Edible and medicinal fungus preservative PA-CMCS as well as preparation method and application thereof

Abstract

The invention provides an edible and medicinal fungus preservative PA-CMCS as well as a preparation method and application thereof, and belongs to the technical field of edible and medicinal fungus preservation. A free radical mediated grafting method is adopted, and procyanidine is grafted on carboxymethyl chitosan so as to obtain procyanidine-carboxymethyl chitosan (PA-CMCS), so that the defect that carboxymethyl chitosan is poor in oxidation resistance is overcome, and the carboxymethyl chitosan is used for fresh keeping of edible and medicinal fungi. The prepared PA-CMCS has a good fresh-keeping effect, the DPPH free radical scavenging rate of the PA-CMCS reaches 75.17% and is improved by 73.64% compared with the DPPH free radical scavenging rate of carboxymethyl chitosan, the ABTS free radical scavenging rate of the PA-CMCS is improved by 64.04%, the tensile strength of the PA-CMCS is higher than that of a carboxymethyl chitosan film, meanwhile, the PA-CMCS has good biological non-toxicity, and the PA-CMCS can be used as a novel bio-based food packaging material. The PA-CMCS has a good antibacterial effect, so that the preservative is a good morchella esculenta preservative.

Description

Technical Field

[0001] The invention relates to the technical field of edible and medicinal fungi preservation, and in particular to an edible and medicinal fungi preservative PA-CMCS and a preparation method and application thereof. Background Art

[0002] Edible and medicinal fungi are perishable foods and need to be preserved during transportation. There are many ways to preserve edible and medicinal fungi, such as preservative treatment, low-temperature refrigeration, controlled atmosphere preservation, vacuum packaging, etc. These methods can significantly extend the storage period and shelf life of edible and medicinal fungi and reduce the economic losses caused by decay and deterioration.

[0003] Morchella is rich in a variety of amino acids and organic germanium needed by the human body, as well as nutrients such as vitamins, minerals, proteins, carbohydrates, etc. Among them, the cap of Morchella contains 7 kinds of essential amino acids for the human body, which is a "very good source of protein" and is known as "the meat in the vegetarian". It has the effects of digesting food and soothing the stomach, resolving phlegm and regulating qi, and is often used to treat symptoms such as indigestion, phlegm and cough. It also has a variety of health care functions such as anti-cancer, cold prevention, and enhancement of human immunity, and is deeply loved by consumers. However, the short storage period of fresh Morchella seriously restricts its circulation in the market. Therefore, a safe and simple preservation method is urgently needed to extend its storage period.

[0004] Most of the current preservatives for edible and medicinal mushrooms are single coating materials. Although they can extend the shelf life of edible and medicinal mushrooms to a certain extent and alleviate nutrient loss, the preservation effect is limited and the stability of the coating needs to be improved. Carboxymethyl chitosan is a water-soluble derivative of chitosan, which has the advantages of high viscosity, good film-forming properties, biocompatibility, biodegradability and non-toxicity. Although carboxymethyl chitosan has excellent properties as a biomaterial, its weak antioxidant capacity is an important limiting factor in its practical application. Therefore, how to improve the antioxidant capacity of carboxymethyl chitosan is crucial to the preservation of morels. Summary of the invention

[0005] The purpose of the present invention is to provide an edible and medicinal fungus preservative PA-CMCS and a preparation method and application thereof. The prepared edible and medicinal fungus preservative PA-CMCS has good film-forming property, hygroscopicity, antioxidant property and broad-spectrum antibacterial effect, and can be used in the preservation of common edible and medicinal fungi.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides an edible and medicinal mushroom preservative PA-CMCS, which is prepared from proanthocyanidins and carboxymethyl chitosan in a molar ratio of 1:0.05-0.4 through a free radical mediated grafting method.

[0008] Preferably, the edible and medicinal mushrooms include Morchella.

[0009] The present invention also provides a method for preparing an edible and medicinal mushroom preservative PA-CMCS, comprising the following steps:

[0010] (1) adding a H2O2 solution containing ascorbic acid to a carboxymethyl chitosan solution, reacting to obtain a mixed solution;

[0011] (2) adding proanthocyanidins to the mixed solution, reacting, and adjusting the pH;

[0012] (3) The pH-adjusted solution was dialyzed, the supernatant was collected by centrifugation, and freeze-dried to obtain the edible and medicinal mushroom preservative PA-CMCS.

