Preparation method of antioxidant feed additive

Abstract

The invention relates to the technical field of chemical treatment of natural plants, in particular to a preparation method of an antioxidant feed additive, which comprises the following steps: taking limonium aureum as a raw material, air-drying and crushing the raw material to obtain a crushed bulk drug; adding the crushed raw material medicines into a solvent, and performing ultrasonic extraction, concentration, alcohol precipitation and centrifugation to obtain limonium aureum polysaccharide, namely the anti-oxidation limonium aureum feed additive; performing a single-factor test according to four factors and five levels, and respectively investigating the influence of the extraction temperature X1, the ultrasonic power X2, the ultrasonic time X3 and the material-liquid ratio X4 on the yield of the polysaccharide in the limonium aureum; on the basis of a single factor level, Box-Behnken response surface design is carried out, and a test is carried out according to a factor level combination; and carrying out analysis on the test data by adopting Design-Expert 8.0. 6 statistical analysis software. The preparation method of the antioxidant feed additive provided by the invention has the beneficial effects that the content of polysaccharide in the antioxidant feed additive reaches 32.26%.

Description

Technical Field

[0001] The invention relates to the technical field of natural plant chemical processing, in particular to a method for preparing an antioxidant feed additive. Background Art

[0002] Limonium aureum (L.) Hill. is a perennial herbaceous plant of the genus Limonium in the family Pleurostigaceae. According to the National Collection of Chinese Herbal Medicines, Limonium aureum has the functions of nourishing blood, promoting blood circulation, stopping bleeding and fighting cancer. The calyx can be used as medicine to relieve pain, reduce inflammation and stop bleeding. It can be used externally to treat various inflammations and taken internally to treat neuralgia, oligomenorrhea, tinnitus, low milk production, toothache, alveolar abscess, cold, fever, sores, and carbuncle.

[0003] As people's living standards continue to improve, more and more people are raising pets, and pet health issues are becoming more and more important. Due to the single diet structure, overnutrition, environmental pollution, stress, lack of exercise and other reasons, pets lose balance between the formation and elimination of active oxygen and free radicals in the body, which causes more than 100 diseases, including the common ones: diabetes, hypertension, atherosclerosis, dementia, nephritis, cataracts, aging, etc. Therefore, antioxidants have become one of the key research and development directions of pet health in recent years. The invention proves that dietary changes can lead to changes in the level of active oxygen ions in the body and change the composition of intestinal microbiota. Therefore, adding antioxidant ingredients to pet food can better maintain the function of cells and tissues and reduce the damage caused by free radicals to the body. Natural antioxidants extracted from plants have the advantages of safety and non-toxicity. As antioxidant pet feed additives, they have broad development and application value and market.

[0004] Polysaccharides from fruits, plants and vegetables are valued by food producers and consumers due to their physical properties, potential to promote health and prevent diseases, and have therefore been used in feed, pharmaceuticals and cosmetics. In recent years, due to the application of new technologies and methods, people have made significant progress in the invention of polysaccharides in plants. The isolated polysaccharides have liver-protecting, anti-inflammatory, immunostimulatory, antioxidant, and anti-tumor effects, playing an important role in the biomedical field.

[0005] Limonium chrysantha contains rich polysaccharides, which are valuable for extraction and utilization. At present, there is no report on the extraction of polysaccharide compounds from Limonium chrysantha at home and abroad. In order to make full use of my country's excellent wild plant resources, the present invention uses the antioxidant activity of Limonium chrysantha as a pet feed additive for the first time, filling the gap in the domestic related market, expanding new inventions and application ideas for natural plants with antioxidant activity, and has a good market application prospect. Summary of the invention

[0006] The purpose of the invention is to provide a method for preparing an antioxidant feed additive in view of the defects in the above-mentioned prior art, which is simple to operate, safe, low in cost, and high in effective ingredient content and yield.

