Peanut red skin procyanidine microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a peanut red skin procyanidine microcapsule as well as a preparation method and application thereof, and belongs to the technical field of microcapsules. The peanut red skin procyanidine microcapsule is prepared by the following method: adding peanut red skin procyanidine powder into a wall material solution, and uniformly mixing to obtain a mixed emulsion; and homogenizing the mixed emulsion, and freeze-drying to obtain the peanut red skin procyanidine microcapsule. The inulin and the whey protein are used as wall materials, the peanut red skin procyanidine is used as a core material, and the proportion of the inulin and the whey protein is optimized, so that the prepared microcapsule can weaken the influence of the peanut red skin procyanidine powder on the color and luster of food and improve the environmental stability and the gastrointestinal tract slow release characteristic of the microcapsule. And meanwhile, the prebiotic inulin is used as a wall material raw material, so that the intestinal microecology can be improved, and the intestinal health can be promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of microcapsules, and in particular relates to a peanut red skin proanthocyanidin microcapsule, a preparation method and application thereof. Background Art

[0002] As a byproduct of the peanut processing industry, peanut skins are rich in polyphenols, among which proanthocyanidins are the main bioactive components of peanut skins. Peanut skin proanthocyanidins are constructed from flavan-3-ol units such as catechins and epicatechins, and are composed of monomers, dimers, trimers, tetramers, and a small amount of pentamers to nonamers. Peanut skin proanthocyanidins have multiple biological functions such as regulating glucose and lipid metabolism, anti-inflammation and anti-oxidation, and have very good application prospects.

[0003] Existing peanut red skin proanthocyanidins are mostly in the form of powder or tablets. They are reddish brown to brownish brown, and will change the color of food after being added to food; they have poor stability and are sensitive to environmental conditions, which seriously limits the high-value utilization of peanut red skin proanthocyanidins; in addition, these proanthocyanidin preparations have no sustained-release effect, and quickly disintegrate in the gastrointestinal tract after oral administration. They have gastrointestinal instability and low bioavailability in the body, which affects its further application in the field of food and functional food.

[0004] Microencapsulation technology is a method of encapsulating active ingredients or sensitive ingredients in wall materials to protect them from humidity, oxygen, light and other environmental factors, and allow the embedded substances to be released slowly and continuously. At present, microencapsulation technology has been widely used in many fields such as food, medicine, chemical industry, biotechnology, etc. Compared with a single wall material, a wall material formed by a combination of multiple raw materials generally has better stability and gastrointestinal sustained release effect, and improves its colon accessibility. Therefore, it is of great significance to provide a peanut red skin proanthocyanidin microcapsule to improve the stability and bioavailability of peanut red skin proanthocyanidin. Summary of the invention

[0005] The present invention provides a method for preparing peanut red coat proanthocyanidin microcapsules, comprising the following steps:

[0006] Peanut red skin proanthocyanidin powder is added to the wall material solution and mixed to obtain a mixed emulsion; then the mixed emulsion is homogenized and freeze-dried to obtain peanut red skin proanthocyanidin microcapsules.

[0007] In the above preparation method, the concentration of peanut red skin proanthocyanidins in the mixed emulsion is selected from 10 to 100 mg / mL, preferably 50 mg / mL.

[0008] In the above preparation method, the homogenization condition is: using a high-speed shearing machine, homogenizing at a rotation speed of 6000 rpm / min for 5 minutes.

[0009] In the above preparation method, the wall material solution is a mixed solution of inulin and whey protein.

[0010] In the above preparation method, the preparation method of the wall material solution is as follows:

[0011] Inulin is dissolved in water to obtain an inulin solution; whey protein is then added to the inulin solution and stirred evenly to obtain a wall material solution.

[0012] In the above-mentioned method for preparing the wall material solution, the concentration of the inulin solution is selected from 100 to 200 mg / mL, preferably 125 mg / mL.

[0013] In the above-mentioned method for preparing the wall material solution, the concentration of the whey protein in the wall material solution is selected from 0 to 100 mg / mL, preferably 75 mg / mL.

