Natural compound coloring agent for cigarette paper and preparation method of natural compound coloring agent

Abstract

The invention relates to a natural compound colorant for cigarette paper and a preparation method thereof, crabapple polysaccharide, crabapple pigment and crabapple flavone in the colorant are extracted from crabapple fruits, and the pigment is composed of the following components: 3-15 parts of crabapple polysaccharide, 1-20 parts of crabapple pigment, 1-15 parts of natural blue pigment, 1-15 parts of natural yellow pigment and 1-8 parts of an auxiliary agent. And 0.1 to 0.5 part of an antioxidant. The invention provides the natural pigment for the cigarette paper, which has better oxidation resistance and can enhance the ash wrapping effect of the cigarette paper.

Description

Technical Field

[0001] The invention belongs to the technical field of cigarette paper and relates to a natural compound colorant for cigarette paper and a preparation method thereof. Background Art

[0002] Cigarette paper is a very important material for cigarettes. It not only wraps the tobacco, but also participates in the burning of the cigarette. Cigarette paper has a direct impact on the burning, tar reduction and ash wrapping of cigarettes. The natural extracts and pigments in colored cigarette paper can increase the aroma of cigarettes and make the smoke soft and delicate, thereby improving the smoking quality of cigarettes. At the same time, colored cigarette paper forms a strong visual contrast with white cigarette paper, which produces a certain visual stimulation for consumers.

[0003] Currently, the commonly used pigments for cigarette paper include chemical synthetic pigments and natural pigments. Natural pigments are pigments obtained from animal and plant cell tissues in nature through certain technical means. Compared with synthetic pigments, they are non-toxic and have natural colors. Most natural pigments also have antioxidant, free radical scavenging and pharmacological effects. When natural pigments are used as pigments for cigarette paper, they can also bring in the unique aroma of natural pigments, which is in harmony with the aroma of tobacco, and can bring consumers dual sensory stimulation of vision and smell, thereby increasing the recognition characteristics of cigarettes. For example, the natural pigments of the gardenia series have the scent of gardenia itself. When used as a colorant, it can bring a subtle floral scent to the cigarette paper, giving consumers a different sensory experience.

[0004] Red ginseng is a perennial herb of the Campanulaceae family. It is also known as spider fruit and water chestnut. It tastes sweet and slightly bitter. It has the effects of moistening the lungs, relieving coughs, nourishing, regulating qi, etc. Red ginseng is rich in polysaccharides, proanthocyanidins and flavonoids.

[0005] Polysaccharides have many primary and secondary groups. Due to their special structure, they can improve the ash retention effect. The natural polysaccharides extracted from the fruit of red ginseng can be used as cigarette paper additives.

[0006] The invention prepares a composite cigarette paper colorant with good antioxidant property and good ash wrapping effect by using red ginseng pigment, red ginseng polysaccharide and flavonoids extracted from red ginseng fruit in cigarette paper colorant. Summary of the invention

[0007] The purpose of the present invention is to provide a natural colorant for cigarette paper with good oxidation resistance and capable of enhancing the ash wrapping effect of cigarette paper and a preparation method thereof in view of the problems that the existing natural pigments for cigarette paper are easily oxidized and faded and have poor ash wrapping effect.

[0008] According to the purpose of the present invention, the present invention provides a natural compound colorant for cigarette paper, which is compounded by the following components: 3-15 parts of red ginseng polysaccharide, 1-20 parts of red ginseng pigment, 1-15 parts of natural blue pigment, 1-15 parts of natural yellow pigment, 1-8 parts of auxiliary agent, and 0.1-0.5 parts of antioxidant.

[0009] Furthermore, the natural blue pigment is one of gardenia blue and seaweed blue, or a combination of both.

[0010] Furthermore, the natural yellow pigment is any one or more combinations of curcumin, gardenia yellow pigment, tea yellow pigment, β-carotene, and monascus yellow pigment.

[0011] Furthermore, the auxiliary agent is one or more of potassium or sodium salts of citric acid, malic acid, tartaric acid, phosphoric acid, etc.

