Caffeine microcapsule prepared from dendrobium officinale polysaccharide and application of caffeine microcapsule

Abstract

The invention belongs to the technical field of dendrobium officinale processing and application, and particularly relates to a caffeine microcapsule prepared from dendrobium officinale polysaccharide and application thereof.Dendrobium officinale powder is added into a deep eutectic solvent for ultrasonic extraction, crude extract is obtained, centrifugation is conducted, supernate is collected, vacuum freeze drying is conducted, and crude dendrobium officinale polysaccharide powder is obtained; dissolving the crude dendrobium polysaccharide powder in water to prepare a crude dendrobium polysaccharide solution, adding papain to carry out enzymolysis reaction, inactivating and centrifuging after the enzymolysis reaction, and taking supernate; dialyzing the supernate, and performing vacuum freeze drying to obtain dendrobium polysaccharides; the preparation method comprises the following steps: by taking caffeine as a core material and dendrobium polysaccharide as a wall material, mixing the core material and the wall material, and performing spray drying to obtain the dendrobium polysaccharide-caffeine microcapsule. According to the method disclosed by the invention, efficient and green extraction of the dendrobium officinale polysaccharide can be realized, and the irritation of caffeine to the stomach and intestine can be effectively relieved by preparing the caffeine microcapsule from the extracted dendrobium officinale polysaccharide.

Description

Technical Field

[0001] The invention belongs to the technical field of dendrobium officinale processing and application, and particularly relates to caffeine microcapsules prepared by using dendrobium officinale polysaccharide and application thereof. Background Art

[0002] Coffee has always been popular among consumers for its unique flavor. Together with cocoa and tea, it constitutes the world's three major non-alcoholic beverages. The caffeine in coffee has physiological effects such as relieving fatigue and exciting nerves, but the stimulating effect of caffeine on gastric acid secretion may increase the risk of gastroesophageal lesions (such as indigestion, gastritis, esophageal burns, etc.). As a traditional medicinal and edible plant resource in my country, Dendrobium candidum is known as the "first of the nine immortal herbs" and contains rich chemical active ingredients, including polysaccharides, polyphenols, amino acids and alkaloids. Among them, polysaccharides are the main functional active ingredients of Dendrobium candidum, which has many health benefits such as improving the gastrointestinal tract, anti-oxidation, improving immunity, anti-tumor and lowering blood sugar. Therefore, the application of Dendrobium candidum polysaccharides in coffee is of great significance in improving the side effects of caffeine on the human body.

[0003] At present, the most widely used method for extracting polysaccharides from Dendrobium officinale is still the traditional hot water extraction method, which has the advantages of low cost and simple operation. In addition, there are many other extraction methods such as ultrasound-assisted extraction, microwave-assisted extraction, enzyme-assisted extraction, and alkaline extraction. Although these methods effectively improve the polysaccharide extraction rate, they are limited by high process requirements and expensive equipment costs, making them unable to be used on a large scale in actual production. Deep eutectic solvent (DES) is a new type of green solvent, which is a mixture of hydrogen bond acceptors and hydrogen bond donors. It has the advantages of low cost, easy synthesis, high extraction efficiency, low toxicity and biodegradability. It has been used to extract a variety of bioactive components (such as proteins, polysaccharides, phenols, etc.). At present, there are few studies on the extraction of Dendrobium officinale polysaccharides using green extraction processes based on DES. Therefore, establishing an efficient, safe and green extraction process for Dendrobium officinale polysaccharides is conducive to the development and application of Dendrobium officinale.

[0004] The encapsulation method is an effective way to improve the utilization and stability of bioactive substances and control the release of active substances. By microencapsulating caffeine to achieve a sustained release effect in the gastrointestinal tract, the side effects of caffeine on the gastrointestinal tract can be further improved. The most commonly used method for preparing microcapsules is spray drying, which has low cost, high encapsulation rate, and can be mass-produced. The choice of encapsulation wall material has a great influence on the encapsulation efficiency, storage stability, and release characteristics in food and the gastrointestinal tract. At present, there are many types of encapsulation wall materials, such as proteins (soy protein, whey protein, etc.), carbohydrates (starch, maltodextrin, etc.), and natural gums (gum arabic, guar gum, etc.).