[0014] In the above-mentioned method for preparing the wall material solution, the concentration of the wall material solution is 200 mg / mL.

[0015] The invention provides peanut red skin proanthocyanidin microcapsules prepared by the method.

[0016] The present invention provides the use of the peanut red skin proanthocyanidin microcapsules in the preparation of health-care foods with the functions of regulating intestinal flora, assisting in lowering blood sugar, assisting in lowering blood lipids or anti-oxidation.

[0017] The beneficial effects of the present invention are:

[0018] The present invention uses inulin and whey protein as wall materials and peanut red skin proanthocyanidins as core materials. By optimizing the ratio of inulin and whey protein, the prepared microcapsules can reduce the influence of peanut red skin proanthocyanidins powder on food color and improve its environmental stability and gastrointestinal sustained-release properties. At the same time, using prebiotic inulin as a wall material raw material can also improve intestinal microecology and promote intestinal health. Using inulin and whey protein as wall materials can make them have important applications in the field of microcapsule technology and realize the effective utilization of peanut red skin proanthocyanidins. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the color comparison of peanut red-coated proanthocyanidin microcapsules and unencapsulated proanthocyanidins;

[0020] Figure 2 This is a scanning electron microscope image of peanut red-coated proanthocyanidin microcapsules;

[0021] Figure 3 The release efficiency of peanut red-coated proanthocyanidins microcapsules in the stomach;

[0022] Figure 4The release efficiency of peanut red-coated proanthocyanidins microcapsules in the intestine;

[0023] Figure 5 Increase the diversity of colonic flora for peanut red-coated proanthocyanidins microcapsules;

[0024] Figure 6 The effect of peanut red-skin proanthocyanidin microcapsules on the relative abundance of colonic flora;

[0025] Figure 7 The effect of peanut red skin proanthocyanidin microcapsules on the metabolites of colonic flora. DETAILED DESCRIPTION

[0026] In the present invention, the proanthocyanidin powder can be purchased from the market or prepared at home.

[0027] The present invention provides a method for preparing proanthocyanidin powder, as follows:

[0028] Weigh a certain mass of peanut skins, crush them, extract them with hot water, filter and concentrate them to obtain peanut skin extract; purify them with macroporous resin, collect 40% ethanol eluate, rotary evaporate and freeze-dry to obtain proanthocyanidin powder.

[0029] Other materials used in the present invention, if not otherwise stated, can be obtained through commercial channels. Other terms used in the present invention, unless otherwise specified, generally have the meanings commonly understood by those of ordinary skill in the art. The present invention is further described in detail below in conjunction with specific examples and with reference to data. The following examples are only for illustrating the present invention, and are not intended to limit the scope of the present invention in any way.

[0030] Example 1

[0031] Preparation of peanut red skin proanthocyanidin microcapsules, the steps are as follows:

[0032] 1g, 1.25g, 1.5g, 1.75g, 2g of inulin were dissolved in 10mL of water, vortexed and mixed, stirred at 50°C for 2h with a magnetic stirrer at 500rpm / min, and then left to stand overnight at room temperature to prepare inulin solutions with concentrations of 100mg / mL, 125mg / mL, 150mg / mL, 175mg / mL, and 200mg / mL. 1g, 0.75g, 0.5g, 0.25g, and 0g of whey protein were added to the inulin solutions, stirred at 500rpm / min with a magnetic stirrer at room temperature to obtain wall material solutions with whey protein concentrations of 100mg / mL, 75mg / mL, 50mg / mL, 25mg / mL, and 0mg / mL, so that the total concentration of the wall material (inulin+whey protein) solution was 200mg / mL. 0.5 g of peanut red skin proanthocyanidin powder was added to the wall material solution, and vortexed to obtain a mixed emulsion with a proanthocyanidin concentration of 50 mg / mL. The mixed emulsion was homogenized at a speed of 6000 rpm / min for 5 min using a high-speed shearing machine, and then freeze-dried for 24 h to obtain peanut red skin proanthocyanidin microcapsule dry powder particles.