[0012] Furthermore, the antioxidant is any one or more combinations of red ginseng flavonoids, VC, tannic acid, and tea polyphenols.

[0013] The method for preparing the above-mentioned natural compound colorant for cigarette paper comprises the following steps:

[0014] Step 1: Take red ginseng pigment, natural blue pigment, natural yellow pigment, add red ginseng polysaccharide, additives and antioxidants, add pure water, stir and mix to ensure that the materials are evenly mixed;

[0015] Step 2: Heat the material obtained in step 1 to 40° C., keep it warm for 10 minutes, and then naturally cool it to room temperature. The obtained material is the colorant used for cigarette paper.

[0016] The preparation of the red ginseng polysaccharide in the above-mentioned natural composite colorant for cigarette paper comprises the following steps: washing and removing impurities from the red ginseng fruit, drying the surface moisture, slicing (thickness of about 2-3 mm), freeze-drying (-50°C, 48 hours), sieving with a 60-mesh sieve after crushing, microwave-assisted extraction (70°C, solid-liquid ratio of 1:20 (g / ml), extraction time of 30 min) three times, centrifugal separation (speed: 5000 rpm, time: 15 min, temperature: 4°C), taking the supernatant and rotary evaporating (temperature: 5 0℃, vacuum degree: -0.08MPa, concentrated to 1 / 5 of the original volume), ethanol precipitation (ethanol concentration: 80%, 4 times the volume of anhydrous ethanol, precipitation temperature: 4℃, precipitation time: 12 hours), centrifugal collection of precipitates (speed: 6000rpm, time: 20min, temperature: 4℃), dissolution of the precipitate with distilled water to remove the protein (add Sevag reagent, the ratio of Sevag reagent is chloroform: n-butanol = 4:1, v / v, oscillate for 30min, let stand to separate, take the supernatant and repeat 3 times). The liquid was subjected to membrane dialysis (dialysis bag molecular weight cutoff: 3500Da, dialysate: distilled water, dialysis time: 48h, and the dialysate was replaced every 12h), and the liquid in the dialysis bag after dialysis was concentrated by rotary evaporation (temperature: 50°C, vacuum degree: -0.08MPa, concentrated to 10-20mg / mL), purified by DEAE-52 ion exchange chromatography (column: 2.6×30cm, eluent: 0.1MNaCl solution, gradient elution 0-0.5MNaCl, flow rate: 1mL / min, collecting the main peak portion), and freeze-dried (pre-freezing: -80°C, 4 hours, followed by -50°C, 24 hours) to obtain red ginseng polysaccharide.

[0017] The extraction of red ginseng pigment from the above-mentioned natural compound colorant for cigarette paper includes the following steps: using supercritical CO2 extraction, crushing the dried red ginseng fruit into 80 mesh samples, adding 75% ethanol (the solid-liquid ratio is 1:1.5), the CO2 flow rate is 4L / h, the extraction time is 70min, the extraction temperature is 50°C, the extraction pressure is 35Mpa, and the red ginseng pigment is obtained.

[0018] The method for extracting flavonoids from the natural compound colorant for cigarette paper comprises the following steps: washing fresh ginseng, slicing (thickness of about 1-2 mm), vacuum drying at 50°C for 24 hours, and grinding into 60-80 mesh powder using a low-temperature pulverizer. Supercritical CO2 extraction and degreasing: extraction pressure 25MPa, extraction temperature 45°C, extraction time 2h, CO2 flow rate: 20L / h. Ultrasonic assisted solvent extraction: adding 70% ethanol by volume at a material-liquid ratio of 1:8, ultrasonic power 400W, ultrasonic frequency 40kHz, extraction temperature 60°C, extraction time 45min, repeating the extraction twice, and vacuum filtering. Accelerated solvent extraction (ASE): solvent 70% ethanol, temperature 80°C, pressure 10MPa, static extraction time 5min, and circulating 3 times. Rotary evaporation concentration: temperature 45°C, pressure -0.08MPa, concentrated to 1 / 10 of the original volume. Macroporous adsorption resin purification: X-5 macroporous adsorption resin, pretreatment: 95% ethanol activation for 24 hours, deionized water washing until alcohol-free, column loading: inner diameter 5cm, height 50cm, sample loading: dilute the concentrate with deionized water, adjust pH to 5.0, sample loading concentration 4g / L, elution: a) deionized water elution (2 column volumes), b) 30% ethanol elution (2 column volumes), c) 70% ethanol elution (5 column volumes), flow rate: 2.5mL / min, collect 70% ethanol eluate. Spray drying: feed temperature 180℃, discharge temperature 85℃, atomization pressure 0.4MPa, feed rate: 15mL / min. Obtain the red ginseng flavonoid extract.

