An improved method for co-producing a pesticide-free mogroside composition

Abstract

The present invention relates to an improved method for co-producing a mogroside composition without pesticide residues, wherein the mogroside is soaked in hot water containing a slow-release oxidant to complete the killing, followed by pulping extraction, countercurrent extraction, horizontal spiral centrifugation, disc centrifugation, ceramic membrane filtration, sterilization, macroporous resin adsorption, resin column washing with dilute alkali solution and water in sequence to remove impurities, gradient elution I with moderate ethanol, gradient elution II with high ethanol aqueous solution, and the eluent is added to modified activated carbon. The extract prepared according to the method of the present invention has no pesticide residues and a high yield of mogroside, and is a high-quality mogroside extract. The process equipment requirements of the present invention are simple, and continuous operation can be performed, and the method is a preparation method of the mogroside extract suitable for industrialization.

Description

Technical Field

[0001] The invention relates to a method for extracting momordica grosvenori, and in particular to a method for co-producing an improved pesticide-residue-free mogroside composition. Background Art

[0002] Mogroside is the main component of monk fruit extract. It is a basically non-toxic, safe to take, high in sweetness, almost zero in calories, does not affect the blood sugar content of normal people, and is safe and healthy. Due to its many excellent properties, mogroside can completely or partially replace sucrose, so it is widely used in the food industry. In addition, mogroside also has very broad application prospects and market potential in the fields of pharmaceuticals, cosmetics and health foods.

[0003] The consumption of mogrosides is concentrated in the United States, Europe, Japan and other regions. At present, the United States is the largest consumer of mogrosides. Since the U.S. FDA approved the use of mogrosides in the market as a common sweetener in 2010, the production and demand of monk fruit extracts have grown steadily, and American consumers have a positive attitude towards monk fruit extracts. From 2011 to the present, the number of new food and beverage products containing monk fruit extracts has continued to rise worldwide. In addition, the application of sugar substitutes containing monk fruit extracts in food and beverages has spread across various fields. With the growing market of monk fruit extracts, international high-end food brands have higher requirements for the quality of monk fruit extracts. The EU and the United States continue to revise pesticide residue standards, especially the EU has significantly increased pesticide residue standards. In order to ensure that monk fruit extracts are competitive in the international market, an important indicator is pesticide residues. There are only a handful of domestic manufacturers that are capable of producing monk fruit extracts without pesticide residues that meet the EU and US Pharmacopoeia standards.

[0004] The existing technologies for reducing pesticide residues or even eliminating pesticide residues in monk fruit extract are summarized as follows:

[0005] CN201410657496.X discloses a method for reducing carbendazim in monk fruit extract, which uses monk fruit extract as raw material, and obtains a monk fruit extract with a carbendazim content of less than 0.01 mg / kg through steps such as deionized water dissolution, acid adjustment, activated carbon column treatment, alkali adjustment, nanofiltration, concentration, and drying. Excessive use of activated carbon in this method will inevitably lead to the loss of mogroside, low mogroside yield, low output per unit mass of monk fruit, and no cost advantage; in addition, this method only has a partial removal effect on carbendazim, a pesticide residue, and does not explain whether it is effective for other types of pesticide residues.

[0006] CN201680034301.3 discloses a pesticide-free monk fruit extract and a preparation method thereof, wherein the monk fruit extract is used as a raw material, and the pesticide-free monk fruit extract is obtained through the steps of dissolution, activated carbon column treatment, ethanol elution, reduced pressure concentration, drying, etc. The disadvantage of this method is also that the means of removing pesticide residues is single and the loss of sweet glycosides is large.

[0007] CN202111362720.9 discloses a method for removing harmful substances from monk fruit extract, which uses monk fruit extract as raw material, and obtains monk fruit extract with pesticide residues, heavy metals and plasticizers removed through steps of dissolution, enzymolysis, alkali adjustment, chelation reaction, concentration, drying, alkaline alcohol elution, concentration, macroporous resin adsorption, desorption, concentration, drying, etc. This method has cumbersome steps, small processing volume, high production cost, and is not suitable for industrial production.

[0008] CN202210409676.0 discloses a large-scale production method of mogrosides for removing pesticide residues, which uses dried monk fruit as raw material, and undergoes hot water extraction, ultrafiltration, anion exchange resin column treatment, macroporous resin adsorption, degradation agent I, degradation agent II, hydrogen peroxide aqueous solution column washing, ethanol analysis, concentration, drying and other steps to obtain mogrosides for removing pesticide residues. The method has complicated steps, and the mogrosides will be partially eluted during the multiple column washing process with multiple solutions, and the cost of dried monk fruit raw materials is high, so it is not suitable for industrial continuous production.

[0009] CN201710388435.1 discloses a method for simultaneously extracting mogroside without pesticide residue and water-soluble dietary fiber, which comprises washing monk fruit, boiling, chromatography, ultrafiltration, nanofiltration, and concentration to obtain mogroside without pesticide residue. The fat-soluble pesticide residue is removed by an alumina chromatography column, and the water-soluble pesticide residue is removed by an activated carbon chromatography column. However, the removal of pesticide residue is not thorough enough.

[0010] CN201510541887.X discloses a method for removing pesticide residues from monk fruit extract, which comprises first treating activated carbon with alkali and acid, applying an aqueous solution of the monk fruit extract to an activated carbon chromatography column, eluting, nanofiltering, vacuum concentrating, and spray drying to obtain an extract having a carbendazim content of less than 0.01 mg / kg.

[0011] It can be seen that most of the existing technologies for removing pesticide residues from monk fruit mainly focus on using activated carbon for adsorption, but activated carbon adsorption can only be applied to limited pesticide residues and is not universal. Moreover, the large-scale use of activated carbon adsorption will inevitably reduce the yield of the effective ingredient mogroside, especially mogroside V, which is the main sweetening agent.