[0033] 1. Optimization of the proportion of wall material components

[0034] The peanut red coat proanthocyanidin microcapsules were prepared according to the method of Example 1, wherein different concentrations of inulin and whey protein were set as follows:

[0035] W0 group: inulin 200 mg / mL, whey protein 0 mg / mL; W1 group: inulin 175 mg / mL, whey protein 25 mg / mL; W2 group: inulin 150 mg / mL, whey protein 50 mg / mL; W3 group: inulin 125 mg / mL, whey protein 75 mg / mL; W4 group: inulin 100 mg / mL, whey protein 100 mg / mL.

[0036] 1. Embedding rate

[0037] Determination of the content of proanthocyanidins on the surface of microcapsules: weigh 10 mg of proanthocyanidin microcapsules in anhydrous ethanol, shake and wash repeatedly, filter, and dilute the filtrate to 10 mL. The content of proanthocyanidins in the filtrate is the content of proanthocyanidins on the surface of the microcapsules.

[0038] Determination of total proanthocyanidin content in microcapsules: weigh 10 mg of proanthocyanidin microcapsules in distilled water, shake and wash repeatedly, filter, and dilute the filtrate to 10 mL. The proanthocyanidin content in the filtrate is the total proanthocyanidin content in the microcapsules.

[0039] Embedding rate calculation formula:

[0040] Embedding rate (%) = (1-microcapsule surface proanthocyanidin content / microcapsule total proanthocyanidin content) × 100

[0041] The test results are shown in Table 1:

[0042] Table 1 Wall material composition and embedding rate of peanut red skin proanthocyanidin microcapsules

[0043]

[0044]

[0045] As shown in Table 1, by optimizing the ratio of inulin and whey protein, the embedding rate of proanthocyanidins was significantly improved. When the inulin concentration was 125 mg / mL and the whey protein concentration was 75 mg / mL, the embedding rate reached 98.47%. When the inulin concentration was 100 mg / mL and the whey protein concentration was 100 mg / mL, the embedding rate did not increase significantly compared with W3.

[0046] 2. Color contrast

[0047] The color of the microcapsules was measured using a colorimeter, and the color parameters (L*, a*, b*) of the microcapsules were evaluated using the CIELab color system, with unencapsulated proanthocyanidins (PSP) as the control. The color difference ΔE* was used to measure the degree of color difference between the proanthocyanidin microcapsules (W0, W1, W2, W3, W4) and unencapsulated proanthocyanidins (PSP).

[0048] Color difference calculation formula:

[0049]

[0050] The comparison results are shown in Table 2 and Figure 1 As shown:

[0051] Table 2 Color parameters of peanut red skin proanthocyanidin microcapsules and unencapsulated proanthocyanidins

[0052]

[0053] As shown in Table 2, compared with unencapsulated proanthocyanidins, different proportions of inulin and whey protein encapsulated proanthocyanidin microcapsules have a significant shielding effect on its red-brown color. The brightness value (L*) of the proanthocyanidin microcapsules is significantly increased compared with the unencapsulated proanthocyanidin powder, and the red-green value (a*) and yellow-blue value (b*) are significantly reduced.

[0054] 3. Microstructure

[0055] The microcapsules were placed on the double-sided conductive adhesive on the stage of a scanning electron microscope, and after gold spraying, the microstructure of the microcapsule sample was observed using a scanning electron microscope (magnification 2000 times).

[0056] The scanning electron microscopy results are as follows Figure 2 As shown:

[0057] By optimizing the ratio of inulin and whey protein, the problem of high porosity and poor mechanical properties of inulin-prepared microcapsules was solved. When the inulin concentration was 200 mg / mL and the whey protein concentration was 0 mg / mL (W0), the surface of the microcapsules was uneven and porous; as the inulin concentration decreased and the whey protein concentration increased, the surface of the microcapsules tended to be smooth and the pores decreased. When the inulin concentration was 125 mg / mL and the whey protein concentration was 75 mg / mL, the surface of the microcapsules was smooth and there were almost no visible pores. This helps to improve its environmental stability and gastrointestinal sustained-release performance.