[0005] However, there is no report on the research of using Dendrobium officinale polysaccharide as wall material to embed caffeine. Therefore, designing a Dendrobium officinale-coffee microcapsule that combines the medicinal value of Dendrobium officinale with the embedding and sustained-release process can provide a new idea for improving the health effects of coffee. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiency of existing coffee in stimulating the gastrointestinal tract, and to provide a caffeine microcapsule prepared by using Dendrobium officinale polysaccharide and its application.

[0007] To achieve the above purpose, the present invention adopts the following technical means:

[0008] The invention discloses a caffeine microcapsule prepared by using dendrobium officinale polysaccharide, comprising the following steps: adding dendrobium officinale powder to a low eutectic solvent for ultrasonic extraction to obtain a crude extract, centrifuging the extract, collecting the supernatant, and vacuum freeze-drying the extract to obtain a crude dendrobium polysaccharide powder; dissolving the crude dendrobium polysaccharide powder in water to prepare a crude dendrobium polysaccharide solution, adding papain to perform an enzymolysis reaction, inactivating the solution after the enzymolysis reaction, and centrifuging the solution to obtain a supernatant; dialyzing the supernatant, and vacuum freeze-drying the solution to obtain dendrobium polysaccharide; using caffeine as a core material and dendrobium polysaccharide as a wall material, mixing the core material and the wall material, and then spray drying the mixture to obtain the caffeine microcapsule prepared by using dendrobium officinale polysaccharide.

[0009] Furthermore, the preparation method of the low eutectic solvent includes: mixing a hydrogen bond acceptor and a hydrogen bond donor, and performing magnetic stirring under high temperature conditions until a uniform, transparent, viscous liquid is formed; the hydrogen bond acceptor is one of betaine and choline chloride; the hydrogen bond donor is one of glycerol, lactic acid, citric acid, propylene glycol, and 1,3-butanediol; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1~7).

[0010] Furthermore, the high temperature condition is 60°C to 90°C.

[0011] Furthermore, the mass ratio of the Dendrobium officinale powder to DES is 1:30 to 100;

[0012] Furthermore, the ultrasonic extraction conditions are: ultrasonic frequency is 20-60 kHz, ultrasonic temperature is 60-80° C., and ultrasonic time is 30-90 min.

[0013] Furthermore, the mass ratio of added papain is 1% to 10%; and the enzymatic hydrolysis reaction is carried out at a temperature of 45 to 70° C. for 0.5 to 3.0 hours.

[0014] Furthermore, the enzyme was inactivated by heating to 100°C for 10 min after enzymatic hydrolysis.

[0015] Furthermore, the vacuum freeze-drying conditions are: initial pre-freezing temperature -50 to -60°C, pre-freezing rate 0.28 to 0.45°C / min, pre-freezing endpoint temperature -65°C, drying chamber pressure 25 to 40Pa, heating plate temperature 30 to 40°C, and drying time 6 to 12h.

[0016] Furthermore, the mass ratio of caffeine to crude dendrobium polysaccharide is 1:10-30.

[0017] Further, the spray drying conditions are: the pump speed is set to 3% to 9%, and the outlet temperature is set to 140 to 180°C;

[0018] The present invention also provides a caffeine microcapsule prepared by using the Dendrobium officinale polysaccharide, which is prepared by the above method.

[0019] The present invention also provides the use of the caffeine microcapsules prepared by using the Dendrobium officinale polysaccharide in preparing beverages.

[0020] Beneficial Effects

[0021] The method for extracting Dendrobium officinale polysaccharide and preparing Dendrobium officinale polysaccharide-caffeine microcapsules based on a natural low eutectic solvent provided by the present invention solves the defects of low extraction efficiency, high process requirements, high equipment cost and the like in the existing technical means for extracting Dendrobium officinale polysaccharide, and realizes efficient and green extraction of Dendrobium officinale polysaccharide. The preparation of caffeine microcapsules by extracting Dendrobium officinale polysaccharide can effectively alleviate the irritation of caffeine on the gastrointestinal tract, and the specific effects are as follows:

[0022] (1) The present invention provides a method for extracting polysaccharides from Dendrobium officinale (DES extraction). The compounds used to synthesize DES are all natural compounds, which are low-cost, non-toxic and environmentally friendly. The synthesis operation is simple and does not require the operator to have a strong professional background. In addition, the extraction efficiency of Dendrobium officinale polysaccharides is greatly enhanced by adjusting the DES ratio (reaching 35.82±0.18%).

