Method for extracting high-purity natural vitamin C from acerola cherry fruits

Abstract

The invention discloses a method for preparing natural vitamin C from acerola cherry fruits, which comprises the following steps: raw material treatment, juice clarification, separation and purification, concentration and crystallization to obtain natural vitamin C crystals, and the content of vitamin C is greater than or equal to 98%. The content of impurities such as metal ions and oxalic acid in the natural vitamin C crystal obtained by the process is low, interference components in the application process are fewer, the process is simple, the preparation can be realized only by taking water as a solvent, no organic solvent is used, and the production and preparation method is green and natural and is easy for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of compound extraction, and particularly relates to a method for high-purity natural vitamin C. Background Art

[0002] Vitamin C is a water-soluble active substance, with antioxidant, anti-aging, cancer prevention and anti-cancer mechanisms, and has good immune regulation function. It plays an important role in maintaining the normal physiological functions and health of the human body, and is also important in the fields of food, medicine and health products.

[0003] Acerola cherries are rich in vitamin C. The vitamin C content in fresh acerola cherries can reach 1.2%-3.5%, which is 50-100 times that of fruits such as citrus and guava, and it is the fruit with the highest known natural vitamin C content in the world. Acerola cherry is a tropical fruit native to Central America. Due to its special economic value, its planting range has gradually expanded from Central America to southern regions of the Americas such as Brazil and the Caribbean. Among them, Brazil is the world's leading producer, consumer and exporter of acerola cherries. Some regions in China grow acerola cherries, such as Hainan, Guangxi, Guangdong, etc. Because acerola cherries have relatively high requirements for precipitation, soil, temperature, etc., only Hainan has successfully introduced and achieved large-scale planting.

[0004] The vitamin C content in domestic acerola cherry extracts is generally 10%-20%, and the vitamin C content in imported acerola cherry powder from abroad can reach 30%-40%. At present, there is no acerola cherry extract product with vitamin C exceeding 50% on the market.

[0005] The prior art discloses some methods for preparing natural vitamin C using acerola cherries and rosa roxburghii tratt as raw materials. For example, CN117322617A discloses a method for preparing a high-purity natural vitamin C acerola cherry extract, which relates to the extraction and purification of vitamin C from acerola cherries. Using acerola cherries as raw materials, through processes such as cold pressing, enzymatic hydrolysis, salting out, desalting, decolorization, membrane separation, and drying, a high-purity (vitamin C ≥ 40%) acerola cherry extract product is prepared.

[0006] CN111349062A discloses a method for extracting vitamin C from acerola cherries, including the following steps:

[0007] (1) Step 1: Wash the acerola cherries thoroughly with clean water and juice them using a juicer; (2) Step 2: Perform cell wall breaking treatment on the acerola cherry cells to allow the cytoplasm to flow out of the cells, obtaining acerola cherry slurry; (3) Step 3: Add a certain proportion of cellulase and pectinase to the acerola cherry slurry, and stir at room temperature for 10 - 12 hours to obtain an enzymolysis mixture; (4) Step 4: Place the above enzymolysis mixture in a centrifuge and centrifuge at 6000 - 10000 r / min for 10 - 20 min to perform solid-liquid separation, obtaining the supernatant; (5) Step 5: Ultrafilter the supernatant obtained in Step 4 using an ultrafiltration membrane to obtain a filtrate; (6) Step 6: Vacuum concentrate the filtrate obtained in Step 5, and then cool and lower the temperature of the concentrated solution to reduce its solubility, and precipitate vitamin C crystals; (7) Step 7: Freeze-dry to obtain acerola cherry vitamin C (vitamin C content ≥ 65%).

[0008] CN118638080B discloses a method for extracting high-purity and high-biological-activity natural vitamin C from Rosa roxburghii Tratt. (1) Place the fresh Rosa roxburghii Tratt. fruits on a press to squeeze and extract juice, discard the residue and take the juice, filter the juice successively with gauze and filter paper to obtain filtrate a, add sodium dihydrogen phosphate, shredded paper pulp and montmorillonite to it, stir for 45 min, then add n-butanol and stir for 1 - 2 hours, let it stand for 28 hours to separate the layers of the juice, absorb the upper clear liquid, add activated carbon and stir for 30 min, then filter the carbon and filter through a membrane to obtain filtrate b; wherein the sodium dihydrogen phosphate is added to filtrate a to a concentration of 0.25% w / w, the shredded paper pulp is added to filtrate a in terms of dry shredded paper to a concentration of 2 - 2.5% w / w, the montmorillonite is added to filtrate a to a concentration of 4 - 5% w / w, the amount of n-butanol added is equivalent to 6.5% - 7.5% of the weight of filtrate a, and the activated carbon is added to filtrate a to a concentration of 0.5% w / w; (2) At room temperature, add acetone to the filtrate b obtained in Step (1), stir for 10 - 20 min and then filter, place the filtrate at 2 - 4 °C and let it stand for 5 - 7 hours, pour off the supernatant, centrifuge the sediment again and then air-dry it at 30 °C in a nitrogen atmosphere until the water content is less than 4% to obtain dry granules; wherein the weight ratio of filtrate b to acetone is 2:1; (3) At room temperature, add the granules obtained in Step (2) to 1.5 times the weight of water and stir to dissolve it, add anhydrous ethanol with the same volume as the amount of water, stir for 10 - 20 min and then filter, place the filtrate at 2 - 4 °C and let it stand for 6 - 10 hours, pour off the supernatant, centrifuge the sediment again and then air-dry it at 30 °C in a nitrogen atmosphere until the water content is less than 2% to obtain dry granules as natural vitamin C (content about 80% - 85%).