[0007] In order to achieve the above purpose, the technical solutions provided are as follows:

[0008] A method for preparing an antioxidant feed additive, characterized in that it comprises the following steps:

[0009] Step 1: Take Limonium sibiricum as a raw material, air-dry and crush the raw material to obtain a crushed raw material drug;

[0010] Step 2: Place an appropriate amount of distilled water in a 250 ml conical flask, add the crushed API obtained in step 1 to the solvent, set the corresponding extraction temperature, ultrasonic power, ultrasonic time and material-liquid ratio to perform ultrasonic extraction, repeat the extraction 3 times, combine the extracts, filter and concentrate;

[0011] Step 3, adding anhydrous ethanol to the concentrated solution obtained in step 2 until the ethanol content is 80% for alcohol precipitation, the alcohol precipitation solution is allowed to stand at 4°C for 24 hours, the precipitate is collected by centrifugation, vacuum freeze-dried at -40°C, and ground into powder to obtain Limonium sibiricum polysaccharide, i.e., an antioxidant Limonium sibiricum feed additive;

[0012] Step 4: Conduct a single factor test according to 4 factors and 5 levels to examine the effects of extraction temperature X1, ultrasonic power X2, ultrasonic time X3, and liquid-to-solid ratio X4 on the yield of polysaccharides from Limonium scabra.

[0013] Step 5: Based on the single factor level of step 4, select the range of factors that have a significant impact on Limonium scabra polysaccharide, conduct Box-Behnken response surface design, and conduct experiments according to the combination of factor levels;

[0014] Step 6: Analyze the test data using Design-Expert 8.0.6 statistical analysis software; the formula for extracting polysaccharides from Limonium truncatum is:

[0015] Y(%)=31.85+1.97X1+1.06X2+0.55X3-0.35X4-0.11X1X2-0.030X1X3+0.098X1X4+0.70X2X3-0.14X2X4-0.19X3X4-3.52X1 2 -3.00X2 2 -3.45X3 2 -2.16X4 2

[0016] Wherein, Y represents the polysaccharide content of Limonium xanthophyllum, X1 represents the extraction temperature, X2 represents the ultrasonic power, X3 represents the ultrasonic time, and X4 represents the solid-liquid ratio.

[0017] Preferably, in step 2, the extraction temperature is 70-90° C., the ultrasonic power is 60-100 W, the ultrasonic time is 30-50 min, and the liquid-to-solid ratio is 1:15-1:25.

[0018] Preferably, in step 2, each group of experimental ultrasonic extractions is repeated 3 times, combined, filtered, and the filtrate is concentrated under reduced pressure in a water bath at 50°C and a vacuum degree of -0.07Mpa, and further alcohol precipitation, centrifugation, and drying are performed to obtain the polysaccharide of Limonium xanthophyllum.

[0019] Preferably, in step five, analysis shows that the optimal extraction process has an extraction temperature of 83° C., an ultrasonic power of 84 W, an ultrasonic time of 41 min, and a solid-liquid ratio of 1:20.

[0020] Preferably, the polysaccharide from Limonium xanthophyllum as an antioxidant feed additive exhibits strong reducing ability and DPPH scavenging effects.

[0021] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing an antioxidant feed additive, the polysaccharide content in the antioxidant feed additive reaches 32.26%, which is significantly improved compared with the prior art, and the process conditions of the method are simple, safe and low in cost, which provides technical support and theoretical basis for the industrial production of polysaccharide antioxidant feed additives of Limonium scabra, expands new research and application ideas for natural plants with antioxidant activity, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The single factor experimental results of the present invention; wherein, A, the effect of extraction temperature on the extraction rate of polysaccharide from Limonium sibiricum; B, the effect of ultrasonic power on the extraction rate of polysaccharide from Limonium sibiricum; C, the effect of ultrasonic time on the extraction rate of polysaccharide from Limonium sibiricum; D, the effect of solid-liquid ratio on the extraction rate of polysaccharide from Limonium sibiricum;