[0012] The inventor's previous patent CN202310284713.4 records an industrial production method for a pesticide-free monk fruit extract, which uses hydrogen peroxide + alkali to kill fresh monk fruit under hot water conditions, and the oxidation of hydrogen peroxide and alkaline conditions are beneficial to the removal of pesticide residues on the surface of monk fruit. However, hydrogen peroxide is easy to decompose under heating conditions, and its oxidizing property gradually decreases. And after a large number of experiments, it was found that it has limited effect on the removal of organophosphorus pesticide residues (methamidophos, omethoate, dimethoate, phorate, diazinon, parathion, methyl parathion, Malathion, isocarbophos, quinalphos, demeton, trichlorfon). The main reason is that organophosphorus is relatively chemically stable and not easily removed by oxidation.

[0013] Therefore, it is of great practical significance to develop an extraction technology and preparation process that can completely remove the pesticide residues in monk fruit and develop high-quality monk fruit products. Summary of the invention

[0014] The technical problem to be solved by the present invention is to overcome the defect of incomplete removal of pesticide residues in the prior art, especially incomplete removal of organophosphorus pesticide residues, and to provide a monk fruit extraction technology that can be industrially produced and completely remove pesticide residues including organophosphorus.

[0015] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0016] An improved method for co-producing a pesticide-residue-free mogroside composition comprises the following steps:

[0017] (1) Fixing the fresh fruit: soaking the whole fresh monk fruit in hot water containing a slow-release oxidant until it is completely submerged, and then taking it out to fix the fresh fruit; the slow-release oxidant is a composite of polyvinyl alcohol and polyhydroxy fatty acid encapsulated ultrafine calcium peroxide;

[0018] (2) Pulping and extraction: Put the withered fresh fruit into a pulping machine and pass superheated water through it to pulp and extract, and obtain a pulping extract; collect the extraction residue for later use;

[0019] (3) Countercurrent extraction: The pulped residue is subjected to countercurrent extraction to obtain a countercurrent extract;

[0020] (4) Horizontal centrifugation: the pulping extract and the countercurrent extract are combined and filtered using a horizontal centrifuge to obtain a horizontal centrifuge filtrate;

[0021] (5) Disc centrifugation: Filter the decanter centrifuge filtrate using a disc centrifuge to obtain a disc centrifuge filtrate;

[0022] (6) Ceramic membrane filtration: filtering the disc centrifugal filtrate with a ceramic membrane to obtain a ceramic membrane filtrate;

[0023] (7) Sterilization: sterilize the ceramic membrane filtrate using UHT equipment, cool it, and obtain a sterilized material;

[0024] (8) Macroporous resin adsorption: passing the sterilized material through a macroporous adsorption resin column;

[0025] (9) Impurity removal: After the macroporous resin adsorption is completed, the resin column is first rinsed with a dilute alkali solution, and then rinsed with pure water until the resin column is neutral;

[0026] (10) Gradient elution I: eluting the macroporous adsorption resin column with a moderate ethanol aqueous solution, adding modified activated carbon to the moderate ethanol eluate, heating, stirring, filtering, concentrating and drying, to obtain the first monk fruit extract;

[0027] (11) Gradient elution II: eluting the macroporous adsorption resin column with a highly ethanol aqueous solution, adding modified activated carbon to the highly ethanol eluent, heating, stirring, filtering, concentrating and drying, to obtain a second monk fruit extract;

[0028] The modified activated carbon is obtained by activating the activated carbon with an activator at high temperature and then washing with water, wherein the activator includes KOH and potassium permanganate.

[0029] Preferably, the slow-release oxidant is obtained by a preparation method comprising the following steps: polyvinyl alcohol and polyhydroxy fatty acid are dissolved in an alcohol aqueous solution, ultrafine calcium peroxide is added under ultrasonic stirring conditions, dispersed evenly, and the dispersion is freeze-dried to obtain the slow-release oxidant.

[0030] Furthermore, the mass ratio of polyvinyl alcohol, polyhydroxy fatty acid, alcohol aqueous solution and ultrafine calcium peroxide is 20-30: 5-8: 100-160: 10-15; the alcohol volume concentration in the alcohol aqueous solution is 40-70 vol%, and the alcohol is selected from at least one of methanol, ethanol, propanol and ethylene glycol, preferably ethanol. Considering the toxicity, methanol is not used as much as possible, but methanol can also complete the present invention and should not be excluded from the substantive content of the present invention.

[0031] Furthermore, the particle size of the ultrafine calcium peroxide is 50-200nm; the preparation method of the ultrafine calcium peroxide comprises the following steps: calcium chloride is dissolved in an alcohol aqueous solution, filtered, a surfactant and ammonia water are added to the filtrate, hydrogen peroxide is slowly added dropwise under stirring conditions, and then a NaOH / KOH solution is added dropwise to generate a white precipitate, filtered, washed, and vacuum freeze-dried to obtain nano calcium peroxide.

[0032] Furthermore, the molar ratio of calcium chloride to hydrogen peroxide is 3-5:1, the mass concentration of hydrogen peroxide is 20-35wt%; the surfactant is PEG with a number average molecular weight of 1000 to 2000, and the amount of surfactant added is 3-6wt% of the mass of calcium chloride; the mass concentration of ammonia water is 20-30%, and the amount of ammonia water added is used to adjust the pH value of the system to 9-10; the slow dripping of hydrogen peroxide is completed within 1-2 hours; the mass concentration of NaOH / KOH solution is 1-5wt%, and the amount added is used to adjust the pH value of the system to 11-12; the alcohol aqueous solution is obtained by mixing ethanol and deionized water, wherein the volume content of ethanol is 30-50%.

[0033] The calcium peroxide prepared by the present invention is nano-scale ultrafine calcium peroxide, which can be better embedded in the polymer and has a better sustained-release effect.

[0034] Furthermore, the ultrasonic stirring condition is stirring at 30-60kHz and 600-1000rpm; the freeze drying is freeze drying the dispersion at -60°C to -30°C and 10-100Pa for 5-10h.

[0035] Preferably, in step (1), the temperature of the hot water is 50-60°C, and the amount of hot water is not particularly limited, as long as it can completely immerse the monk fruit, and the soaking time is 3-6h; the mass concentration of the slow-release oxidant is 2-3wt%. Compared with the inventor's previous patent 202310284713.4, the process of the present invention adopts a slow-release oxidant, reduces the hot water temperature and prolongs the soaking time. Although this prolongs the time of the entire process, the oxidation effect is better and more thorough, and the removal effect of pesticide residues, especially organophosphorus pesticide residues, is better.

