Method for extracting brown pigment from chestnut bracts

Abstract

The invention relates to the technical field of extraction, in particular to a method for extracting brown pigment from chestnut bracts. The extraction method provided by the invention comprises the following steps: carrying out multi-stage extraction on dried Chinese chestnut bud powder by adopting an ethanol aqueous solution to obtain an extract liquid; sequentially concentrating and drying the leach liquor to obtain the brown pigment in the chestnut bracts, the volume concentration of the ethanol aqueous solution is 30-70%; the grain size of the Chinese chestnut bud powder is less than 30 meshes. According to the method, the ethanol water solution with the volume concentration of 30-70% is used as an extracting agent, polyphenol compounds in Chinese chestnut bracts can be effectively dissolved, damage of a solvent to heat-sensitive components can be reduced, and the extraction rate of the brown pigment is increased; and a multi-stage extraction mode is adopted, so that effective components in the Chinese chestnut bracts can be more sufficiently extracted, and the total yield of the brown pigment is improved. In addition, the grain size of the Chinese chestnut bud powder is limited, so that the sufficient contact area of the Chinese chestnut bud powder and the ethanol water solution can be ensured, the extraction efficiency is improved, and the extraction time is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of extraction, and in particular to a method for extracting brown pigment from chestnut bracts. Background Art

[0002] Solvent extraction, also known as liquid-solid extraction, is a method that uses a solvent to extract a specific component from a solid sample. Chestnut bud pigment can contain up to 42.35% total polyphenols by weight, making it the primary component of chestnut bud pigment. Existing chestnut bud pigment extraction technologies primarily rely on solvent extraction. While simple, traditional solvent extraction methods often suffer from significant component loss, resulting in low chestnut bud pigment extraction yields. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a method for extracting brown pigment from chestnut husks. The extraction method provided by the present invention has a high extraction rate of chestnut husk brown pigment.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for extracting brown pigment from chestnut bracts, comprising the following steps:

[0006] The dried chestnut bud powder is subjected to multi-stage extraction using an ethanol aqueous solution to obtain an extract;

[0007] The extract is concentrated and dried in sequence to obtain the brown pigment in the chestnut husk;

[0008] The volume concentration of the ethanol aqueous solution is 30-70%;

[0009] The particle size of the chestnut husk powder is less than 30 meshes.

[0010] Preferably, the multi-stage extraction is performed in three steps;

[0011] The volume ratio of the ethanol-water solution used in the first extraction, the second extraction and the third extraction is 5:3:2.

[0012] Preferably, the temperatures for the first extraction, the second extraction and the third extraction are all 50-80° C., and the time for each extraction is 1.5-3.5 hours.

[0013] Preferably, the total material-liquid ratio of the multi-stage extraction is 1 g:10-30 mL.

[0014] Preferably, the concentration temperature is 43-45° C., and the vacuum degree is 0.09 MPa.

[0015] Preferably, the drying is vacuum drying, and the drying temperature is 55-60°C.

[0016] Preferably, the method for obtaining the dried chestnut bud powder comprises the following steps: drying, crushing and sieving the impurity-removed chestnut buds in sequence, and the sieved material is the dried chestnut bud powder.

[0017] Preferably, the drying temperature is 70-80°C.

[0018] The present invention provides a method for extracting brown pigment from chestnut buds, comprising the following steps: performing multi-stage extraction on dried chestnut bud powder using an ethanol aqueous solution to obtain an extract; sequentially concentrating and drying the extract to obtain the brown pigment from chestnut buds; the volume concentration of the ethanol aqueous solution is 30-70%; and the particle size of the chestnut bud powder is less than 30 meshes. The present invention uses an ethanol aqueous solution with a volume concentration of 30-70% with moderate polarity as an extractant, which can effectively dissolve polyphenol compounds in chestnut buds, while also reducing the damage of the solvent to heat-sensitive components such as polyphenol compounds (methyl gallate, protocatechuic aldehyde, resorcinol, etc.), polyphenol oxidase (PPO), peroxidase (POD), and sugar compounds, thereby improving the extraction rate of the brown pigment; the multi-stage extraction method can more fully extract the effective component (brown pigment) from the chestnut buds and improve the overall yield of the brown pigment. In addition, the particle size of the chestnut hull powder defined in the present invention can ensure sufficient contact area between the chestnut hull powder and the ethanol aqueous solution, thereby improving the extraction efficiency and shortening the extraction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a broken line graph of the extraction rate of chestnut bud pigment in Examples 1 to 5 and Comparative Example 1;

[0020] Figure 2 The figure is a line graph showing the extraction rate of the chestnut bud pigment in Example 1 and Examples 6 to 9;

[0021] Figure 3 The figure is a broken line graph of the extraction rate of chestnut bud pigment in Example 1, Examples 10-11 and Comparative Examples 2-3;

[0022] Figure 4 It is a line graph of the extraction rate of chestnut bract pigment in Example 1, Examples 12 to 14 and Comparative Example 4. DETAILED DESCRIPTION

[0023] The present invention provides a method for extracting brown pigment from chestnut bracts, comprising the following steps:

[0024] The dried chestnut bud powder is subjected to multi-stage extraction using an ethanol aqueous solution to obtain an extract;

[0025] The extract is concentrated and dried in sequence to obtain the brown pigment in the chestnut husk.