[0023] Figure 2The invention provides a response surface and contour lines for the influence of various influencing factors on the extraction rate of polysaccharides from Limonium scabra; wherein, A, the response surface and contour lines for the influence of extraction temperature and ultrasonic power on the extraction rate of polysaccharides from Limonium scabra; B, the response surface and contour lines for the influence of extraction temperature and ultrasonic time on the extraction rate of polysaccharides from Limonium scabra; C, the response surface and contour lines for the influence of extraction temperature and solid-liquid ratio on the extraction rate of polysaccharides from Limonium scabra; D, the response surface and contour lines for the influence of ultrasonic power and ultrasonic time on the extraction rate of polysaccharides from Limonium scabra; E, the response surface and contour lines for the influence of ultrasonic power and solid-liquid ratio on the extraction rate of polysaccharides from Limonium scabra; F, the response surface and contour lines for the influence of ultrasonic time and solid-liquid ratio on the extraction rate of polysaccharides from Limonium scabra;

[0024] Figure 3 The antioxidant activity of different concentrations of Limonium frutescens polysaccharides of the present invention; wherein, A, the activity of Limonium frutescens polysaccharides and VC in scavenging DPPH free radicals; B, the activity of Limonium frutescens polysaccharides and VC in scavenging hydroxyl free radicals; C, the iron ion chelating ability; D, the total reducing power of Limonium frutescens polysaccharides and VC. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1: Extraction of Limonium aurantium polysaccharide

[0027] In the extraction experiment of polysaccharides from Limonium scabra, about 10.0g of plant material was taken, crushed, and an appropriate amount of distilled water was added and mixed in a 250mL conical flask. The method of ultrasonic-assisted extraction of polysaccharides was adopted, and the required temperature, ultrasonic power, time and material-liquid ratio were selected, and the sample was extracted with continuous ultrasonic waves of different power outputs and a frequency of 40kHz. During the extraction, the temperature was controlled at a level within the range of ±1℃.

[0028] Repeat the extraction three times, combine the filtrates and concentrate them with a rotary evaporator, add anhydrous ethanol to the concentrate until the ethanol content is 80% for alcohol precipitation, place the alcohol precipitation solution at 4°C for 24 hours, collect the precipitate by centrifugation at 3000rpm / min, freeze-dry in a vacuum at -40°C, and grind into powder to obtain the polysaccharide of Limonium eryngii, that is, the antioxidant Limonium eryngii feed additive. The percentage (Y) is calculated by the following formula:

[0029]

[0030] Where Wt is the mass of crude extract, and Wi is the mass of Limonium xanthophyllum powder.

[0031] Example 2: Single Factor Experiment

[0032] Taking the polysaccharide yield of Limonium candidum as the evaluation index, the effects of four factors, namely extraction temperature X1, ultrasonic power X2, ultrasonic time X3, and liquid-to-solid ratio X4, on the polysaccharide yield of Limonium candidum were investigated respectively, and each factor was set at 5 levels for a single factor experiment.

[0033] Table 1 Single factor test level table

[0034]

[0035] The experimental design is as follows:

[0036] ①Comparison of extraction temperature: ultrasonic power is 70W, ultrasonic time is 30min, liquid-to-solid ratio is 1:15, and extraction temperature is set at 20, 40, 60, 80 and 100℃ respectively;

[0037] ②Comparison of ultrasonic power: extraction temperature was 60℃, ultrasonic time was 30min, liquid-to-solid ratio was 1:15, and ultrasonic power was set to 30, 50, 70, 90 and 110W respectively;

[0038] ③Comparison of ultrasonic time: extraction temperature was 60℃, ultrasonic power was 70W, liquid-to-solid ratio was 1:15, and ultrasonic time was set to 10, 20, 30, 40 and 50min respectively;

[0039] ④ Comparison of liquid-to-solid ratio: the extraction temperature was 60°C, the ultrasonic power was 70 W, the ultrasonic time was 30 min, and the liquid-to-solid ratio was set to 1:5, 1:10, 1:15, 1:20 and 1:25 respectively.

[0040] Each group of the above experiments was repeated 3 times, and the average value was taken. The extract was treated with the method in Example 1 to determine the polysaccharide content of Limonium xanthophyllum.

