Rhodobacter tofu polysaccharide extract as well as preparation method and application thereof
By preparing the Rhodobacter tofu polysaccharide extract, the negative charge functional groups in its structure react with heavy metal Pb ions, the shortcomings in reducing the heavy metal content in food in the prior art are solved, and the food safety is improved.
Patent Information
- Application Number
- CN202510389782.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-07-04
AI Technical Summary
In the prior art, there are few studies on the use of functional extracts of fermented bean dregs to reduce the content of effective heavy metals in food.
Rhodobacter tofu is used as raw material, and polysaccharide extract of Rhodobacter tofu is prepared through hot water extraction, ethanol precipitation, dialysis and other steps. The negatively charged functional groups in its structure complex, precipitation, ion exchange and other reactions are used to complex, precipitate, and ion exchange with heavy metal Pb ions to reduce the bioavailability of heavy metals in food.
Effectively reduce the biological effectiveness of heavy metal Pb in food, reduce its toxicity, improve food safety, and is suitable for food such as soy products.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of food and biological fermentation, and particularly relates to a polysaccharide extract of red mushroom tofu, a preparation method thereof, and an application thereof. Background Art
[0002] Red mushroom tofu is a delicious food made from the bean dregs left after grinding tofu. It is fermented and has the advantages of wide raw material sources, simple preparation methods, and low costs, so it is very popular among people. Further research and development of red mushroom tofu and further in-depth utilization of its active ingredients are beneficial to enhancing the industrial value of red mushroom tofu.
[0003] Fermented bean dregs products contain rich protein and polysaccharide components, but are mainly applied to their antibacterial, anti-inflammatory, lipid-lowering, and antioxidant activities. For example, Yao Heng disclosed in the paper "Study on the Process and Properties of Polysaccharide Production by Fermenting Bean Dregs with Morchella esculenta" that using bean dregs as raw materials and adopting a semi-solid fermentation method to ferment bean dregs with Morchella esculenta to produce polysaccharides, the obtained crude polysaccharide (CMP) has a certain inhibitory effect on Escherichia coli and Salmonella, and has a certain lipid-lowering function; the purified acidic polysaccharide (PMP) has good antioxidant activity. Dong Weiliang disclosed in the paper "Preparation of Soybean Polypeptides and Polysaccharides by Fermenting Bean Dregs with Aspergillus oryzae" that using bean dregs as raw materials, after hydrolysis and fermentation, the soluble part of the fermentation product is rich in nutrients, rich in polysaccharides and soybean protein peptides beneficial to human health, and can be used as a functional food raw material.
[0004] At present, there are few research reports on using functional extracts of fermented bean dregs to reduce the content of effective heavy metals in food. Summary of the Invention
[0005] Aiming at the above-mentioned shortcomings and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method of a polysaccharide extract of red mushroom tofu.
[0006] Another object of the present invention is to provide a polysaccharide extract of red mushroom tofu prepared by the above method.
[0007] Another object of the present invention is to provide the application of the above polysaccharide extract of red mushroom tofu in reducing the content of effective heavy metal Pb in food.
[0008] The object of the present invention is achieved by the following technical solutions:
[0009] A preparation method of a polysaccharide extract of red mushroom tofu includes the following preparation steps:
[0010] (1) Extraction of polysaccharide: Extract red mushroom tofu with hot water, filter and concentrate the filtrate to obtain a water extract of red mushroom tofu;
[0011] (2) Deproteinization: The aqueous extract of red mushroom tofu obtained in step (1) is precipitated with ethanol, the precipitate is centrifuged and dissolved in deionized water, and then the Sevag method is used to remove proteins to obtain a crude polysaccharide solution;
[0012] (3) Removal of small molecules: The crude polysaccharide solution obtained in step (2) is filled into a dialysis bag and dialyzed to remove small molecules, and then freeze-dried to obtain red mushroom tofu polysaccharide extract (EPS).
[0013] Furthermore, the red mushroom tofu mentioned in step (1) refers to red mushroom tofu prepared by fermenting with any one or a combination of two of Neurospora crassa and Weissella as fermentation bacteria; more preferably, red mushroom tofu prepared by fermenting with Neurospora crassa ZK, with the preservation number: GDMCC No: 65602 as the fermentation bacteria.