[0036] In the present invention, step (1) is to remove the pesticide residues from the whole monk fruit while killing the whole monk fruit, so that the internal components of the monk fruit (especially mogroside) do not contact the oxidant and the alkali, and the loss of mogroside does not occur, and the trace amount of oxidation products is prevented from diffusing and infiltrating into the inside of the monk fruit. The slow-release oxidant will slowly release the oxidizing components in hot water and produce Ca(OH)2, so that the system is weakly alkaline to a certain extent, which is also conducive to the removal of pesticide residues on the surface of the monk fruit. No inorganic alkali needs to be added externally. One of the purposes of withering fresh monk fruit is to passivate and inactivate various biological enzymes and proteins of monk fruit to prevent browning caused by Maillard reaction, thereby ensuring that the color of the extract, filtrate and concentrate in the subsequent steps is light; the second purpose of withering is to kill various endophytic fungi and other microorganisms carried by the fresh monk fruit itself. The enzymes produced by these microorganisms may have a negative effect on the degradation of mogroside; the third purpose of withering is that the alkaline aqueous solution can leach flavonoids, phenolic acids, oils and most pigments and pesticide residues in the shell of the fresh monk fruit, thereby removing most impurities and pesticide residues, indirectly improving the quality of materials in subsequent steps, reducing the difficulty of separation and purification, and improving product quality and taste.

[0037] Preferably, in step (2), the temperature of the superheated water is 102-115°C, preferably 105-110°C. The temperature of the superheated water should not be too high, otherwise it will be unstable. The amount of superheated water used is 1-1.5 times the weight of the fresh fruit of monk fruit, while warm water extraction generally requires 10-20 times, and multiple extractions are required to achieve a satisfactory yield. The high-temperature, high-pressure superheated water generated by the secondary heating method is transported to the inside of the pulper under the traction of the pressure-resistant pipe. Under the action of the pressure reducing valve installed in the pressure-resistant pipe, the flow rate and flow velocity of the superheated water can be adjusted. When the superheated water pours out from the spray head at the end of the pressure-resistant pipe, the pressure is quickly released, accompanied by a violent mass transfer and heat transfer process. The inventors found that the extraction efficiency of this process is better than that of the ordinary normal pressure hot water pulping extraction process at any temperature (normal temperature to 100°C), and it greatly saves water resources and reduces the treatment cost of the extracted wastewater.

[0038] The use of superheated water to pulp monk fruit has not been reported before. The inventors found that the advantages of using superheated water to pulp monk fruit during the extraction process are: first, saving water and ensuring that most of the mogrosides are leached; second, completing the extraction process in large quantities and quickly, improving production efficiency; third, preventing contamination from external microorganisms and avoiding the degradation of mogrosides.

[0039] Preferably, in step (3), the amount of water in the countercurrent extraction is 1.5-3 times the weight of the fresh monk fruit, and the extraction temperature is 85-95° C. The purpose of reusing the pulped extraction residue for countercurrent extraction is to completely leach the mogrosides remaining in the pulped extraction residue, thereby increasing the total yield of mogrosides.

[0040] The horizontal screw centrifuge, disc centrifuge and ceramic membrane in step (4), step (5) and step (6) are purchased through commercial channels. The process parameters are well known in the art and there are no special requirements.

[0041] Preferably, the UHT sterilization temperature in step (7) is 100-115° C., and the sterilization time is 2-30 seconds. The purpose of using UHT sterilization for the ceramic membrane filtrate is to kill the microorganisms that may exist in the ceramic membrane filtrate (because during the process of horizontal spiral centrifugation, disc centrifugation and ceramic membrane filtration, the materials are inevitably exposed to the air and there is a risk of contamination), ensuring that the subsequent chromatography step will not breed microorganisms and will not cause the degradation of mogroside.

[0042] The macroporous adsorption resin in step (8) refers to the macroporous adsorption resin commonly used in the industry for extracting monk fruit, such as D101 type, AB-8 type, etc. The volume dosage of the macroporous adsorption resin is 0.15-0.25 times the mass of the fresh monk fruit, and the unit is cubic meter: ton.

[0043] Preferably, in step (9), the alkali solution is a sodium hydroxide and / or potassium hydroxide aqueous solution with a mass percentage concentration of 0.3%-0.5%, and the amount of the alkali solution is 1-3BV. After the macroporous resin adsorption is completed, the purpose of washing the resin column with a dilute alkali solution is to remove impurities such as flavonoids, pigments and agricultural residues adsorbed in the macroporous resin column, thereby increasing the content of the product in the subsequent steps and improving the color of the product. If the concentration of the alkali solution is too low or the amount is too small, the above purpose cannot be achieved; if the concentration of the alkali solution is too high or the amount is too large, a small amount of mogroside may be eluted, resulting in a low yield of mogroside.

[0044] Preferably, in step (10) and step (11), the modified activated carbon is activated carbon subjected to an activation modification treatment comprising the following steps: the activated carbon and the activator are mixed evenly, ground into powder, pre-calcined at 300-400°C for 1-2h under an inert atmosphere to remove moisture from the material, then activated at 600-700°C for 3-5h, cooled to room temperature after activation, neutralized with dilute acid (such as dilute hydrochloric acid), then immersed in hot water under ultrasonic conditions, and finally washed with water to neutrality (pH 6-7); the modifier is a mixture of KOH and potassium permanganate in a mass ratio of 10-15:1.

[0045] Furthermore, the amount of activator used is 0.5-0.8 times the mass of the activated carbon, and the powder is ground into particles with a size of 0.5-2 mm. The size should not be too small, otherwise the strength of the modified activated carbon will be low, which is not conducive to the regeneration of the activated carbon; the size should not be too large, otherwise the modification will not be thorough, and the effect of adsorbing pesticide residues will decrease after modification.

[0046] Furthermore, the hot water washing under ultrasonic conditions is carried out at 300-500W ultrasonic power, 120-180kHz ultrasonic frequency, using 70-90°C hot water for immersion, and the immersion time is 1-2h, during which the hot water is replaced 1-3 times. If the activated carbon is not washed after activation, its pores are still occupied by non-bulk substances. In addition to the selection of the activator, the key to obtaining activated carbon with high specific surface area is the subsequent water washing to remove non-bulk substances. The present invention uses hot water immersion under ultrasonic conditions, which can save water and effectively and thoroughly remove non-bulk substances in the pores of activated carbon.