[0041] Under the condition of only one variable factor, the effects of various extraction factors on the extraction rate of polysaccharides from Limonium scabra Figure 1 As shown in the figure, the extraction rate of polysaccharides first increases and then decreases with the increase of the variable value. When the extraction temperature is 80℃, the ultrasonic power is 90w, the extraction time is 40min, and the solid-liquid ratio is 1:20g / mL, the polysaccharide extraction rate is the highest.

[0042] Example 3: Model building

[0043] 1. Response surface design

[0044] According to the results of the single-factor experiment, four factors, extraction temperature (X1), ultrasonic power (X2), ultrasonic time (X3), and liquid-to-solid ratio (X4), were selected as variables. The Box-Behnken response surface design was performed using Design-Expert 8.0.6 software, with -1, 0, and 1 representing the variable levels. The true values ​​and coding levels of the independent variables are shown in Table 2.

[0045] Table 2 Box-Behnken test design factors and levels

[0046]

[0047] 2. Box-Behnken test and results

[0048] The experimental scheme obtained by Box-Behnken software is shown in Table 3, with a total of 29 groups. Each group was repeated 3 times and the polysaccharide content of Limonium xanthophyllum was measured. The average value was calculated and filled in Table 3, and analyzed by Box-Behnken software.

[0049] 3. Model building and variance analysis

[0050] Design-Expert 8.0.6 software was used to perform multivariate linear regression fitting analysis on the experimental scheme and experimental results, and the regression equation for the relationship between the polysaccharide content of Limonium xanthophyllum and various factors was obtained as follows. The results of variance analysis are shown in Table 4.

[0051] Y(%)=31.85+1.97X1+1.06X2+0.55X3-0.35X4-0.11X1X2-0.030X1X3+0.098X1X4+0.70X2X3-0.14X2X4-0.19X3X4-3.52X1 2 -3.00X2 2 -3.45X3 2 -2.16X4 2

[0052] Wherein, Y represents the polysaccharide content of Limonium xanthophyllum, X1 represents the extraction temperature, X2 represents the ultrasonic power, X3 represents the ultrasonic time, and X4 represents the solid-liquid ratio.

[0053] Table 3 Box-Behnken test results

[0054]

[0055]

[0056] Table 4 Response surface quadratic simulation variance analysis

[0057]

[0058] Note: P≤0.01 indicates that the factor has a very significant effect on the response value; P≥0.05 indicates that the factor has a significant effect on the response value.

[0059] As shown in Table 3, the model is extremely significant (P = 0.0001 < 0.01), and the lack of fit term is not significant (P = 0.8986 > 0.05), indicating that non-experimental factors have little effect on the results and the model has good experimental stability. 2 =0.987, indicating that the model fits the actual experiment well and the results can be explained by the fitted model. Corrected determination coefficient R 2 Adj is 0.974, which is consistent with R 2 The results are close, indicating that the model has sufficient accuracy and universality. Therefore, this model can be used to analyze and predict the influence of various factors on the extraction rate in the extraction experiment of Limonium truncatum. The order of factors affecting the yield of polysaccharides from Limonium truncatum is as follows: extraction temperature > ultrasonic power > ultrasonic time > solid-liquid ratio.

[0060] 4. Response surface interaction analysis

[0061] The response surface and contour lines of the model are shown in Figure 2 , which intuitively reflects the impact of each factor on the response value.

[0062] The shape of the contour line reflects the interaction between the factors. The elliptical contour line indicates that the interaction between the two is significant. The response surface diagram is formed by fixing the ultrasonic power, ultrasonic time, liquid-to-solid ratio and extraction time in sequence. The contour line diagram is elliptical and the 3D diagram is steep, indicating that the interaction is more significant. Figure 2 It can be seen that the response surface curve of extraction temperature is significantly steeper than the curves of ultrasonic power, ultrasonic time and solid-liquid ratio, indicating that the extraction temperature has a more significant effect on the response value of polysaccharide extraction.