[0014] More preferably, the method for fermentation preparation is: Filter the sterilized fresh soybean dregs, stir-fry them, and then inoculate with fermentation bacteria for fermentation culture to obtain fermented red mushroom tofu.
[0015] Furthermore, the hot water extraction mentioned in step (1) refers to hot water bath extraction at 90 - 100 °C for 1 - 3 h; the number of times of hot water extraction is 1 - 3 times.
[0016] Furthermore, the water consumption for hot water extraction in step (1) is 10 - 30 times the mass of red mushroom tofu; the concentration refers to concentrating to 1 / 2 - 1 / 6 of the original volume.
[0017] Furthermore, the ethanol precipitation in step (2) refers to mixing and stirring with ethanol at 2 - 6 times the volume of the aqueous extract of red mushroom tofu, and then standing and precipitating at 0 - 10 °C for 12 - 48 h.
[0018] Furthermore, the dialysis in step (3) refers to dialysis using a dialysis bag with a molecular weight cut-off of 30,000 - 100,000.
[0019] A red mushroom tofu polysaccharide extract is prepared by the above method.
[0020] The application of the above red mushroom tofu polysaccharide extract in reducing the content of effective heavy metal Pb in food.
[0021] Furthermore, the application method is:
[0022] Add the red mushroom tofu polysaccharide extract to food and mix evenly to reduce the content of effective heavy metal Pb in food.
[0023] As a biological adsorption EPS, the polysaccharide extract of the red mushroom tofu contains many negatively charged functional groups in its structure, such as carboxyl groups, hydroxyl groups, phosphate groups, sulfate groups, and amino groups. These functional groups can react with positively charged heavy metal Pb ions through complexation, precipitation, ion exchange, redox reactions, etc., thereby reducing the bioavailability of heavy metal Pb and alleviating its toxicity.
[0024] Preferably, the food is soy products, and the addition amount of the polysaccharide extract of the red mushroom tofu is 0.5% - 1% of the mass of the soy products.
[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0026] (1) The present invention uses red mushroom tofu as a raw material to extract polysaccharide functional components, and verifies the differences in the polysaccharide extraction rate and components of red mushroom tofu obtained by different fermentation strains through experiments.
[0027] (2) The present invention verifies the application effect of the polysaccharide extract of red mushroom tofu in reducing the content of available heavy metal Pb in food, and has good prospects for reducing the bioavailability of heavy metal Pb in food, alleviating its toxicity, and improving food safety. Description of the Drawings
[0028] Figure 1 It is a standard curve graph of the polysaccharide concentration and ultraviolet absorbance obtained during the determination of the polysaccharide content in Example 1.
[0029] Figure 2 It is an infrared spectrum graph of the polysaccharide extract of the red mushroom tofu obtained in Example 1.
[0030] Figure 3 It is a determination result graph of the Congo red test of the polysaccharide extract of the red mushroom tofu obtained in Example 1.
[0031] Figure 4 It is a determination result graph of the thermal stability analysis of the polysaccharide extract of the red mushroom tofu obtained in Example 1.
[0032] Figure 5 It is an AFM graph of the polysaccharide extract of the red mushroom tofu obtained in Example 1.
[0033] Figure 6 It is a comparison graph of the detection results of the rapid detection kit for heavy metal lead in the soybean residue samples before and after being treated with the polysaccharide extract of the red mushroom tofu in Example 1.
[0034] Figure 7 It is a change graph of the Pb content in the red mushroom tofu obtained by fermentation culture for different times in Example 1.
[0035] Figure 8The surface microscopic morphology map and Pb element distribution map of the red mushroom tofu obtained by fermentation culture for different times in Example 1. Detailed implementation manners
[0036] The present invention will be further described in detail below in conjunction with examples and drawings, but the implementation manners of the present invention are not limited thereto.