[0026] The invention adopts ethanol aqueous solution to carry out multi-stage extraction on dried chestnut bud powder to obtain an extract.

[0027] As an embodiment, the particle size of the chestnut hull powder is less than 30 mesh. In the present invention, under the above particle size, sufficient contact area between the chestnut hull powder and the solvent can be ensured, thereby improving the extraction efficiency.

[0028] As an embodiment, the method for obtaining the dried chestnut bud powder comprises the following steps: drying, crushing and sieving the impurity-removed chestnut buds in sequence, and the sieved material is the dried chestnut bud powder.

[0029] As an embodiment, the drying temperature is 70-80° C., and in a specific embodiment, it can be 70° C., 75° C. or 80° C.; the sieve size is 30 mesh.

[0030] As an embodiment, the volume concentration of the ethanol aqueous solution is 30-70%, and in specific embodiments, it can be 30%, 40%, 50%, 60% or 70%. The present invention uses an ethanol aqueous solution with a volume concentration of 30-70% with moderate polarity as an extractant, which can effectively dissolve the polyphenol compounds in the chestnut husk, and can also reduce the damage of the solvent to heat-sensitive components such as polyphenol compounds (methyl gallate, protocatechuic aldehyde, resorcinol, etc.), polyphenol oxidase (PPO), peroxidase (POD), and sugar compounds, thereby improving the extraction rate of brown pigment.

[0031] As an embodiment, the multi-stage extraction is performed in three steps, including a first extraction, a second extraction, and a third extraction. The present invention adopts a multi-stage extraction method to more fully extract the effective component (brown pigment) in the chestnut husk and improve the overall yield of the brown pigment.

[0032] As an embodiment, the volume ratio of the ethanol-water solution used in the first extraction, the second extraction and the third extraction is 5:3:2.

[0033] In the present invention, three extractions are helpful to gradually extract and reduce the active ingredients remaining in the solid matrix.

[0034] As an embodiment, the first extraction is to mix the dried chestnut bud powder with an ethanol aqueous solution, and perform the first extraction to obtain a first extract and a first residue respectively.

[0035] As an embodiment, the total material-liquid ratio of the multi-stage extraction is 1g:10-30mL. In specific embodiments, it can be 1g:10mL, 1g:15mL, 1g:20mL, 1g:25mL or 1g:30mL.

[0036] As an embodiment, during the second leaching, the first residue is mixed with an ethanol aqueous solution and subjected to a second leaching to obtain a second leachate and a second residue, respectively.

[0037] As an embodiment, the third leaching is to mix the second residue with an ethanol aqueous solution, and perform a third leaching to obtain a third leachate and a third residue respectively.

[0038] As an embodiment, the present invention combines the first leachate, the second leachate and the third leachate as the leachate.

[0039] As an embodiment, the temperature of the first extraction, the second extraction and the third extraction is 50-80°C, and in specific embodiments, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the time of each extraction is 1.5-3.5h, and in specific embodiments, it can be 1.5h, 2h, 2.5h, 3h or 3.5h.

[0040] If the extraction temperature is too high, it will affect the color value and stability of the brown pigment. High temperature causes structural changes in heat-sensitive components such as polyphenol compounds (methyl gallate, protocatechuic aldehyde, resorcinol, etc.), polyphenol oxidase (PPO), peroxidase (POD), and sugar compounds. For example, under high temperature conditions, sugars will react with brown pigment to produce black substances, resulting in a reduced extraction rate; low temperature leads to incomplete extraction. The present invention performs extraction in a water bath at 50 to 80°C. The conditions are mild and can improve the extraction rate and efficiency of brown pigment without destroying heat-sensitive components. After obtaining the extract, the present invention concentrates and dries the extract in sequence to obtain the brown pigment in chestnut husks.

[0041] In one embodiment, the concentration is carried out under reduced pressure, the concentration temperature is 43-45° C., and in a specific embodiment, it can be 43° C., 44° C., or 45° C., and the vacuum degree of the concentration is 0.09 MPa. In one embodiment, the concentration is carried out under reduced pressure in a rotary evaporator.