[0023] (2) The present invention removes macromolecular protein impurities in the crude Dendrobium polysaccharide extract by adding papain, while the traditional deproteinization method uses toxic reagents such as chloroform, trichloroacetic acid, etc. Therefore, the method used in the present invention is mild, has no toxic pollution, and has a small loss of polysaccharides, and is suitable for deproteinization treatment in food-grade polysaccharides.

[0024] (3) Dendrobium officinale polysaccharide has the effects of nourishing the stomach and promoting fluid production and thickening the stomach and intestines, thereby improving gastroenteritis, whereas caffeine stimulates the gastric mucosa and promotes gastric acid secretion, which can easily cause discomfort symptoms in people with gastrointestinal sensitivity. The present invention combines Dendrobium officinale polysaccharide with caffeine to effectively alleviate the negative effects of caffeine on people with gastrointestinal sensitivity.

[0025] (4) With the aid of the Dendrobium officinale polysaccharide extracted by the above method, the present invention uses the Dendrobium officinale polysaccharide as a wall material for the embedding of caffeine for the first time, with a high embedding efficiency (reaching 83.7±0.81%), achieving a sustained release effect of caffeine, and further solving the problem of caffeine as the main component of coffee causing great gastrointestinal irritation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the standard curve of glucose.

[0027] Figure 2 This is the standard curve of caffeine.

[0028] Figure 3 Release kinetics of Dendrobium officinale polysaccharide-caffeine microcapsules. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the content of the present invention, the present invention is further described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention and should not be construed as all the embodiments of the present invention.

[0030] 1. Experimental samples, main reagents and instruments

[0031] Sample: Dried Dendrobium officinale purchased from Yunshan Dendrobium officinale base was used as the test object.

[0032] Reagents: Caffeine standard was purchased from Sigma-Aldrich, USA, with a purity greater than 99%. All water used in the experiment was deionized water, and all other experimental reagents were analytical grade.

[0033] Instruments: Spray dryer (GP-P2000, Shanghai Guxin Biotechnology Co., Ltd.); UV spectrophotometer (UV-1900, Shimadzu Corporation, Japan); high-speed universal pulverizer (FW-100, Tianjin Huaxin Instrument Factory); constant temperature water bath (HWS-24, Shanghai Yiheng Scientific Instrument Co., Ltd.)

[0034] Example 1 Extraction of Dendrobium officinale polysaccharides and preparation of caffeine microcapsules

[0035] S1. Mix betaine and lactic acid in a molar ratio of 1:5, stir magnetically at 80°C until a uniform, transparent, viscous liquid is formed, and store for later use. Add a certain amount of distilled water to dilute the mixture before formal use so that the water content in the final DES is 20%.

[0036] S2. Take dried Dendrobium candidum, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium candidum powder; weigh the Dendrobium candidum powder, add DES at a mass ratio of 1:50, perform ultrasonic extraction (ultrasonic frequency of 40 kHz, ultrasonic time of 60 min, ultrasonic temperature of 70°C), centrifuge the crude extract (8000 rpm, 10 min), collect the supernatant, and perform vacuum freeze drying (pre-freezing initial temperature -55°C, pre-freezing rate 0.35°C / min, pre-freezing end temperature -65°C, drying chamber pressure 35 pa, heating plate temperature 35 ℃) to obtain crude dendrobium polysaccharide powder; dissolve the crude dendrobium polysaccharide powder in water to prepare a crude dendrobium polysaccharide solution (20 mg / mL), take 20 mL and place it in a centrifuge tube, add 4% papain (800 U / mg), perform enzymolysis at 60℃ for 2h, heat to 100℃ for inactivation for 10min after enzymolysis, wait for the solution temperature to cool to room temperature, centrifuge (10000rpm, 20min) to remove the precipitate of the denatured enzyme, and take the supernatant; place the supernatant in a dialysis bag, dialyze with distilled water, and vacuum freeze-dry to obtain Dendrobium officinale polysaccharide.

[0037] S3. Caffeine was used as the core material and the dried Dendrobium officinale polysaccharide was used as the wall material to prepare caffeine microcapsules, wherein the mass ratio of caffeine to Dendrobium officinale polysaccharide was 1:20. The core material and the wall material were mixed, dissolved in distilled water, and stirred until all the materials were completely dissolved to obtain a mixed solution with a final solid content of 10%. The mixed solution was spray-dried at a pump speed of 6% and an outlet temperature of 160°C to obtain Dendrobium officinale polysaccharide-caffeine microcapsules, which were stored dry at room temperature away from light.

