Asparagus flavone as well as preparation method and application thereof
Through steam explosion and enzymatic binding resin separation, high-concentration asparagus flavonoids were prepared and made into nano-coated film liquid, which solved the application of asparagus flavonoids in food preservation and achieved a good 90-day preservation effect of sauce-bacon.
Patent Information
- Application Number
- CN202411413869.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-01-14
AI Technical Summary
The prior art has failed to effectively verify whether the flavonoids extracted from the old stems of asparagus have food preservation effects, and the extraction method has a significant impact on the types and content of flavonoid compounds. How to prepare asparagus flavonoids for food preservation is a key issue.
After steam blasting treatment, enzymatic decomposition was carried out, combined with resin separation and purification, high concentration of asparagus flavonoids were prepared, and nanoparticles were made into film-forming agent to form asparagus flavonoid nanocoating liquid, which was used to preserve freshness of bacon.
The extraction rate of flavonoids is significantly improved. The prepared asparagus flavonoid nanocoating liquid can keep the sauce and bacon for 90 days at 4°C, maintain its sensory quality, and effectively control the TVB-N content and total colony count.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of flavonoid extraction and food preservation, in particular to asparagus flavonoids and a preparation method and application thereof. Background Art
[0002] Asparagus is one of the most popular vegetable varieties. It is not only delicious but also nutritionally balanced. The edible part of asparagus is its tender stems, and the remaining lignified part is called old asparagus stems. As a kind of vegetable waste, the application of old asparagus stems has attracted much attention. Existing studies have shown that old asparagus stem extracts have lipid-lowering, blood sugar-lowering and anti-tumor activities. Studies on polysaccharides from old asparagus stems have shown significant antioxidant effects in vitro. This provides guidance for the comprehensive utilization of old asparagus stems.
[0003] The main active ingredients in the old stem extract of asparagus are flavonoids. Existing studies have shown that guava flavonoid extracts have a certain preservation effect on shrimp and fish mince. However, there are differences in the types and contents of flavonoids extracted from different plants. Therefore, whether the flavonoids extracted from old stems of asparagus have a preservation effect remains to be verified. At the same time, the extraction method also has a significant impact on the types and contents of flavonoids. Therefore, how to prepare asparagus flavonoids so that they can be used for food preservation is a key technical problem that we need to solve. Summary of the invention
[0004] The purpose of the present invention is to provide an asparagus flavonoids and a preparation method and application thereof, so that the prepared asparagus flavonoids have a good preservation effect, especially for foods such as marinated bacon.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] The present invention provides a method for preparing asparagus flavonoids, comprising the following steps:
[0007] (1) taking old asparagus stems, drying them, and cutting them into segments to obtain old asparagus stem segments;
[0008] (2) steam-exploding the old asparagus stem segments to obtain steam-exploded asparagus;
[0009] (3) crushing the steam-exploded asparagus and performing enzymolysis, collecting the enzymolysis solution, and obtaining a crude asparagus flavonoid extract;
[0010] (4) separating and purifying the crude asparagus flavonoid extract by resin to obtain a purified asparagus flavonoid solution;
[0011] (5) The asparagus flavonoids solution is concentrated and then freeze-dried to obtain asparagus flavonoids.
[0012] Preferably, in step (1), the old asparagus stems are dried to a moisture content of 45-55%, and the drying temperature is 50-60° C.; the length of the old asparagus stem segments is 0.5-1 cm; and in step (2), the temperature of the steam explosion treatment is 160-190° C., the pressure is 0.5-1.5 MPa, and the time is 60-90 min.
[0013] Preferably, the conditions for the crushing in step (3) are: grinding at 1000-3000 r / min for 0.5-1 h; the enzyme used for enzymatic hydrolysis is cellulase, and the activity of the cellulase is 50-60 U / g; the temperature of the enzymatic hydrolysis is 45-55°C, the power of the ultrasound is 300-400 W, and the time is 30-60 min; the enzymatic hydrolysis solution collected in step (3) is centrifuged on the product after enzymatic hydrolysis, the centrifugal speed is 5000-7000 r / min, and the time is 8-12 min.
[0014] Preferably, the resin in step (4) is AB-8 resin, and the resin has an adsorption flow rate of 1 to 3 mL / min during separation and purification; 75 to 85% ethanol solution is used for elution, and the elution flow rate is 1 to 2 mL / min, and the eluate is collected to obtain a purified asparagus flavonoid solution; the freeze-drying temperature in step (5) is -40 to -20°C, and the time is 24 to 48 hours.