[0013] Preferably, in step (1), the content of ascorbic acid in the H2O2 solution containing ascorbic acid is 0.01-0.05 g / mL; the concentration of the H2O2 solution is 0.2-1 mol / L; the volume ratio of the carboxymethyl chitosan solution to the H2O2 solution containing ascorbic acid is 5-25:1; and the reaction time is 0.5-1 h.

[0014] Preferably, in step (2), the reaction time is 12 h to 24 h; and the pH is 6.8 to 7.2.

[0015] Preferably, in step (3), the molecular weight cut-off of the dialysis is 3.5 to 7 KDa.

[0016] The present invention also provides an application of an edible and medicinal fungus preservative PA-CMCS in preserving edible and medicinal fungi. The application method comprises directly applying the edible and medicinal fungus preservative PA-CMCS on the edible and medicinal fungi or preparing the PA-CMCS film.

[0017] Preferably, the PA-CMCS film is prepared by mixing the edible and medicinal mushroom preservative PA-CMCS with glycerol and gelatin.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] (1) The present invention adopts a free radical mediated grafting method to graft proanthocyanidins onto carboxymethyl chitosan to obtain proanthocyanidins-carboxymethyl chitosan (PA-CMCS) to improve the disadvantage of weak antioxidant capacity of carboxymethyl chitosan, and use it for the preservation of edible and medicinal fungi.

[0020] (2) The PA-CMCS prepared by the present invention has a good preservation effect, and its DPPH free radical scavenging rate reaches 75.17%, which is 73.64% higher than that of carboxymethyl chitosan, and 64.04% higher than that of ABTS free radical scavenging rate, and has the highest antioxidant performance. The tensile strength is higher than that of carboxymethyl chitosan film, and it has good biological non-toxicity, and can be prepared into a film and used as a new type of bio-based food packaging material.

[0021] (3) The PA-CMCS prepared by the present invention has good antibacterial effect and can significantly reduce the total colony count in Morchella, and is a good Morchella preservative. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 is the grafting effect in Experimental Example 1 of the present invention, wherein a is the grafting rate standard curve, and b is the grafting amount;

[0024] Figure 2 The ultraviolet spectra of CMCS, PA, and PA-CMCS in Experimental Example 1 of the present invention are shown in FIG.

[0025] Figure 3 The infrared spectra of CMCS, PA, and PA-CMCS in Experimental Example 1 of the present invention;

[0026] Figure 4 is the DPPH free radical scavenging ability of CMCS, PA, and PA-CMCS in Experimental Example 1 of the present invention;

[0027] Figure 5 is the ABTS free radical scavenging ability of CMCS, PA, and PA-CMCS in Experimental Example 1 of the present invention;

[0028] Figure 6 It is the preservation effect of morels in Test Example 2 of the present invention, wherein a is the weight loss rate of CMCS, the control group and PA-CMCS; b is the hardness of CMCS, the control group and PA-CMCS; c is the browning degree of CMCS, the control group and PA-CMCS; d is the PPO activity of CMCS, the control group and PA-CMCS; e is the respiration intensity of CMCS, the control group and PA-CMCS; f is the relative conductivity of CMCS, the control group and PA-CMCS. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] The present invention provides a method for preparing an edible and medicinal mushroom preservative PA-CMCS, comprising the following steps:

[0035] (1) Adding a H2O2 solution containing ascorbic acid to a carboxymethyl chitosan solution, reacting, and obtaining a mixed solution; wherein the content of ascorbic acid in the H2O2 solution containing ascorbic acid is 0.01-0.05 g / mL; the concentration of the H2O2 solution is 0.2-1 mol / L; the volume ratio of the carboxymethyl chitosan solution to the H2O2 solution containing ascorbic acid is 5-25:1; and the reaction time is 0.5-1 h.

[0036] (2) Adding proanthocyanidins to the mixed solution, reacting, and adjusting the pH; wherein the reaction time is 12 h to 24 h; and the pH is 6.8 to 7.2.

[0037] (3) The pH-adjusted solution was dialyzed, the supernatant was collected by centrifugation, and freeze-dried to obtain the edible and medicinal mushroom preservative PA-CMCS.