[0038] Example 2 Extraction of Dendrobium officinale polysaccharides and preparation of caffeine microcapsules

[0039] S1. Mix betaine and lactic acid in a molar ratio of 1:1, stir magnetically at 60°C until a uniform, transparent, viscous liquid is formed, and store for later use. Add a certain amount of distilled water to dilute the mixture before formal use so that the water content in the final DES is 10%.

[0040] S2. Take dried Dendrobium candidum, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium candidum powder; weigh the Dendrobium candidum powder, add DES at a mass ratio of 1:30, perform ultrasonic extraction (ultrasonic frequency of 20 kHz, ultrasonic time of 30 min, ultrasonic temperature of 60°C), centrifuge the crude extract (8000 rpm, 10 min), collect the supernatant, and perform vacuum freeze drying (pre-freezing initial temperature -50°C, pre-freezing rate 0.28°C / min, pre-freezing end temperature -65°C, drying chamber pressure 25 pa, heating plate temperature 30 ℃) to obtain crude dendrobium polysaccharide powder; dissolve the crude dendrobium polysaccharide powder in water to prepare a crude dendrobium polysaccharide solution (20 mg / mL), take 20 mL and place it in a centrifuge tube, add 1% papain (800 U / mg), perform enzymolysis at 60℃ for 2h, heat to 100℃ for inactivation for 10min after enzymolysis, cool the solution to room temperature, centrifuge (10000rpm, 20min) to remove the precipitate of the denatured enzyme, and take the supernatant; place the supernatant in a dialysis bag, dialyze with distilled water, and vacuum freeze-dry to obtain Dendrobium officinale polysaccharide.

[0041] S3. Caffeine was used as the core material and the dried Dendrobium officinale polysaccharide was used as the wall material to prepare caffeine microcapsules, wherein the mass ratio of caffeine to Dendrobium officinale polysaccharide was 1:10. The core material and the wall material were mixed, dissolved in distilled water, and stirred until all the materials were completely dissolved to obtain a mixed solution with a final solid content of 10%. The mixed solution was spray-dried at a pump speed of 6% and an outlet temperature of 160°C to obtain Dendrobium officinale polysaccharide-caffeine microcapsules, which were stored dry at room temperature away from light.

[0042] Example 3 Extraction of Dendrobium officinale polysaccharide and preparation of caffeine microcapsules

[0043] S1. Mix betaine and lactic acid in a molar ratio of 1:7, stir magnetically at 90°C until a uniform, transparent, viscous liquid is formed, and store for later use. Add a certain amount of distilled water to dilute the mixture before formal use so that the water content in the final DES is 30%.

[0044] S2. Take dried Dendrobium officinale, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium officinale powder; weigh the Dendrobium officinale powder, add DES at a mass ratio of 1:100, perform ultrasonic extraction (ultrasonic frequency of 60 kHz, ultrasonic time of 90 min, ultrasonic temperature of 80°C), centrifuge the crude extract (8000 rpm, 10 min), collect the supernatant, and perform vacuum freeze drying (pre-freezing initial temperature -60°C, pre-freezing rate 0.45°C / min, pre-freezing end temperature -65°C, drying chamber pressure 40 pa, heating plate temperature 40 ℃) to obtain crude dendrobium polysaccharide powder; dissolve the crude dendrobium polysaccharide powder in water to prepare a crude dendrobium polysaccharide solution (20 mg / mL), take 20 mL and place it in a centrifuge tube, add 10% papain (800 U / mg), perform enzymolysis at 60℃ for 2h, heat to 100℃ for inactivation for 10min after enzymolysis, wait for the solution temperature to cool to room temperature, centrifuge (10000rpm, 20min) to remove the precipitate of the denatured enzyme, and take the supernatant; place the supernatant in a dialysis bag, dialyze with distilled water, and vacuum freeze-dry to obtain Dendrobium officinale polysaccharide.

[0045] S3. Caffeine was used as the core material and the dried Dendrobium officinale polysaccharide was used as the wall material to prepare caffeine microcapsules, wherein the mass ratio of caffeine to Dendrobium officinale polysaccharide was 1:30. The core material and the wall material were mixed, dissolved in distilled water, and stirred until all the materials were completely dissolved to obtain a mixed solution with a final solid content of 10%. The mixed solution was spray-dried at a pump speed of 6% and an outlet temperature of 160°C to obtain Dendrobium officinale polysaccharide-caffeine microcapsules, which were stored dry at room temperature away from light.