[0058] 4. Sustained release effect

[0059] Simulated gastric fluid: 775 mg NaCl, 275 mg KCl, 37.5 mg CaCl2·2H2O and 150 mg NaHCO3 were dissolved in 250 mL distilled water to prepare gastric electrolyte solution (GES). Gastric fluid is composed of GES (150 mL), pepsin (35.4 mg) and 1.0 M CH3COONa solution (pH 5.0, 1.5 mL). 5.0 mg / mL proanthocyanidin microcapsule solution was evenly mixed with an equal volume of gastric fluid, and the final solution pH was adjusted to 2.0 with 0.1 M hydrochloric acid solution, and simulated gastric digestion was started at 37 ° C. The digestive fluid was collected at 0 h, 0.5 h, 1 h, 1.5 h, and 2 h, and the content of released proanthocyanidins was determined.

[0060] Simulated intestinal fluid: 82.5 mg CaCl2·2H2O, 162.5 mg KCl and 1.35 g NaCl were dissolved in 250 mL distilled water, mixed with 7% pancreatic enzyme solution and 4% bile salt solution (1:1:2, v / v / v), added to the gastric digestion sample (3:10, v / v), and the solution pH was adjusted to 7.0 with 0.2 M NaOH solution. After incubation at 37°C for 0 h, 0.5 h, 1 h, 1.5 h, and 2 h, the digestion fluid was collected again to determine the content of released proanthocyanidins.

[0061] The test results are as follows Figure 3 and Figure 4 As shown:

[0062] By optimizing the ratio of inulin and whey protein, the sustained release effect of proanthocyanidins microcapsules in the gastrointestinal tract was significantly enhanced, and the colon accessibility was significantly improved. Compared with the W0 microcapsules with an inulin concentration of 200 mg / mL and a whey protein concentration of 0 mg / mL, the increase in the proportion of whey protein in the wall material (W1, W2, W3, W4) significantly reduced the release efficiency of peanut red skin proanthocyanidins in the gastrointestinal tract. Among them, there was no significant difference in the release efficiency of W2, W3, and W4 microcapsules in the gastrointestinal tract.

[0063] 2. Impact on intestinal flora and intestinal health

[0064] Considering that the encapsulation rate of W3 and W4 microcapsules is significantly better than that of W0, W1 and W2, and there is no significant difference between W3 and W4 in terms of physical and chemical indicators such as color contrast, microstructure and sustained release effect, from the perspective of economic cost, W3 microcapsules with inulin concentration of 125 mg / mL and whey protein concentration of 75 mg / mL as wall materials are better. Therefore, peanut red skin proanthocyanidin microcapsules W3 were selected for subsequent in vitro colon fermentation studies, including the study of intestinal flora diversity, relative abundance of colon flora and metabolites of colon flora.

[0065] The culture medium for colon fermentation contains peptone (2 g / L), yeast extract (2 g / L), L-cysteine ​​salt (0.5 g / L), K2HPO4 (0.04 g / L), KH2PO4 (0.04 g / L), NaCl (0.1 g / L), CaCl2·2H2O (0.01 g / L), MgSO4·7H2O (0.01 g / L), etc. The prepared culture medium is adjusted to pH 7.0 with 1M NaOH solution, and oxygen in the culture medium is removed with nitrogen, and then added to an anaerobic fermentation bottle, and sterilized at 121°C for 15 min to obtain a culture medium for colon fermentation.

[0066] Fresh feces from 6 healthy adults were collected in fecal protection solution, vortexed and mixed, centrifuged at 500g for 2 minutes, and the supernatant was taken. The concentration of unencapsulated proanthocyanidins in the anaerobic fermentation system was 1 mg / mL, the concentration of microcapsules was 5 mg / mL (of which the concentration of encapsulated proanthocyanidins was 1 mg / mL), and the concentration of fecal bacteria was 1%. After 24 hours of dark fermentation at 37°C, 5 mL of fermentation liquid was taken, centrifuged at 5000g for 5 minutes, and the precipitate was used for intestinal flora 16S rRNA sequencing analysis, and the supernatant was used for intestinal flora metabolite detection. The in vitro fermentation group without proanthocyanidins was used as a control to explore the effects of the prepared proanthocyanidin microcapsules on intestinal flora and metabolites.