[0038] The sources of materials used in the following examples and test examples are as follows:

[0039] Fresh morels, from Aksu, Xinjiang Uygur Autonomous Region; carboxymethyl chitosan, proanthocyanidins, and Folin phenol reagent, from Shanghai Yuanye Biotechnology Co., Ltd.; 2,2'-azobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH), from Shanghai Aladdin Biochemical Technology Co., Ltd.; potassium dihydrogen phosphate, potassium persulfate, disodium hydrogen phosphate, polyvinylpyrrolidone (PVP), barium chloride, and catechol, from Shanghai Sinopharm Group.

[0040] Example 1

[0041] Embodiment 1 of the present invention provides a method for preparing an edible and medicinal mushroom preservative PA-CMCS, which specifically comprises the following steps:

[0042] (1) Weigh 1 g of carboxymethyl chitosan and dissolve it in 100 ml of distilled water. Stir with a magnetic stirrer until it is completely dissolved. Add 4 mL of H2O2 solution (1 mol / L) containing 0.2 g of ascorbic acid and stir for 60 min to obtain a mixed solution.

[0043] (2) 0.3281 g of proanthocyanidin was added to the mixed solution, and stirred with a magnetic stirrer until it was completely dissolved. After standing at room temperature for 12 hours, NaOH (1 mol / L) was added dropwise to the reaction solution to adjust its pH to 7.0.

[0044] (3) The reaction solution was injected into a dialysis bag with a molecular weight cutoff of 3 KDa, and dialyzed with distilled water at room temperature for 48 h (dialysis water was changed every 12 h). The solution was centrifuged at 8000 r / min for 10 min using a high-speed centrifuge, filtered with gauze, and the supernatant was collected. The supernatant was poured into a plate, placed in an ultra-low temperature refrigerator for 2 h, then taken out and placed in a freeze dryer for freeze drying for 24 h to obtain the edible and medicinal mushroom preservative PA-CMCS.

[0045] Test Example 1

[0046] Test Example 1 of the present invention carried out covalent structural characterization and property determination on the edible and medicinal mushroom preservative PA-CMCS prepared in Example 1, and the main steps were as follows:

[0047] (1) The grafting rate of the sample was determined by the Folin phenol method. The phenol content in the PA-CMCS graft was calculated using PA as the standard curve and expressed as the equivalent of PA contained in unit mass of PA-CMCS (mg / g). The results are shown in Figure 1 As shown:

[0048] Figure 1 Figure b shows that when the molar ratio of CMCS to PA repeating units increased from 1:0.05 to 1:0.3, the phenol content of PA-CMCS showed a significant upward trend (P<0.05). This phenomenon can be attributed to the gradual accumulation of PA groups on the CMCS chain in the early stage of the reaction. However, when the molar ratio further increased from 1:0.3 to 1:0.4, the increase in phenol content was no longer significant (P>0.05). This may be because the reaction sites of CMCS have been completely occupied by PA groups, and the reaction between CMCS and PA has reached a saturated state, at which time the optimal grafting conditions are obtained. Therefore, the optimal molar ratio of CMCS to PA repeating units is 1:0.3, at which time, the phenol content of PA-CMCS is 400.6 mg / g.

[0049] (2) UV spectra of proanthocyanidins, carboxymethyl chitosan, and edible and medicinal mushroom preservative PA-CMCS (2 mg / mL) were measured in the scanning range of 250-400 nm. The results are as follows: Figure 2 As shown:

[0050] Most polysaccharides have no absorption peak in the UV-visible spectrum range of 250-400nm, while polyphenols contain aromatic rings and generally have obvious absorption peaks in this UV-visible spectrum range. Figure 2 It shows that carboxymethyl chitosan has no absorption peak in the range of 250-400nm, and proanthocyanidins have a characteristic absorption peak in the range of 250-400nm, located at 279nm, mainly due to the benzene ring structure of proanthocyanidins. In this wavelength range, the graft copolymer of proanthocyanidins and carboxymethyl chitosan also shows a characteristic absorption peak, which is located at 278nm. This shows that proanthocyanidins have been successfully grafted with carboxymethyl chitosan.

