Preparation method of pilose antler mushroom extract and application of pilose antler mushroom extract in nitrite adsorption and / or lipid lowering product

Abstract

The invention discloses a preparation method of a pilose antler mushroom extract and application of the pilose antler mushroom extract in products with nitrite adsorption and / or lipid lowering efficacy, SDF in pilose antler mushroom is extracted, it is found that the content of SDF in pilose antler mushroom is high, the pilose antler mushroom has good in-vitro lipid lowering activity, and the pilose antler mushroom is a high-quality edible mushroom raw material capable of being used for lipid lowering functional food development. A biological activity experiment shows that the pilose antler mushroom SDF extract can well remove DPPH and ABTS free radicals, adsorb nitrite and inhibit the activity of cholesterol esterase and pancreatic lipase, and shows good oxidation resistance, nitrite adsorption and lipid-lowering activity.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and specifically relates to a preparation method of a pilose antler mushroom extract and application of the extract in products with nitrite absorption and / or lipid-lowering effects. Background Art

[0002] Dietary fiber (DF) is a polysaccharide that cannot be digested and absorbed by the human body. According to its solubility in water, it is divided into soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Usually, dietary fiber samples with a soluble dietary fiber ratio exceeding 10% of the total fiber content will be identified as high-quality dietary fiber. Therefore, the level of soluble dietary fiber is an important indicator for evaluating dietary fiber. Compared with IDF, SDF exhibits better functional activity and health benefits.

[0003] Edible fungi are an important source of a large class of potential functional dietary fiber. Currently, research on the functional activity of edible fungi dietary fiber mainly focuses on anti-cancer, anti-oxidation, regulation of intestinal flora and improvement of constipation. Therefore, it is necessary to conduct more in-depth and systematic research on dietary fiber from edible fungi to understand its biological activity and processing characteristics. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0005] As one aspect of the present invention, the present invention provides a method for preparing a Pleurotus eryngii extract, which comprises the following steps:

[0006] Pleurotus eryngii fruiting body powder is added into water, stirred, pH is adjusted, α-amylase, protease and amyloglucosidase are added in sequence for enzymolysis, supernatant is collected by centrifugation, ethanol is added for standing, and precipitation is collected by centrifugation to obtain soluble dietary fiber of Pleurotus eryngii.

[0007] As a preferred embodiment of the method for preparing the Pleurotus eryngii extract of the present invention: the method for preparing the Pleurotus eryngii fruiting body powder comprises drying the Pleurotus eryngii fruiting bodies, mechanically crushing the powder, and passing the powder through a 40-80 mesh sieve to obtain the Pleurotus eryngii fruiting body powder.

[0008] As a preferred solution of the method for preparing the Pleurotus eryngii extract of the present invention: the Pleurotus eryngii fruiting body powder is added into water, and the solid-liquid ratio is 1:10-80.

[0009] As a preferred solution of the method for preparing the Pleurotus eryngii extract of the present invention: the stirring temperature is 40-50° C., and the stirring time is 0.5-3 h; and the pH is adjusted to 6.0-6.5.

[0010] As a preferred scheme of the preparation method of the Pleurotus eryngii extract of the present invention: α-amylase, protease, and amyloglucosidase are added in sequence for enzymatic hydrolysis, including adding thermostable α-amylase at 95-100° C. for 30-40 min of enzymatic hydrolysis, then cooling to 55-60° C., adding protease for enzymatic hydrolysis for 30-40 min, then adding acetic acid to adjust the pH to 4.5, and adding amyloglucosidase for enzymatic hydrolysis at 55-60° C. for 30-40 min.

[0011] As a preferred solution of the method for preparing the Pleurotus eryngii extract of the present invention: the adding ethanol and letting it stand comprises adding 95% ethanol and letting it stand at 2-8°C for 6k114h.