[0047] In the prior art, KOH is generally used to activate activated carbon. At a suitable activation temperature, the generated steam is diffused in the carbon layer to form a new pore structure and generate new micropores. However, this activation method consumes a large amount of KOH. The preparation of high specific surface area activated carbon even requires an alkali-carbon ratio of more than 3 (KOH is more than 3 times the mass of activated carbon). On the one hand, it causes serious waste of KOH, and a large amount of KOH will also aggravate the corrosion of equipment. A large amount of acid washing to neutrality is required later, resulting in excessive production costs. The prior art uses new activation methods such as carbon dioxide and water vapor, but the equipment is expensive, the operating conditions are strict, and the activation time is long. At present, most of them are small-scale theoretical research in laboratories and are not suitable for industrial production. The present invention creatively uses KOH and potassium permanganate as activators, significantly reducing the amount of KOH used and lowering the activation temperature; and the inventors also unexpectedly found that the modified activated carbon obtained after adding a certain amount of potassium permanganate has an enhanced adsorption capacity for organic matter. The possible reason is that after adding potassium permanganate, the activated carbon has certain oxygen-containing active functional groups after activation, which is conducive to the adsorption of agricultural residues.

[0048] The activated carbon is not particularly limited. In one embodiment of the present invention, the specific surface area of ​​the activated carbon before modification is 400-800 m 2 / g. Commercially available activated carbon is generally within the above range. In the adsorption of pesticide residues, the micropores (<2nm) and mesopores (2-50nm) on the activated carbon play a major role. The specific surface area of ​​the activated carbon after the activation modification treatment of the present invention is significantly increased to 2000m 2 / g or more, proving that more micropores and mesopores appeared during the modification process, which can more effectively adsorb pesticide residues.

[0049] Preferably, in step (10), the volume percentage concentration of the moderate ethanol aqueous solution is 30-45 vol%, and the amount of the moderate ethanol is 3-5 BV. The purpose of using moderate ethanol for elution is to obtain an elution product with a relatively large amount and a relatively high content of mogroside V. If the concentration of moderate ethanol is too low or the amount used is too small, the amount of mogroside V in the eluted product (i.e., the first monk fruit extract) is small and the content is low; if the concentration of moderate ethanol is too high or the amount used is too large, the components adsorbed by the macroporous resin may be completely eluted, resulting in no product or very little product in the subsequent high-ethanol elution step.

[0050] Preferably, in step (10), the amount of the modified activated carbon is 0.05-0.1wt% of the weight of the fresh monk fruit, the heating temperature is 60-90°C, and the stirring time is 1-3 hours. If the amount of the modified activated carbon is too small, the heating temperature is too low, or the stirring time is too short, the above purpose cannot be fully achieved; if the amount of the modified activated carbon is too large, the heating temperature is too high, or the stirring time is too long, it will not only cause waste of materials and energy, but also may cause loss of mogroside.

[0051] Preferably, in step (11), the volume percentage concentration of the high-ethanol is 50-75 vol%, and the amount of the high-ethanol is 1-3 BV. The purpose of using high-ethanol elution is to completely elute the components that are not completely eluted by medium ethanol, so as to obtain an elution product with a relatively small amount and a relatively low content of mogroside V. If the concentration of high-ethanol is too low or the amount used is too little, it may cause incomplete elution of mogroside, resulting in a low overall yield of mogroside; if the concentration of high-ethanol is too high or the amount used is too much, it will cause a waste of solvent and energy.

[0052] Preferably, in step (11), the amount of modified activated carbon is 0.02-0.05wt% of the weight of the fresh monk fruit, the heating temperature is 60-90°C, and the stirring time is 1-3 hours.

[0053] In the present invention, a slow-release oxidant is used in the early stage, which has a better removal effect on oxidizable pesticide residues. In the subsequent modified activated carbon adsorption stage, the amount of modified activated carbon used can be further reduced, thereby reducing production costs and being more suitable for industrial preparation.

[0054] In the present application, 1 BV = 1 resin column volume.

[0055] The principle of the method of the present invention is as follows:

[0056] The pesticide residues in Momordica grosvenori mainly come from direct spraying residues and indirect air, soil and water pollution. First, in the step of killing green, the whole Momordica grosvenori fruit is soaked in hot water of slow-release oxidant for a long time, which can achieve the purpose of removing most of the pesticide residues on the surface of Momordica grosvenori, and will not have an adverse effect on the sweet glycosides inside the Momordica grosvenori; the superheated water pulping treatment can significantly reduce the amount of water used, increase the yield of mogrosides, and prevent microbial contamination and breeding; secondly, before the macroporous adsorption resin is eluted with ethanol, the pesticide residues can be further removed by washing with alkali solution; finally, modified activated carbon is added to the ethanol desorption liquid and heated and stirred, which can maximize the adsorption effect of activated carbon on pesticide residues and impurities (the adsorption effect of activated carbon on pesticide residues in alcohol phase is better than that in water phase). The present invention is more thorough and thorough for organophosphorus pesticide residues through the use of slow-release oxidants, and then the modification of activated carbon significantly increases the adsorption capacity of activated carbon on pesticide residues, thereby thoroughly removing the pesticide residues in the Momordica grosvenori extract.

[0057] The beneficial effects of the method of the present invention are as follows:

[0058] (1) The present invention prepares a slow-release oxidant, which can effectively remove a large amount of easily oxidized agricultural residues during the withering stage of Momordica grosvenori, reduce the amount of activated carbon used in subsequent activated carbon adsorption, thereby achieving the purpose of completely removing agricultural residues and improving the yield of mogroside.

[0059] (2) The present invention can completely remove agricultural residues by modifying the activated carbon, thereby achieving the purpose of high-quality monk fruit extract, meeting the market requirements of high-end food additives, sweeteners, etc. exported to the international market, and the product has a high premium.

[0060] (3) The present invention uses superheated water to extract the monk fruit pulp, thereby increasing the yield of mogroside.