[0051] (3) Infrared spectrometry was performed using a Fourier transform infrared spectrometer at a wave number of 4000-400 cm -1 Measurement with a resolution of 2cm -1 , the results are as follows Figure 3 As shown:

[0052] Infrared spectroscopy can analyze the functional groups of compounds and confirm the formation of PA-CMCS grafts. Figure 3 It shows that CMCS is at 1613cm -1The characteristic peak at 1425cm is the overlapping peak of the NH bending vibration absorption peak of -NH2 and the asymmetric stretching vibration absorption peak of COO-. -1 The characteristic peak at 1631 cm is the symmetrical stretching absorption peak of COO-. After grafting, the infrared spectrum of PA-CMCS has some changes compared with CMCS, which provides evidence for the successful formation of the grafted product: First, PA-CMCS has a strong absorption peak at 1631 cm -1 A new absorption peak appeared at 1518 cm -1 、1412cm -1 and 1150cm -1 This effectively confirms that PA has been successfully grafted onto CMCS. Third, the symmetric stretching absorption peaks of CN and CO were observed in the CMCS spectrum, which are located at 1311 cm -1 and 1051cm -1 These characteristic peaks also appeared in the spectrum of PA-CS1, indicating that PA-CMCS retained the polysaccharide backbone of CMCS.

[0053] (4) The DPPH free radical scavenging ability of proanthocyanidins, carboxymethyl chitosan, and edible and medicinal fungi preservative PA-CMCS was determined. Figure 4 As shown:

[0054] As a natural antioxidant polyphenol compound, proanthocyanidins have a significant ability to scavenge DPPH free radicals due to their rich phenolic hydroxyl groups. Figure 4 The results showed that within the test concentration range, the scavenging activity of proanthocyanidins on DPPH free radicals remained stable at about 80.0%. In contrast, the scavenging activity of carboxymethyl chitosan on DPPH free radicals was relatively weak, less than 5.0% at the test concentration, and its scavenging activity did not show obvious fluctuations with the change of concentration.

[0055] (5) The ABTS free radical scavenging ability of proanthocyanidins, carboxymethyl chitosan, and edible and medicinal fungi preservative PA-CMCS was determined. Figure 5 As shown:

[0056] Figure 5 The results show that within the set test concentration range, PA exhibits high efficiency in scavenging ABTS free radicals, with a peak scavenging rate of 90.2%. However, CMCS has a weaker scavenging ability for ABTS free radicals, with the highest scavenging rate at the test concentration being only 0.7%. After grafting, the scavenging rate of PA-CMCS for ABTS free radicals is concentration-dependent, and the scavenging activity increases with increasing concentration.

[0057] (6) The antibacterial activity of carboxymethyl chitosan and edible and medicinal fungi preservative PA-CMCS was determined. The results are shown in Tables 1 and 2.

[0058] Table 1 Minimum inhibitory concentration of PA-CMCS and CMCS

[0059]

[0060] Table 2 Diameters of inhibition zones of PA-CMCS and CMCS

[0061]

[0062] As shown in Table 1, the minimum inhibitory concentrations of PA-CMCS against Bacillus subtilis, Escherichia coli and Staphylococcus aureus are 4, 6 and 8 mg / mL, respectively. PA-CMCS has the strongest inhibitory ability against Bacillus subtilis, followed by Escherichia coli and Bacillus subtilis. CMCS still has visible strain growth at a concentration of 8 mg / mL, proving that the antibacterial activity of PA-CMCS is higher than that of CMCS. As can be seen from Table 2, PA-CMCS has stronger antibacterial activity than CMCS. This shows that the antibacterial properties of PA are improved after CMCS is grafted, and the synergistic effect of PA and CMCS can enhance its antibacterial effect.

[0063] Test Example 2

[0064] In Experimental Example 2 of the present invention, the PA-CMCS film was prepared using the edible and medicinal mushroom preservative PA-CMCS prepared in Example 1, and its performance was tested. The specific method is as follows:

[0065] (1) Accurately weigh 0.8 g of the edible and medicinal mushroom preservative PA-CMCS prepared in Example 1, 0.24 g of glycerol, and 1 g of gelatin. Dissolve the edible and medicinal mushroom preservative PA-CMCS in 40 mL of distilled water and stir with a magnetic stirrer until it is completely dissolved.

[0066] (2) The weighed glycerol and gelatin were added to the proanthocyanidin and carboxymethyl chitosan graft solution respectively, the solution was mixed at 60°C for 30 minutes, and the solution was ultrasonically degassed for 10 minutes using an ultrasonic cleaning machine. The solution was poured into a mold, dried at room temperature for two days, and then peeled from the mold to prepare a composite film.