[0037] Example 1
[0038] A preparation method of a polysaccharide extract from red mushroom tofu includes the following preparation steps:
[0039] (1) Preparation of red mushroom tofu: After sterilizing fresh bean dregs, filter them through a 20-mesh sieve. Then stir-fry in an iron pot until the moisture content is 75%. Take 200 g of the stir-fried bean dregs, take 1 wt% of the inoculum of Neurospora crassa ZK (preserved in Guangdong Microbial Culture Collection Center on October 21, 2024, preservation number: GDMCC No: 65602) spore powder, stir evenly, and place it in a small storage basket (14.5 * 14.5 * 5.5 cm) with flannelette. Place it in a constant temperature and humidity incubator at 28 °C and 75% humidity for fermentation culture for 48 h to obtain fermented red mushroom tofu.
[0040] (2) Extraction of polysaccharide: Add 5 g of red mushroom tofu sample to 20 times the volume of distilled water, extract at 95 °C for 2 h, filter and separate the filter residue, and extract the filter residue again by water bath in the same method as above. Combine the supernatants of the two times, and concentrate it to 1 / 4 of the original volume at 50 °C using a rotary evaporator to obtain the water extract of red mushroom tofu.
[0041] (3) Deproteinization: Add 4 times the volume of pre-cooled 75% ethanol solution to the water extract of red mushroom tofu obtained in step (1), continuously stir during the addition process, and then place it in a refrigerator at 4 °C for alcohol precipitation for 24 h. Dissolve the precipitate obtained by centrifuging the alcohol-soluble solution in deionized water. Place it in a screw-cap Erlenmeyer flask with 1 / 4 volume of chloroform-n-butanol solution (pre-prepared 4:1 mixed solution by volume), shake well for 30 min, centrifuge at 8000 r / min for 10 min, and then separate the water phase from the chloroform. Add the chloroform-n-butanol solution to the water phase again, repeat the above process until there are no white water bubbles on the water layer after shaking, and take the water phase to obtain the crude polysaccharide solution after deproteinization.
[0042] (4) Removal of small molecules: The crude polysaccharide solution obtained in step (2) was filled into a dialysis bag with a molecular weight cut-off of 60,000 and dialyzed for 48 h, with water changed every 8 h. After dialysis, it was centrifuged (4000 r / min, 10 min), the supernatant was filtered by suction, and the bottom precipitate was discarded. Finally, the filtrate was concentrated in a round-bottom flask at 60 °C using a rotary evaporator and freeze-dried to obtain the polysaccharide extract (EPS) of red mushroom tofu.
[0043] I. The polysaccharide content of the polysaccharide extract of red mushroom tofu obtained in this example was determined (using the phenol-sulfuric acid method and ultraviolet spectroscopy analysis), and the standard curve of the polysaccharide was y = 7.9964x, R 2 = 0.9981, as Figure 1 shown. The polysaccharide content in the crude polysaccharide solution obtained in step (3) of this example was determined to be 0.5153 mg / ml. The polysaccharide composition of the freeze-dried EPS is shown in Table 1 below.
[0044] Table 1. Polysaccharide composition of the polysaccharide extract of red mushroom tofu
[0045] Compound Name Component Content (mg / g) Mannose 8.393 Ribose 2.212 Rhamnose 11.651 Glucuronic Acid 2.749 Galacturonic Acid 6.568 Glucose 0.000 Galactose 42.290 Xylose 0.000 Arabinose 89.740 Fucose 4.195 Fructan 40.222 Glucan 4.351
[0046] II. The molecular weight of the polysaccharide extract of red mushroom tofu obtained in this example was determined (using gel permeation chromatography), and the determination results are shown in Table 2 below.
[0047] Table 2. Polysaccharide molecular weight of the polysaccharide extract of red mushroom tofu
[0048] Retention Time Number-Average Mn Weight-Average Mw Mz Mw / Mn 8.751 21976 82147 666028 3.7380
[0049] Molecular weight is an important structural feature of polysaccharides, and the size of the molecular weight also affects the biological activity of polysaccharides. Some studies have shown that a higher polysaccharide molecular weight will lead to poorer water solubility and an increase in solution viscosity (Zhu et al., 2016; Phil et al., 2018). At the same time, a higher polysaccharide molecular weight will also reduce the biological activity of polysaccharides and their effects in aspects such as anti-inflammatory, immune, and antioxidant (Zhang et al., 2014). On the contrary, due to the weaker hydrogen bond force within the molecule, low molecular weight polysaccharides have more free amino and hydroxyl groups, which are more conducive to the exertion of biological activity (Brasselet et al., 2019; Li et al., 2022; Zhu et al., 2021). From the results in Table 2, it can be seen that the number-average molecular weight (Mn) of the polysaccharide of the obtained polysaccharide extract of red mushroom tofu is 21976 Da, the weight-average molecular weight (Mw) is 82147 Da, the Z-average molecular weight (Mz) is 666028 Da, and the polydispersity index PD (Mw / Mn) is 3.7380.