[0012] The beneficial effects of the present invention are as follows: the present invention extracts SDF from velvet antler mushroom, and finds that the SDF content in velvet antler mushroom is high and has good in vitro lipid-lowering activity, and is a high-quality edible fungus raw material that can be used for the development of lipid-lowering functional foods. Biological activity experiments show that the velvet antler mushroom SDF extract can better scavenge DPPH and ABTS free radicals, adsorb nitrite, inhibit cholesterol esterase and pancreatic lipase activities, and exhibits good antioxidant, nitrite adsorption and lipid-lowering activities. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for describing the embodiment, wherein:

[0014] Figure 1 The soluble dietary fiber content of different edible fungi is compared.

[0015] Figure 2 This is the effect of SDF of different edible fungi on DPPH free radical scavenging activity.

[0016] Figure 3 This is the effect of SDF of different edible fungi on the ABTS free radical scavenging activity.

[0017] Figure 4 The effect of SDF of different edible fungi on nitrite adsorption capacity.

[0018] Figure 5 The effect of SDF of different edible fungi on glucose adsorption capacity.

[0019] Figure 6 This is the effect of SDF of different edible fungi on the inhibition rate of α-glucosidase.

[0020] Figure 7 This is the effect of SDF of different edible fungi on the inhibition rate of cholesterol esterase.

[0021] Figure 8 This is the effect of SDF of different edible fungi on the inhibition rate of pancreatic lipase.

[0022] Fig. 9 This is the HPAEC spectrum of the monosaccharide composition of SDF of Pleurotus eryngii.

[0023] Fig.10 This is the FT-IR image of Pleurotus eryngii SDF.

[0024] Fig.11 SEM images of Pleurotus eryngii SDF, A. magnification is 500 times, B. magnification is 1500 times.

[0025] Fig.12 The adsorption effect of nitrite on Pleurotus eryngii samples extracted by different methods. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0027] Embodiment 1:

[0028] The harvested fruiting bodies of edible fungi were washed with clean water to remove dust from the surface, dried to constant weight, crushed with a high-speed grinder, sieved to 60 mesh, and set aside.

[0029] Soluble dietary fiber from different edible fungi was extracted by water extraction: 1 g of each edible fungus powder was weighed, deionized water was added at a solid-liquid ratio of 1:40, magnetic stirring was performed at 50 °C for 1 h, the pH was adjusted to 6.5, 50 μg of thermostable α-amylase (CAS: 9000-85-5) was added, and the mixture was shaken at 95 °C for 35 min, cooled to 60 °C, 100 μg of protease (CAS: 9014-01-1, derived from Bacillus subtilis) was added at 60 °C, and magnetic stirring was performed for 30 min. n, 25 mL of acetic acid was added to adjust the pH to 4.5, 100 μg of amyloglucosidase (CAS: 9032-08-0) was added at 60°C, the reaction was shaken in a water bath for 30 min, the supernatant was collected and concentrated to 10 mL, 4 times the volume of 95% ethanol was added for precipitation, the mixture was allowed to stand overnight at 4°C, the precipitate was collected by centrifugation at 300 rpm for 10 min, the precipitate was reconstituted with pure water, and the soluble dietary fiber of different edible fungi varieties was obtained after vacuum freeze-drying.

[0030] Determination of soluble dietary fiber content: SDF was extracted from each edible fungus variety, the freeze-dried mass was weighed and the SDF content was calculated according to the following formula:

[0031]

[0032] DPPH free radical scavenging experiment:

[0033] DPPH is a single electron and exists in the form of a stable free radical in an organic solvent. It can accept an electron or a hydrogen ion. DPPH has a maximum absorption at 517nm, and the alcohol solution is purple. Free radical scavengers can capture DPPH single electrons, making the solution lighter in color and the absorbance at 517nm also decreases. The degree of absorbance reduction is proportional to the number of free radicals scavenged. The greater the degree of reduction, the stronger the antioxidant property. Therefore, it is often used to determine the antioxidant capacity of samples. Through the SDF determination of different varieties of edible fungi, the edible fungi were screened according to the comparison of SDF yields, and their DPPH free radical scavenging activity was determined.