[0046] Example 4 Extraction of Dendrobium officinale polysaccharide and preparation of caffeine microcapsules

[0047] Same as Example 1, except that lactic acid is replaced by glycerol.

[0048] Example 5 Extraction of Dendrobium officinale polysaccharide and preparation of caffeine microcapsules

[0049] Same as Example 1, except that lactic acid is replaced by propylene glycol.

[0050] Example 6 Extraction of Dendrobium officinale polysaccharides and preparation of caffeine microcapsules

[0051] Same as Example 1, except that betaine is replaced by choline chloride.

[0052] Comparative Example 1

[0053] The same as Example 1, except that the ultrasound in S2 is replaced by heating, that is, S2 is specifically as follows:

[0054] S2. Take the dried Dendrobium officinale, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium officinale powder; weigh the Dendrobium officinale powder, add DES at a mass ratio of 1:50, place it in a 70°C water bath and heat it for 1 hour, centrifuge the crude extract (8000rpm, 10min), collect the supernatant, and perform vacuum freeze drying (pre-freezing initial temperature -55°C, pre-freezing rate 0.35°C / min, pre-freezing end temperature -65°C, drying chamber pressure 35pa, heating plate temperature 35°C) to obtain crude Dendrobium polysaccharide powder ; Take crude dendrobium polysaccharide powder and dissolve it in water to prepare a crude dendrobium polysaccharide solution (20 mg / mL), take 20 mL and place it in a centrifuge tube, add 4% papain (800 U / mg), and perform enzymolysis at 60°C for 2 hours. After enzymolysis, heat to 100°C for inactivation for 10 minutes, and after the solution temperature is cooled to room temperature, centrifuge (10000 rpm, 20 minutes) to remove the precipitate of the denatured enzyme and take the supernatant; place the supernatant in a dialysis bag, dialyze with distilled water, and vacuum freeze-dry to obtain Dendrobium officinale polysaccharide.

[0055] Comparative Example 2

[0056] Same as Example 1, except that DES in S2 is replaced with pure water, that is, S2 is specifically as follows:

[0057] S2. Take dried Dendrobium candidum, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium candidum powder; weigh the Dendrobium candidum powder, add pure water at a mass ratio of 1:50, perform ultrasonic extraction (ultrasonic frequency of 40 kHz, ultrasonic time of 60 min, ultrasonic temperature of 70°C), centrifuge the crude extract (8000 rpm, 10 min), collect the supernatant, and perform vacuum freeze drying (pre-freezing initial temperature -55°C, pre-freezing rate 0.35°C / min, pre-freezing end temperature -65°C, drying chamber pressure 35 pa, heating plate temperature 35 ℃) to obtain crude dendrobium polysaccharide powder; dissolve the crude dendrobium polysaccharide powder in water to prepare a crude dendrobium polysaccharide solution (20 mg / mL), take 20 mL and place it in a centrifuge tube, add 4% papain (800 U / mg), perform enzymolysis at 60℃ for 2h, heat to 100℃ for inactivation for 10min after enzymolysis, wait for the solution temperature to cool to room temperature, centrifuge (10000rpm, 20min) to remove the precipitate of the denatured enzyme, and take the supernatant; place the supernatant in a dialysis bag, dialyze with distilled water, and vacuum freeze-dry to obtain Dendrobium officinale polysaccharide.

[0058] Comparative Example 3

[0059] The same as Example 1, except that the vacuum freeze drying in S2 is replaced by hot air drying, that is, S2 is specifically as follows:

[0060] S2. Take dried Dendrobium candidum, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium candidum powder; weigh the Dendrobium candidum powder, add DES at a mass ratio of 1:50, perform ultrasonic extraction (ultrasonic frequency of 40kHz, ultrasonic time of 60min, ultrasonic temperature of 70°C), centrifuge the crude extract (8000rpm, 10min), collect the supernatant, and perform hot air drying (temperature of 55°C) to obtain crude Dendrobium polysaccharide powder; take the crude Dendrobium polysaccharide powder and add water-soluble After hydrolysis, a crude dendrobium polysaccharide solution (20 mg / mL) was prepared, 20 mL of which was placed in a centrifuge tube, 4% papain (800 U / mg) was added, and the enzymatic hydrolysis reaction was carried out at 60° C. for 2 hours. After the enzymatic hydrolysis, it was heated to 100° C. for inactivation for 10 minutes. After the solution temperature was cooled to room temperature, it was centrifuged (10000 rpm, 20 minutes) to remove the precipitate of the denatured enzyme, and the supernatant was taken; the supernatant was placed in a dialysis bag, dialyzed with distilled water, and dried with hot air to obtain Dendrobium officinale polysaccharide.