[0019] The beneficial effects of the present invention are:

[0020] (1) Red ginseng is rich in polysaccharides, proanthocyanidins and flavonoids. Extracting polysaccharides, pigments and flavonoids from red ginseng can achieve multiple uses. Applying it to cigarette paper can ensure consistent smoking taste.

[0021] (2) Panax ginseng polysaccharide has many primary and secondary groups. Due to its special structure, it has a certain improvement in ash retention and can enhance the ash wrapping effect of cigarette paper.

[0022] (3) Panax notoginseng flavonoids are a kind of substance with good antioxidant properties. They can scavenge hydroxyl radicals (·OH) and superoxide anion radicals (O2-·). In addition to improving the fading effect of cigarette paper, they can also improve the taste of smoke. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the extraction and preparation process of red ginseng polysaccharides.

[0024] Figure 2 This is the process flow for extracting and preparing red ginseng pigment.

[0025] Figure 3 This is the process flow of extracting and preparing flavonoids from red ginseng.

[0026] Figure 4 The invention discloses a process for preparing a natural compound colorant for cigarette paper.

[0027] Figure 5 This is a comparison diagram of the static ash column in Example 1.

[0028] Figure 6 This is a comparison diagram of the static ash column in Example 2.

[0029] Figure 7 This is a comparison diagram of the static ash column in Example 3. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Embodiment 1:

[0032] like Figure 4 As shown, a method for preparing a natural compound colorant for cigarette paper comprises the following steps:

[0033] Step 1: Take 20 parts of natural pigments (including 10 parts of red ginseng pigments, 6 parts of gardenia yellow, and 4 parts of gardenia blue), 0.2 parts of red ginseng flavonoids, 5 parts of red ginseng polysaccharides, 4 parts of additives (including 2 parts of sodium citrate and 2 parts of potassium citrate), and 69.8 parts of pure water, stir and mix for 30 minutes to ensure that the materials are evenly mixed.

[0034] Step 2: Heat the material obtained in step 1 to 40° C., keep it warm for 10 minutes, and then naturally cool it to room temperature. The obtained material is the colorant used for cigarette paper.

[0035] Step 3: Soak the cigarette paper in the colorant for 5 seconds, take it out after it reaches saturation, scrape off the excess dye with a glass rod, put the cigarette paper in a 90℃ oven, bake for 3 minutes, and ensure that the paper is dry.

[0036] Evaluation of smoking colored cigarettes:

[0037]

[0038] Comprehensive description: The dyed cigarette paper has a light fruity aroma, good harmony, a slight irritation reduction effect, a slightly improved smoke quality, and a slight moisturizing effect.

[0039] The cigarette paper dyed with this formula is brown, which is closer to the color of freshly cured tobacco leaves and gives a natural feel.

[0040] Evaluation of the ash packaging effect:

[0041] The 3-sides-3-cigarette experiment method was used: 15 colored cigarette papers No. 1 were randomly divided into 5 groups, 3 cigarettes in each group, and the image data of 3 cigarettes in the same group were collected from different burning surfaces: the overlap surface A of the cigarette paper, the back surface B of the overlap surface, and the side surface C of the overlap surface. Figure 5 As shown:

[0042] Observe the static ash column: After lighting the cigarette, insert it into the cigarette holder of the test box and let it burn to more than 2 / 3 of the length of the cigarette to form a vertical ash column. Compare the ash value and grayscale value to determine the ash effect.