[0034] The specific experimental operation is as follows: First, prepare the reagents, mainly including the preparation of DPPH solution and sample solution. DPPH solution: prepare 0.1mM DPPH solution and store it in anhydrous ethanol in the dark; sample solution preparation: prepare 1mg / mL of each sample solution, centrifuge and take the supernatant after full dissolution. Secondly, add 1mL of different sample solutions to 1mL DPPH solution, mix well, and keep it in the dark for 30min at room temperature. In addition, mix 1mL of water with 1ml DPPH solution as the blank group, and mix 1mL of sample solution with 1mL of anhydrous ethanol as the control group. Perform three parallel experiments each time and take the average. Calculate the DPPH clearance rate according to the following formula:

[0035]

[0036] A1: absorbance value of the sample group; A2: absorbance value of the control group; A0: absorbance value of the blank group.

[0037] ABTS free radical scavenging experiment:

[0038] Potassium persulfate (K2S2O8) reacts with ABTS to generate stable ABTS + Cationic free radicals have a maximum absorbance at 734nm. Antioxidants can react with ABTS + The color of the solution becomes lighter and the absorbance at 734 also decreases, indicating that ABTS + The free radicals were scavenged, which indicated its antioxidant capacity. The scavenging activity of each edible fungus on ABTS free radicals was determined.

[0039] The specific experimental operation is as follows: First, the reagents are prepared, mainly including ABTS solution, potassium persulfate solution, phosphate buffer and 1 mg / mL sample solution; secondly, 5 mL of the prepared ABTS solution and potassium persulfate solution are taken, mixed and kept away from light for 12 hours to obtain ABTS assay solution. Before use, the ABTS assay solution is diluted with pH 6.6 phosphate buffer to 734 nm and the absorbance value is 0.7; 0.2 mL of 1 mg / mL sample solution is taken, 2 mL of ABTS solution is added and mixed, and the reaction is kept away from light for 6 minutes. The absorbance value at 734 nm is A1. 0.2 mL of distilled water and 2 mL of ABTS solution are mixed as the blank group, and 0.2 mL of sample solution and 2 mL of phosphate buffer are mixed as the control group. Three parallel experiments are performed each time and the average is taken. The ABTS clearance rate is calculated according to the following formula:

[0040]

[0041] A1: absorbance value of the sample group; A2: absorbance value of the control group; A0: absorbance value of the blank group.

[0042] Evaluation of nitrite adsorption capacity of different SDF samples:

[0043] Nitrite is a common pickling agent in the development of meat products. After being ingested by the human body, it can combine with nitrogen-containing substances produced by amino acid metabolism to form nitrosamines, which are compounds with strong carcinogenic risks and can also cause damage to the human nervous system. This study used pH2 and pH7 reaction systems to simulate the pH environment in the stomach and intestines to explore the adsorption capacity of SDF of different samples on nitrite. The adsorption capacity of each edible fungus on nitrite was determined.

[0044] The experimental operation is as follows: 0.1 g of sample was added to 25 mL of sodium nitrite solution with a mass concentration of 20 ug / mL, the pH value was adjusted to 2.0 and 7.0 respectively, and the mixture was shaken at 37°C and 120 r / min for 2 h, then centrifuged (4000 r / min, 20 min), the supernatant was separated, 1 mL of supernatant was taken, 2 mL of 4 g / L p-aminobenzenesulfonic acid solution was added, the mixture was mixed and placed in dark for 5 min, 1 mL of 2 g / L naphthylethylenediamine hydrochloride solution was added, 6 mL of distilled water was added to make the volume 10 mL, the mixture was mixed, the mixture was placed in dark for 15 min, and the absorbance was measured at 538 nm. The standard curve y=0.0395x+0.0493(R 2 =0.9991) to calculate the mass concentration of nitrite in the supernatant. The nitrite adsorption capacity of different soluble dietary fiber samples was calculated by the following formula:

[0045] Nitrite adsorption capacity (ug / g) = (M1-M2) / M0

[0046] M1: nitrite content in the system before adsorption (ug); M2: nitrite content in the system after adsorption (ug); M0: mass of SDF sample (g)

[0047] Activity evaluation of glucose adsorption capacity of different SDF samples:

[0048] The main mechanism of dietary fiber's inhibition of glucose diffusion is that the sticky soluble fiber increases the viscosity of the system, thereby inhibiting the diffusion of glucose; the physical adsorption of glucose by fiber causes glucose to be adsorbed into the pores of the fiber, thereby reducing the diffusion rate of glucose; the barrier effect of fiber particles on glucose and the binding effect of the cross-linked pore structure in the fiber on the infiltrated glucose can both reduce the diffusion amount of glucose.