[0009] CN117179302A discloses a preparation method of high-purity natural vitamin C rose roxburghii extract. The preparation method includes the following steps: (1) adding frozen fresh rose roxburghii fruits into water for homogenization treatment, and performing extraction after completion to obtain the extracted liquid; (2) adding a composite enzyme preparation to the extracted liquid for enzymatic hydrolysis treatment to obtain the enzymatically hydrolyzed liquid; (3) performing solid-liquid separation on the liquid to obtain a clear liquid and residues; (4) decolorizing the clear liquid through an adsorbent to obtain the decolorized liquid; (5) adding an embedding deodorant to the liquid to obtain the deodorized liquid; (6) directionally intercepting the target substance from the deodorized liquid, and collecting the permeate and the retentate; (7) drying the retentate and the permeate, and collecting the dry powder. The preparation method proposed by the present invention uses rose roxburghii as the raw material, and through processes such as cold pressing, enzymatic hydrolysis, desalting, decolorization, membrane separation, and drying, prepares a rose roxburghii extract product with a high purity (≥40%) of vitamin C content, friendly sensory flavor, and good stability.

[0010] From the above public information, at present, when extracting and purifying natural vitamin C using acerola cherry fruits as the raw material, the highest vitamin C content is about 65%. When preparing high-purity natural vitamin C using rose roxburghii as the raw material, the vitamin C content can reach 80%-85%. The vitamin C obtained by the first method has low purity, and the second method has relatively high purity of natural vitamin C, but the purification method is complex, and organic solvents such as n-butanol and acetone are used, and the raw material is not acerola cherry fruits. There is currently no report on purifying the natural vitamin C content to more than 90% using acerola cherry as the raw material. Summary of the Invention

[0011] The purpose of the present invention is to provide a method for extracting high-purity natural vitamin C using acerola cherry fruits as the raw material, with a vitamin C content of ≥98%, low contents of impurities such as metal ions and oxalic acid, fewer interfering components during application, and a simple process, which can be achieved only using water as the solvent, without using any organic solvents, and the production preparation method is green and natural, and is easy to industrialize.

[0012] To achieve the above purpose, the present invention adopts the following technical solutions:

[0013] A method for preparing natural vitamin C from acerola cherry fruits includes the following steps:

[0014] I. Raw material treatment: Prepare acerola cherry juice from fresh acerola cherry fruits at a temperature of 0°C - 30°C and collect it;

[0015] II. Juice clarification: Add a clarifying agent to the juice, stir well, let it stand at 20 - 30°C for 2 - 8h, filter or centrifuge to remove the precipitate, and obtain a clarified liquid;

[0016] III. Separation and purification: The clarified liquid is preliminarily filtered through a ceramic membrane or an ultrafiltration membrane at 0 - 10°C; the filtrate is then finely filtered through a nanofiltration membrane, and the clear liquid is collected;

[0017] IV. Concentration: The clear liquid is concentrated through a reverse osmosis membrane at 0 - 10°C to obtain concentrated liquid I, and concentrated liquid I is continuously concentrated under vacuum with the vacuum concentration temperature ≤ 40°C to obtain concentrated liquid II;

[0018] V. Crystallization: Seed crystals are added to concentrated liquid II, allowed to stand for crystallization, vacuum filtered, and the filter cake is dried by vacuum pumping; it is dried under vacuum at ≤ 40°C or freeze-dried to obtain natural vitamin C crystals, wherein the vitamin C content ≥ 98%.

[0019] In some embodiments, the acerola cherries used in step I are 5 - 7 mature green fruits, selected from acerola cherries without rot or deterioration, with surface impurities removed, and after being washed clean, an appropriate amount of purified water is selectively added for crushing treatment, and the water addition amount is 0.5 - 2 times the mass of the raw materials to obtain acerola cherry jam. The acerola cherry jam is filled into a non-woven bag and juiced with a hydraulic press.

[0020] In some embodiments, in step I, the hydraulic pressure for hydraulic juicing is 10 - 50 tons, and the non-woven bag is 100 - 300 mesh.

[0021] In some embodiments, in step II, the clarifying agent used is one of chitosan, ZTC1 + 1, gelatin, pectinase, and cellulase, and the addition amount of the clarifying agent is 0.1wt% - 0.5wt% of the acerola cherry juice.

[0022] In some embodiments, in step II, the filter paper process used is normal pressure filtration, and the centrifugation speed for the centrifugation process is 4000 - 8000 rpm / min.

[0023] In some embodiments, in step III, a ceramic membrane with a pore size of 50 nm or an organic ultrafiltration membrane with a cut-off molecular weight of 40000D - 100000D is used for the preliminary filtration.

[0024] In some embodiments, in step III, an organic nanofiltration membrane with a cut-off molecular weight of 200D - 1000D is used for the fine filtration.