[0063] Through response surface software Box-Behnken analysis and mathematical regression model optimization of data, the optimal extraction process for ultrasound-assisted extraction of polysaccharides from Limonium xanthophyllum was obtained as follows: extraction temperature 83°C, ultrasonic power 84W, ultrasonic time 41min, solid-liquid ratio 1:20, and the predicted polysaccharide extraction rate was 32.36%.

[0064] 5. Process verification test

[0065] The extraction was carried out under the optimized conditions (extraction temperature 83°C, ultrasonic power 84W, ultrasonic time 41min, solid-liquid ratio 1:20), and the determination was repeated 3 times under this condition. The content of polysaccharide in Limonium fulgens was determined, and the average value was 32.11% (see Table 5), which was close to the theoretical calculated value, indicating that the optimization scheme was feasible.

[0066] Table 5 Confirmatory results analysis

[0067]

[0068] During the ultrasonic extraction process, the extraction temperature, ultrasonic power, ultrasonic time and material-liquid ratio will affect the content of the obtained extract. The single factor results show that under the condition of only one variable factor, the extraction rate of polysaccharides first increases and then decreases with the increase of the variable value. However, when the factors affect each other, the polysaccharide content in the extract of Limonium truncatum was determined by the extraction process optimized by the response surface methodology, and the total polysaccharide content in the extract of Limonium truncatum was 32.11% in the validation test of the optimal extraction process, which is not much different from the simulation prediction value of 32.26%, indicating that the optimized extraction process parameters obtained based on the response surface methodology are accurate and reliable, and have good stability.

[0069] Example 4: Study on the in vitro antioxidant activity of Limonium truncatum antioxidant feed additive

[0070] 1. Scavenging effect of DPPH free radicals

[0071] Accurately weigh 100 mg of dry powder of Limonium fluorescens polysaccharide, fully dissolve it with appropriate amount of up water (10 ml), and prepare 10 ml of extract mother solution with a concentration of 10 mg / ml. Pipette extract solutions of different concentrations (31.25 μg / mL~1 mg / mL), 100 μl of VC solution are added to 96-well plates, 200 μl of 0.2 mM DPPH solution is added to each well, mixed and placed in a dark place for 30 min, the absorbance Ai is measured at 517 nm, ethanol is used instead of DPPH solution to measure Aj, double distilled water is used instead of extract solution to measure A0, and each sample is repeated three times.

[0072]

[0073] Figure 3A shows the scavenging activity of Limonium chrysantha polysaccharide on DPPH free radicals compared with VC. At the lowest concentration (31.25 μg / mL), the scavenging rate of Limonium chrysantha polysaccharide on DPPH is still 24.8%. Moreover, with the increase of the concentration of Limonium chrysantha polysaccharide, its scavenging activity gradually increases, indicating that the scavenging effect of Limonium chrysantha polysaccharide is closely related to the concentration of Staphylococcus aureus polysaccharide in the range of 31.25 μg / mL to 1 mg / mL. When the concentration of Limonium chrysantha polysaccharide and VC increases from 31.25 μg / ml to 250 μg / ml, the scavenging activity of Limonium chrysantha polysaccharide and VC on DPPH free radicals increases quadratically. At the doses of 500 and 1000 μg / ml, there is no significant difference in the scavenging ability of Limonium chrysantha polysaccharide and VC on DPPH (p>0.05). Therefore, compared with VC, we believe that Limonium chrysantha polysaccharide has a very strong scavenging effect on DPPH free radicals.

[0074] 2. Scavenging effect of OH free radicals

[0075] 50 μl of different concentrations of Limonium polysaccharide solution and VC solution were respectively added to a 96-well plate, and 50 μl of 9 mM FeSO4 solution was added in sequence. After mixing, 50 μl of 9 mM salicylic acid-ethanol was added, and finally 50 μl of 3.8 mM H2O2 solution was added. Mix well, react at 37 °C for 30 min, and measure the absorbance Ai at 510 / 532 nm. Distilled water was used instead of hydrogen peroxide solution to measure Aj, and double distilled water was used instead of extract solution to measure A0. Each sample was repeated three times.

