Stevia rebaudiana extract, and preparation method therefor and use thereof
Patent Information
- Application Number
- PCT/CN2025/117616
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2025-08-28
- Publication Date
- 2026-10-01
Smart Images
Figure PCTCN2025117616-APPB-I100001
Abstract
Description
A Stevia extract, its preparation method and application Technical Field
[0001] This invention belongs to the field of plant extract technology, specifically relating to a stevia extract, its preparation method, and its application. Background Technology
[0002] Stevia, also known as stevia glycoside, is a substance derived from stevia, a perennial herbaceous plant belonging to the Asteraceae family, native to eastern Paraguay in South America. Also known as "sweet grass," stevia is now successfully cultivated in China and Southeast Asia. Stevia extract contains stevia sugar, which is 300 times sweeter than sucrose, while its energy content is only one-ninth that of sucrose. Although only 60-70g of stevia sugar can be extracted from 1kg of leaves, it remains a highly regarded safe natural sugar source. Stevia not only boasts high sweetness, low energy, non-toxicity, and no side effects, but it is also rich in flavonoids, alkaloids, water-soluble chlorophyll, lutein, as well as neutral water-soluble oligosaccharides, free sugars, amino acids, and lipids.
[0003] Currently, common extraction methods for steviol glycosides include water extraction, ethanol extraction, organic solvent extraction, and high-pressure solvent extraction. Water extraction involves mixing dried stevia powder with water in a specific ratio, heating to boiling, maintaining the temperature for a period (e.g., 60-90 minutes), cooling, and filtering to obtain the extract. This method is relatively low-cost, but its extraction efficiency and purity are relatively low, requiring multiple subsequent purification steps. Ethanol extraction uses ethanol as a solvent, extracting steviol glycosides through reflux extraction or ultrasound-assisted extraction. For example, stevia powder is mixed with ethanol in a specific ratio, refluxed multiple times at 70-90℃, and the extract is then concentrated after membrane filtration, desalting and decolorizing with ion exchange resin. Ultrasound-assisted extraction can further improve the extraction rate and purity by treating the extract with ultrasonic equipment at a specific temperature. Extraction using organic solvents such as methanol and ethyl acetate usually requires subsequent purification steps such as precipitation, filtration, and recrystallization. All of these methods are costly, produce low purity, and involve complex subsequent processing.
[0004] Therefore, developing an optimal extraction method and process for stevia to obtain high-purity stevia glycosides is a pressing technical problem that needs to be solved. Summary of the Invention
[0005] The purpose of this invention is to provide a stevia extract, its preparation method and application, in order to solve the problem of low extraction efficiency of stevia extract in the prior art.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] The first aspect of this invention provides a method for preparing stevia extract, comprising the following preparation steps:
[0008] Step 1: Take stevia leaves, dry them, then pulverize and sieve them to obtain stevia powder;
[0009] Step 2: Add stevia powder to pure water, heat to 60-70℃ and stir to extract, filter to obtain filtrate I;
[0010] Step 3: Add the precipitant to filtrate I, heat to 80-85℃ and stir for 0.5-1h, adjust the pH value, continue stirring for 0.5-1h, keep warm and let stand for 4.0-4.5h, cool to room temperature, and filter to obtain filtrate II;
[0011] Step 4: Filtrate II is adsorbed and eluted through macroporous adsorption resin to obtain eluent; the eluent is then desalted, decolorized, vacuum concentrated, dried, and recrystallized to obtain stevia extract.
[0012] As a further aspect of the present invention, the sieve mesh used in step 1 is 120-160 mesh. After drying, pulverizing, and sieving, stevia leaves yield stevia powder particles with uniform particle size and large specific surface area, which can provide favorable conditions for subsequent reactions, increase the contact area with the solvent, accelerate the dissolution and diffusion process, and thus improve the extraction efficiency.
[0013] As a further aspect of the present invention, in step 2, the amount of pure water used is 15-30 times the mass of stevia powder, and the extraction time is 2-3 hours. Using too little pure water will result in a low stevia glycoside extraction rate, while using too much pure water will lead to excessively high extraction costs.