[0067] (3) Prepare CMCS membrane and blank group membrane using the methods of steps (1) and (2).

[0068] (4) The water vapor permeability and tensile strength of the CMCS membrane, the blank group membrane, and the PA-CMCS membrane were tested respectively. The results are shown in Table 3.

[0069] Table 3 Performance test of membrane

[0070]

[0071] Table 3 shows that the water vapor permeability of PA-CMCS membrane and CMCS membrane is significantly different from that of the blank group membrane. The water vapor permeability of PA-CMCS membrane, CMCS membrane and blank group membrane is 6.797±0.106×10 -10 g mm / h cm 2 Pa, 6.643±0.193×10 -10 g mm / h cm 2 Pa and 7.334±0.274×10 -10 g mm / h cm 2 The water vapor permeability of PA-CMCS membrane is slightly higher than that of CMCS membrane, which may be because the phenolic hydroxyl groups promote the transfer of water molecules in the matrix.

[0072] The mechanical properties of the membrane play a decisive role in its compressive resistance in food processing and transportation. Membranes with excellent mechanical properties can effectively protect food from damage. As shown in Table 3, the tensile strength of the PA-CMCS membrane is higher than that of the CMCS membrane. This may be because CMCS and PA form intramolecular and intermolecular hydrogen bonds after grafting, making the structure more compact, thereby enhancing the structural stability of the entire composite membrane polymer.

[0073] Test Example 3

[0074] Test Example 3 of the present invention tested the preservation effect of the edible and medicinal mushroom preservative PA-CMCS prepared in Example 1 on Morchella edulis. The results are as follows: Figure 6 As shown, the specific steps are as follows:

[0075] (1) Sample processing: Pre-cooled fresh Morchella samples were evenly divided into three groups according to quality grades. Group 1 was smeared with distilled water as the control group, Group 2 was smeared with a certain concentration of CMCS, and Group 3 was smeared with a certain concentration of PA-CMCS. After natural drying, the samples were wrapped with gauze and plastic wrap and stored at a constant temperature of 4°C. Samples were taken on the 1st, 4th, 7th, 9th, 11th, and 14th days to measure relevant indicators.

[0076] (2) Determine the weight loss rate by weighing method:

[0077] The weightlessness of Morchella is due to the loss of water from the cell surface due to transpiration. Figure 6 As shown in Figure a, the weight loss rate of each treatment group increased with the increase of storage days, with a slower increase in the early stage and a faster increase in the later stage. At the early stage of storage and at the end of storage, the weight loss rate of Morchella treated with film coating was lower than that of the control group, which indicates that the film formed after PA-CMCS coating can slow down transpiration and effectively prevent the loss of water in Morchella.

[0078] (3) Determination of hardness using texture analyzer method:

[0079] Hardness is one of the important indicators for evaluating the freshness and quality of morels. The hardness changes of morels during storage are shown in Figure 6 In the middle b, at the beginning of storage, the hardness of the control group was significantly lower than that of the two groups treated with PA-CMCS and CMCS coating. At the end of storage, the hardness of the control group was the lowest, only 0.376N. The results show that coating the Morchella before storage can effectively alleviate the softening of the Morchella tissue structure.

[0080] (4) The browning degree was determined by OD value method:

[0081] The morels turn brown, their original color changes, and their commodity value decreases. Figure 6 As shown in Figure c, the browning degree of Morchella increases with the increase of storage days. The browning degree of Morchella treated with PA-CMCS and CMCS coatings is lower than that of the control group. This may be because a thin film is formed on the surface of Morchella after coating, which prevents the Morchella from contacting with air and causing oxidation.

[0082] (5) Determination of polyphenol oxidase (PPO) activity:

[0083] PPO activity is one of the important factors that lead to tissue browning of Morchella during postharvest storage. Figure 6 As shown in middle d, at the beginning of storage, due to the low temperature environment, its PPO activity showed a downward trend. However, as the storage time prolonged, the morels gradually entered the mature and senescent stage, and its PPO activity began to gradually increase. Especially on the 7th day of storage, the PPO activity of morels reached its peak, and then began to gradually decline. Compared with the control group, the PPO activity of morels treated with PA-CMCS coating technology remained at a low level throughout the storage period. This result shows that PA-CMCS coating technology can effectively inhibit the PPO activity of morels and help extend its storage life

[0084] (6) Determination of respiratory intensity by titration analysis:

[0085] Respiration intensity is an indicator for judging the freshness of Morchella after harvest. Figure 6 As shown in Figure e, the respiration intensity of each group reached the maximum on the 7th day, metabolism accelerated, and nutrient consumption increased. The respiration intensity of Morchella in the control group was the highest, indicating that the coating treatment could effectively inhibit the respiration of Morchella.