[0067] The results of the intestinal flora diversity test are as follows Figure 5 As shown:

[0068] When the inulin concentration was 125 mg / mL and the whey protein concentration was 75 mg / mL, the proanthocyanidin microcapsules prepared with inulin-whey protein as the wall material significantly improved the Simpson, Shannon and Pielou_e α-diversity indices of the intestinal flora compared with the non-encapsulated proanthocyanidin fermentation group during the in vitro simulated colon fermentation process.

[0069] The relative abundance test results of colonic flora are as follows Figure 6 As shown:

[0070] Compared with unencapsulated proanthocyanidins, when the inulin concentration was 125 mg / mL and the whey protein concentration was 75 mg / mL, the proanthocyanidin microcapsules prepared with inulin-whey protein as the wall material significantly increased the relative abundance of short-chain fatty acid-producing bacteria Anaerostipes and Bacteroides plebeius, which has the function of enhancing the intestinal mucosal barrier, during in vitro simulated colonic fermentation; and significantly reduced the relative abundance of lipopolysaccharide-producing bacteria Sutterella, Alistipes finegoldii, which produces enterotoxins associated with colorectal cancer, and Haemophilus and Haemophilus parainfluenzae, which are associated with intestinal inflammation. Proanthocyanidin microcapsules play a positive role in intestinal health.

[0071] The results of colonic flora metabolite test are as follows Figure 7 As shown:

[0072] Proanthocyanidins are biotransformed by colonic flora and metabolized into phenylvalerolactone and phenolic acid compounds, which are absorbed by the body and have a positive effect. Figure 7 As shown in the figure, compared with unencapsulated proanthocyanidins, the relative abundance of reported proanthocyanidin metabolites such as 2-methoxy-3,4-dimethylphenylacetic acid and hydroxyphenylacetic acid was significantly increased after proanthocyanidin microcapsules were metabolized by colonic flora, indicating that proanthocyanidins can be better metabolized and utilized by the body after being encapsulated by inulin-whey protein. In addition, compared with unencapsulated proanthocyanidins, the relative abundance of metabolites with nutritional and anti-inflammatory effects such as sesamol, pyrazinoylguanidine, agmatine and glucosamine was significantly increased after proanthocyanidin microcapsules were metabolized by colonic flora, which plays a positive role in intestinal and body health.

[0073] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing peanut red coat proanthocyanidin microcapsules, characterized in that: The steps include: Peanut red skin proanthocyanidin powder is added to the wall material solution and mixed to obtain a mixed emulsion; then the mixed emulsion is homogenized and freeze-dried to obtain peanut red skin proanthocyanidin microcapsules.

2. The preparation method according to claim 1, characterized in that: The concentration of peanut red skin proanthocyanidins in the mixed emulsion is selected from 10 to 100 mg / mL.

3. The preparation method according to claim 1, characterized in that: The homogenization conditions are: using a high-speed shearing machine and homogenizing at a rotation speed of 6000 rpm / min for 5 minutes.

4. The preparation method according to claim 1, characterized in that: The wall material solution is a mixed solution of inulin and whey protein.

5. The preparation method according to claim 4, characterized in that: The wall material solution is prepared by the following method: Inulin is dissolved in water to obtain an inulin solution; whey protein is then added to the inulin solution and stirred evenly to obtain a wall material solution.

6. The preparation method according to claim 5, characterized in that: The concentration of the inulin solution is selected from 100 to 200 mg / mL.

7. The preparation method according to claim 5, characterized in that: The concentration of the whey protein in the wall material solution is selected from 0 to 100 mg / mL.

8. The preparation method according to claim 5, characterized in that: The concentration of the wall material solution is 200 mg / mL.

9. Peanut red skin proanthocyanidin microcapsules prepared by the method according to any one of claims 1 to 8.

10. Use of the peanut red skin proanthocyanidin microcapsules according to claim 9 in the preparation of health foods with the functions of regulating intestinal flora, assisting in lowering blood sugar, assisting in lowering blood lipids or anti-oxidation.

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