[0025] In some embodiments, in step IV, the concentration first uses a reverse osmosis membrane to concentrate at a low temperature to a concentration ratio of 5 - 10:1 m / v, and the reverse osmosis membrane concentrated liquid is continuously concentrated by a pressure reduction method to 15 - 20:1 m / v, with the pressure reduction concentration temperature being 30 - 50°C and the vacuum degree being -0.07 MPa to -0.095 MPa.

[0026] In some embodiments, in step V, the standing temperature of the concentrated liquid is 0 - 4°C, and the standing time is 10 - 24 h.

[0027] In some embodiments, in Step 5, the drying temperature is 30 - 40 °C, the vacuum degree is -0.07 MPa to -0.095 MPa or freeze-drying is used.

[0028] In Step 1 of the present invention, the recovery rate of vitamin C from fresh fruit to juice is > 90%.

[0029] In Step 2 of the present invention, the recovery rate of vitamin C in the juice after clarification treatment is 95% - 98%, for example 96% - 97%.

[0030] In Step 3 of the present invention, the recovery rate of vitamin C in primary filtration and fine filtration is 80% - 85%.

[0031] In Step 4 of the present invention, the recovery rate of vitamin C in reverse osmosis membrane concentration is 95% - 98%.

[0032] In Step 5 of the present invention, the recovery rate of crystalline vitamin C is 60% - 70%.

[0033] In Step 5 of the present invention, the vitamin C content of the final product is 98.1% - 99.9%.

[0034] Compared with the prior art, the present invention uses fresh acerola cherries as raw materials, and high-purity natural vitamin C is extracted through specific technological means, with its content ≥ 98%. The content of impurities such as metal ions and oxalic acid in the natural vitamin C crystals obtained by this process is low, there are fewer interfering components during application, and the process is simple, which can be achieved only with water as the solvent without using any organic solvents. The production and preparation method is green and natural, and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the process flow chart of the present invention;

[0036] Figure 2 is the liquid chromatogram of the reference substance;

[0037] Figure 3 is the liquid chromatogram of Example 1;

[0038] Figure 4 is the liquid chromatogram of Example 2;

[0039] Figure 5 is the liquid chromatogram of Example 5;

[0040] Figure 6 is the liquid chromatogram of Example 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0042] The technological process for preparing natural vitamin C from acerola cherry fruits adopted in the following embodiments is shown in Figure 1 As shown, in the present invention, room temperature refers to 20°C - 30°C, low temperature refers to 0°C - 10°C, and chilled water refers to purified water at 0 - 4°C. This process includes the following steps:

[0043] 1. Raw material treatment: Select fresh acerola cherries without rot or deterioration, wash them with clean water to remove surface impurities. Add an appropriate amount of purified water to the washed raw materials and crush them with a crusher to obtain acerola cherry jam. Put the acerola cherry jam into a non-woven bag and extract juice with a hydraulic press, collect the acerola cherry juice, and it is required to operate at normal temperature or low temperature. The recovery rate of vitamin C in the juice obtained in this step is > 90%.

[0044] 2. Juice clarification: Add a clarifying agent (chitosan, ZTC1+1, gelatin, pectinase, cellulase) to the juice, stir well, let it stand at 20 - 30°C for 2 - 8h, and filter or centrifuge to remove the precipitate. In this step, the recovery rate of vitamin C in the clarified juice is 95% - 98%, for example, 96% - 97%.

[0045] 3. Separation and purification: The clarified liquid is preliminarily filtered with a ceramic membrane or an ultrafiltration membrane; the filtrate is then finely filtered with a nanofiltration membrane, and the clear liquid is collected, and it is required to operate at low temperature. In this step, the recovery rate of vitamin C in the preliminary filtration and fine filtration is 80% - 85%.

[0046] 4. Concentration: The clear liquid is concentrated with a reverse osmosis membrane to obtain concentrated liquid I. Concentrated liquid I is continuously concentrated in vacuo to a certain volume, and the vacuum concentration temperature ≤ 40°C to obtain concentrated liquid II. Reverse osmosis membrane concentration is required to be carried out at low temperature. In this step, the recovery rate of vitamin C after reverse osmosis membrane concentration is 95% - 98%.

[0047] 5. Crystallization: Add an appropriate amount of crystal seeds to concentrated liquid II, let it stand and crystallize at 0 - 4°C for 10 - 24h, and filter in vacuo. The filter cake is dried in vacuo. The wet crystals are dried under vacuum conditions at ≤ 40°C or freeze-dried to obtain natural vitamin C crystals. In this step, the recovery rate of vitamin C in the crystallization is 60% - 70%, and the vitamin C content in the obtained final product is ≥ 98%, for example, it can reach 98.1% - 99.9%.

[0048] The content of vitamin C in the vitamin crystals is determined by the method specified in "GB5009.86 - 2016", specifically as follows:

[0049] Preparation of reference solution: Weigh an appropriate amount of L-ascorbic acid standard precisely, dissolve and make up the volume with 20 g / L metaphosphoric acid solution. After thorough mixing, dilute with 20 g / L metaphosphoric acid solution to make the concentration of the reference solution within the range of 10 mg / L - 500 mg / L for determination.