[0015] The invention also provides asparagus flavonoids obtained by the preparation method.
[0016] The present invention also provides a method for preparing asparagus flavonoids nano coating liquid, comprising the following steps:
[0017] S1. Mix the asparagus flavonoids and zein according to claim 5 with an ethanol solution to obtain an asparagus flavonoids-zein ethanol solution;
[0018] S2: the asparagus flavonoids-zein ethanol solution is allowed to stand in vacuum, and then freeze-dried to obtain asparagus flavonoids nanoparticles;
[0019] S3: mixing the asparagus flavonoid nanoparticles with a film-forming agent to obtain an asparagus flavonoid nano-coating liquid.
[0020] Preferably, the mass volume of the asparagus flavonoids, zein and ethanol solution in step S1 is 10-20 mg: 150-250 mg: 100 mL, and the concentration of the ethanol solution is 70-75%; the vacuum standing time in step S1 is based on the evaporation of the solution until there is no alcohol taste; the freeze-drying temperature is -40 to -20°C, and the time is 24 to 48 hours.
[0021] Preferably, the step of mixing the asparagus flavonoid nanoparticles with the film-forming agent in step S3 is: after dissolving gelatin in water, adding asparagus flavonoid nanoparticles and glycerol to obtain an asparagus flavonoid nano coating liquid; the mass volume ratio of the gelatin, asparagus flavonoid nanoparticles, glycerol and water is 2-3g:0.1-0.3g:8-10g:100mL.
[0022] The invention also provides an asparagus flavonoid nano coating liquid obtained by the preparation method.
[0023] The present invention also provides an application of the asparagus flavonoids or the asparagus flavonoids nano coating liquid as a preservative for marinated bacon.
[0024] The invention first performs steam explosion and then ultrasonic enzymolysis on old asparagus stems to obtain a crude extract, and the crude extract is separated and purified by resin to obtain an asparagus flavonoid solution, in which the concentration of flavonoid compounds can reach 0.648 mg / mL, and the extraction rate of flavonoid compounds is significantly improved compared with other extraction methods.
[0025] The prepared asparagus flavonoids are made into nanoparticles and mixed with a film-forming agent to obtain an asparagus flavonoid nano-coating liquid, which can be directly used for preserving marinated bacon. The marinated bacon is preserved with the asparagus flavonoid nano-coating liquid at 4°C for 90 days, and the marinated bacon still has good sensory quality. DETAILED DESCRIPTION
[0026] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0027] Example 1
[0028] In this example, various methods were used to extract flavonoids from old asparagus stems and the contents of flavonoids in the asparagus flavonoid solutions extracted and purified using different methods were determined.
[0029] Method 1:
[0030] Take old asparagus stems and bake them at 55°C until the water content is 50%, then cut them into small pieces of 1 cm in length, put them in a steam explosion machine for explosion, control the steam explosion pressure to be 1MPa, the temperature to be 180°C, and the time to be 90min, and after the end, obtain steam-exploded asparagus. Crush the steam-exploded asparagus, grind it at 2000r / min for 45min, collect the crushed asparagus, add cellulase according to the enzymatic activity of 60U / g, and perform ultrasonic enzymolysis at 350W and 50°C for 45min, after the enzymatic hydrolysis is completed, centrifuge (6000r / min, 10min), collect the enzymatic hydrolyzate, and obtain the crude asparagus flavonoid extract.
[0031] Method 2:
[0032] Take old asparagus stems and bake them at 55°C until the moisture content is 10%, crush them through a 40-mesh sieve, add cellulase solution, the solid-liquid ratio is 1g:10mL, so that the enzyme activity reaches 60U / g, and ultrasonic enzymolysis is carried out at 350W and 50°C for 45min. After the enzymolysis is completed, the enzymolysis product is placed in a steam explosion machine, and the steam explosion pressure is controlled to be 1MPa, the temperature is 180°C, and the time is 90min for steam explosion treatment. After the steam explosion treatment, centrifuge (6000r / min, 10min), collect the liquid part, and obtain the asparagus flavonoid crude extract.