[0050] III. The structure of the polysaccharide extract of red mushroom tofu obtained in this example was determined. The infrared spectrum of the obtained EPS is as follows Figure 2 shown. There is a strong and broad absorption peak at 3422 cm -1 . This is usually attributed to the stretching vibration of the O-H bond in the polysaccharide molecule. Polysaccharides contain a large number of hydroxyl groups, and hydrogen bonds are easily formed between and within molecules, making the vibration frequency range of the O-H bond wider, thus generating a broad peak. The presence of this peak indicates the existence of abundant hydroxyl groups in the polysaccharide molecule. The absorption peak at 2944 cm -1 corresponds to the stretching vibration of the C-H bond, indicating the presence of saturated hydrocarbon group structures in the polysaccharide molecule, which may be caused by the C-H bond vibration in groups such as methyl and methylene on the sugar ring. This reflects part of the structural characteristics of the carbon skeleton of the polysaccharide molecule. The absorption peak near 1741 cm -1 is related to the stretching vibration of the C=O bond and may originate from the carboxyl group (-COOH) in the polysaccharide. The absorption peaks at 1632 cm -1 and 1423 cm -1 may be due to the amide I band (C=O stretching vibration) in the polysaccharide; the absorption peak near 1423 cm -1 may be the bending vibration peak of O-H. The absorption peak at 1246 cm -1 may be related to the stretching vibration of the C-O bond, and the strong absorption peak near 1075 cm -1 is usually the characteristic absorption peak of the C-O-C bond (glycosidic bond) in the polysaccharide. The glycosidic bond is the key chemical bond connecting monosaccharide units to form a polysaccharide chain. The presence and intensity of this absorption peak can be used to evaluate the degree of polymerization of the polysaccharide and the type of glycosidic bond. Through the Fourier transform infrared spectroscopy analysis of this polysaccharide sample, the presence of various chemical bonds and functional groups such as O-H, C-H, C=O, C-O, and C-O-C in the polysaccharide was determined, initially revealing the molecular structural characteristics of EPS. Different molecular structures have different chemical properties. It can be seen that EPS has a large number of functional groups such as hydroxyl, carboxyl, and C-O. These functional groups bind to heavy metal ions through mechanisms such as coordination, electrostatic attraction, or ion exchange, providing the possibility for subsequent heavy metal adsorption.
[0051] The triple helix structure was determined by the Congo red test: Weigh an appropriate amount of polysaccharide accurately and prepare a solution with a concentration of 1 mg / ml. Mix the polysaccharide solution and the Congo red solution in equal proportions. Add 1 mol / L sodium hydroxide solution to each tube so that the final concentration of the sodium hydroxide solution is 0, 0.1, 0.2, 0.3, 0.5, 0.6 mol / L. After mixing and shaking evenly, let it stand at room temperature for 25 min, and perform wavelength scanning within the wavelength range of 400 - 600 nm to determine the maximum absorption wavelength of the system. Then, use the final concentration of NaOH in each mixed system as the abscissa and the maximum absorption wavelength as the ordinate to plot a curve, with distilled water as the blank control. The results are as follows Figure 3As shown. Congo red is an acidic dye that is water-soluble and alcohol-soluble and can form a stable complex with polysaccharide molecules with a triple helical structure. Within a specific concentration range, when the concentration of sodium hydroxide (NaOH) exceeds a certain threshold, the maximum absorption wavelength of the complex will drop sharply. Figure 3 As shown in the figure, when the NaOH concentration is 0.4M NaOH, the maximum absorption wavelength decreases greatly, so it can be concluded that EPS has a triple helix structure. Polysaccharides with a triple helix structure usually contain abundant functional groups such as hydroxyl (-OH), carboxyl (-COOH) and amino (-NH2), which play a key role in the adsorption of heavy metal ions.