[0050] Preparation of test solution: Acerola cherry powder: Weigh approximately 25 mg (M) of the sample powder precisely, place it in a 25 mL (V1) volumetric flask, shake and dissolve with 20 g / L metaphosphoric acid solution and make up the volume, shake well, filter through a syringe filter, and you will get the test solution.

[0051] Chromatographic conditions: C18 chromatographic column (4.6 * 250 mm, 5 μm, or a chromatographic column with equivalent performance, such as Waters T3). Mobile phase: A: 6.8 g of potassium dihydrogen phosphate and 0.91 g of cetyltrimethylammonium bromide, dissolve with water and make up the volume to 1 L (adjust the pH to 2.5 - 2.8 with phosphoric acid); Mobile phase B: 100% methanol, mix A and B in a ratio of 98:2, filter through a 0.45 μm filter membrane, and degas by ultrasonic treatment. Detection wavelength: 245 nm, column temperature: 25 °C, injection volume: 20 μL, flow rate: 1.0 mL / min.

[0052] Content determination: Precisely pipette 20 μL each of the reference solution and the test solution, inject them into the liquid chromatograph for determination, and obtain the chromatographic peak areas of L-ascorbic acid in the reference solution and the test solution.

[0053] The liquid chromatogram of the reference in the present invention is as Figure 2 shown.

[0054] Example 1

[0055] In this example, high-purity natural vitamin C is extracted from acerola cherries, including the following steps:

[0056] 1. 5 kg of 6-ripe fresh acerola cherries (produced in Hainan), after cleaning, add 2.5 kg of purified water, crush them into jam with a crusher, put the jam into a 200-mesh non-woven bag, and filter it while it is cold with a hydraulic press at a pressure of 10 tons to obtain 4.8 kg of juice, and the operating temperature is room temperature.

[0057] 2. Add 0.1 wt% of chitosan solution to the juice for clarification, let it stand at a temperature of 20 °C for 4 h, filter the liquid and solid by ordinary pressure filtration with filter paper, first filter the supernatant, and then filter the lower precipitate to obtain filtrate a;

[0058] 3. Filter filtrate a through a 50 nm ceramic membrane filter, perform 2 times of top washing during the filtration process, and the top washing volume is 2 - 3 times of the minimum retained liquid volume to obtain filtrate b; Filter filtrate b through a 1000D nanofiltration membrane to obtain filtrate c;

[0059] 4. The filtrate c is continuously concentrated by a reverse osmosis membrane for about 30 min, and the concentration ratio is 6:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid I; the concentrated liquid I is continuously concentrated under reduced pressure to 15:1 to obtain concentrated liquid II;

[0060] 5. A small amount of seed crystals are added to the concentrated liquid II, and it is left standing at 0 - 4 °C for 10 h. A large number of crystals appear in the solution. It is vacuum filtered with filter paper, and the filter cake is rinsed with a small amount of frozen purified water. Filtration is continued until no liquid flows out of the Buchner funnel, obtaining off-white brittle wet crystals. The wet crystals are dried in a vacuum drying oven at 30 °C and -0.095 MPa to obtain 44.9 g of the dried product, with a yield of 0.90%. The vitamin C content detected by HPLC is 98.92%. The liquid chromatography diagram is as Figure 3 shown.

[0061] Example 2

[0062] In this example, high-purity natural vitamin C is extracted from acerola cherries, including the following steps:

[0063] 1. 5 kg of 6-ripe fresh acerola cherries (produced in Hainan), after being cleaned, 10 kg of purified water is added, and they are crushed into jam by a crusher. The jam is filled into a 150-mesh non-woven bag and filter-pressed while cold with a hydraulic filter press at a hydraulic pressure of 10 tons to obtain 12.9 kg of fruit juice, and the operating temperature is normal temperature.

[0064] 2. 0.2 wt% of chitosan is added to the fruit juice for clarification. The standing temperature is 20 °C, the standing time is 4 h, and it is filtered under normal pressure with filter paper to obtain filtrate a;

[0065] 3. The filtrate a is filtered through a 50-nm filter element ceramic membrane, and 2 top washes are carried out during the filtration process. The top wash amount is 2 - 3 times the minimum retentate amount to obtain filtrate b; the filtrate b is filtered through a 1000D nanofiltration membrane to obtain filtrate c;

[0066] 4. The filtrate c is continuously concentrated by a reverse osmosis membrane for about 1.2 h, and the concentration ratio is 5.5:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid I; the concentrated liquid I is continuously concentrated under reduced pressure to 16:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid II;

[0067] 5. A small amount of seed crystals are added to the concentrated liquid II, and it is left standing for crystallization at 0 - 4 °C for 10 h. It is vacuum filtered with filter paper, and the filter cake is rinsed with a small amount of frozen purified water. Filtration is continued until no liquid flows out to obtain off-white brittle wet crystals. The wet crystals are dried in a vacuum drying oven at 30 °C and -0.095 MPa to obtain 42.5 g of the dried product, with a yield of 0.85%. The vitamin C content detected by HPLC is 99.47%. The liquid chromatography diagram is as Figure 4 shown.