[0033] Method 3:
[0034] Take old asparagus stems and bake them at 55°C until the moisture content is 10%, crush them through a 40-mesh sieve, add 70% ethanol solution at a solid-liquid ratio of 1:10, perform ultrasonic extraction (350W, 45min), filter, and concentrate under reduced pressure until there is no alcohol taste to obtain a crude asparagus flavonoid extract.
[0035] The AB-8 resin is first soaked in ethanol to fully swell, then washed with ethanol until the washing liquid has no white turbidity after adding water, then washed out the ethanol with distilled water, and finally transferred to acid-base treatment. For acid-base treatment, 4BV 5% hydrochloric acid solution is used to pass through the resin layer at a flow rate of 5BV / h and soak for 3h, then washed with distilled water at the same flow rate until the pH of the effluent is neutral, then 4BV 5% sodium hydroxide solution is used to pass through the resin layer at the same flow rate and soak for 3h, and finally washed with distilled water until the pH of the effluent is neutral.
[0036] Weigh 10 mg of rutin standard, dissolve it with 30% ethanol and dilute it to a 100 mL volumetric flask, shake well to obtain a rutin standard solution with a concentration of 0.1 mg / mL, and set aside. Accurately weigh 0, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, 14.0, and 16.0 mL in 9 50 mL volumetric flasks, add 1.5 mL of NaNO2 solution to each, mix well and place for 6 minutes, then add 1.5 mL of 10% Al(NO3)3 solution, shake well, place for 6 minutes, add 10 mL of 4% NaOH solution, dilute to the scale with 30% ethanol, and obtain concentrations of 0, 0.004, 0.008, 0.012, 0.016, 0.020, 0.024, 0.028, and 0.032 mg / mL. After 10 minutes, perform colorimetric determination at a wavelength of 510 nm, with 0 concentration as the blank control. The regression equation of the relationship curve between rutin concentration X and absorbance value Y calculated according to the measurement results is: Y = 7.747X + 0.0029, R 2 =0.9949.
[0037] 400 g of the pretreated AB-8 resin was loaded into a (1.8×60) cm glass chromatography column. According to 10 g of asparagus raw material, the crude asparagus flavonoid extract prepared by the above methods 1 to 3 was added with water to make the volume to 100 mL and loaded onto the column. The flow rate was controlled to be 2 mL / min. After complete adsorption, 200 mL of 80% ethanol was used for elution at a flow rate of 1 mL / min, and the mixture was collected step by step (5 mL / tube). The eluate from tubes 12 to 23 was collected in method 1 to obtain 60 mL of a purified asparagus flavonoid solution. The eluate from tubes 15 to 26 was collected in method 2 to obtain 60 mL of a purified asparagus flavonoid solution. The eluate from tubes 10 to 19 was collected in method 3 to obtain 50 mL of a purified asparagus flavonoid solution.
[0038] After diluting the asparagus flavonoid solution under each method by 10 times, 0.5 mL was taken to measure the absorbance value, and the corresponding flavonoid concentration was calculated according to the regression equation. The results are shown in Table 1.
[0039] Table 1 Concentration of flavonoids in asparagus flavonoid solutions under different methods
[0040]
[0041]
[0042] As shown in Table 1, among the three methods, the concentration of flavonoids extracted by method 1 was the highest, followed by method 3, and method 2 was the least.
[0043] The asparagus flavonoids solutions prepared by each method were concentrated and freeze-dried (-40°C, 48h) to obtain asparagus flavonoids for later use.
[0044] Example 2
[0045] The three asparagus flavonoids prepared in Example 1 were prepared into nanoparticles and their encapsulation rates were measured.
[0046] Weigh 200 mg of zein and add it to 100 mL of 70% ethanol solution, stir and dissolve (500 r / min, 10 min) to obtain 3 portions of zein ethanol solution with a concentration of 2 mg / mL, then weigh 20 mg of three kinds of asparagus flavonoids respectively and add them to the above zein ethanol solution, stir at 500 r / min for 10 min to obtain asparagus flavonoid-zein ethanol solution, place it under vacuum and let it stand to allow ethanol to evaporate until there is no alcohol taste, and then freeze-dry it (-40°C, 24 h) to obtain asparagus flavonoid nanoparticles.