[0043] According to the experimental results, the concentration of red ginseng polysaccharide has a significant improvement on ash wrapping, the ash color is whiter than the standard sample, and the number and area of ​​cracks on the cigarette paper are significantly less than the standard sample. Comprehensive comparison shows that the ash wrapping effect of this cigarette paper is better than the standard sample.

[0044] After the cigarette paper was dyed, it was placed in a cool place without direct sunlight for one month and then compared with the fading of the newly dyed cigarette paper. The cigarette paper dyed with pigment No. 1 had slight fading.

[0045] Embodiment 2:

[0046] like Figure 4 As shown, a method for preparing a natural compound colorant for cigarette paper comprises the following steps:

[0047] Step 1: Take 30 parts of natural pigments (including 6 parts of red ginseng pigments, 7 parts of gardenia yellow, and 17 parts of gardenia blue), 0.4 parts of antioxidants (red ginseng flavonoids: VC=1:1), 3 parts of red ginseng polysaccharides, 4 parts of auxiliary agents (including 2 parts of sodium citrate and 2 parts of potassium citrate), and 62.6 parts of pure water, stir and mix for 30 minutes to ensure that the materials are evenly mixed.

[0048] Step 2: Heat the material obtained in step 1 to 40° C., keep it warm for 10 minutes, and then naturally cool it to room temperature. The obtained material is the colorant used for cigarette paper.

[0049] Step 3: Soak the cigarette paper in the colorant for 5 seconds, take it out after it reaches saturation, scrape off the excess dye with a glass rod, put the cigarette paper in a 90℃ oven, bake for 3 minutes, and ensure that the paper is dry.

[0050] Evaluation of smoking colored cigarettes:

[0051]

[0052] Comprehensive description: The dyed cigarette paper has fruity and floral aromas, which are more comfortable and harmonious when combined with the tobacco aroma. It has a slight smell and has a better effect of reducing irritation and increasing moisturizing.

[0053] The cigarette paper dyed with this formula pigment is black, creating a strong visual contrast.

[0054] Evaluation of the ash packaging effect:

[0055] The 3-sides-3-cigarette experiment method was used: 15 colored cigarette papers No. 1 were randomly divided into 5 groups, 3 cigarettes in each group, and the image data of 3 cigarettes in the same group were collected from different burning surfaces: the overlap surface A of the cigarette paper, the back surface B of the overlap surface, and the side surface C of the overlap surface. Figure 6 As shown:

[0056] Observe the static ash column: After lighting the cigarette, insert it into the cigarette holder of the test box and let it burn to more than 2 / 3 of the length of the cigarette to form a vertical ash column. Compare the ash value and grayscale value to determine the ash effect.

[0057] According to the experimental results, the concentration of red ginseng polysaccharide has no obvious effect on ash wrapping, the ash color is close to the standard sample, and the number and area of ​​cracks on the cigarette paper are slightly more than the standard sample. Comprehensive comparison shows that the ash wrapping effect of colored cigarette paper under this formula is not good.

[0058] After the cigarette paper is dyed, it is placed in a cool place without direct sunlight for one month and then compared with the fading of the newly dyed cigarette paper. The cigarette paper dyed with pigment No. 2 has no obvious fading phenomenon, indicating that this concentration and ratio of antioxidants have a good antioxidant effect and a better color protection effect.

[0059] Embodiment 3:

[0060] like Figure 4 As shown, a method for preparing a natural compound colorant for cigarette paper comprises the following steps:

[0061] Step 1: Take 25 parts of natural pigments (including 17 parts of red ginseng pigments, 2 parts of gardenia yellow, and 6 parts of gardenia blue), 0.5 parts of antioxidants (red ginseng flavonoids: VC=1:1), 7 parts of red ginseng polysaccharides, 4 parts of auxiliary agents (including 2 parts of sodium citrate, 2 parts of potassium citrate), and 63.5 parts of pure water, stir and mix for 30 minutes to ensure that the materials are evenly mixed.