[0068] Example 3

[0069] In this embodiment, high-purity natural vitamin C is extracted from acerola cherries, and the steps are as follows:

[0070] 1. 40 kg of 6-ripe fresh acerola cherries (origin: Hainan) are cleaned, then 35 kg of purified water is added, and they are crushed by a crusher to obtain jam. The jam is filled into a 300-mesh non-woven fabric bag and pressed by a hydraulic filter press while it is cold. The hydraulic pressure is 30 tons, and 62.1 kg of fruit juice is obtained. The operating temperature is normal temperature.

[0071] 2. Chitosan accounting for 0.1 wt% of the fruit juice is added for clarification. The static temperature is 20 °C, the static time is 4 h, and then centrifugation is carried out with a disc centrifuge at a speed of 7500 rpm to obtain centrifuged clear liquid a;

[0072] 3. Clear liquid a is filtered through a 100,000 D organic ultrafiltration membrane. During the filtration process, backwashing is carried out twice, and the backwashing volume is 2-3 times the minimum retentate volume, to obtain filtrate b; Filtrate b is filtered through a 500 D nanofiltration membrane to obtain filtrate c;

[0073] 4. Filtrate c is continuously concentrated by a reverse osmosis membrane. The concentration time is about 6 h, and the concentration ratio is 7:1 (raw material mass: concentrated liquid volume), to obtain concentrated liquid I; Concentrated liquid I is continuously concentrated under reduced pressure at a ratio of 17:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid II;

[0074] 5. A small amount of seed crystals is added to concentrated liquid II, and it is left standing at 0-4 °C for 10 h. A large number of crystals appear in the solution. Vacuum filtration is carried out with filter paper, and a small amount of frozen purified water is added to wash the filter cake. Filtration is continued until no liquid flows out of the Buchner funnel, to obtain off-white fragile wet crystals. The wet crystals are dried in a vacuum drying oven at 30 °C and -0.095 MPa, and 344.5 g of dry product is obtained. The yield is 0.86%, and the vitamin C content detected by HPLC is 98.34%.

[0075] Example 4

[0076] In this embodiment, high-purity natural vitamin C is extracted from acerola cherries, and the steps are as follows:

[0077] 1. 5 kg of 6-ripe fresh acerola cherries without rot (origin: Hainan) are selected, cleaned, then 10 kg of purified water is added, and they are crushed by a crusher to obtain jam. The jam is filled into a 200-mesh non-woven fabric bag and pressed by a hydraulic filter press while it is cold. The hydraulic pressure is 10 tons, and 13.4 kg of fruit juice is obtained. The operating temperature is normal temperature.

[0078] 2. ZTC+1 fruit juice clarifier accounting for 0.1 wt% of the fruit juice is added for clarification. The clarification treatment temperature is 20 °C, the static time is 4 h, and then centrifugation is carried out with a refrigerated centrifuge at a speed of 6000 rpm to obtain centrifuged clear liquid a;

[0079] 3. The clear liquid a is filtered through an 80,000D organic ultrafiltration membrane. During the filtration process, backwashing is carried out twice, and the backwashing volume is 2 - 3 times the minimum retentate volume, to obtain filtrate b; the filtrate b is filtered through an 800D nanofiltration membrane to obtain filtrate c;

[0080] 4. The filtrate c is continuously concentrated by a reverse osmosis membrane. The concentration time is about 1.3 h, and the concentration ratio is 9:1 (raw material mass: concentrated liquid volume), to obtain concentrated liquid I; the concentrated liquid I is continuously concentrated under reduced pressure to 18:1 to obtain concentrated liquid II;

[0081] 5. A small amount of seed crystals is added to the concentrated liquid II, and it is left standing at 0 - 4 °C for 10 h. A large number of crystals appear in the solution. It is vacuum filtered with filter paper, and a small amount of frozen purified water is added to wash the filter cake. Filtration is continued until no liquid flows out of the Buchner funnel, to obtain off - white fragile wet crystals. The wet crystals are dried in a vacuum drying oven at 30 °C and - 0.095 MPa, to obtain 45.7 g of the dried product, with a yield of 0.91%. The vitamin C content detected by HPLC is 98.29%.

[0082] Example 5

[0083] This example extracts high - purity natural vitamin C from acerola cherries, including the following steps:

[0084] 1. 5 kg of 5 - ripe fresh acerola cherries (produced in Hainan) are cleaned, 4 kg of purified water is added, and they are crushed by a crusher to obtain jam. The jam is filled into a 200 - mesh non - woven fabric bag and pressed by a hydraulic filter press while it is cold. The hydraulic pressure is 20 tons, to obtain 7.1 kg of fruit juice, and the operating temperature is normal temperature.