[0049] The experimental operation is as follows: 1g sample is mixed with 100mL glucose solution (100mmol / L) evenly, reacted at 37℃ for 6h, centrifuged at 3500g for 15min, the supernatant is taken, and the glucose content in the supernatant is determined using a glucose kit. At the same time, 100mL glucose solution is used as a positive control, and 1g sample plus 100mL phosphate buffer (0.1M, pH=6.5) is used as a negative control. The ability to adsorb glucose is expressed as:

[0050] Glucose adsorption capacity (mmol / g) = [glucose amount in positive control group - (glucose amount in sample group - glucose amount in negative control group)] / sample mass

[0051] Inhibitory activity of different SDF samples on α-glucosidase:

[0052] α-glucosidase present in human intestinal epithelial cells can directly participate in the metabolic pathways of starch, sucrose, maltose, glycogen, etc. It can hydrolyze and break the α-glucosidic bonds of polysaccharides or oligosaccharides to convert them into α-D-glucose. Intestinal α-glucosidase can promote the conversion of carbohydrates consumed by the human body into glucose for human absorption, increasing blood sugar after meals. α-glucosidase inhibitors can reduce the intestinal absorption rate of glucose and improve the rapid rise in blood sugar in diabetic patients after eating.

[0053] The specific experimental operation is as follows: take 25ul sample solution, mix with 25ul α-glucosidase solution (1U / mL), and react at 37°C for 10min. Then, add 25ul PNPG (5mmol / L) and keep at 37°C for 10min, then add 50ul Na2CO3 solution (0.1mol / L) to terminate the reaction, use acarbose as a positive control, and repeat three times for each group. After the experiment, take 200ul of liquid from each tube and place it in a 96-well plate, and read the absorbance at 450nm using a spectrophotometer. The α-glucosidase inhibition rate is calculated by the formula:

[0054] α-glucosidase inhibition rate (%) = [1-(A4-A3) / (A2-A1)] × 100%

[0055] Analysis of monosaccharide composition of Pleurotus eryngii SDF:

[0056] Weigh 2 mg of Pleurotus eryngii SDF into an acid hydrolysis bottle, add 3 mL of 2 mol / L trifluoroacetic acid, mix well, and place in a 110°C oil bath for 4 hours for hydrolysis. After the hydrolysis is completed, use nitrogen to blow dry the trifluoroacetic acid in the hydrolysis bottle, add 3 mL of methanol, blow dry again with nitrogen, and repeat the operation 3 times. Add ultrapure water to dissolve the hydrolyzed SDF in the bottle, and use high-performance anion exchange chromatography to analyze the monosaccharide composition of the sample.

[0057] Fourier infrared spectroscopy analysis of Pleurotus eryngii SDF: Weigh a certain amount of Pleurotus eryngii SDF powder, use KBr to make tablets, mix a small amount of sample powder with KBr in a certain proportion, grind it thoroughly, and use a mold to press it into a transparent sheet of appropriate thickness. -1 Scan at different wave numbers.

[0058] SDF scanning electron microscope analysis of Pilosa velutipes: The microstructure of the SDF sample powder of Pilosa velutipes was observed using a scanning electron microscope. A small amount of SDF sample was taken with double-sided tape, sprayed with a thin layer of gold powder, and placed in a scanning electron microscope for scanning. The parameters were set to an acceleration voltage of 5kV and observed at magnifications of 500 and 1500 times.

