 4 is that the blanching time in step S1 is 1 min, 2 min, and 3 min, respectively.

[0127] Comparative Example 6

[0128] This comparative example provides a color-protecting treatment process for Artemisia annua, which differs from Example 1 in that the color-protecting solution includes 0% citric acid.

[0129] Comparative Example 7

[0130] This comparative example provides a color-protecting treatment process for Artemisia annua, which differs from Example 1 in that the color-protecting solution contains 0% ascorbic acid.

[0131] Comparative Example 8

[0132] This comparative example provides a color-protecting treatment process for Artemisia annua, which differs from Example 1 in that the color-protecting solution contains 0% calcium chloride.

[0133] Comparative Example 9

[0134] This comparative example provides a color-protecting treatment process for Artemisia annua. The difference from Example 1 is that step S2 is performed first, followed by step S1.

[0135] In Examples 1-4 and Comparative Examples 1-5, after blanching, the polyphenol oxidase activity in *Artemisia annua* was detected using a UV spectrophotometer. Specifically, 1g of blanched *Artemisia annua* was added to 10mL of phosphate buffer and ground into a homogenate in an ice-water bath. The homogenate was centrifuged at 5000 rpm for 15 min, and the supernatant was collected and stored at 4℃ for later analysis. The polyphenol oxidase activity in *Artemisia annua* was determined as follows: 0.5mL of phosphate buffer and 1mL of 0.2mol·L⁻¹ solution were added to the supernatant. -1 Using catechol solution as substrate, the solution was poured into a 1cm cuvette and mixed well. 0.5mL of enzyme solution was added, and the mixture was quickly placed in a UV spectrophotometer to measure the absorbance (OD value) change at 420nm. The reaction time was 4 min, and data were recorded every 30s. This was repeated three times to obtain the desired results. Figure 15 The graph showing the relationship between bleaching temperature and absorbance, and Figure 16 The graph shown represents the relationship between blanching time and absorbance, where the OD value indicates the activity of polyphenol oxidase.

[0136] pass Figure 15 It can be seen that the absorbance value first decreases and then increases with increasing blanching temperature, indicating that the activity of polyphenol oxidase is first inhibited and then enhanced with increasing temperature. Figure 16 It can be seen that the absorbance value gradually decreases with the extension of blanching time, indicating that the activity of polyphenol oxidase is gradually inhibited as the blanching time increases. Furthermore, when blanching at 90-100℃ for 4-5 minutes, polyphenol oxidase is at a low activity level, and the optimal blanching parameter is: blanching at 95℃ for 5 minutes.

[0137] In addition, after testing, the green value a* of the pepper wormwood prepared in Comparative Examples 6-9 was significantly greater than that in the examples, and the chlorophyll content was significantly lower than that in the examples. This indicates that citric acid, ascorbic acid, and calcium chloride in the color-protecting solution are indispensable for the color-protecting treatment of pepper wormwood. Furthermore, the order of blanching and color-protecting treatment also affects the final quality of pepper wormwood. Only by blanching first and then color-protecting treatment can the green value of pepper wormwood be significantly extended. If soaking in the color-protecting solution first and then blanching is performed, the treatment effect will be affected.

[0138] The materials and reagents used in this invention are as follows:

[0139] Fresh Artemisia annua: Hami Changzheng Wild Vegetable Development Co., Ltd.; Ascorbic acid (food grade): Heilongjiang Xinhecheng Biotechnology Co., Ltd.; Citric acid (food grade): Shandong Yingxuan Industrial Co., Ltd.; Calcium chloride (food grade): Jiangsu Kelunduo Food Ingredients Co., Ltd.; Hydroquinone: Tianjin Yongsheng Fine Chemical Co., Ltd.; PBS buffer: Kebo Technology Co., Ltd.; Anhydrous ethanol (analytical grade): Tianjin Zhiyuan Chemical Reagent Co., Ltd.; Acetone: Tianjin Zhiyuan Chemical Reagent Co., Ltd.

[0140] The main instruments and equipment used in this invention are as follows:

[0141] LE203E Electronic Balance: Mettler Toledo Instruments Ltd.; HH-6A Thermostatic Water Bath: Changzhou Guoyu Instrument Manufacturing Co., Ltd.; 755B Ultraviolet Spectrophotometer: Shanghai Jinghua Technology Co., Ltd.; TGL-20bR Centrifuge: Shanghai Anting Scientific Instrument Factory; CR-400 Colorimeter: Konica Minolta.