[0085] 2. Pectinase accounting for 0.45 wt% of the fruit juice is added for clarification. The clarification treatment temperature is 30 °C, the standing time is 3 h, and it is filtered with filter paper to obtain filtrate a;

[0086] 3. The filtrate a is filtered through a 60,000D organic ultrafiltration membrane. During the filtration process, backwashing is carried out twice, and the backwashing volume is 2 - 3 times the minimum retentate volume, to obtain filtrate b; the filtrate b is filtered through a 300D nanofiltration membrane to obtain filtrate c;

[0087] 4. The filtrate c is continuously concentrated by a reverse osmosis membrane. The concentration time is about 45 min, and the concentration ratio is 6.5:1 (raw material mass: concentrated liquid volume), to obtain concentrated liquid I; the concentrated liquid I is continuously concentrated under reduced pressure to 17:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid II;

[0088] 5. A small amount of seed crystals was added to Concentrate II, and it was left standing at 0 - 4°C for 10 h. A large number of crystals appeared in the solution. It was vacuum filtered with filter paper, and the filter cake was rinsed with a small amount of frozen purified water, and then continued to be filtered until no liquid flowed out of the Buchner funnel, obtaining off-white fragile wet crystals. The wet crystals were dried in a vacuum drying oven at 30°C and -0.095 MPa, obtaining 43.3 g of dry product, with a yield of 0.87%. The vitamin C content detected by HPLC was 99.23%. The liquid chromatogram is as shown in Figure 5 shown.

[0089] Example 6

[0090] In this example, high-purity natural vitamin C was extracted from acerola cherries, including the following steps:

[0091] 1. 10 kg of 5-ripe fresh acerola cherries (produced in Hainan) were cleaned, then 10 kg of purified water was added, and they were crushed by a crusher to obtain jam. The jam was filled into a 200-mesh non-woven fabric bag and pressed by a hydraulic filter press while it was cold. The hydraulic pressure was 20 tons, obtaining 16.5 kg of fruit juice, and the operating temperature was normal temperature.

[0092] 2. 0.45 wt% of pectinase was added to the fruit juice for clarification treatment. The clarification treatment temperature was 25°C, the standing time was 4 h, and it was filtered with filter paper to obtain filtrate a;

[0093] 3. Filtrate a was filtered through a 50,000 D organic ultrafiltration membrane. During the filtration process, 2 top washes were carried out, and the top wash volume was 3 - 5 times the minimum retentate volume, obtaining filtrate b; Filtrate b was filtered through a 200 D nanofiltration membrane to obtain filtrate c;

[0094] 4. Filtrate c was continuously concentrated with a reverse osmosis membrane. The concentration temperature was 0 - 10°C, the concentration time was about 1.5 h, and the concentration ratio was 8.5:1 (raw material mass: concentrate volume), obtaining Concentrate I; Concentrate I was continuously concentrated under reduced pressure to 20:1 (raw material mass: concentrate volume), obtaining Concentrate II;

[0095] 5. A small amount of seed crystals was added to Concentrate II, and it was left standing at 0 - 4°C for 10 h. A large number of crystals appeared in the solution. It was vacuum filtered with filter paper, and the filter cake was rinsed with a small amount of frozen purified water, and then continued to be filtered until no liquid flowed out of the Buchner funnel, obtaining off-white fragile wet crystals. The wet crystals were freeze-dried, obtaining 90.4 g of dry product, with a yield of 0.90%. The vitamin C content detected by HPLC was 99.89%. The liquid chromatogram is as shown in Figure 6 shown.

[0096] Example 7

[0097] In this example, high-purity natural vitamin C was extracted from acerola cherries, including the following steps:

[0098] 1. 50 kg of 5-ripe fresh acerola cherries (origin: Hainan), after being cleaned, are added with 50 kg of purified water, crushed by a crusher to obtain jam. The jam is filled into a 300-mesh non-woven fabric bag and pressed by a hydraulic filter press while it is cold. The hydraulic pressure is 50 tons, and 83.4 kg of fruit juice is obtained. The operating temperature is normal temperature.

[0099] 2. Add pectinase at 0.45 wt% of the fruit juice for clarification treatment. The clarification treatment temperature is 30 °C, the standing time is 3 h, and it is centrifuged by a disc centrifuge. The centrifuge speed is 7500 rpm to obtain centrifuged clear liquid a;

[0100] 3. Filter clear liquid a through a 50-nm ceramic membrane. During the filtration process, perform 2 top washes, and the top wash volume is 3 - 5 times the minimum retained liquid volume to obtain filtrate b; Filter filtrate b through a 200D nanofiltration membrane to obtain filtrate c;

[0101] 4. Continue to concentrate filtrate c with a reverse osmosis membrane. The concentration time is about 7 h, and the concentration ratio is 7.5:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid I; Concentrated liquid I is further concentrated under reduced pressure to 17:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid II;

[0102] 5. Add a small amount of crystal seeds to concentrated liquid II, stand at 0 - 4 °C for 10 h. A large number of crystals appear in the solution. Filter with a filter paper under vacuum, wash the filter cake with a small amount of frozen purified water, and continue to filter until no liquid flows out of the Buchner funnel to obtain off-white fragile wet crystals. The wet crystals are freeze-dried to obtain 458.4 g of dry product, and the yield is 0.92%. The vitamin C content detected by HPLC is 99.07%.

[0103] Example 8

[0104] This example extracts high-purity natural vitamin C from acerola cherries, including the following steps:

[0105] 1. 10 kg of 5-ripe fresh acerola cherries (origin: Hainan), after being cleaned, are added with 20 kg of purified water, crushed by a crusher to obtain jam. The jam is filled into a 300-mesh non-woven fabric bag and pressed by a hydraulic filter press while it is cold. The hydraulic pressure is 30 tons, and 26.4 kg of fruit juice is obtained. The operating temperature is normal temperature.