[0059] Figure 1 Comparison of soluble dietary fiber content of different edible fungi, different lowercase letters indicate significant differences (p < 0.05). Pleurotus eryngii has the highest SDF content of 14.73%, followed by Pleurotus geesteranus, Pleurotus eryngii and Pleurotus ostreatus with 11.50, 11.62 and 12.01% respectively, while Ganoderma lucidum has the lowest SDF content of 3.28%.

[0060] The SDF of Pleurotus geesteranus, Pleurotus eryngii, Pleurotus eryngii and Pleurotus ostreatus all showed a certain ability to scavenge DPPH free radicals (see Figure 2 ). At the same mass concentration, the DPPH free radical scavenging ability of Pleurotus eryngii SDF is the strongest. When the concentration of Pleurotus eryngii SDF sample is 1 mg / mL, its DPPH free radical scavenging rate is 80.38%. Figure 3 As shown, Pleurotus eryngii SDF has the strongest ABTS free radical scavenging ability, with a scavenging rate of 68.73%, which is consistent with the trend of DPPH free radical scavenging activity determination, indicating that Pleurotus eryngii SDF has good antioxidant activity.

[0061] Adsorption capacity of nitrite: The adsorption effect of SDF of edible fungi on nitrite is as follows Figure 4 . In the simulated gastric fluid environment (pH2), the adsorption effect of SDF on nitrite is better than that of the intestinal environment (pH7). In the pH2 environment, the adsorption effect of SDF of Pleurotus eryngii on nitrite is significantly higher than that of SDF of other edible fungi, and the adsorption capacity of SDF of Pleurotus eryngii on nitrite is weak, which is 218.91μg / g; in the pH7 environment, the adsorption capacity of SDF of Pleurotus eryngii on nitrite is stronger. The results show that the adsorption capacity of all SDF samples in the pH2 environment is significantly higher than that in the pH7 environment, indicating that the adsorption of nitrite by dietary fiber mainly occurs in gastric fluid.

[0062] Adsorption capacity of glucose: Figure 5 The results show the glucose adsorption capacity of SDF of various edible fungi at a glucose concentration of 100 mmol / L. Among them, the adsorption capacity of Pleurotus eryngii SDF for glucose is significantly higher than that of other edible fungi SDF, reaching 1.631 mmol / g.

[0063] Inhibition of α-glucosidase activity: Inhibition of α-glucosidase activity is an important indicator for evaluating the effect of dietary fiber on reducing the rate of glucose production. Inhibition of α-glucosidase activity can effectively control postprandial blood sugar levels. Figure 6 As shown, the SDF inhibition rate of Pleurotus eryngii was the highest (10.71%).

[0064] In vitro lipid-lowering activity: Inhibitory activity against cholesterol esterase: Inhibitory activity against cholesterol esterase is an important indicator for evaluating the in vitro lipid-lowering activity of dietary fiber. Inhibition of cholesterol esterase can slow down the rate at which the body converts cholesterol esters into free cholesterol and is absorbed by the human body, thereby achieving a lipid-lowering effect. Figure 7 It can be seen that the SDF of Pleurotus geesteranus, Pleurotus eryngii, Pleurotus eryngii and Pleurotus ostreatus all have an inhibitory effect on cholesterol esterase, among which the SDF of Pleurotus eryngii has the highest inhibition rate of 51.46%. Figure 8 It can be seen that the SDF of each edible fungus has different inhibitory effects on pancreatic lipase. The SDF of Pleurotus eryngii has the strongest inhibition rate on pancreatic lipase, reaching 36.45%, followed by Pleurotus geesteranus, which is 20.25%, and the inhibition rate of Pleurotus eryngii is the lowest, which is 5.30%.

[0065] Analysis of monosaccharide composition of Pleurotus eryngii SDF: To further investigate the structure-activity relationship of Pleurotus eryngii SDF, monosaccharide composition, infrared spectroscopy and scanning electron microscopy were performed on Pleurotus eryngii SDF. The ion chromatograms of the monosaccharide standard mixture and the hydrolyzate of Pleurotus eryngii SDF are shown in Figure 2. Fig. 9, it was found that the SDF of Pleurotus eryngii is composed of glucose, galactose, mannose and glucuronic acid, and is a heteropolysaccharide. Among them, glucose accounts for the largest proportion and is the main monosaccharide in the SDF of Pleurotus eryngii (see Table 1). The molar percentage of galactose: glucose: mannose: glucuronic acid is 11.58: 80.23: 4.93: 3.26.