[0076]

[0077] The experimental results showed that the polysaccharide of Limonium scabra had the ability to scavenge hydroxyl free radicals in the concentration range of 31.25-1000 μg / mL. Figure 3 B. The hydroxyl radical scavenging effect of VC and Limonium sibiricum polysaccharide increases with the increase of their concentration. When the VC concentration reaches 1000μg / ml, VC can effectively scavenge almost 100% of hydroxyl radicals. At the same time, the scavenging effect of Limonium sibiricum polysaccharide was also studied. At the highest concentration (1000μg / mL), the scavenging rate of Limonium sibiricum polysaccharide on hydroxyl radicals was 33.6%, which was lower than 50%.

[0078] 3. Fe 2+ Chelating ability

[0079] 100 μl of different concentrations of Limonium sibiricum polysaccharide solution and EDTA-2Na were respectively added to a 96-well plate, and 5 μl of 2 mM FeCl2 solution and 20 μl of 5 mM ferrozine were added in sequence. The plate was allowed to stand at room temperature for 10 min, and 75 μl of distilled water was added. The absorbance Ai was measured at 560 / 562 nm. Distilled water was used instead of ferrozine solution to measure Aj, and double distilled water was used instead of Limonium sibiricum polysaccharide solution to measure A0.

[0080] Each sample was repeated three times. EDTA-2Na was used as a positive control.

[0081]

[0082] Antioxidants are often used as metal ion chelators to prevent free radical chain reactions. Chelators can inhibit the formation of OH by forming complexes with iron ions, thereby exerting their antioxidant effects. Therefore, this study determined the iron ion chelating ability of Staphylococcus aureus polysaccharides. Figure 3 C It can be seen that as the content of Limonium sibiricum polysaccharide increases from 250μg / mL to 1000μg / mL, the iron ion chelating ability is significantly improved. At a concentration of 1000μg / mL, the chelating ability of Limonium sibiricum polysaccharide is 62.7%. At concentrations of 250μg / mL and 500μg / mL, the chelating rates of EDTA-2Na are 54.5% and 68.8%, respectively. It is well known that EDTA-2Na is a strong chelating agent and is often used to chelate metal ions and separate metals. Therefore, compared with EDTA-2Na, Limonium sibiricum polysaccharide has a certain iron ion chelating ability, but this ability is not strong.

[0083] 4. Determination of total reducing power

[0084] Take 100 μl of different concentrations of Limonium xanthophyllum polysaccharide solution and VC solution respectively, add 250 μl of phosphate buffer (pH=6.6) and potassium ferrocyanide (K3Fe(CN)6) solution (1wt%) respectively, mix well and place in a 50°C water bath for 20 min, then add 250 μl of trichloroacetic acid solution (10wt%), mix well and centrifuge at 4000 rpm for 10 min, take 50 μl of supernatant, add to a 96-well plate, add 50 μl of distilled water and ferric chloride (FeCl3, 0.1wt%) respectively, mix well, let stand for 10 min, measure the absorbance at 700 nm, and repeat three times for each sample.

[0085] Ferric reducing power=A i -A j

[0086] Potassium ferrocyanide (Fe 2+) is formed by the reaction of a substance with a reduction potential with ferric chloride to form a trivalent iron complex with maximum absorption at 700nm. Figure 3 D shows that the iron reducing ability of VC and Limonium sibiricum polysaccharide is dose-dependent. The iron reducing power of Limonium sibiricum polysaccharide increases linearly, and its curve shape is similar to that of VC. The results show that the reducing power of Limonium sibiricum polysaccharide is close to that of VC, but the reducing power of the sample is slightly weaker than that of VC. Based on the strong reducing power of VC, we concluded that Limonium sibiricum polysaccharide has strong reducing power.