[0061] Comparative Example 4

[0062] Same as Example 1, except that the papain in S2 is replaced by Sevage reagent (chloroform / n-butanol volume ratio 4:1), that is, S2 is specifically as follows:

[0063] S2. Take dried Dendrobium officinale, crush it, and screen it through a 30-mesh sieve to obtain Dendrobium officinale powder; weigh the Dendrobium officinale powder, add pure water in a mass ratio of 1:50, perform ultrasonic extraction (ultrasonic frequency is 40kHz, ultrasonic time is 60min, and ultrasonic temperature is 70°C), centrifuge the crude extract (8000rpm, 10min), collect the supernatant, and perform hot air drying (temperature is 55°C) to obtain crude Dendrobium officinale polysaccharide powder; take the crude Dendrobium officinale polysaccharide powder and dissolve it in water to prepare a crude Dendrobium officinale polysaccharide solution (20mg / mL), take 20mL and place it in a centrifuge tube, add Sevage reagent, oscillate and react for 30min, centrifuge (10000rpm, 20min), and take the supernatant; place the supernatant in a dialysis bag, dialyze with distilled water, and vacuum freeze-dry to obtain Dendrobium officinale polysaccharide.

[0064] Comparative Example 5

[0065] Same as Example 1, except that lactic acid is replaced by fructose.

[0066] Test Example 1 Determination of the extraction rate of Dendrobium officinale polysaccharides

[0067] The glucose standard curve was drawn by the phenol-sulfuric acid method, with absorbance as the ordinate and glucose concentration as the abscissa. The regression equation was calculated, y = 0.0104x + 0.0058, and the correlation coefficient was 0.9992. Figure 1The crude dendrobium polysaccharides obtained by drying in Examples 1 to 12 and Comparative Examples 1 to 2 were determined by the same phenol-sulfuric acid method, and the polysaccharide extraction rate was calculated according to the standard curve and formula (1):

[0068]

[0069] Wherein: m1, the mass of polysaccharide in Dendrobium officinale polysaccharide, g; m, the mass of weighed Dendrobium officinale powder, g.

[0070] The results are shown in Table 1:

[0071] Table 1 Results of extraction yield of polysaccharides from Dendrobium candidum

[0072] Dendrobium officinale polysaccharide yield / % Example 1 35.82±0.18 Example 2 30.64±0.64 Example 3 27.89±0.49 Example 4 25.82±1.73 Example 5 24.10±3.41 Example 6 31.88±2.62 Comparative Example 1 20.65±0.24 Comparative Example 2 16.73±0.09 Comparative Example 3 14.56±0.18 Comparative Example 4 25.34±0.18 Comparative Example 5 7.26±0.12

[0073] Test Example 2 Determination of Caffeine Microcapsule Encapsulation Efficiency

[0074] a. Drawing of caffeine standard curve

[0075] Weigh 0.10 mg of caffeine standard accurately, dissolve it in 1 mL of dimethyl sulfoxide (DMSO) to prepare a standard stock solution, dilute the standard stock solution with DMSO to prepare a series of standard solutions with different concentrations (5, 10, 15, 20, 25, 30, 35, 40, 45 μg / mL), and scan and measure at 260-360 nm. The maximum absorption peak is at 275 nm. With absorbance (A) as the ordinate and concentration (C) as the abscissa, calculate the regression equation, A=0.0411C+0.0171, and the correlation coefficient is 0.9995. Figure 2 shown.

[0076] b. Determination of caffeine content in microcapsules

[0077] 0.05 g of the Dendrobium officinale polysaccharide-caffeine microcapsule sample prepared in Examples 1 to 3 was accurately weighed and dispersed in 10 mL of DMSO. After vigorous vortexing, the absorbance was measured at 275 nm. The DMSO-Dendrobium officinale polysaccharide solution was used as a control. According to the absorbance of the measured sample, the caffeine content was calculated according to the standard curve and formula (2):

[0078]

[0079] Where: X, the caffeine content in each gram of microcapsules, mg / g; C1, the caffeine concentration calculated according to the standard curve, μg / mL.