[0052] 4. Thermal stability analysis of the red fungus tofu polysaccharide extract obtained in this example (using differential thermogravimetric method): Weigh an appropriate amount of sample and place it in an alumina crucible (100 μL), and use a differential scanning calorimeter (DSC) for testing; equipment model: Mettler DSC 3; test parameters, sample purge gas: nitrogen, flow rate: 50 ml / min; initial temperature 30°C, heating to 800°C at 10°C / min, constant temperature 1min, test results are as follows Figure 4 As shown. From the TG graph, we can see that: Initial stage (room temperature to 200℃): The curve starts to decline from a mass percentage close to 100%, and the mass loss in this stage is relatively slow. This may be due to the escape of small molecular volatiles in the sample. At lower temperatures, these substances have weaker binding forces with the sample. As the temperature rises, they gradually detach from the sample, resulting in a decrease in mass. The first stage of weight loss (about 200℃-350℃): The curve shows a clear downward trend with a large slope, indicating that the sample has experienced a more drastic mass loss in this temperature range. This is likely to be due to the decomposition of some organic components with poor thermal stability in the sample, the chemical bonds breaking and the escape of volatile products, which significantly reduces the mass of the sample. The second stage of weight loss (about 350℃-550℃): The curve continues to decline rapidly, and the mass loss is further aggravated. This shows that in addition to the previously decomposed components, there may be other organic components or some inorganic-organic complexes that decompose or structurally destroy in this temperature range, and continue to release volatile substances. The third stage (about 550℃-900℃): The curve tends to be flat, and the mass percentage finally stabilizes at a lower level. This indicates that most of the decomposable or volatile components in the sample have reacted completely, and the remaining ones may be some inorganic components with higher thermal stability, such as metal oxides, salts, etc., which basically no longer change in mass within this temperature range.
[0053] V. Atomic Force Microscope (AFM) Characterization of the Polysaccharide Extract from Red Bacteria Tofu Obtained in this Example: Atomic Force Microscope (AFM) can characterize the surface morphology and properties of samples, and directly observe and analyze biological macromolecules under physiological environment. In recent years, AFM has been widely used in the conformational analysis of polysaccharide macromolecules (Posé et al., 2012; Gao et al., 2008; Jin et al., 2006). Figure 5 Shows the AFM characterization results of EPS polysaccharide. From Figure 5 it can be seen that the EPS polysaccharide image presents small bright spots and shows an "island-like" appearance in the three-dimensional image. However, the sizes and heights of the islands are different, indicating that the polysaccharide molecules are intertwined with each other in aqueous solution, presenting an irregular agglomerated state. The thickness of the polysaccharide chain is 0.5 - 2.0 nm, which may be caused by hydrogen bonds between single polysaccharide chains, ionic bonds and van der Waals forces between molecules. The root mean square roughness Rp is 0.962 ± 0.0750, and the average roughness Ra is 0.695 ± 0.0622.
[0054] VI. Application of the Polysaccharide Extract from Red Bacteria Tofu Obtained in this Example in Reducing the Content of Effective Heavy Metal Pb in Food:
[0055] (1) Weigh 0.0408 g of freeze-dried EPS, dissolve it in 1 mL of distilled water, add it to the soybean residue and mix well, and then use a rapid heavy metal lead detection kit to quickly detect the heavy metal lead element. The detection results are as Figure 6 shown. Lead in food is a toxic heavy metal. Excessive intake of lead can cause poisoning, which can lead to anemia, nervous system disorders and kidney damage. Therefore, we use a rapid heavy metal lead detection kit to judge whether the lead content in the sample exceeds the standard through the change of color. If the sample is light yellow, the sample is qualified and negative. If the sample shows orange-red or red, it is unqualified and positive. From Figure 6 it can be seen that the untreated soybean residue sample is an orange positive sample, while the soybean residue treated with EPS is a light yellow negative sample.
[0056] (2) The Pb contents of the untreated soybean residue and the soybean residue treated with EPS were measured by Atomic Absorption Spectroscopy. The test results are shown in Table 3 below.