[0061] (4) The method can simultaneously obtain two pesticide-free monk fruit extract products with different content specifications, which can meet the requirements on the content, quality, color, taste and other aspects of monk fruit glycosides; the method of the present invention adjusts the content and proportion of various glycosides (mainly six kinds of glycosides) in monk fruit, and the proportion and content of various glycosides in the two specifications of the final obtained products are optimized to meet different consumption scenarios and needs.

[0062] (5) The method of the present invention perfectly integrates three technical means for removing pesticide residues into the entire production and processing process of the monk fruit extract, thereby saving the production and processing costs while ensuring that the pesticide residue index of the product is qualified.

[0063] (6) Since the method of the present invention adopts the original key operation steps and combination of "whole fresh fruit withering + superheated (alkaline) water pulping + intermediate UHT sterilization", the yield of mogroside V in the method of the present invention is high and the taste of the monk fruit extract is not affected. DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with the embodiments.

[0065] The fresh Momordica fruit used in the embodiment of the present invention was purchased from Guilin, Guangxi, wherein the mass percentage content of Momordica 11-O-glycoside V was 0.045wt%, the mass percentage content of Mogroside V was 0.491wt%, the mass percentage content of Mogroside VI was 0.028wt%, the mass percentage content of Mogroside 11-O-glycoside V was 0.016wt%, the mass percentage content of Mogroside IV was 0.013wt%, the mass percentage content of Mogroside III was 0.006wt%, and the mass percentage content of total Momordica glycosides was 0.599wt%; the horizontal screw centrifuge and the disc centrifuge used in the embodiment of the present invention were purchased from Jiangsu Dongbang Machinery Co., Ltd.; the ceramic membrane used in the embodiment of the present invention was purchased from Nanjing Fulinde Environmental Protection Technology Co., Ltd.; the macroporous adsorption resin used in the embodiment of the present invention was purchased from Xi'an Lanxiao Science and Technology New Materials Co., Ltd.; the raw materials or chemical reagents used in the embodiment of the present invention, unless otherwise specified, were obtained through conventional commercial channels.

[0066] The unmodified activated carbon was purchased from Jiangsu Suqi Carbon Technology Co., Ltd. and was in the form of 3-5 mm granules with a specific surface area of ​​about 800 m 2 / g. ,

[0067] The embodiment of the present invention adopts high performance liquid chromatography (HPLC) external standard method to detect the content of mogroside V; and adopts liquid chromatography-gas chromatography-mass spectrometry (GC-MS) to detect pesticide residues.

[0068] Preparation Example 1

[0069] 10 kg of commercial activated carbon (BET = 800 m 2 / g) and 5kg modifier (a mixture of KOH and potassium permanganate in a mass ratio of 10:1) were mixed evenly, ground into powder of about 1mm in size, and put into a heating furnace with intelligent temperature control, which was filled with nitrogen in advance. The mixture was pre-burned at 300℃ for 2h, with a water content of <0.1%, and then heated to 600℃, kept warm and activated for 5h, cooled to room temperature, neutralized with 1wt% dilute hydrochloric acid, and then put into an ultrasonic cleaning instrument, immersed in 90℃ hot water under ultrasonic conditions (300W, 150kHz) for 2h, during which the hot water was changed twice; finally, washed with water until the pH of the washing liquid was 6.8, taken out, and dried to obtain modified activated carbon. According to GB / T 7702.20-2008, the specific surface area (BET) of the modified activated carbon obtained in Preparation Example 1 was 2420m 2 / g.

[0070] Preparation Example 2

[0071] 10 kg of commercial activated carbon (BET = 800 m 2 / g) and 8kg modifier (a mixture of KOH and potassium permanganate in a mass ratio of 15:1) were mixed evenly, ground into powder of about 1mm in size, and put into a heating furnace with intelligent temperature control, which was filled with nitrogen in advance. The mixture was pre-burned at 400℃ for 1h, with a water content of <0.1%, and then heated to 700℃, kept warm for 3h, cooled to room temperature, neutralized with 1wt% dilute hydrochloric acid, and then put into an ultrasonic cleaning instrument, immersed in 90℃ hot water under ultrasonic conditions (300W, 180kHz) for 2h, during which the hot water was changed twice; finally, washed with water until the pH of the washing liquid was 6.7, taken out, and dried to obtain modified activated carbon. According to GB / T 7702.20-2008, the specific surface area (BET) of the modified activated carbon obtained in Preparation Example 2 was 2260m 2 / g.

[0072] Preparation Example 3

[0073] (1) 1 mol of calcium chloride was dissolved in 5 times the mass of ethanol aqueous solution (the volume ratio of ethanol to water was 3:7), filtered, and the filtrate was added with 5 wt% of PEG1200 and 25 wt% of ammonia water in an amount such that the pH of the system was 9.6. Under stirring at 200 rpm, 30 wt% of hydrogen peroxide was slowly added dropwise, and the amount of hydrogen peroxide was 4.2 mol parts (in terms of H2O2). Then, NaOH / KOH solution was added dropwise to make the pH of the system 12, and a white precipitate was generated. The precipitate was filtered, washed three times with anhydrous ethanol, and vacuum freeze-dried at -80°C and 100 Pa to obtain nano calcium peroxide with a particle size D50 of 120 nm.

[0074] (2) 20 parts by weight of polyvinyl alcohol (number average molecular weight of about 50,000) and 8 parts by weight of polyhydroxy fatty acid (number average molecular weight of about 6,000) are dissolved in 100 parts by weight of ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), and 10 parts by weight of ultrafine calcium peroxide powder prepared in step (1) are added in three batches under 60 kHz ultrasonic conditions, stirred at 800 rpm for 1 hour, and freeze-dried at -60°C and 100 Pa for 10 hours to obtain a sustained-release oxidant.

[0075] Comparative Preparation Example 1

[0076] 10 kg of commercial activated carbon (BET = 800 m 2 / g) and 30kg KOH were mixed evenly, ground into powder with a size of about 1mm, and put into a heating furnace with intelligent temperature control. The heating furnace was filled with nitrogen in advance, pre-burned at 400℃ for 1h, with a water content of <0.1%, then heated to 700℃, kept warm for 3h, cooled to room temperature, neutralized with 1wt% dilute hydrochloric acid, and then put into an ultrasonic cleaning instrument, put into 90℃ hot water and immersed for 2h under ultrasonic conditions (300W, 180kHz), during which the hot water was changed twice; finally washed with water until the pH of the washing liquid was 6.7, taken out, and dried to obtain modified activated carbon. According to GB / T 7702.20-2008, the specific surface area (BET) of the modified activated carbon obtained in the test comparative preparation example 1 is 1700m 2 / g.