[0014] As a further embodiment of the present invention, the precipitant in step 3 comprises the following raw materials in parts by weight: 30-45 parts modified activated carbon, 3-3.5 parts ferrous sulfate, and 5-6 parts calcium hydroxide.
[0015] As a further aspect of the present invention, the modified activated carbon is prepared by the following steps:
[0016] Activated carbon and chitosan were added to an acetic acid solution and ultrasonically dispersed for 1.0-1.5 h. Under a nitrogen atmosphere, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were stirred for another 8-12 h. After filtration, washing, and vacuum drying, modified activated carbon was obtained.
[0017] As a further embodiment of the present invention, the ratio of activated carbon, chitosan, acetic acid solution, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide is 0.2-0.3g: 0.25-0.35g: 100mL: 0.60-0.62g: 0.80-0.84g.
[0018] As a further embodiment of the present invention, the amount of precipitant used in step 3 is 5-15% of the volume of filtrate I.
[0019] As a further embodiment of the present invention, the pH value is adjusted to 10.0-10.5 in step 3.
[0020] As a further embodiment of the present invention, the macroporous adsorption resin in step 4 is one of LX-T28 resin, LX-T81 resin, D101 resin and AB-8 resin.
[0021] A second aspect of the present invention provides a stevia extract obtained by the preparation method described in the first aspect above.
[0022] A third aspect of the present invention provides the use of the stevia extract described in the second aspect above in food.
[0023] The beneficial effects of this invention are:
[0024] This invention discloses a method for preparing stevia extract (i.e., stevia glycosides). The method involves drying, pulverizing, and sieving stevia leaves to obtain stevia leaf powder with uniform particle size. This powder is then subjected to water extraction, precipitant treatment, macroporous adsorption resin treatment, vacuum concentration, drying, and recrystallization to obtain stevia glycosides with high extraction efficiency and high purity, thereby improving product quality and reducing costs. Furthermore, the obtained stevia glycosides have advantages such as high sweetness and low calories, and are widely used in food.
[0025] In this invention, a precipitant used in the preparation of stevia extract is composed of modified activated carbon, ferrous sulfate, and calcium hydroxide mixed in a specific weight ratio. The modified activated carbon is obtained by coating the surface of activated carbon with chitosan through an amidation reaction. Activated carbon has excellent adsorption capacity and can effectively perform adsorption separation and decolorization. Cross-linking and coating the activated carbon surface with chitosan significantly increases the hydrophilicity of the activated carbon, allowing it to disperse uniformly in solution. On the other hand, chitosan can adsorb some proteins. Simultaneously, the chitosan coated on the activated carbon surface has good mechanical properties, making it less prone to being dispersed in solution, thus prolonging its effect and resulting in excellent precipitation and flocculation. Ferrous sulfate can remove some proteins, colored substances, and other impurities such as off-flavors, while calcium hydroxide can remove colloidal impurities in the extract. This effectively prevents the deterioration of macroporous resin and reduces the consumption of macroporous adsorption resin, thereby further reducing production costs and saving resources.
