Preparation method of water-retaining agent for edible mushroom cultivation
The composite water retention agent prepared by cross-linking γ-polyglutamic acid and chitosan solves the problem of low water utilization efficiency in edible fungi cultivation, improves yield and bioconversion rate, and achieves environmentally friendly and safe efficient moisture management. Meets the requirements of degradability and pollution-free.
Patent Information
- Application Number
- CN202310714255.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-16
- Publication Date
- 2024-12-17
AI Technical Summary
The existing water-retaining agents for edible fungi cultivation have insufficient environmental protection and safety, which leads to a long growth cycle of edible fungi and low water utilization efficiency, which increases the amount of water replenishment.
A composite water retention agent with a three-dimensional network structure is prepared by cross-linking γ-polyglutamic acid (γ-PGA) and chitosan (CS). It has high biocompatibility, unique swelling performance and sustained release performance, and is used for consumption. Fungal cultivation solves the problem of low water conservation and utilization efficiency.
It improves the water utilization efficiency of edible fungi, reduces the hydration workload, and significantly improves the yield and bioconversion rate of white lingering mushrooms. The water retention agent is degradable, safe and non-toxic, and meets the requirements of environmental protection and sustainable development.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of water retaining agent preparation, and in particular to a method for preparing a water retaining agent for edible fungus cultivation. Background Art
[0002] The edible fungus industry is a truly eco-friendly industry that uses agricultural and forestry waste to produce high-quality protein through fungus cultivation. The edible fungus industry is also a new engine for the development of the health industry. Many edible fungi have been proven to have anti-inflammatory and immunity-enhancing effects, such as shiitake polysaccharides. In addition, the terminal waste of the edible fungus industry, fungus residue, is an excellent matrix for improving soil and livestock feed, and can also be designed and synthesized into organic fertilizer.
[0003] Because fungus crops grow fast, have high bioconversion rates, good economic benefits, small investment, short cycles, quick results and significant benefits, the input-output ratio is 1:3-5, and the economic benefits are more than 10 times that of field crops. "One acre of garden is equal to ten acres of field, one acre of fungi is equal to ten acres of garden."
[0004] In the past decade, my country's edible fungi production and output value have undergone tremendous changes. In 2021, my country's edible fungi production was 41.3394 million tons, with an output value of 347.563 billion yuan, accounting for more than 75% of the world's production. It has also become my country's fifth largest planting industry, second only to grain, vegetables, fruits, and oilseeds, and surpassing cotton, tea, sugar, etc.
[0005] Water is one of the factors that affect the growth of edible fungi and is closely related to the growth and development of edible fungi. The artificial substitute cultivation cycle of edible fungi is as long as 3-6 months. Maintaining the water content in the cultivation material has a great influence on the fruiting effect and yield. Both white mushroom and shiitake mushroom have high requirements for the water content of the cultivation material during the cultivation process. Studies have shown that for every 1kg of white mushroom produced, 4kg to 5kg of water is consumed, and its water consumption is 4 to 5 times the amount of mushroom production. During the fruiting period, the fruiting body cannot get sufficient water supply, which is prone to problems such as small mushroom body and slow growth, resulting in low bioconversion rate and low yield. There are three common measures to maintain the water content of the cultivation material during the cultivation of edible fungi: First, control the appropriate water content when mixing the material to prevent the mycelium from breathing poorly, growing poorly, rotting sticks and other problems caused by too high or too low water content; second, control the humidity of the environment space to more than 80%, and control it to more than 90% during fruiting; third, for varieties such as shiitake mushrooms with a longer fruiting period, each mushroom stick needs to be watered during the fruiting process, which is labor-intensive. Therefore, adding water retaining agent is a simple and efficient way to maintain the moisture content of the cultivation medium.
[0006] Pleurotus nebrodensis, also known as Asafoetida, Asafoetida, and Snow Mountain Ganoderma, belongs to the Fungi, Basidiomycetes, Fungi, Agaricales, Pleurotaceae, and Pleurotus. It originally grew in the Gobi region of Xinjiang, my country, and was domesticated and commercialized by Chinese researchers after 1995. Its fruiting body is white, the mushroom body is hypertrophic, the cap is thick and the handle is thick, the texture is dense, the meat is tender, and the flavor is excellent. It has a very high edible value; it is also extremely nutritious, rich in a large number of amino acids, mineral elements, vitamins, etc., and has multiple health benefits such as antioxidant, immune regulation, anti-tumor, anti-radiation, and lowering blood lipids. In addition, it is also known for its health benefits of preventing and treating rickets, osteomalacia, insecticides, and anti-cancer in children. It is a rare mushroom that combines medicinal and edible uses and has broad market development prospects.