[0086] (7) Determination of relative conductivity using the conductivity method:

[0087] When Morchella is damaged or aged, the permeability of the cell membrane increases, causing electrolytes in the cell to leak out, thereby increasing relative conductivity. Figure 6 It can be seen from the figure that the relative conductivity of Morchella showed an overall upward trend during the entire storage period after harvest. On the 11th day of storage, the relative conductivity of the control group reached 74.62%, and the relative conductivity of Morchella treated with PA-CMCS and CMCS coating was 60.93% and 63.45%. Therefore, the cell membrane integrity of Morchella can be effectively maintained by PA-CMCS and CMCS coating during storage.

[0088] (8) The total number of colonies was determined using a colony count test piece. The total number of colonies in the sample was determined according to GB 4789.2-2016. The results are shown in Table 4:

[0089] Table 4 Total colony count

[0090]

[0091] Microbial contamination can lead to various changes in the sensory quality of edible and medicinal mushrooms, produce unpleasant odors and soften the tissue. As shown in Table 4, at the end of storage, the total colony count of the morels in the control group was significantly higher than that in the PA-CMCS and CMCS coating groups. The total colony count of the morels treated with PA-CMCS coating was the lowest, which may be because the film formed on the surface of the morels reduced the contact between the morels and the outside air, inhibiting the growth and reproduction of aerobic bacteria; and PA-CMCS itself has certain antibacterial properties, which reduced the total colony count in the morels.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A edible and medicinal mushroom preservative PA-CMCS, characterized in that: The edible and medicinal mushroom preservative PA-CMCS is prepared from proanthocyanidins and carboxymethyl chitosan in a molar ratio of 1:0.05-0.4 through a free radical mediated grafting method.

2. The edible and medicinal mushroom preservative PA-CMCS according to claim 1, characterized in that: The edible and medicinal mushrooms include morels.

3. A method for preparing the edible and medicinal mushroom preservative PA-CMCS according to claim 1 or 2, characterized in that: The steps include: (1) adding a H2O2 solution containing ascorbic acid to a carboxymethyl chitosan solution to react and obtain a mixed solution; (2) Add proanthocyanidins to the mixed solution, react, and adjust the pH; (3) The pH-adjusted solution is dialyzed, the supernatant is collected by centrifugation, and freeze-dried to obtain the edible and medicinal mushroom preservative PA-CMCS.

4. The method for preparing the edible and medicinal mushroom preservative PA-CMCS according to claim 3, characterized in that: In step (1), the content of ascorbic acid in the H2O2 solution containing ascorbic acid is 0.01-0.05 g / mL; the concentration of the H2O2 solution is 0.2-1 mol / L; the volume ratio of the carboxymethyl chitosan solution to the H2O2 solution containing ascorbic acid is 5-25:1; and the reaction time is 0.5-1 h.

5. The method for preparing the edible and medicinal mushroom preservative PA-CMCS according to claim 3, characterized in that: In step (2), the reaction time is 12 h to 24 h; the pH is 6.8 to 7.

2.

6. The method for preparing the edible and medicinal mushroom preservative PA-CMCS according to claim 3, characterized in that: In step (3), the molecular weight cut-off of the dialysis is 3.5-7 KDa.

7. An application of the edible and medicinal fungi preservative PA-CMCS prepared by the preparation method of the edible and medicinal fungi preservative PA-CMCS according to any one of claims 1 to 2 or the edible and medicinal fungi preservative PA-CMCS according to any one of claims 3 to 6 in preserving edible and medicinal fungi, characterized in that: The application method is to directly apply the edible and medicinal fungus preservative PA-CMCS on the edible and medicinal fungus or prepare it into a PA-CMCS film.

8. The use of the edible and medicinal fungi preservative PA-CMCS in the preservation of edible and medicinal fungi according to claim 7, characterized in that: The PA-CMCS film is prepared by mixing edible and medicinal mushroom preservative PA-CMCS with glycerol and gelatin.

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