[0057] Table 3. Pb Contents of Soybean Residue Samples before and after Treatment (mg / kg)
[0058] Sample Name Untreated Soybean Residue Soybean Residue Treated with EPS Content of Pb 0.502±0.018 0.344±0.047
[0059] The lead content in beans will directly determine whether the product is qualified. If it is qualified, it will be put into production, and unqualified products will be directly eliminated or processed. From the above results, it can be seen that EPS can reduce the content of available lead in the sample, and the rapid lead detection kit can turn positive into negative.
[0060] (3) The atomic absorption spectrometry was used to test the change of Pb content in the red mushroom tofu obtained by fermentation culture in this example for different times, and the results are as Figure 7 shown. The surface microtopography map and Pb element distribution map of the red mushroom tofu obtained by fermentation culture for different times are as Figure 8 shown. Combining the above rapid detection kit, it can be concluded that the two detection results are consistent. It is concluded that EPS has the effect of reducing the content of available lead in the soybean residue sample.
[0061] Example 2
[0062] A preparation method of a polysaccharide extract from red mushroom tofu includes the following preparation steps:
[0063] (1) Preparation of red mushroom tofu: After sterilizing fresh soybean residue, it is filtered through a 20-mesh sieve. Then it is stir-fried in an iron pot until the moisture content is 75%. Take 200 g of the stir-fried soybean residue, and take 1 wt% of the inoculation amount of the composite bacteria (Neurospora crassa ZK and Weissella viridescens (purchased commercially) mixed in a mass ratio of 1:1) spore powder, stir evenly, and place it in a small storage basket (14.5*14.5*5.5 cm) with flannelette. It is placed in a constant temperature and humidity incubator at 28 °C and 75% humidity for fermentation culture for 48 h to obtain fermented red mushroom tofu.
[0064] Steps (2)-(4) are the same as those in Example 1 to obtain a polysaccharide extract (EPS) from red mushroom tofu.
[0065] The polysaccharide content in the crude polysaccharide solution obtained in this example is 0.0455 mg / ml. The polysaccharide composition of the freeze-dried EPS is shown in Table 4 below.
[0066] Table 4. Polysaccharide composition of the polysaccharide extract from red mushroom tofu
[0067] Compound Name Component Content (mg / g) Mannose 7.884 Ribose 1.531 Rhamnose 12.107 Glucuronic Acid 0.000 Galacturonic Acid 3.629 Glucose 0.000 Galactose 29.259 Xylose 0.000 Arabinose 16.716 Fucose 1.780 Fructan 7.685 Glucan 4.720
[0068] The application of the polysaccharide extract from red mushroom tofu obtained in this example in reducing the content of available heavy metal Pb in food. According to the method of Example 1, the Pb content of the untreated soybean residue and the soybean residue treated with EPS was tested, and the test results are shown in Table 5 below.
[0069] Table 5. Pb content (mg / kg) of soybean residue samples before and after treatment
[0070] Sample Name Untreated Soybean Residue Soybean Residue Treated with EPS Content of Pb 0.502±0.018 0.362±0.027
[0071] Example 3
[0072] A method for preparing a polysaccharide extract from red mushroom tofu, comprising the following preparation steps:
[0073] (1) Preparation of red mushroom tofu: After sterilizing fresh soybean dregs, filter through a 20-mesh sieve. Then stir-fry in an iron pot until the moisture content is 75%. Take 200 g of the stir-fried soybean dregs, and mix evenly with 1 wt% inoculum of Weissella viridescens (purchased commercially) spore powder, and place it in a small storage basket (14.5*14.5*5.5 cm) with flannel. Ferment and culture in a constant temperature and humidity incubator at 28 °C and 75% humidity for 48 h to obtain fermented red mushroom tofu.
[0074] Steps (2) to (4) are the same as those in Example 1 to obtain a polysaccharide extract (EPS) from red mushroom tofu.
[0075] The polysaccharide content in the crude polysaccharide solution obtained in this example is 0.421 mg / ml. The polysaccharide composition of the freeze-dried EPS is shown in Table 6 below.