[0062] Step 2: Heat the material obtained in step 1 to 40° C., keep it warm for 10 minutes, and then naturally cool it to room temperature. The obtained material is the colorant used for cigarette paper.

[0063] Step 3: Soak the cigarette paper in the colorant for 5 seconds, take it out after it reaches saturation, scrape off the excess dye with a glass rod, put the cigarette paper in a 90℃ oven, bake for 3 minutes, and ensure that the paper is dry.

[0064]

[0065] Comprehensive description: The dyed cigarette paper has a sweet fruity aroma, which is in good harmony with the smoke, has the effect of reducing irritation and removing impurities, promoting salivation and adding sweetness to the smoke.

[0066] The colorant of this formula appears brown when dyed on cigarette paper, which is similar to the color of cigars and gives a sense of luxury.

[0067] Evaluation of the ash packaging effect:

[0068] The 3-sides-3-cigarette experiment method was used: 15 colored cigarette papers No. 1 were randomly divided into 5 groups, 3 cigarettes in each group, and the image data of 3 cigarettes in the same group were collected from different burning surfaces: the overlap surface A of the cigarette paper, the back surface B of the overlap surface, and the side surface C of the overlap surface. Figure 7 As shown:

[0069] Observe the static ash column: After lighting the cigarette, insert it into the cigarette holder of the test box and let it burn to more than 2 / 3 of the length of the cigarette to form a vertical ash column. Compare the ash value and grayscale value to determine the ash effect.

[0070] According to the experimental results, the concentration of red ginseng polysaccharide has a significant improvement on the ash wrapping effect, the ash color is similar to the standard sample, and the number and area of ​​cracks on the cigarette paper are significantly less than the standard sample. Comprehensive comparison shows that the colored cigarette paper with this formula has a better ash wrapping effect.

[0071] After the cigarette paper is dyed, it is placed in a cool place without direct sunlight for one month and then compared with the fading of the newly dyed cigarette paper. The cigarette paper dyed with pigment No. 3 has no obvious fading phenomenon, indicating that this concentration and ratio of antioxidants have a good antioxidant effect and a better color protection effect.

[0072] In the above embodiment, Figure 1As shown in the figure, the preparation of red ginseng polysaccharide includes the following steps: washing and removing impurities from the red ginseng fruit, drying the surface moisture, slicing (thickness of about 2-3 mm), freeze-drying (-50°C, 48 hours), crushing and sieving with a 60-mesh sieve, microwave-assisted extraction (70°C, solid-liquid ratio 1:20 (g / ml), extraction time 30 min) three times, centrifugal separation (speed: 5000 rpm, time: 15 min, temperature: 4°C), taking the supernatant and rotary evaporating (temperature: 50°C, vacuum degree : -0.08MPa, concentrated to 1 / 5 of the original volume), ethanol precipitation (ethanol concentration: 80%, 4 times the volume of anhydrous ethanol, precipitation temperature: 4°C, precipitation time: 12 hours), centrifugal collection of the precipitate (speed: 6000rpm, time: 20min, temperature: 4°C), dissolution of the precipitate with distilled water to remove the protein (add Sevag reagent, the ratio of Sevag reagent is chloroform: n-butanol = 4:1, v / v, oscillation for 30min, standing for stratification, taking the supernatant and repeating 3 times). The liquid was subjected to membrane dialysis (dialysis bag molecular weight cutoff: 3500Da, dialysate: distilled water, dialysis time: 48h, and the dialysate was replaced every 12h), and the liquid in the dialysis bag after dialysis was concentrated by rotary evaporation (temperature: 50°C, vacuum degree: -0.08MPa, concentrated to 10-20mg / mL), purified by DEAE-52 ion exchange chromatography (column: 2.6×30cm, eluent: 0.1MNaCl solution, gradient elution 0-0.5MNaCl, flow rate: 1mL / min, collecting the main peak portion), and freeze-dried (pre-freezing: -80°C, 4 hours, followed by -50°C, 24 hours) to obtain red ginseng polysaccharide.