[0080] c. Calculation of caffeine embedding efficiency in microcapsules

[0081] The caffeine embedding efficiency was calculated according to formula (3):

[0082]

[0083] Wherein: Y, caffeine embedding efficiency, %; M1, mass of microcapsules, g; X, caffeine content per gram of microcapsules, mg / g; M2, mass of caffeine added when preparing microcapsules, g.

[0084] The results are shown in Table 2:

[0085] Table 2 Caffeine microcapsule encapsulation efficiency results

[0086] Embedding efficiency / % Example 1 83.7±0.81 Example 2 62.8±0.59 Example 3 73.2±0.35

[0087] Test Example 3 In vitro simulated release of caffeine microcapsules

[0088] The Dendrobium officinale polysaccharide-caffeine microcapsules prepared by the method of Example 1 were placed in 20 mL of deionized water and placed on a magnetic stirrer. The speed was adjusted to 50 r / min and the temperature was 30°C. The concentration of caffeine in the solution was measured at 1, 7, 13, 19, 25, 30, 35, and 40 min, respectively. The results are as follows: Figure 3 The cumulative release of non-microencapsulated caffeine reached about 25%, 58%, and 76% at 1, 3, and 5 minutes, and was almost completely released at 7 minutes. Figure 3 The results show that the microencapsulated caffeine exhibits a slow release pattern, indicating that microencapsulation can hinder the diffusion of caffeine in the system. Within 10 minutes of the start of release, the cumulative release of Dendrobium officinale microcapsules is 45%, and the release is complete in about 40 minutes. Therefore, in practical applications, the microcapsules can effectively reduce the irritation of caffeine to the stomach and intestines.

[0089] Test Example 4 Effect of caffeine microcapsules prepared from Dendrobium officinale polysaccharide on gastric acid secretion in rats

[0090] 50 healthy male SD rats were placed in an animal breeding room at room temperature (22-25°C) and relative humidity of 50%-70%, and randomly divided into 5 groups, namely, a normal group (Group A, raised according to the standard method, without any experimental treatment), a control group (Group B, raised according to the standard method, without sample treatment, and finally induced gastric injury), a caffeine group (Group C, rats were gavaged with 10 mg caffeine / kg, and finally induced gastric injury), a Dendrobium officinale polysaccharide group (Group D, rats were gavaged with 200 mg Dendrobium officinale polysaccharide / kg, and finally induced gastric injury), and a Dendrobium officinale polysaccharide-caffeine microcapsule group (Group E, rats were gavaged with the caffeine microcapsule sample prepared in Example 1, and finally induced gastric injury), with 10 rats in each group. In the following 2 weeks, the 5 experimental groups of SD rats were gavaged once a day. After 2 weeks, rats in all groups except the normal group were gavaged with 1 mL of ethanol solution (ethanol dissolved in 150 mmol / L hydrochloric acid to make a 60% ethanol solution) to induce gastric injury. Rats in all groups were killed by cervical dislocation 1 hour later. A small incision was made at the gastric cardia of the mice, and the contents were squeezed out and placed in a centrifuge tube. The tube was centrifuged at 14000 g for 10 min, and the supernatant was taken. 9 times the volume of double distilled water was added, and the pH value was determined by titration with 0.1 M NaOH. The results are shown in Table 1:

[0091] Table 1 Effect of Dendrobium officinale polysaccharide on pH value of gastric contents in rats

[0092]

[0093] When gastric injury occurred in rats, the pH value of gastric contents decreased, that is, the pH value of gastric contents of rats in group B decreased from the normal value (3.81) to 1.62. After oral administration of caffeine, gastric injury of rats in group C was further aggravated, and the pH value of gastric contents decreased to 1.49, indicating that caffeine stimulated the increase of gastric acid secretion in rats. In group D, the pH value of gastric contents of rats was increased to 3.23 after oral administration of Dendrobium officinale polysaccharide, indicating that Dendrobium officinale can reduce the degree of gastric injury. After oral administration of prepared Dendrobium officinale polysaccharide-caffeine microcapsules, the pH value of gastric contents of rats in group E was significantly increased compared with rats only administered with caffeine (group C). This indicates that Dendrobium officinale polysaccharide can help reduce gastric acid secretion in rats, avoid the stimulation of gastric acid on gastric mucosa, and alleviate the increase of gastric acid secretion in rats induced by caffeine.