[0106] 2. Add cellulase at 0.4 wt% of the fruit juice for clarification. The clarification treatment temperature is 25 °C, the standing time is 5 h, and it is centrifuged. The rotation speed is 5000 rpm to obtain centrifuged clear liquid a;

[0107] 3. Filter clear liquid a through a 50000D organic ultrafiltration membrane. During the filtration process, perform 2 top washes, and the top wash volume is 3 - 5 times the minimum retained liquid volume to obtain filtrate b; Filter filtrate b through a 200D nanofiltration membrane to obtain filtrate c;

[0108] 4. The filtrate c is continuously concentrated by a reverse osmosis membrane for about 2.5 h with a concentration ratio of 8:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid I; the concentrated liquid I is continuously concentrated under reduced pressure to 16.5:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid II;

[0109] 5. A small amount of seed crystals is added to the concentrated liquid II, and it is left standing at 0 - 4 °C for 10 h. A large number of crystals appear in the solution. It is vacuum filtered with a filter paper, and the filter cake is rinsed with a small amount of frozen purified water and continuously filtered until no liquid flows out to obtain off - white fragile wet crystals. The wet crystals are freeze - dried to obtain 91.2 g of a dried product with a yield of 0.91%, and the vitamin C content detected by HPLC is 99.65%.

[0110] Example 9

[0111] This example extracts high - purity natural vitamin C from acerola cherries, including the following steps:

[0112] 1. 10 kg of 6 - mature fresh acerola cherries (produced in Hainan), after being cleaned, 15 kg of purified water is added, and they are crushed by a crusher to obtain jam. The jam is filled into a 200 - mesh non - woven bag and pressed by a hydraulic filter press while it is cold. The hydraulic pressure is 30 tons to obtain 21 kg of fruit juice, and the operating temperature is normal temperature.

[0113] 2. Gelatin accounting for 0.1 wt% of the fruit juice is added for clarification. The clarification temperature is 30 °C, the standing time is 5 h, and it is centrifuged by a centrifuge at a speed of 7000 rpm to obtain centrifuged clear liquid a;

[0114] 3. The clear liquid a is filtered through a 50 - nm ceramic membrane, and 2 top - washes are carried out during the filtration process. The top - wash volume is 3 - 5 times the minimum retained liquid volume to obtain filtrate b; the filtrate b is filtered through a 300D nanofiltration membrane to obtain filtrate c;

[0115] 4. The filtrate c is continuously concentrated by a reverse osmosis membrane for about 2 h with a concentration ratio of 10:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid I; the concentrated liquid I is continuously concentrated under reduced pressure to 17:1 (raw material mass: concentrated liquid volume) to obtain concentrated liquid II;

[0116] 5. A small amount of seed crystals is added to the concentrated liquid II, and it is left standing at 0 - 4 °C for 20 h. A large number of crystals appear in the solution. It is vacuum filtered with a filter paper, and the filter cake is rinsed with a small amount of frozen purified water and continuously filtered until no liquid flows out to obtain off - white fragile wet crystals. The wet crystals are vacuum - dried at 35 °C to obtain 92.0 g of a dried product with a yield of 0.92%, and the vitamin C content detected by HPLC is 98.73%.

[0117] Comparative Example 1

[0118] This comparative example extracts high - purity natural vitamin C from acerola cherries, including the following steps:

[0119] 1. 5 kg of 5-6 mature acerola cherries are cleaned, 7.5 kg of purified water is added, and they are crushed by a crusher to obtain jam. The jam is filled into a 200-mesh non-woven bag and pressed by a hydraulic filter press while cold. The hydraulic pressure is 30 tons, and 11 kg of fruit juice is obtained. The operating temperature is room temperature.

[0120] 2. A certain proportion of cellulase (12 mg / kg of fruit juice) and pectinase (50 mg / kg of fruit juice) are added to the acerola cherry fruit juice. Under room temperature conditions, it is stirred and enzymatically hydrolyzed for 10 - 12 hours.

[0121] 3. The above enzymatic hydrolysate is centrifuged by a centrifuge at a speed of 8000 r / min for 10 min, and the supernatant is taken.

[0122] 4. The supernatant is filtered through a 0.002 - µm (equivalent to 1000 D) membrane, and the filtrate is collected.

[0123] 5. The ultrafiltration membrane filtrate is vacuum concentrated. The concentration temperature is 30 - 40 °C, and the vacuum degree is -0.095 MPa. It is concentrated to solid contents of 30%, 40%, 50%, 60%, 70%, 80%, 90% respectively, and left to stand at 0 - 4 °C for 7 days. No crystals precipitate. After detection, the vitamin C content is about 30% (dry basis).

[0124] Comparative Example 2

[0125] In this comparative example, high-purity natural vitamin C is extracted from acerola cherries, including the following steps:

[0126] 1. 5 kg of 5-6 mature acerola cherries are cleaned, 7.5 kg of purified water is added, and they are crushed by a crusher to obtain jam. The jam is filled into a 200-mesh non-woven bag and pressed by a hydraulic filter press while cold. The hydraulic pressure is 30 tons, and 10.5 kg of fruit juice is obtained. The operating temperature is room temperature.