[0073] In the above embodiment, if Figure 2 As shown, the extraction of red ginseng pigment includes the following steps: using supercritical CO2 extraction, crushing the dried red ginseng fruit into 80 mesh samples, adding 75% ethanol (solid-liquid ratio is 1:1.5), CO2 flow rate is 4L / h, extraction time is 70min, extraction temperature is 50℃, extraction pressure is 35Mpa, and red ginseng pigment is obtained.

[0074] In the above embodiment, if Figure 3As shown in the figure, the extraction method of flavonoids from red ginseng includes the following steps: washing fresh red ginseng, slicing (thickness of about 1-2 mm), vacuum drying at 50°C for 24 hours, and grinding into 60-80 mesh powder using a low-temperature pulverizer. Supercritical CO2 extraction and degreasing: extraction pressure 25MPa, extraction temperature 45°C, extraction time 2h, CO2 flow rate: 20L / h. Ultrasonic assisted solvent extraction: adding 70% ethanol by volume at a material-liquid ratio of 1:8, ultrasonic power 400W, ultrasonic frequency 40kHz, extraction temperature 60°C, extraction time 45min, repeating the extraction twice, and vacuum filtering. Accelerated solvent extraction (ASE): solvent 70% ethanol, temperature 80°C, pressure 10MPa, static extraction time 5min, and cycle 3 times. Rotary evaporation concentration: temperature 45°C, pressure -0.08MPa, concentrated to 1 / 10 of the original volume. Macroporous adsorption resin purification: X-5 macroporous adsorption resin, pretreatment: 95% ethanol activation for 24 hours, deionized water washing until alcohol-free, column loading: inner diameter 5cm, height 50cm, sample loading: dilute the concentrate with deionized water, adjust pH to 5.0, sample loading concentration 4g / L, elution: a) deionized water elution (2 column volumes), b) 30% ethanol elution (2 column volumes), c) 70% ethanol elution (5 column volumes), flow rate: 2.5mL / min, collect 70% ethanol eluate. Spray drying: feed temperature 180℃, discharge temperature 85℃, atomization pressure 0.4MPa, feed rate: 15mL / min. Obtain the red ginseng flavonoid extract.

[0075] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A natural compound colorant for cigarette paper, characterized in that: The invention comprises the following raw materials in parts by weight: 3-15 parts of red ginseng polysaccharide, 1-20 parts of red ginseng pigment, 1-15 parts of natural blue pigment, 1-15 parts of natural yellow pigment, 1-8 parts of auxiliary agent, and 0.1-0.5 parts of antioxidant.

2. The natural compound colorant for cigarette paper according to claim 1, characterized in that: The natural blue pigment is one of gardenia blue and seaweed blue or a combination of both.

3. The natural compound colorant for cigarette paper according to claim 1, characterized in that: The natural yellow pigment is any one or more combinations of curcumin, gardenia yellow pigment, tea yellow pigment, beta-carotene and monascus yellow pigment.

4. The natural cigarette paper pigment according to claim 1, characterized in that: The auxiliary agent is one or more of potassium salts or sodium salts of citric acid, malic acid, tartaric acid, phosphoric acid and the like.

5. The natural compound colorant for cigarette paper according to claim 1, characterized in that: The antioxidant is any one or more combinations of red ginseng flavonoids, VC, tannic acid and tea polyphenols.

6. A method for preparing a natural compound colorant for cigarette paper according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Take red ginseng pigment, natural blue pigment, natural yellow pigment, add red ginseng polysaccharide, additives and antioxidants, add pure water, stir and mix to ensure that the materials are evenly mixed; Step 2: Heat the material obtained in step 1 to 40° C., keep it warm for 10 minutes, and then naturally cool it to room temperature. The obtained material is the colorant used for cigarette paper.