[0047] Take a certain amount of asparagus flavonoid nanoparticles, add water to dissolve, place in an ultrafiltration concentration centrifuge tube, centrifuge at 4°C (8000r / min, 10min), take the ultrafiltration membrane permeate, measure its flavonoid content, i.e., free flavonoid content A1 (determined according to the method in Example 1), and take the amount added when preparing asparagus flavonoid nanoparticles as the total content of asparagus flavonoids A0, and calculate the embedding rate based on this. The results show that the embedding rates of the three asparagus flavonoid nanoparticles are 78% (method 1), 78% (method 2), and 75% (method 3), respectively. It can be seen that there is no significant difference in the embedding rate of the three asparagus flavonoids.
[0048] Example 3
[0049] The three asparagus flavonoid nanoparticles prepared in Example 2 were made into asparagus flavonoid nano-coating liquid, and used for the preservation of marinated bacon.
[0050] (1) Preparation of coating solution
[0051] Preparation of asparagus flavonoid nano coating liquid: gelatin, asparagus flavonoid nanoparticles, glycerol and water were weighed according to the mass ratio of 3g: 0.2g: 10g: 100mL. First, gelatin was added with water and heated to dissolve to obtain a gelatin solution, and then asparagus flavonoid nanoparticles and glycerol were added to obtain an asparagus flavonoid nano coating liquid. In order to fully dissolve, the asparagus flavonoid nanoparticles and glycerol were mixed in this embodiment and then added to the gelatin solution.
[0052] Preparation of potassium sorbate coating solution: The asparagus flavonoid nanoparticles were replaced with potassium sorbate according to the above method, and the concentration of potassium sorbate was 0.2%.
[0053] Preparation of asparagus flavonoid coating solution: replacing asparagus flavonoid nanoparticles with an equal amount of asparagus flavonoids embedded in the asparagus flavonoids according to the above method.
[0054] Preparation of gelatin coating solution: Based on the above method, the asparagus flavonoids nanoparticles are omitted to prepare the gelatin coating solution.
[0055] (2) Preparation of marinated bacon
[0056] The preparation of marinated bacon includes two steps: pickling and marinating. After the last brushing of the marinade, it is hung in a ventilated place to dry. After 20 days, the unique flavor of the marinated bacon will be formed, and the production is complete.
[0057] (3) Freshness preservation
[0058] Take the prepared marinated bacon samples and apply the four coating liquids in (1) respectively, and evenly apply them on the surface of the bacon. At the same time, the marinated bacon without any coating liquid is used as a blank control. The treated marinated bacon samples are stored at 4°C. After 90 days, the sensory evaluation of each treatment is carried out, and the volatile basic nitrogen (TVB-N) value and the total number of colonies are measured.
[0059] 1. Sensory evaluation
[0060] Five professional sensory testers were selected to conduct sensory evaluation on the above-treated marinated bacon. The sensory evaluation criteria are shown in Table 2, and the evaluation results are shown in Table 3.
[0061] Table 2 Sensory scoring standards for marinated bacon
[0062]
[0063] 2. Determination of TVB-N content
[0064] TVB-N is the value of alkaline nitrogen-containing substances such as amines that are converted into protein in meat due to the action of enzymes and bacteria during the storage process of the product. TVB-N value has become one of the important methods for evaluating the freshness of aquatic products. Refer to GB / T5009.228-2016 "National Food Safety Standard Determination of Volatile Basic Nitrogen in Food". The test results are shown in Table 3.
[0065] 3. Determination of total colony count
[0066] Most of the spoilage of products is caused by the growth and reproduction of microorganisms. The degree of spoilage mainly depends on the reproduction rate of microorganisms. Therefore, the total colony count can be an important indicator to measure the freshness of aquatic products. Refer to GB 4789.2-2016 "National Food Safety Standard Food Microbiology Test Colony Count Determination". The test results are shown in Table 3.
[0067] Table 3 Sensory scores, TVB-N content and total bacterial counts of each treatment
[0068]
[0069] As shown in Table 3, asparagus flavonoids nano coating liquid 1 (prepared by method 1) has the same sensory score, TVB-N content and total bacterial count as potassium sorbate coating liquid, but asparagus flavonoids nano coating liquid 2 (prepared by method 2) and asparagus flavonoids nano coating liquid 3 (prepared by method 3) have poor preservation effects. In addition, the concentration of flavonoids in asparagus flavonoids solutions prepared by methods 2 and 3 is found to be higher than that of asparagus flavonoids nano coating liquid 2. However, there is no significant difference in the preservation effect between the two, which may be due to the difference in the preservation effect caused by the different types of flavonoids extracted by the two methods. In addition, preparing asparagus flavonoids in the form of nanoparticles is more conducive to the preservation of marinated bacon.