[0042] As an embodiment, the drying is vacuum drying.

[0043] As an embodiment, the drying temperature is 55-60°C, and in specific embodiments can be 55°C, 56°C, 57°C, 58°C, 59°C or 60°C.

[0044] In the present invention, reduced pressure concentration can remove the solvent at a lower temperature, reduce thermal degradation, and maintain the stability of the brown pigment active ingredient. In the present invention, vacuum drying can further reduce the drying temperature and protect heat-sensitive substances.

[0045] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] The impurity-removed chestnut husks were dried in a drying oven at 80°C, and then crushed through a 30-mesh sieve, and the sieved material was the dry chestnut husk powder;

[0048] Dried chestnut bud powder is mixed with 50 vol% ethanol aqueous solution, and the first extraction is carried out in a water bath at 70°C to obtain a first extract and a first residue, respectively; the first residue is mixed with 50 vol% ethanol aqueous solution, and the second extraction is carried out in a water bath at 70°C to obtain a second extract and a second residue, respectively; the third residue is mixed with 50 vol% ethanol aqueous solution, and the third extraction is carried out in a water bath at 70°C to obtain a third extract; wherein, the volume ratio of the 50 vol% ethanol aqueous solution added in the first extraction, the second extraction and the third extraction is 5:3:2, and the solid-liquid ratio of the chestnut bud powder and the 50 vol% ethanol aqueous solution (total amount) during the multi-stage extraction is 1 g:20 mL (abbreviated as 1:20); the extraction time for the first extraction, the second extraction and the third extraction is 3 h.

[0049] combining the first extract, the second extract, and the third extract to obtain an extract;

[0050] The extract is concentrated (temperature is 45° C., vacuum degree is 0.09 MPa) and dried (temperature is 60° C.) in sequence to obtain brown pigment in chestnut husks. The extraction rate of brown pigment in fresh chestnut husks is 81.20%.

[0051] Comparative Example 1

[0052] The only difference from Example 1 is that the volume concentration of the ethanol aqueous solution is 20% and the brown pigment extraction rate is 37.88%.

[0053] Example 2

[0054] The only difference from Example 1 is that the volume concentration of the ethanol aqueous solution is 30% and the brown pigment extraction rate is 51.36%.

[0055] Example 3

[0056] The only difference from Example 1 is that the volume concentration of the ethanol aqueous solution is 40% and the brown pigment extraction rate is 66.99%.

[0057] Example 4

[0058] The only difference from Example 1 is that the volume concentration of the ethanol aqueous solution is 60% and the brown pigment extraction rate is 64.36%.

[0059] Example 5

[0060] The only difference from Example 1 is that the volume concentration of the ethanol aqueous solution is 70% and the brown pigment extraction rate is 58.24%.

[0061] Figure 1 The extraction rate of chestnut bud pigment in Examples 1 to 5 and Comparative Example 1 is shown in the broken line graph. Figure 1 It can be seen that under the conditions of multi-stage extraction material-liquid ratio of 1g:20mL, extraction temperature of 70℃, and graded extraction time of 3h each time, the extraction rate of chestnut bud pigment increases with the increase of ethanol solution volume fraction, but when the ethanol solution volume fraction is 50%, the pigment extraction rate reaches the maximum value. When the ethanol volume fraction continues to increase, the extraction rate shows a downward trend. This is because the ethanol molecules in the solution form hydrogen bonds with water, which reduces the overall polarity and affects the extraction of the pigment. Therefore, the optimal value of the ethanol volume fraction is 50%.

[0062] Example 6

[0063] The only difference from Example 1 is that the extraction time for the first extraction, the second extraction and the third extraction is 1.5 h, and the extraction rate of brown pigment is 40.61%.

[0064] Example 7

[0065] The only difference from Example 1 is that the extraction time for the first extraction, the second extraction and the third extraction is 2 hours, and the extraction rate of brown pigment is 49.35%.

[0066] Example 8

[0067] The only difference from Example 1 is that the extraction time for the first extraction, the second extraction and the third extraction is 2.5 hours, and the extraction rate of brown pigment is 69.66%.

[0068] Example 9

[0069] The only difference from Example 1 is that the extraction time for the first extraction, the second extraction and the third extraction is 3.5 hours, and the extraction rate of brown pigment is 58.64%.

[0070] Figure 2The extraction rate of chestnut bud pigment in Example 1 and Examples 6 to 9 is a broken line graph. Figure 2 The results show that under the conditions of a multi-stage extraction material-liquid ratio of 1g:20mL, an extraction temperature of 70°C, and a volume fraction of 50% ethanol solution, the extraction rate of chestnut bud pigment increases with extraction time, reaching a peak at 3 hours and then declining. Prolonged heating may render the pigment unstable and partially decompose, so the optimal extraction time is 3 hours.