7. The method for preparing a natural compound colorant for cigarette paper according to claim 6, characterized in that: The preparation method of the red ginseng polysaccharide comprises the following steps: The red ginseng fruit was washed and cleaned, the surface moisture was dried, sliced ​​to a thickness of 2-3 mm, freeze-dried at -50°C for 48 hours, crushed and sieved with a 60-mesh sieve, microwave-assisted extraction, extraction temperature of 70°C, solid-liquid ratio of 1:20 g / ml, extraction time of 30 min, extracted three times, centrifuged at a speed of 5000 rpm, time of 15 min, temperature of 4°C, and the supernatant was rotary evaporated at 50°C and vacuum degree of -0.08 MPa, and concentrated to 1 / 5 of the original volume; Ethanol precipitation, ethanol concentration: 80%, 4 times the volume of anhydrous ethanol, precipitation temperature: 4°C, precipitation time: 12 hours, centrifugal collection of precipitate, precipitation speed: 6000rpm, time: 20min, temperature: 4°C, dissolve the precipitate with distilled water to remove the protein, add Sevag reagent, the ratio of Sevag reagent is chloroform: n-butanol = 4:1, v / v, shake for 30min, let stand and separate, take the supernatant and repeat 3 times; The liquid was subjected to membrane dialysis, the molecular weight cutoff of the dialysis bag was 3500Da, the dialysate was distilled water, the dialysis time was 48h, the dialysate was replaced every 12h, the liquid in the dialysis bag after dialysis was concentrated by rotary evaporation, the temperature was 50°C, the vacuum degree was -0.08MPa, and it was concentrated to 10-20mg / mL, and purified by DEAE-52 ion exchange chromatography, column: 2.6×30cm, eluent: 0.1MNaCl solution, gradient elution 0-0.5MNaCl, flow rate: 1mL / min, the main peak part was collected, freeze-dried, pre-frozen: -80°C, 4 hours, and then -50°C, 24 hours to obtain red ginseng polysaccharide.

8. The method for preparing a natural compound colorant for cigarette paper according to claim 6, characterized in that: The method for extracting red ginseng pigment comprises the following steps: using supercritical CO2 extraction, crushing sun-dried red ginseng fruit into 80-mesh samples, adding 75% ethanol, with a solid-liquid ratio of 1:1.5, a CO2 flow rate of 4 L / h, an extraction time of 70 min, an extraction temperature of 50° C., and an extraction pressure of 35 MPa to obtain the red ginseng pigment.

9. The method for preparing a natural compound colorant for cigarette paper according to claim 6, characterized in that: The method for extracting flavonoids from red ginseng comprises the following steps: washing fresh red ginseng, slicing the slices to a thickness of 1-2 mm, vacuum drying at 50° C. for 24 hours, and grinding the slices into 60-80 mesh powder using a low-temperature pulverizer; Supercritical CO2 extraction for fat removal: extraction pressure 25MPa, extraction temperature 45℃, extraction time 2h, CO2 flow rate: 20L / h; Ultrasonic-assisted solvent extraction: adding 70% ethanol by volume at a solid-liquid ratio of 1:8, ultrasonic power 400W, ultrasonic frequency 40kHz, extraction temperature 60℃, extraction time 45min, repeated extraction twice, vacuum filtration; Accelerated solvent extraction ASE: solvent 70% ethanol, temperature 80°C, pressure 10MPa, static extraction time 5min, 3 cycles; Rotary evaporation concentration: temperature 45°C, pressure -0.08MPa, concentrated to 1 / 10 of the original volume; Macroporous adsorption resin purification: X-5 macroporous adsorption resin, pretreatment: 95% ethanol activation for 24 hours, deionized water washing until alcohol-free, column loading: inner diameter 5cm, height 50cm, sample loading: dilute the concentrate with deionized water, adjust pH to 5.0, sample loading concentration 4g / L; Elution: a, deionized water elution, b, 30% ethanol elution, c, 70% ethanol elution, flow rate: 2.5 mL / min, collecting 70% ethanol eluate; spray drying: feed temperature 180°C, discharge temperature 85°C, atomization pressure 0.4 MPa, feed rate: 15 mL / min; obtain red ginseng flavonoids.

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