[0127] 2. 0.45 wt% of pectinase based on the fruit juice is added for clarification treatment. The clarification treatment temperature is 25 °C, the standing time is 4 h, and it is filtered through filter paper to obtain filtrate a;

[0128] 3. Filtrate a is filtered through a 50000-D organic ultrafiltration membrane. During the filtration process, 2 top washes are carried out, and the top wash volume is 3 - 5 times the minimum retentate volume to obtain filtrate b; Filtrate b is filtered through a 200-D nanofiltration membrane to obtain filtrate c;

[0129] 4. Filtrate c is vacuum concentrated at a temperature of 40 °C and a pressure of -0.095 MPa until the concentration ratio is 20:1 (raw material mass: concentrated liquid volume), and the concentration time is 8 h - 10 h;

[0130] 5. Add a small amount of seed crystals to the concentrated solution, and let it stand for crystallization at 0-4°C for 10h-24h. After static crystallization, filter it by vacuum suction with filter paper. Add a small amount of frozen purified water to wash the filter cake, and continue suction filtration until no liquid flows out of the Buchner funnel, obtaining light yellow wet crystals. The wet crystals are freeze-dried to obtain 33.4 g of dry product, with a yield of 0.67%. The vitamin C content is detected by HPLC to be 78.33%.

[0131] Table 1 Detection Results of Samples in Examples and Comparative Examples

[0132]

Claims

1. A method for preparing natural vitamin C from acerola fruit, characterized in that: The steps include:

1. Raw material processing: preparing acerola cherry juice from fresh acerola cherry fruit at a temperature of 0°C-30°C and collecting the juice; 2. Juice clarification: add clarifier to the juice, stir thoroughly, let stand at 20-30℃ for 2-8h, filter or centrifuge to remove the precipitate, and obtain the clarified liquid; 3. Separation and purification: Preliminary filtration of the clarified liquid with a ceramic membrane or ultrafiltration membrane at 0-10°C; fine filtration of the filtrate with a nanofiltration membrane to collect the clear liquid; 4. Concentration: Concentrate the clear liquid with a reverse osmosis membrane at 0-10°C to obtain concentrated liquid I. Continue to vacuum concentrate concentrated liquid I at a vacuum concentration temperature of ≤40°C to obtain concentrated liquid II.

5. Crystallization: adding seed crystals to the concentrated solution II, allowing it to stand for crystallization, vacuum filtering, and vacuum drying the filter cake; drying or freeze-drying at ≤40°C under vacuum conditions to obtain natural vitamin C crystals, wherein the vitamin C content is ≥98%.

2. The method according to claim 1, characterized in that: In step 1, the acerola cherry used is 5-70% mature green fruit, which is selected from acerola cherries without rot and deterioration, and surface impurities are removed. After cleaning, an appropriate amount of purified water is selectively added for crushing, and the amount of water added is 0.5-2 times the mass of the raw material to obtain acerola cherry jam, and the acerola cherry jam is put into a non-woven bag and squeezed with a hydraulic press; the hydraulic pressure of the hydraulic squeeze is 10-50 tons, and the non-woven bag is 100-300 meshes.

3. The method according to claim 1, characterized in that In step 2, the clarifier used is one of chitosan, ZTC1+1, gelatin, pectinase, and cellulase, and the amount of the clarifier added is 0.1wt%-0.5wt% of the acerola cherry juice; The filter paper process used is atmospheric pressure filtration, and the centrifugal process has a centrifugal speed of 4000-8000rpm / min; The primary filtration uses a ceramic membrane with a pore size of 50nm, or an organic ultrafiltration membrane with a molecular weight cutoff of 40000D-100000D; In step three, fine filtration uses an organic nanofiltration membrane with a molecular weight cutoff of 200D-1000D.

4. The method according to claim 1, characterized in that In step 4, the concentrate is first concentrated using a reverse osmosis membrane at low temperature to a concentration ratio of 5-10:1 m / v, and the reverse osmosis membrane concentrate is further concentrated to 15-20:1 m / v by reduced pressure, the reduced pressure concentration temperature is 30-50°C, and the vacuum degree is -0.07MPa to -0.095MPa.

5. The method according to claim 1, characterized in that In step 5, the concentrated solution is placed at a temperature of 0-4°C for 10-24 hours; The drying temperature is 30-40°C, the vacuum degree is -0.07MPa~-0.095MPa or freeze drying.

6. The method according to claim 1, characterized in that In step 1, the recovery rate of vitamin C in the juice is greater than 90%.

7. The method according to claim 1, characterized in that The recovery rate of vitamin C in the juice after clarification in step 2 is 95%-98%, preferably 96%-97%.

8. The method according to claim 1, characterized in that: The recovery rate of vitamin C in the primary filtration and fine filtration in step 3 is 80%-85%.

9. The method according to claim 1, characterized in that: In step 4, the recovery rate of vitamin C concentrated by reverse osmosis membrane is 95%-98%.

10. The method according to claim 1, characterized in that In step 5 of the present invention, the recovery rate of crystalline vitamin C is 60%-70%; and the vitamin C content of the final product is 98.1%-99.9%.

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