[0007] Super-absorbent polymers (SAP) are a series of functional polymer materials with high water absorption function. The water it absorbs is hundreds to thousands of times heavier than itself, and it has excellent water retention performance. Once it absorbs water and swells into a hydrogel, it is difficult to separate water even under pressure. It has the ability to absorb and retain water. It is a compound that solves the problem of water shortage in agriculture and is of great significance in alleviating the problem of water loss in cultivation materials during edible fungus cultivation.
[0008] The existing water-retaining agents for edible fungi cultivation materials are mostly polyacrylamide. Although they have good water-retaining effects, polyacrylamide itself cannot be completely degraded, and its monomer acrylamide has central and peripheral nerve toxicity. The environmental protection and safety of using such water-retaining agents for edible fungi cultivation need to be studied.
[0009] Therefore, based on the principle of maintaining sustainable development and developing ecological agriculture, we designed and synthesized a degradable, high-water-retaining, high-temperature-resistant, safe and non-toxic γ-polyglutamic acid-chitosan (γ-PGA-CS) composite water-retaining agent with γ-polyglutamic acid as the main raw material, and applied it to the cultivation of edible fungi to solve the water loss problem caused by the long cultivation cycle of edible fungi and reduce the heavy workload caused by water replenishment. Under the premise of meeting the requirements of degradability and non-polluting properties, its water utilization efficiency is improved, thereby achieving the purpose of promoting production increase, laying the foundation for the application of new degradable water-retaining agents in edible fungi. Summary of the invention
[0010] The technical problem solved by the present invention is to overcome the defects and shortcomings of the existing water retaining agent for edible fungus cultivation, and to prepare a polymer with a three-dimensional network structure by chemical and physical crosslinking methods using γ-PGA as a monomer. γ-polyglutamic acid (γ-PGA) composite water retaining agent is a new functional polymer material with good biocompatibility, having a three-dimensional network structure, and a polymer network system in which polymer chains are bonded by physical forces (hydrogen bonds, Coulomb forces, coordination bonds, etc.) or chemical bonds (covalent bonds). The structure of the water retaining agent contains a large number of hydrophilic groups, which can swell in water to absorb water and retain a large amount of water without dissolving, and has the advantages of unique swelling properties, sustained release properties, biocompatibility, etc.
[0011] In order to achieve the above object, the present invention adopts the following design scheme:
[0012] A water retaining agent for edible fungus cultivation was prepared by using γ-polyglutamic acid (γ-PGA) as the main raw material and introducing chitosan (CS) for cross-linking. The preparation method and test method steps are as follows:
[0013] The γ-polyglutamic acid (γ-PGA) fermentation liquid was dissolved in distilled water to a final concentration of 2%, stirred until the solution was clear, then chitosan (CS) was added to dissolve, glacial acetic acid was slowly dripped in, and stirred for 2 minutes. The mixture was washed with distilled water several times until neutral, and vacuum dried to obtain a γ-polyglutamic acid-chitosan (γ-PGA-CS) composite water retaining agent.
[0014] Determination of swelling degree of water retaining agent: Weigh a certain mass of water retaining agent and dry it to constant weight. Take the same mass of water retaining agent and soak it in distilled water and physiological saline, absorb water to constant weight, and use the weighing method to determine the swelling degree. The formula is as follows:
[0015]
[0016] Note: Q t --swelling degree of hydrogel; W m -- the net weight of the initial hydrogel (the weight of the hydrogel after drying); W0--the weight of the hydrogel and the soaked tea bag; W t --The weight of the hydrogel and tea bag after swelling to time t.
[0017] Determination of water absorption rate of water retaining agent: Weigh a certain mass of dry water retaining agent, place it in distilled water, and swell to equilibrium at room temperature. The water absorption rate is calculated according to the following formula: A = (m-m0) / m0, Note: A - water absorption rate (%); m0 - mass of dry water retaining agent, in grams (g); m - mass after swelling equilibrium, in grams (g).
[0018] Determination of thermal stability of water retaining agent: Determination of water absorption rate of water retaining agent after sterilization at 121℃ for 20min
[0019] When the final concentration of γ-PGA fermentation broth is 2%, the addition ratio of γ-PGA fermentation broth to CS is 8:6, and pH=4, this condition is the optimal synthesis condition for designing and synthesizing the γ-PGA-CS composite water-retaining agent.
[0020] The present invention also provides a method for measuring various indicators after the water retaining agent prepared above is added to the edible fungus cultivation material, as described below:
[0021] Determination of moisture content in edible fungus cultivation materials
[0022] Three bags were randomly selected from each group each time after the mixture was mixed and bagged (0d), when the bags were full of mycelium (33d), in the middle of the ripening period (65d), when buds appeared (81d), and at the end of the first wave of mushroom production (100d). Sampling was carried out using the three-point method. After mixing, 1g of each sample was taken and the moisture content was determined using a moisture meter.