[0026] This invention provides a method for preparing stevia extract, which is convenient to operate, simple in process, and suitable for large-scale production. Detailed Implementation
[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1
[0028] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0029] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0030] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0031] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0032] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0033] Modified activated carbon is prepared through the following steps:
[0034] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0035] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0036] The stevia extract was prepared through the above steps. Example 2
[0037] The only difference from Example 1 is that the preparation steps of the modified activated carbon are different:
[0038] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0039] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0040] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0041] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0042] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0043] Modified activated carbon is prepared through the following steps:
[0044] 0.25 g of activated carbon and 0.30 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0045] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0046] The stevia extract was prepared through the above steps. Example 3
[0047] The only difference from Example 1 is that the preparation steps of the modified activated carbon are different:
[0048] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0049] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0050] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0051] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0052] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0053] Modified activated carbon is prepared through the following steps:
[0054] 0.3 g of activated carbon and 0.35 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Under a nitrogen atmosphere, 0.62 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.84 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0055] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0056] The stevia extract was prepared through the above steps. Example 4
[0057] The only difference from Example 1 is that the sieve mesh is different in the crushing and sieving process in step 1:
[0058] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0059] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 160 mesh to obtain stevia powder;
[0060] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0061] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0062] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0063] Modified activated carbon is prepared through the following steps:
[0064] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0065] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0066] The stevia extract was prepared through the above steps. Example 5
[0067] The only difference from Example 1 is the amount of pure water used in step 2:
[0068] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0069] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0070] Step 2: Add stevia powder to 28 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0071] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0072] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0073] Modified activated carbon is prepared through the following steps:
[0074] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0075] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0076] The stevia extract was prepared through the above steps. Example 6
[0077] The only difference from Example 1 is the amount of precipitant used in step 3:
[0078] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0079] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0080] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0081] Step 3: Add 15% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0082] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0083] Modified activated carbon is prepared through the following steps:
[0084] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0085] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0086] The stevia extract was prepared through the above steps. Example 7
[0087] The only difference from Example 1 is the pH value in step 3:
[0088] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0089] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0090] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0091] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH value to 10.5, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0092] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0093] Modified activated carbon is prepared through the following steps:
[0094] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0095] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0096] The stevia extract was prepared through the above steps. Example 8
[0097] The only difference from Example 1 is the amount of precipitant used in step 3:
[0098] This embodiment provides a method for preparing stevia extract, and the preparation steps are as follows:
[0099] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0100] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0101] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0102] The precipitant comprises the following raw materials in parts by weight: 40 parts modified activated carbon, 3.3 parts ferrous sulfate, and 5.5 parts calcium hydroxide.
[0103] Modified activated carbon is prepared through the following steps:
[0104] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0105] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0106] The stevia extract was prepared through the above steps.
[0107] Comparative Example 1
[0108] The only difference from Example 1 is that the precipitant raw material does not contain modified activated carbon:
[0109] A method for preparing stevia extract, comprising the following steps:
[0110] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0111] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0112] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0113] The precipitant comprises the following raw materials in parts by weight: 3 parts ferrous sulfate and 5 parts calcium hydroxide.
[0114] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0115] The stevia extract was prepared through the above steps.
[0116] Comparative Example 2
[0117] The only difference from Example 1 is that the sieve mesh is different in the grinding and sieving process in step 1:
[0118] A method for preparing stevia extract, comprising the following steps:
[0119] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 100 to obtain stevia powder;
[0120] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0121] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0122] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0123] Modified activated carbon is prepared through the following steps:
[0124] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0125] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0126] The stevia extract was prepared through the above steps.
[0127] Comparative Example 3
[0128] The only difference from Example 1 is the amount of pure water used in step 2:
[0129] A method for preparing stevia extract, comprising the following steps:
[0130] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0131] Step 2: Add stevia powder to 10 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0132] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0133] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0134] Modified activated carbon is prepared through the following steps:
[0135] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0136] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0137] The stevia extract was prepared through the above steps.
[0138] Comparative Example 4
[0139] The only difference from Example 1 is the amount of precipitant used in step 3:
[0140] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0141] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0142] Step 3: Add 3% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II;
[0143] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0144] Modified activated carbon is prepared through the following steps:
[0145] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0146] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0147] The stevia extract was prepared through the above steps.
[0148] Comparative Example 5
[0149] The only difference from Example 1 is the amount of precipitant used in step 3:
[0150] A method for preparing stevia extract, comprising the following steps:
[0151] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0152] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0153] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0154] The precipitant comprises the following raw materials in parts by weight: 20 parts modified activated carbon, 3 parts ferrous sulfate, and 5 parts calcium hydroxide.
[0155] Modified activated carbon is prepared through the following steps:
[0156] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0157] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0158] The stevia extract was prepared through the above steps.
[0159] Comparative Example 6
[0160] The only difference from Example 1 is the amount of precipitant used in step 3:
[0161] A method for preparing stevia extract, comprising the following steps:
[0162] Step 1: Take stevia leaves, dry them, then crush and sieve them with a sieve mesh of 120 to obtain stevia powder;
[0163] Step 2: Add stevia powder to 15 times the amount of pure water, heat to 60℃ and stir for 2 hours. After filtration, obtain filtrate I.
[0164] Step 3: Add 5% of the volume of filtrate I to filtrate I, heat to 80℃ and stir for 0.5h, adjust the pH to 10.0, continue stirring for 0.5h, keep warm and let stand for 4.0h, cool to room temperature, and filter to obtain filtrate II.