[0142] Furthermore, the storage period of the *Artemisia annua* prepared in the examples and comparative examples was tested, and the following results were obtained:

[0143] Compared to Comparative Examples 1-2, the average storage time of Artemisia annua in Examples 1-4 was extended by approximately 20 days.

[0144] Compared to Comparative Examples 3-5, the average storage time of Artemisia annua in Example 4 was extended by approximately 14 days.

[0145] Compared to Comparative Example 6, the average storage time of Artemisia annua in Example 1 was extended by approximately 29 days.

[0146] Compared to Comparative Example 7, the average storage time of Artemisia annua in Example 1 was extended by approximately 24 days.

[0147] Compared to Comparative Example 8, the average storage time of Artemisia annua in Example 1 was extended by approximately 27 days.

[0148] Compared to Comparative Example 9, the average storage time of Artemisia annua in Example 1 was extended by approximately 23 days.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A response surface methodology-optimized color-protecting treatment process for Artemisia annua, characterized in that, Includes the following steps: S1: Blanch the fresh pepper shoots that need to be processed; S2: Cool the blanched scallion greens and then soak them in a color-protecting solution; the color-protecting solution includes citric acid, ascorbic acid, calcium chloride and water; S3: Drain the soaked artemisia.

2. The color-protecting treatment process for Artemisia annua according to claim 1, characterized in that, In step S1, the temperature for blanching is 90-100℃, and the blanching time is 4-5 minutes.

3. The color-protecting treatment process for Artemisia annua according to claim 2, characterized in that, In step S1, the temperature for blanching is 95℃ and the blanching time is 5 minutes.

4. The color-protecting treatment process for Artemisia annua according to claim 1, characterized in that, In step S2, the optimal soaking data is obtained through the following method: The optimal soaking data for Artemisia annua in the color-protecting solution was determined by using historical soaking data of Artemisia annua in the color-protecting solution; The historical soaking data includes the mass concentration of citric acid, the mass concentration of ascorbic acid, the mass concentration of calcium chloride, the soaking time, and the green a* value of Artemisia annua after soaking. The optimal soaking data includes the optimal soaking time, the optimal mass concentration of citric acid in the color-protecting solution, the optimal mass concentration of ascorbic acid, and the optimal mass concentration of calcium chloride.

5. The color-protecting treatment process for Artemisia annua according to claim 4, characterized in that, Determining the optimal soaking data for Artemisia annua in a color-protecting solution based on historical soaking data includes the following steps: A1: Collect historical soaking data of Artemisia annua in color-protecting solution; A2: A response surface regression equation was constructed using response surface methodology, with the mass concentrations of citric acid, ascorbic acid, and calcium chloride, and the soaking time as independent variables, and the green a* value of the pepper stalk after soaking as the green a* value of the response quantity. ； Wherein, k1, k2, k3, k4, k5, k6, k7, k8, k9, k 10 k 11 k 12 k 13 k 14 k 15 Let A be a constant, B be the mass concentration of citric acid, C be the mass concentration of ascorbic acid, and D be the soaking time. A3: Solve the green a* value response surface regression equation to obtain the initial soaking data; A4: Correct the initial soaking data obtained in step A3 according to the actual process to obtain the optimal soaking data.

6. The color-protecting treatment process for Artemisia annua according to claim 5, characterized in that, In step A2, the green a* value response surface regression equation is: 。 7. The color-protecting treatment process for Artemisia annua according to claim 4, characterized in that, In step A4, the optimal soaking data are as follows: the optimal soaking time is 40 min, the optimal mass concentration of citric acid in the color-protecting solution is 0.06%, the optimal mass concentration of ascorbic acid is 0.04%, and the optimal mass concentration of calcium chloride is 0.75%.

8. The color-protecting treatment process for Artemisia annua according to claim 1, characterized in that, In step S2, the color-protecting solution contains 0.06% citric acid, 0.04% ascorbic acid, and 0.75% calcium chloride by weight percentage, and the soaking time is 40 minutes.

9. The color-protecting treatment process for Artemisia annua according to claim 1, characterized in that, In step S2, the soaking temperature is 25-30℃, and the mass ratio of pepper wormwood to color-protecting solution is 1:4-1:

6.

10. The color-protecting treatment process for Artemisia annua according to claim 9, characterized in that, In step S2, the mass ratio of pepper wormwood to color-protecting solution is 1:5.

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