[0023] Determination of water content in fruiting bodies of edible fungi
[0024] Five fruiting bodies were randomly selected from each treatment group, and 1 g was taken to measure the water content using a moisture meter. The average value was taken as the water content of the fruiting bodies in this group.
[0025] Determination of water use efficiency of edible fungi
[0026] Water use efficiency (g·kg -1 ) = one-wave mushroom fruiting body yield / total water consumption, where the total water consumption is the sum of the water used for cultivation and mixing and the water used for spraying (calculated based on 100 bags).
[0027] The specific technical principles are:
[0028] Chitosan (CS) is a natural polysaccharide with a wide range of sources and has good biocompatibility, biodegradability, safety and antibacterial properties. There are amino groups and hydroxyl groups on the molecular chain, and many hydrophilic monomers can be easily grafted onto its molecular chain. In an acidic environment, the amino groups of the chitosan side chains can be protonated to form positively charged polymers, which can be combined with the carboxyl groups of the γ-polyglutamic acid side chains, i.e., anionic polymers, to synthesize a composite electrolyte hydrogel. After dissolving γ-PGA and CS, glacial acetic acid is added dropwise, stirred, cross-linked, and vacuum dried to obtain a γ-polyglutamic acid-chitosan (γ-PGA-CS) composite water-retaining agent. DETAILED DESCRIPTION
[0029] The present invention is described below by specific embodiments. Unless otherwise specified, the technical means used in the present invention are methods known to those skilled in the art. In addition, the embodiments should be understood as illustrative rather than limiting the scope of the present invention, and the essence and scope of the present invention are limited only by the claims. For those skilled in the art, various changes or modifications to the material composition and dosage in these embodiments, without departing from the essence and scope of the present invention, also belong to the protection scope of the present invention.
[0030] Example 1 Cultivation of Pleurotus eryngii
[0031] The cultivation experiment was as follows:
[0032] The process is carried out according to the seed production-bagging-inoculation-germination-scratching-after-ripening-bud thinning-mushroom fruiting-harvesting process. After crushing the γ-PGA-CS composite water retainer, mix it into the cultivation material according to the dosage of 10g per bag, and fill it with high-pressure polypropylene plastic bags with specifications of 17cm×38cm (the dry mass of each treatment bag is the same 680g), and 100 bags are used for each treatment. The control group is the one without adding water retainer to the cultivation material, and the experimental group is the one with γ-PGA-CS water retainer. The bags are sterilized, inoculated at both ends, and placed in the same greenhouse for routine management and germination. After buds appear, the principle of thinning buds is adopted to remove excess young mushrooms, keeping the large ones and removing the small ones, keeping the middle ones and removing the edges, and keeping the good ones and removing the inferior ones. Water is sprayed every day after the mushrooms start to fruit, and the air humidity in the greenhouse is maintained at 80%-85%, and the total amount of water sprayed is recorded.
[0033] Test results:
[0034] The addition of γ-PGA-CS composite water retainer can promote the filling of bags and the early appearance of buds of Pleurotus nebrodensis; it has a significant effect on the yield and bioconversion rate of Pleurotus nebrodensis. The addition of γ-PGA-CS composite water retainer is conducive to the increase of Pleurotus nebrodensis yield. The addition of γ-PGA-based composite water retainer in the cultivation material of Pleurotus nebrodensis can advance the filling of bags of Pleurotus nebrodensis by 3 days and the appearance of buds by 6-7 days. The yield of Pleurotus nebrodensis per bag reaches 0.290 kg, and the bioconversion rate reaches 41.65%, which is significantly different from the control group. The results of sampling and testing at each cultivation period show that the water content in the cultivation material of the treatment group at different cultivation stages is basically the same. The water content of the fruiting bodies in each treatment group is also basically the same. Since the fruiting body yield increases significantly after the addition of water retainer, and the total water consumption is the same, the water use efficiency of the γ-PGA-CS group and the control group is calculated to be 225g / kg and 110g / kg, respectively, which is 102% higher than that of the control group. The water use efficiency of the experimental group is significantly higher than that of the control group.
Claims
1. A water retaining agent for edible fungus cultivation was prepared by using γ-polyglutamic acid (γ-PGA) as the main raw material and introducing chitosan (CS) for cross-linking.
2. The method for preparing a water retaining agent for edible fungus cultivation as claimed in claim 1, comprising the following steps: absorbing γ-polyglutamic acid (γ-PGA) fermentation liquid and dissolving it in distilled water to a final concentration of 2%, stirring until the solution is clear, then adding chitosan (CS) to dissolve, the ratio of γ-PGA fermentation liquid to CS is 8:6, slowly dripping glacial acetic acid to pH = 4, stirring for 2 minutes, washing with distilled water several times until neutral, and vacuum drying to obtain a γ-polyglutamic acid-chitosan (γ-PGA-CS) composite water retaining agent.