[0076] Table 6. Polysaccharide composition of the polysaccharide extract from red mushroom tofu
[0077] Compound Name Component Content (mg / g) Mannose 12.730 Ribose 1.471 Rhamnose 9.838 Glucuronic Acid 3.176 Galacturonic Acid 0.000 Glucose 0.000 Galactose 31.601 Xylose 0.000 Arabinose 97.020 Fucose 5.134 Fructan 54.462 Glucan 4.821
[0078] Application of the polysaccharide extract from red mushroom tofu obtained in this example in reducing the content of heavy metal Pb in food. According to the method in Example 1, test the Pb content of the untreated soybean dregs and the soybean dregs treated with EPS. The test results are shown in Table 7 below.
[0079] Table 7. Pb content (mg / kg) of soybean dreg samples before and after treatment
[0080] Sample Name Untreated Soybean Residue Soybean Residue Treated with EPS Content of Pb 0.502±0.018 0.380±0.035
[0081] From the above results, it can be seen that the polysaccharide content in the crude polysaccharide solution obtained by the present invention using Neurospora crassa to prepare red mushroom tofu and extract is higher, and at the same time, the effect of reducing the content of effective heavy metal Pb in food is better.
[0082] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.
Claims
1. A preparation method of a polysaccharide extract from red mushroom tofu, characterized in that, It includes the following preparation steps: (1) Extraction of polysaccharide: The red mushroom tofu is extracted with hot water, filtered, and the filtrate is concentrated to obtain the water extract of red mushroom tofu; (2) Deproteinization: The water extract of red mushroom tofu obtained in step (1) is precipitated with ethanol, centrifuged, and the precipitate is dissolved in deionized water. Then, the Sevag method is used to remove proteins to obtain a crude polysaccharide solution; (3) Removal of small molecules: The crude polysaccharide solution obtained in step (2) is placed in a dialysis bag for dialysis to remove small molecules, and then freeze-dried to obtain the polysaccharide extract of red mushroom tofu.
2. The preparation method of a polysaccharide extract of red mushroom tofu according to claim 1, wherein, The red mushroom tofu mentioned in step (1) refers to the red mushroom tofu prepared by fermenting with any one or a combination of two of Neurospora crassa and Weissella as the fermenting bacteria; more preferably, the red mushroom tofu prepared by fermenting with Neurospora crassa ZK, with the preservation number: GDMCC No: 65602 as the fermenting bacteria.
3. The preparation method of a polysaccharide extract from red mushroom tofu according to claim 2, characterized in that, The method for fermentation preparation is: Filter the sterilized fresh soybean dregs, stir-fry them, and then inoculate with fermenting bacteria for fermentation culture to obtain the fermented red mushroom tofu.
4. The preparation method of a polysaccharide extract of red mushroom tofu according to claim 1, characterized in that, The hot water extraction mentioned in step (1) refers to hot water bath extraction at 90-100°C for 1-3 h; the number of times of hot water extraction is 1-3 times; the water consumption for hot water extraction is 10-30 times the mass of red mushroom tofu; the concentration refers to concentration to 1 / 2-1 / 6 of the original volume.
5. The preparation method of a polysaccharide extract of red mushroom tofu according to claim 1, characterized in that, The ethanol precipitation mentioned in step (2) refers to mixing and stirring with ethanol 2-6 times the volume of the water extract of red mushroom tofu, and then standing and precipitating at 0-10°C for 12-48 h.
6. The preparation method of a polysaccharide extract from red mushroom tofu according to claim 1, characterized in that, The dialysis mentioned in step (3) refers to dialysis using a dialysis bag with a molecular weight cut-off of 30,000-100,000.
7. A polysaccharide extract of red mushroom tofu, characterized in that, Prepared by the method described in any one of claims 1-6.
8. Use of a polysaccharide extract of red mushroom tofu as described in claim 7 in reducing the content of effective heavy metal Pb in food.
9. The application according to claim 8, wherein The application method is as follows: Add the polysaccharide extract of red mushroom tofu to the food and mix evenly to reduce the content of effective heavy metal Pb in the food.
10. The application according to claim 9, wherein, The food is soy products, and the addition amount of the polysaccharide extract of red mushroom tofu is 0.5%-1% of the mass of the soy products.
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