[0070] It can be seen from the above examples that the present invention provides a method for preparing asparagus flavonoids and asparagus flavonoid nano-fresh-keeping liquid. The asparagus flavonoids and asparagus flavonoid nano-fresh-keeping liquid prepared by the method have good fresh-keeping effects on marinated bacon.
[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing asparagus flavonoids, characterized in that: The steps include: (1) taking old asparagus stems, drying them, and cutting them into segments to obtain old asparagus stem segments; (2) steam-exploding the old asparagus stem segments to obtain steam-exploded asparagus; (3) crushing the steam-exploded asparagus and performing ultrasonic enzymolysis, collecting the enzymolysis solution to obtain a crude asparagus flavonoid extract; (4) separating and purifying the crude asparagus flavonoid extract by resin to obtain a purified asparagus flavonoid solution; (5) The asparagus flavonoids solution is concentrated and then freeze-dried to obtain asparagus flavonoids.
2. The preparation method according to claim 1, characterized in that In step (1), the old asparagus stems are dried to a moisture content of 45-55%, and the drying temperature is 50-60° C.; the length of the old asparagus stem segments is 0.5-1 cm; and in step (2), the temperature of the steam explosion treatment is 160-190° C., the pressure is 0.5-1.5 MPa, and the time is 60-90 min.
3. The preparation method according to claim 2, characterized in that: The conditions for the crushing in step (3) are: grinding at 1000-3000 r / min for 0.5-1 h; the enzyme used for enzymatic hydrolysis is cellulase, and the activity of the cellulase is 50-60 U / g; the temperature of the enzymatic hydrolysis is 45-55° C., the power of the ultrasound is 300-400 W, and the time is 30-60 min; the enzymatic hydrolysis solution collected in step (3) is centrifuged on the product after enzymatic hydrolysis, the centrifugal speed is 5000-7000 r / min, and the time is 8-12 min.
4. The preparation method according to claim 3, characterized in that: The resin in step (4) is AB-8 resin, and the adsorption flow rate of the resin during separation and purification is 1 to 3 mL / min; 75 to 85% ethanol solution is used for elution, and the elution flow rate is 1 to 2 mL / min, and the eluate is collected to obtain a purified asparagus flavonoid solution; the freeze-drying temperature in step (5) is -40 to -20°C, and the time is 24 to 48 hours.
5. Asparagus flavonoids obtained by the preparation method according to any one of claims 1 to 4.
6. A method for preparing asparagus flavonoids nano coating liquid, characterized in that: The steps include: S1. Mix the asparagus flavonoids and zein according to claim 5 with an ethanol solution to obtain an asparagus flavonoids-zein ethanol solution; S2: the asparagus flavonoids-zein ethanol solution is allowed to stand in vacuum, and then freeze-dried to obtain asparagus flavonoids nanoparticles; S3: mixing the asparagus flavonoid nanoparticles with a film-forming agent to obtain an asparagus flavonoid nano-coating liquid.
7. The preparation method according to claim 6, characterized in that: The mass volume of the asparagus flavonoids, zein and ethanol solution in step S1 is 10-20 mg: 150-250 mg: 100 mL, and the concentration of the ethanol solution is 70-75%; the vacuum standing time in step S1 is based on the evaporation of the solution until there is no alcohol taste; the freeze-drying temperature is -40--20° C., and the time is 24-48 hours.
8. The preparation method according to claim 7, characterized in that: The step of mixing the asparagus flavonoid nanoparticles with the film-forming agent in step S3 is: after dissolving gelatin in water, adding asparagus flavonoid nanoparticles and glycerol to obtain asparagus flavonoid nano coating liquid; the mass volume ratio of the gelatin, asparagus flavonoid nanoparticles, glycerol and water is 2-3g:0.1-0.3g:8-10g:100mL.
9. An asparagus flavonoids nano coating liquid obtained by the preparation method according to any one of claims 6 to 8.
10. Use of the asparagus flavonoids according to claim 5 or the asparagus flavonoids nano coating liquid according to claim 9 as a preservative for marinated bacon.