[0165] The precipitant comprises the following raw materials in parts by weight: 30 parts modified activated carbon, 1.5 parts ferrous sulfate, and 4 parts calcium hydroxide.
[0166] Modified activated carbon is prepared through the following steps:
[0167] 0.2 g of activated carbon and 0.25 g of chitosan were added to 100 mL of acetic acid solution (volume fraction 25%) and ultrasonically dispersed for 1.0 h. Then, under a nitrogen atmosphere, 0.60 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.80 g of N-hydroxysuccinimide were added and stirred for another 8 h. The mixture was then filtered, washed, and dried in a vacuum drying oven at 40 °C for 24 h to obtain modified activated carbon.
[0168] Step 4: Adsorb and elute filtrate II through D101 resin to obtain eluent; then desalt, decolorize, vacuum concentrate, dry, and recrystallize the eluent to obtain stevia extract.
[0169] The stevia extract was prepared through the above steps.
[0170] The extraction rate and mass fraction of stevia extract (i.e., stevia glycoside) during the preparation process in Examples 1-8 and Comparative Examples 1-6 are shown in Table 1.
[0171]
[0172] As can be seen from Table 1, compared with Comparative Examples 1-6, the preparation method of stevia extract provided in Example-8 and the stevia extract obtained therefrom have better extraction rate and mass fraction. It can be seen that the stevia extract and its preparation method provided by the present invention have the advantages of high extraction efficiency and high extract purity, and the preparation method is simple and suitable for large-scale production.
[0173] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0174] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing stevia extract, characterized in that, The preparation steps include the following: Step 1: Take stevia leaves, dry them, then pulverize and sieve them to obtain stevia powder; Step 2: Add stevia powder to pure water, heat to 60-70℃ and stir to extract, filter to obtain filtrate I; Step 3: Add the precipitant to filtrate I, heat to 80-85℃ and stir for 0.5-1h, adjust the pH value, continue stirring for 0.5-1h, keep warm and let stand for 4.0-4.5h, cool to room temperature, and filter to obtain filtrate II; Step 4: Filtrate II is adsorbed and eluted through macroporous adsorption resin to obtain eluent; the eluent is then desalted, decolorized, vacuum concentrated, dried, and recrystallized to obtain stevia extract.
2. The method for preparing stevia extract according to claim 1, characterized in that, In step 1, the sieve mesh size is 120-160 mesh.
3. The method for preparing stevia extract according to claim 1, characterized in that, In step 2, the amount of pure water used is 15-30 times the mass of stevia powder, and the extraction time is 2-3 hours.
4. The method for preparing stevia extract according to claim 1, characterized in that, The precipitant mentioned in step 3 comprises the following raw materials in parts by weight: 30-45 parts modified activated carbon, 3-3.5 parts ferrous sulfate, and 5-6 parts calcium hydroxide.
5. The method for preparing stevia extract according to claim 4, characterized in that, The modified activated carbon is prepared by the following steps: Activated carbon and chitosan were added to an acetic acid solution and ultrasonically dispersed for 1.0-1.5 h. Under a nitrogen atmosphere, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were stirred for another 8-12 h. After filtration, washing, and vacuum drying, modified activated carbon was obtained.
6. The method for preparing stevia extract according to claim 5, characterized in that, The ratio of activated carbon, chitosan, acetic acid solution, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide is 0.2-0.3g: 0.25-0.35g: 100mL: 0.60-0.62g: 0.80-0.84g.
7. The method for preparing stevia extract according to claim 1, characterized in that, In step 3, the amount of precipitant used is 5-15% of the volume of filtrate I; And / or, in step 3, adjust the pH to 10.0-10.
5.
8. The method for preparing stevia extract according to claim 1, characterized in that, In step 4, the macroporous adsorption resin is one of LX-T28 resin, LX-T81 resin, D101 resin, and AB-8 resin.
9. A stevia extract, characterized in that, The stevia extract includes the stevia extract prepared by the preparation method according to any one of claims 1-8.
10. An application of the stevia extract as described in claim 9 in food.