[0077] Example 1

[0078] (1) Fixing the fresh fruit: 2 tons of mature and intact fresh monk fruit were selected and placed in 60° C. hot water containing 2 wt % of the slow-release oxidant prepared in Preparation Example 3, so that the fresh fruit was completely submerged in the hot water for 4 hours, and then the fresh fruit was removed from the hot water to obtain the fixed fresh fruit;

[0079] (2) Pulping extraction: the fresh fruit is fed into a pulping machine at a feeding rate of 1 ton / hour, and superheated water at a temperature of 105°C is introduced at a flow rate of 1 ton / hour for pulping extraction to obtain a pulping extract; the extraction residue is collected for later use;

[0080] (3) Countercurrent extraction: The pulped residue is subjected to countercurrent extraction, with a water consumption of 3 tons and an extraction temperature of 94° C. to obtain a countercurrent extract;

[0081] (4) Horizontal centrifugation: The pulping extract and the countercurrent extract were combined and filtered using a horizontal centrifuge (rotation speed 5000 rpm) to obtain a horizontal centrifuge filtrate;

[0082] (5) Disc centrifugation: Filter the decanter centrifuge filtrate using a disc centrifuge (6000 rpm) to obtain a disc centrifuge filtrate;

[0083] (6) Ceramic membrane filtration: The disc centrifugal filtrate is filtered through an alumina ceramic membrane (0.2 μm) to obtain a ceramic membrane filtrate;

[0084] (7) Sterilization: sterilize the ceramic membrane filtrate using UHT equipment at a sterilization temperature of 110° C. for 10 seconds, and cool to obtain a sterilized material;

[0085] (8) Macroporous resin adsorption: The sterilized material is passed through a D101 macroporous adsorption resin column, column volume = 1.0 cubic meter = 1 BV;

[0086] (9) Impurity removal: After the macroporous resin is adsorbed onto the column, the resin column is first rinsed with 2BV of 0.5wt% NaOH aqueous solution, and then rinsed with pure water until the resin column is neutral;

[0087] (10) Gradient elution I: First, the macroporous adsorption resin column was eluted with 4 BV of moderate ethanol with a concentration of 35%, and 1.7 kg of the modified activated carbon prepared in Preparation Example 1 was added to the moderate ethanol eluate, heated to 70° C., stirred for 3 hours, filtered, concentrated and dried, and 15.07 kg of the first monk fruit extract was obtained;

[0088] (11) Gradient elution II: Use 2BV of high-grade ethanol with a volume percentage concentration of 72% to elute the macroporous adsorption resin column, add 0.8 kg of activated carbon prepared in Preparation Example 1 to the high-grade ethanol eluate, heat to 70°C, stir for 3 hours, filter, concentrate and dry, and obtain 5.60 kg of the second monk fruit extract.

[0089] The content of the first monk fruit extract obtained in Example 1 was 5.28%wt% of momordica glycoside V, 52.32%wt% of mogroside V, 2.98%wt% of mogroside VI, 1.50%wt% of mogroside IV, 0.85%wt% of mogroside III, and 6.3%wt% of total momordica glycosides. The content of the second Momordica grosvenori extract obtained in this embodiment is 0.71%wt% of Momordica 11-O glycoside V, 24.91wt% of Mogroside V, 1.05%wt% of Mogroside VI, 1.23%wt% of Mogroside Simen, 1.96%wt% of Mogroside IV, 0.62%wt% of Mogroside III, and 30.48wt% of total Momordica grosvenori glycosides. After calculation, the total yield of Mogroside V is 94.50%, and the total yield of total Momordica grosvenori glycosides is 94.04%.

[0090] More than 400 pesticide residues were detected by liquid chromatography and gas chromatography-mass spectrometry (GC-MS). The pesticide residue detection results of the first monk fruit extract and the second monk fruit extract obtained in this embodiment were: not detected. Among them, organophosphorus (methamidophos, omethoate, dimethoate, phorate, diazinon, parathion, methyl parathion, malathion, isocarbophos, quinalphos, demeton, trichlorfon) were not detected.

[0091] Example 2

[0092] (1) Fixing the fresh fruit: 2 tons of mature and intact fresh monk fruit were selected and placed in 50° C. hot water containing 3 wt % of the slow-release oxidant prepared in Preparation Example 4, so that the fresh fruit was completely submerged in the hot water for 6 hours, and then the fresh fruit was taken out of the hot water to obtain the fixed fresh fruit;

[0093] (2) Pulping extraction: the fresh fruit is fed into a pulping machine at a feeding rate of 1 ton / hour, and superheated water at a temperature of 105°C is introduced at a flow rate of 1.5 tons / hour for pulping extraction to obtain a pulping extract; the extraction residue is collected for later use;

[0094] (3) Countercurrent extraction: The pulped residue is subjected to countercurrent extraction, with a water consumption of 4 tons and an extraction temperature of 90° C. to obtain a countercurrent extract;

[0095] (4) Horizontal centrifugation: the pulping extract and the countercurrent extract are combined and filtered using a horizontal centrifuge to obtain a horizontal centrifuge filtrate;

[0096] (5) Disc centrifugation: Filter the decanter centrifuge filtrate using a disc centrifuge to obtain a disc centrifuge filtrate;

[0097] (6) Ceramic membrane filtration: filtering the disc centrifugal filtrate with a ceramic membrane to obtain a ceramic membrane filtrate;

[0098] (7) Sterilization: sterilize the ceramic membrane filtrate using UHT equipment at a sterilization temperature of 105° C. for 12 seconds, and cool to obtain a sterilized material;

[0099] (8) Macroporous resin adsorption: The sterilized material is passed through a D101 macroporous adsorption resin column, with a column volume of 1.0 cubic meter = 1 BV;

[0100] (9) Impurity removal: After the adsorption of the macroporous resin is completed, the resin column is first rinsed with a 2BV mass percentage of 0.5wt% KOH aqueous solution, and then rinsed with pure water until the resin column is neutral;

[0101] (10) Gradient elution I: First, the macroporous adsorption resin column was eluted with 3.5 BV of moderate ethanol with a concentration of 38%, and 2 kg of the activated carbon prepared in Preparation Example 2 was added to the moderate ethanol eluate, heated to 80° C., stirred for 2 hours, filtered, concentrated and dried, and 15.93 kg of the first monk fruit extract was obtained;

[0102] (11) Gradient elution II: Use 1.5 BV of 70% high-grade ethanol to elute the macroporous adsorption resin column, add 1.2 kg of the activated carbon prepared in Preparation Example 2 to the high-grade ethanol eluate, heat to 80°C, stir for 2 hours, filter, concentrate and dry, and obtain 4.08 kg of the second monk fruit extract.