[0066] Table 1 Analysis of monosaccharide composition of Pleurotus eryngii SDF

[0067]

[0068] Fig. 9 In the formula, 1-fucose, 2-rhamnose, 3-arabinose, 4-galactose, 5-glucose, 6-xylose, 7-mannose, 8-fructose, 9-galacturonic acid, and 10-glucuronic acid.

[0069] Infrared spectrum analysis of Pleurotus eryngii SDF: In the Fourier infrared spectrum of Pleurotus eryngii SDF (see Fig.10 ), at 3422cm -1 A large broad absorption peak caused by the stretching vibration of OH hydroxyl groups appeared at the wavelength of 2926 cm, indicating that there are more hydrogen bonds in the molecule, which increases the hydrophilicity of SDF. -1 The weak absorption peak near 1612cm comes from the stretching vibration of CH in the methylene group of polysaccharide, which is a typical absorption peak of polysaccharide structure. -1 The peaks near 1408cm are vibration peaks caused by bending and stretching of lignin aromatic hydrocarbons, and it is inferred that the SDF of Pleurotus eryngii contains lignin; -1 The absorption peaks around 1078cm are CH stretching vibrations; -1 The peaks appearing at are caused by the contraction vibration of CO in cellulose and hemicellulose, indicating that the SDF of Pleurotus eryngii may contain cellulose and hemicellulose. The results show that the infrared spectrum of SDF of Pleurotus eryngii has typical characteristic absorption peaks of polysaccharides, which is composed of polysaccharide compounds.

[0070] Scanning electron microscope analysis of SDF of Pleurotus eryngii: Some functional properties of dietary fiber are determined by the microstructure. The microstructure of SDF was observed using a scanning electron microscope (SEM). Fig.11 A), Pleurotus eryngii SDF presents two morphological structures, namely smooth flakes and pore structures. Fig.11 In B, it was found that the SDF of Pleurotus eryngii contained a large number of cracks and holes, which were beneficial to increase the exposure of the groups and improve the ability of dietary fiber to absorb glucose, cholesterol and harmful substances in the gastrointestinal tract.

[0071] In summary, the present invention extracted SDF from Pleurotus eryngii, and found that the SDF content in Pleurotus eryngii was high and had good in vitro lipid-lowering activity. It is a high-quality edible fungus raw material that can be used for the development of lipid-lowering functional foods. Biological activity experiments show that the SDF extract of Pleurotus eryngii can better scavenge DPPH and ABTS free radicals, adsorb nitrite, inhibit the activity of cholesterol esterase and pancreatic lipase, and exhibit good antioxidant, nitrite adsorption and lipid-lowering activities.

[0072] Embodiment 2:

[0073] Ultrasonic extraction of SDF from Pleurotus eryngii: weigh the sieved edible fungus powder and add deionized water at a solid-liquid ratio of 1:40, extract by ultrasonic (250w) at 50°C for 1h, centrifuge at 300rpm for 10min, collect the supernatant and concentrate to 10mL, add 4 times the volume of 95% ethanol for precipitation, let stand overnight at 4°C, collect the precipitate by centrifugation, reconstitute with pure water, and obtain soluble dietary fiber after vacuum freeze-drying.