[0087] In summary, the present invention provides an optimized preparation process of an antioxidant feed additive, and shows strong reducing ability and DPPH scavenging effect. The content of polysaccharide extracted from the antioxidant feed additive reaches 32.26%, which is significantly improved compared with the prior art, and the process conditions of the method are simple, safe, low-cost, and easy to industrialize.

[0088] It provides technical support and theoretical basis for the industrial production of polysaccharide antioxidant feed additives from Limonium cannabinum, expands new research and application ideas for natural plants with antioxidant activity, and has certain guiding significance for the comprehensive utilization of Limonium cannabinum.

[0089] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing an antioxidant feed additive, characterized in that: The steps include: Step 1: Take Limonium sibiricum as a raw material, air-dry and crush the raw material to obtain a crushed raw material drug; Step 2: Place an appropriate amount of distilled water in a 250 ml conical flask, add the crushed API obtained in step 1 to the solvent, set the corresponding extraction temperature, ultrasonic power, ultrasonic time and material-liquid ratio to perform ultrasonic extraction, repeat the extraction 3 times, combine the extracts, filter and concentrate; Step 3, adding anhydrous ethanol to the concentrated solution obtained in step 2 until the ethanol content is 80% for alcohol precipitation, the alcohol precipitation solution is allowed to stand at 4°C for 24 hours, the precipitate is collected by centrifugation, vacuum freeze-dried at -40°C, and ground into powder to obtain Limonium sibiricum polysaccharide, i.e., an antioxidant Limonium sibiricum feed additive; Step 4: Conduct a single factor test according to 4 factors and 5 levels to examine the effects of extraction temperature X1, ultrasonic power X2, ultrasonic time X3, and liquid-to-solid ratio X4 on the yield of polysaccharides from Limonium scabra. Step 5: Based on the single factor level of step 4, select the range of factors that have a significant impact on Limonium scabra polysaccharide, conduct Box-Behnken response surface design, and conduct experiments according to the combination of factor levels; Step 6: Analyze the test data using Design-Expert 8.0.6 statistical analysis software; the formula for extracting polysaccharides from Limonium truncatum is: Y(%)=31.85+1.97X1+1.06X2+0.55X3-0.35X4-0.11X1X2-0.030X1X3+0.098X1X4+0.70 X2X3-0.14X2X4-0.19X3X4-3.52X1 2 -3.00X2 2 -3.45X3 2 -2.16X4 2 Wherein, Y represents the polysaccharide content of Limonium xanthophyllum, X1 represents the extraction temperature, X2 represents the ultrasonic power, X3 represents the ultrasonic time, and X4 represents the solid-liquid ratio.

2. The method for preparing an antioxidant feed additive according to claim 1, characterized in that: In step 2, the extraction temperature is 70-90° C., the ultrasonic power is 60-100 W, the ultrasonic time is 30-50 min, and the liquid-to-solid ratio is 1:15-1:

25.

3. The method for preparing an antioxidant feed additive according to claim 1, characterized in that: In step 2, the ultrasonic extraction was repeated 3 times for each test, the mixture was combined, filtered, and the filtrate was concentrated under reduced pressure in a water bath at 50°C and a vacuum degree of -0.07 MPa, and further alcohol precipitation, centrifugation, and drying were performed to obtain the polysaccharide of Limonium xanthophyllum.

4. The method for preparing an antioxidant feed additive according to claim 1, characterized in that: In step five, analysis revealed that the optimal extraction process had an extraction temperature of 83°C, an ultrasonic power of 84W, an ultrasonic time of 41min, and a solid-liquid ratio of 1:

20.

5. A polysaccharide from Limonium xanthophyllum obtained by extracting the preparation method of an antioxidant feed additive as described in any one of claims 1 to 4.

6. Use of the polysaccharide of Limonium xanthophyllum according to claim 5 as an antioxidant feed additive in the preparation of antioxidant feed.

7. The use according to claim 6, characterized in that: Determination of the DPPH free radical scavenging activity, iron ion chelating ability, hydroxyl free radical scavenging activity and total reducing power of Limonium xanthophyllum polysaccharide as an antioxidant feed additive.

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