[0103] The content of the first Momordica grosvenori extract obtained in this embodiment was 5.04wt% of Momordica 11-O-glycoside V, 50.36wt% of Mogroside V, 2.84wt% of Mogroside VI, 1.35wt% of Mogroside A, 0.82wt% of Mogroside IV, 0.45wt% of Mogroside III and 0.6wt% of total Momordica grosvenori glycosides. The content of the second monk fruit extract obtained in this embodiment is 0.65wt% of mogroside V, 26.75% of mogroside V, 1.54wt% of mogroside VI, 1.86wt% of mogroside IV, 2.67wt% of mogroside III, and 34.44wt% of total monk fruit glycosides. Among them, the total yield of mogroside V is 92.80%, and the yield of total monk fruit glycosides is 92.65%.

[0104] More than 400 pesticide residues were detected by liquid chromatography and gas chromatography-mass spectrometry (GC-MS). The pesticide residue detection results of the first monk fruit extract and the second monk fruit extract obtained in this embodiment were: not detected. Among them, organophosphorus (methamidophos, omethoate, dimethoate, phorate, diazinon, parathion, methyl parathion, malathion, isocarbophos, quinalphos, demeton, trichlorfon) were not detected.

[0105] Comparative Example 1

[0106] Step (10) and step (11) use the activated carbon prepared in Comparative Preparation Example 1, and the operations of the remaining steps are consistent with those in Example 1.

[0107] More than 400 pesticide residues were tested by liquid chromatography and gas chromatography-mass spectrometry (GC-MS). The pesticide residue test results of the first monk fruit extract obtained in this example were: 0.23 mg / kg of dimethomorph, 0.11 mg / kg of isoprodinil, 0.05 mg / kg of oxadixyl, 0.27 mg / kg of propamocarb and propamocarb salt, and other items were below the quantitative limit or not detected;

[0108] The pesticide residue test results of the second monk fruit extract in this case were: 0.12 mg / kg of dimethomorph, 0.06 mg / kg of isoprodinil, 0.05 mg / kg of oxadixyl, 0.22 mg / kg of propamocarb and propamocarb salt, and other items were below the quantitative limit or not detected.

[0109] Comparative Example 2

[0110] The pulping extraction in step (2) is changed to: the withered fresh fruit is fed into the pulping machine at a feeding rate of 1 ton / hour, and hot water at a temperature of 70°C is introduced at a flow rate of 3 tons / hour for pulping and extraction to obtain a pulping extract; the extraction residue is collected for standby use; the operation of the remaining steps is the same as that in Example 1. That is, the superheated water pulping extraction in step (2) is changed to warm water pulping extraction.

[0111] Finally, 14.41 kg of the first monk fruit extract and 5.27 kg of the second monk fruit extract were obtained.

[0112] By high performance liquid phase HPLC external standard method detection, the content of mogroside V in the first monk fruit extract obtained in this example was 49.06%, and the content of total monk fruit glycosides was 60.18%; the content of mogroside V in the second monk fruit extract obtained was 23.60%, and the content of total monk fruit glycosides was 29.25%; after calculation, the total yield of mogroside V was 84.66%, and the yield of total monk fruit glycosides was 85.25%.

[0113] Comparative Example 3

[0114] The other operations and conditions are the same as those in Example 1, except that in step (1), the slow-release oxidant is replaced by an equal mass of calcium peroxide.

[0115] The final yield and purity of mogrosides were basically unaffected, and were equivalent to those in Example 1. The final product was tested for more than 400 pesticide residues by liquid chromatography-gas spectrometry (GC-MS), and the content of methylamidophos in the first monk fruit extract was 0.11 mg / kg, and the content of methylamidophos in the second monk fruit extract was 0.07 mg / kg.

[0116] Comparative Example 4

[0117] The "gradient elution I" step in step (10) was not performed, and the operations of the remaining steps were consistent with those in Example 1 (ie, gradient elution was not performed and high ethanol was directly used for elution), and 20.11 kg of the only monk fruit extract was finally obtained.

[0118] Detected by HPLC external standard method, the content of the single Momordica grosvenori extract obtained in this example was 4.13wt% of Momordica 11-O-glycoside V, 44.68wt% of Mogroside V, 2.57wt% of Mogroside VI, 1.45wt% of Mogroside Simen, 1.17wt% of Mogroside IV, 0.54wt% of Mogroside III, and the total content of sweet glycosides was 54.54wt%. Among them, the yield of Mogroside V was 91.50%, and the yield of total Momordica grosvenori glycosides was 91.55%.