[0074] The test method for the adsorption capacity of nitrite is the same as that in Example 1: 0.1 g of sample is added to 25 mL of a sodium nitrite solution with a mass concentration of 20 ug / mL, the pH values ​​are adjusted to 2.0 and 7.0 respectively, and the mixture is shaken at 37°C and 120 r / min for 2 h, then centrifuged (4000 r / min, 20 min), the supernatant is separated, 1 mL of the supernatant is taken, 2 mL of 4 g / L p-aminobenzenesulfonic acid solution is added, the mixture is mixed and placed in a dark place for 5 min, 1 mL of 2 g / L naphthylethylenediamine hydrochloride solution is added, 6 mL of distilled water is added to make the volume 10 mL, the mixture is mixed, the mixture is placed in a dark place for 15 min, and the absorbance is measured at 538 nm. The standard curve y=0.0395x+0.0493 (R 2 =0.9991) to calculate the mass concentration of nitrite in the supernatant. The nitrite adsorption capacity of different soluble dietary fiber samples was calculated by the following formula:

[0075] Nitrite adsorption capacity (ug / g) = (M1-M2) / M0

[0076] M1: nitrite content in the system before adsorption (ug); M2: nitrite content in the system after adsorption (ug); M0: mass of SDF sample (g).

[0077] Adsorption capacity of nitrite: Example 1 Water extraction method and control example 1 Ultrasonic extraction method The adsorption effect of nitrite on velvet mushroom samples is as follows Fig.12As shown. In the simulated gastric fluid environment (pH2), SDF has a better adsorption effect on nitrite than in the intestinal environment (pH7). In the pH2 environment, the adsorption of nitrite by the water extraction sample of Example 1 is significantly higher than that by the ultrasonic extraction sample, which are 1343.11μg / g and 1023.79μg / g respectively; in the pH7 environment, the adsorption capacity of nitrite by the two extraction methods is not much different. The results show that the adsorption of nitrite by water-extracted dietary fiber mainly occurs in gastric fluid.

[0078] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a Pleurotus eryngii extract, characterized in that: The following steps are included: Pleurotus eryngii fruiting body powder is added into water, stirred, pH is adjusted, α-amylase, protease and amyloglucosidase are added in sequence for enzymolysis, supernatant is collected by centrifugation, ethanol is added for standing, and precipitation is collected by centrifugation to obtain soluble dietary fiber of Pleurotus eryngii.

2. The method for preparing the Pleurotus eryngii extract according to claim 1, characterized in that: The preparation method of the velvet antler mushroom fruiting body powder comprises the steps of drying the velvet antler mushroom fruiting bodies, mechanically crushing the velvet antler mushroom fruiting bodies, and passing the velvet antler mushroom fruiting body powder through a 40-80 mesh sieve.

3. The method for preparing the Pleurotus eryngii extract according to claim 1 or 2, characterized in that: The velvet antler mushroom fruiting body powder is added into water, and the solid-liquid ratio is 1:10-80.

4. The method for preparing the Pleurotus eryngii extract according to claim 1 or 2, characterized in that: The stirring temperature is 40-50° C., and the stirring time is 0.5-3 h; and the pH is adjusted to 6.0-6.

5.

5. The method for preparing the Pleurotus eryngii extract according to claim 1 or 2, characterized in that: The method includes sequentially adding α-amylase, protease and amyloglucosidase for enzymolysis, including adding thermostable α-amylase at 95-100° C. for 30-40 minutes of enzymolysis, cooling to 55-60° C., adding protease for 30-40 minutes of enzymolysis, adding acetic acid to adjust the pH to 4.5, and adding amyloglucosidase for 30-40 minutes of enzymolysis at 55-60° C.

6. The method for preparing the Pleurotus eryngii extract according to claim 1 or 2, characterized in that: The adding ethanol and letting it stand comprises adding 95% ethanol and letting it stand at 2-8° C. for 6-14 hours.

7. Use of the Pleurotus eryngii extract prepared by the method for preparing the Pleurotus eryngii extract according to claim 1 in products with nitrite absorption and / or lipid-lowering effects.

8. Use of the Pleurotus ostreatus extract prepared by the method for preparing the Pleurotus ostreatus extract according to claim 1 in preparing products with antioxidant function.

9. Use of the Pleurotus eryngii extract prepared by the method for preparing the Pleurotus eryngii extract according to claim 1 in preparing a product with glucose adsorption function.

10. Use of the Pleurotus eryngii extract prepared by the method for preparing the Pleurotus eryngii extract according to claim 1 in preparing a product for inhibiting α-glucosidase.

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