[0071] Example 10

[0072] The only difference from Example 1 is that during the multi-stage extraction, the solid-liquid ratio of chestnut bud powder to 50 vol% ethanol aqueous solution is 1 g:10 mL (abbreviated as 1:10), and the brown pigment extraction rate is 52.36%.

[0073] Example 11

[0074] The only difference from Example 1 is that during the multi-stage extraction, the solid-liquid ratio of chestnut bud powder to 50 vol% ethanol aqueous solution is 1 g:30 mL (abbreviated as 1:30), and the brown pigment extraction rate is 46.89%.

[0075] Comparative Example 2

[0076] The only difference from Example 1 is that during the multi-stage extraction, the solid-liquid ratio of chestnut husk powder to 50 vol% ethanol aqueous solution is 1 g:40 mL (abbreviated as 1:40), and the brown pigment extraction rate is 33.85%.

[0077] Comparative Example 3

[0078] The only difference from Example 1 is that during the multi-stage extraction, the solid-liquid ratio of chestnut husk powder to 50 vol% ethanol aqueous solution is 1 g:50 mL (abbreviated as 1:50), and the brown pigment extraction rate is 22.66%.

[0079] Figure 3 This is a line graph showing the extraction yield of chestnut bud pigment in Example 1, Examples 10-11, and Comparative Examples 2-3. Under the conditions of an extraction temperature of 70°C, a 50% ethanol solution volume fraction, and a 3-hour extraction time for each step, the extraction yield increases with decreasing solid-to-liquid ratio and increasing solution concentration. The extraction yield peaks at a solid-to-liquid ratio of 1g:20mL and then declines. Below a solid-to-liquid ratio of 1g:20mL, the chestnut bud pigment cannot fully dissolve, resulting in a decrease in extraction yield. Therefore, the optimal solid-to-liquid ratio is 1g:20mL.

[0080] Example 12

[0081] The only difference from Example 1 is that the extraction temperature is 50° C. each time and the brown pigment extraction rate is 59.76%.

[0082] Example 13

[0083] The only difference from Example 1 is that the extraction temperature is 60° C. each time and the brown pigment extraction rate is 77.10%.

[0084] Example 14

[0085] The only difference from Example 1 is that the extraction temperature is 80° C. each time and the brown pigment extraction rate is 68.67%.

[0086] Comparative Example 4

[0087] The only difference from Example 1 is that the extraction temperature is 90° C. each time and the brown pigment extraction rate is 39.16%.

[0088] Figure 4 This is a line graph of the extraction yield of chestnut bud pigment in Example 1, Examples 12-14, and Comparative Example 4. Under the conditions of a multi-stage extraction material-liquid ratio of 1g:20mL, a volume fraction of 50% ethanol solution, and a 3-hour extraction time per step, the extraction yield of brown pigment increases with increasing extraction temperature, reaching a peak at 70°C and then showing a downward trend. When the extraction temperature is below 70°C, the chestnut bud pigment is incompletely extracted, resulting in a decrease in extraction yield. When the temperature is too high, the heat-sensitive components undergo structural changes, reducing the extraction yield. Therefore, the optimal extraction temperature is 70°C.

[0089] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for extracting brown pigment from chestnut bracts, characterized in that: The following steps are involved: The dried chestnut husk powder is subjected to multi-stage extraction using ethanol aqueous solution to obtain an extract; The extract is concentrated and dried in sequence to obtain the brown pigment in the chestnut husk; The volume concentration of the ethanol aqueous solution is 30-70%; The particle size of the chestnut husk powder is less than 30 meshes.

2. The extraction method according to claim 1, characterized in that The multi-stage extraction is performed in three steps; The volume ratio of the ethanol-water solution used in the first extraction, the second extraction and the third extraction is 5:3:

2.

3. The extraction method according to claim 2, characterized in that The temperatures of the first leaching, the second leaching and the third leaching are all 50-80° C., and the time of each leaching is 1.5-3.5 hours.

4. The extraction method according to claim 2 or 3, characterized in that The total material-liquid ratio of the multi-stage extraction is 1g:10-30mL.

5. The extraction method according to claim 1, characterized in that The concentration temperature is 43-45° C., and the vacuum degree is 0.09 MPa.

6. The extraction method according to claim 1, characterized in that The drying is vacuum drying, and the drying temperature is 55-60°C.

7. The extraction method according to claim 1, characterized in that The method for obtaining the dried chestnut husk powder comprises the following steps: sequentially drying, crushing and sieving the impurity-removed chestnut husks, and the sieved material is the dried chestnut husk powder.

8. The extraction method according to claim 7, characterized in that The drying temperature is 70-80°C.

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