Claims

1. An improved method for co-producing a pesticide-residue-free mogroside composition, characterized in that: The following steps are involved: (1) Fixing fresh fruit: soaking whole fresh monk fruit in hot water containing a slow-release oxidant until the fruit is completely submerged and then fishing out to obtain the fixed fresh fruit; the slow-release oxidant is a composite of polyvinyl alcohol and polyhydroxy fatty acid encapsulating ultrafine calcium peroxide; the slow-release oxidant is obtained by a preparation method comprising the following steps: dissolving polyvinyl alcohol and polyhydroxy fatty acid in an alcohol aqueous solution, adding ultrafine calcium peroxide under ultrasonic stirring, dispersing the mixture uniformly, and freeze-drying the dispersion to obtain the slow-release oxidant; Furthermore, the mass ratio of polyvinyl alcohol, polyhydroxy fatty acid, alcohol aqueous solution, and ultrafine calcium peroxide is 20-30: 5-8: 100-160: 10-15; (2) Pulping and extraction: put the withered fresh fruit into a pulping machine and pass superheated water through it to pulp and extract, and obtain a pulping extract; collect the extraction residue for later use; the temperature of the superheated water is 105-110°C; the amount of superheated water used is 1-1.5 times the weight of the fresh monk fruit; (3) Countercurrent extraction: The pulped residue is subjected to countercurrent extraction to obtain a countercurrent extract; (4) Horizontal centrifugation: The pulping extract and the countercurrent extract are combined and filtered using a horizontal centrifuge to obtain a horizontal centrifuge filtrate; (5) Disc centrifugation: Filter the decanter centrifugal filtrate with a disc centrifuge to obtain disc centrifugal filtrate; (6) Ceramic membrane filtration: Filter the disc centrifugal filtrate through a ceramic membrane to obtain a ceramic membrane filtrate; (7) Sterilization: sterilize the ceramic membrane filtrate using UHT equipment, cool it, and obtain the sterilized material; (8) Macroporous resin adsorption: passing the sterilized material through a macroporous adsorption resin column; (9) Impurity removal: After the macroporous resin adsorption is completed, the resin column is first rinsed with a dilute alkali solution, and then rinsed with pure water until the resin column is neutral; (10) Gradient elution I: eluting the macroporous adsorption resin column with a moderate ethanol aqueous solution, adding modified activated carbon to the moderate ethanol eluent, heating, stirring, filtering, concentrating and drying, and obtaining the first monk fruit extract; (11) Gradient elution II: eluting the macroporous adsorption resin column with a highly ethanol aqueous solution, adding modified activated carbon to the highly ethanol eluent, heating, stirring, filtering, concentrating and drying, to obtain a second monk fruit extract; The modified activated carbon is activated carbon that has been subjected to an activation modification treatment including the following steps: after the activated carbon and the modifier are evenly mixed, they are ground into powder, pre-burned at 300-400°C for 1-2h under an inert atmosphere to remove moisture from the material, then activated at 600-700°C for 3-5h, cooled to room temperature after activation, neutralized with dilute acid, then immersed in hot water under ultrasonic conditions, and finally washed with water until neutral; the modifier is a mixture of KOH and potassium permanganate in a mass ratio of 10-15:1; The amount of modifier used is 0.5-0.8 times the mass of activated carbon, and the powder is ground into particles with a size of 0.5-2mm; The hot water washing under ultrasonic conditions is performed by immersing in hot water at 70-90° C. at an ultrasonic power of 300-500 W and an ultrasonic frequency of 120-180 kHz for 1-2 hours.

2. The co-production method according to claim 1, characterized in that: The particle size of the ultrafine calcium peroxide is 50-200nm; the preparation method of the ultrafine calcium peroxide comprises the following steps: calcium chloride is dissolved in an alcohol aqueous solution, filtered, a surfactant and ammonia water are added to the filtrate, hydrogen peroxide is slowly added dropwise under stirring conditions, and then NaOH and / or KOH solution is added dropwise to generate a white precipitate, filtered, washed, and vacuum freeze-dried to obtain the ultrafine calcium peroxide.

3. The co-production method according to claim 2, characterized in that: The molar ratio of calcium chloride to hydrogen peroxide is 3-5:1, and the mass concentration of hydrogen peroxide is 20-35 wt%; the surfactant is selected from PEG with a number average molecular weight of 1000 to 2000, and the amount of surfactant added is 3-6 wt% of the mass of calcium chloride; the mass concentration of ammonia water is 20-30%, and the amount of ammonia water added is adjusted to a pH of 9-10; The slow dripping of hydrogen peroxide is completed within 1-2 hours; the mass concentration of NaOH / KOH solution is 1-5wt%, and the added amount makes the pH of the system 11-12; the alcohol-water solution is obtained by mixing ethanol and deionized water, wherein the volume content of ethanol is 30-50%.

4. The co-production method according to claim 2, characterized in that: The ultrasonic stirring condition is stirring at 30-60kHz and 600-1000rpm; the freeze drying is freeze drying the dispersion at -60°C to -30°C and 10-100Pa for 5-10h.

5. The co-production method according to claim 1, characterized in that: In step (1), the temperature of the hot water is 50-60° C., the soaking time is 3-6 hours, and the mass concentration of the slow-release oxidant is 2-3wt%.

6. The co-production method according to claim 1, characterized in that: In step (3), the amount of water in the countercurrent extraction is 1.5-3 times the weight of the fresh monk fruit, and the extraction temperature is 85-95°C; The UHT sterilization temperature in step (7) is 100-115°C, and the sterilization time is 2-30 seconds; The macroporous adsorption resin in step (8) is D101 type or AB-8 type, and the volume dosage of the macroporous adsorption resin is 0.15-0.25 times the mass of the fresh monk fruit, and the unit is cubic meter: ton; In step (9), the alkali solution is a sodium hydroxide and / or potassium hydroxide aqueous solution with a mass percentage concentration of 0.3%-0.5%, and the amount of the alkali solution used is 1-3BV.

7. The co-production method according to claim 1, characterized in that: The specific surface area of ​​activated carbon before modification is 400-800 m 2 / g; the specific surface area of ​​the modified activated carbon is 2000 m 2 / g or above.

8. The co-production method according to claim 1, characterized in that: In step (10), the volume percentage concentration of the moderate ethanol aqueous solution is 30-45 vol%, the amount of the moderate ethanol is 3-5 BV; the stirring time is 1-3 hours; In step (11), the volume percentage concentration of the high-grade ethanol is 50-75 vol%, and the amount of the high-grade ethanol used is 1-3 BV.

9. The co-production method according to claim 1, characterized in that: In step (10), the amount of the modified activated carbon is 0.05-0.1 wt% of the weight of the fresh monk fruit, and the heating temperature is 60-90°C.

10. The co-production method according to claim 1, characterized in that: In step (11), the amount of modified activated carbon is 0.02-0.05wt% of the weight of fresh monk fruit, the heating temperature is 60-90°C, and the stirring time is 1-3 hours.