[0094] In summary, the present invention is a method for extracting Dendrobium officinale polysaccharides and preparing caffeine microcapsules based on a natural deep eutectic solvent, which belongs to the technical field of Dendrobium officinale processing and application. First, a natural deep eutectic solvent is prepared to extract Dendrobium officinale polysaccharides in a green and efficient manner, and then the extracted Dendrobium officinale polysaccharides are used as wall materials to embed caffeine. This method is simple to operate, low in cost, efficient in extraction, and high in embedding rate. By combining Dendrobium officinale polysaccharides with caffeine, it has an alleviating effect on gastrointestinal problems caused by increased gastric acid secretion induced by caffeine.

[0095] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; therefore, although this specification has described the present invention in detail with reference to the above embodiments, a person skilled in the art should understand that the present invention can still be modified or replaced by equivalents; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A caffeine microcapsule prepared by using Dendrobium officinale polysaccharide, characterized in that: The following steps are involved: The powder of Dendrobium officinale is added to a low eutectic solvent for ultrasonic extraction to obtain a crude extract, which is then centrifuged, the supernatant is collected, and vacuum freeze-dried to obtain a crude Dendrobium officinale polysaccharide powder; the crude Dendrobium officinale polysaccharide powder is dissolved in water to prepare a crude Dendrobium officinale polysaccharide solution, papain is added to perform an enzymatic hydrolysis reaction, the solution is inactivated and centrifuged after the enzymatic hydrolysis reaction, and the supernatant is collected; the supernatant is dialyzed and vacuum freeze-dried to obtain Dendrobium officinale polysaccharide; caffeine is used as a core material and Dendrobium officinale polysaccharide is used as a wall material, the core material and the wall material are mixed and spray-dried to obtain caffeine microcapsules prepared using Dendrobium officinale polysaccharide.

2. The caffeine microcapsules prepared using Dendrobium officinale polysaccharide according to claim 1, characterized in that: The preparation method of the low eutectic solvent comprises: mixing a hydrogen bond acceptor and a hydrogen bond donor, and performing magnetic stirring under high temperature conditions until a uniform, transparent, viscous liquid is formed; the hydrogen bond acceptor is one of betaine and choline chloride; the hydrogen bond donor is one of glycerol, lactic acid, citric acid, propylene glycol, and 1,3-butanediol; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1-7).

3. The caffeine microcapsules prepared using Dendrobium officinale polysaccharide according to claim 2, characterized in that: The high temperature condition is 60°C to 90°C.

4. The caffeine microcapsules prepared using Dendrobium officinale polysaccharide according to claim 1, characterized in that: The ultrasonic extraction conditions are as follows: ultrasonic frequency is 20-60 kHz, ultrasonic time is 30-90 min, and ultrasonic temperature is 60-80°C.

5. The caffeine microcapsules prepared by using Dendrobium officinale polysaccharide according to claim 1, characterized in that: The mass ratio of added papain is 1% to 10%; the enzymatic hydrolysis reaction is carried out at a temperature of 45 to 70° C. for 0.5 to 3.0 hours.

6. The caffeine microcapsules prepared by using Dendrobium officinale polysaccharide according to claim 1, characterized in that: After enzymatic hydrolysis, heat to 100°C for inactivation for 10 min.

7. The caffeine microcapsules prepared by using Dendrobium officinale polysaccharide according to claim 1, characterized in that: The vacuum freeze-drying conditions are as follows: initial pre-freezing temperature of -50 to -60°C, pre-freezing rate of 0.28 to 0.45°C / min, end point pre-freezing temperature of -65°C, drying chamber pressure of 25 to 40 Pa, heating plate temperature of 30 to 40°C, and drying time of 6 to 12 hours.

8. The caffeine microcapsules prepared by using Dendrobium officinale polysaccharide according to claim 1, characterized in that: The mass ratio of caffeine to crude dendrobium polysaccharide is 1:10-30.

9. A caffeine microcapsule prepared by using Dendrobium officinale polysaccharide, characterized in that: Prepared by the method according to any one of claims 1 to 8.

10. Use of the caffeine microcapsules according to claim 9 in preparing beverages.

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