Biological enhancement method for selenium-rich edible mushrooms

Abstract

The invention relates to the technical field of edible mushroom cultivation, and particularly discloses a biological enhancement method for selenium-rich edible mushrooms. According to the method, a selenium source with a specific concentration is added into an edible mushroom culture medium, and optimized culture conditions are combined, so that the yield of the edible mushrooms in the growth process is increased, and selenium elements are efficiently absorbed and converted, and therefore, an edible mushroom product rich in organic selenium is obtained. The method is easy to operate, low in cost and suitable for large-scale production of the selenium-rich edible mushrooms, and has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of edible mushroom cultivation, and particularly relates to a biological fortification method for selenium-rich edible mushrooms. Background Art

[0002] Common edible mushrooms include Auricularia auricula, Lentinula edodes, Hericium erinaceus, Pleurotus ostreatus, Flammulina velutipes, Hericium erinaceus, Ganoderma lucidum, etc. They are delicious in taste and rich in nutrition, containing various nutrients such as protein, polysaccharide, vitamin, and mineral, and are deeply loved by consumers, having broad application prospects in the fields of food and health products. Selenium is an essential trace element for the human body, with various physiological functions such as antioxidant, immune enhancement, and cancer prevention. However, the distribution of selenium in nature is uneven, and the selenium content in soil and food is low in many regions, resulting in insufficient selenium intake by the human body. Edible mushrooms have strong selenium enrichment ability and can convert inorganic selenium into organic selenium, being an ideal selenium supplement source.

[0003] Currently, the traditional production method of selenium-rich edible mushrooms is mainly to add a selenium source (such as sodium selenite) to the culture medium, but the traditional method has the problem of low selenium utilization rate. For example, in the conventional selenium-rich cultivation of edible mushrooms, only a small amount of the added sodium selenite can be converted into organic selenium, and most of the selenium is discarded with the waste culture medium. In addition, adding a high concentration of selenium will also cause the growth of edible mushrooms to be inhibited. Therefore, it is of great practical significance to develop a biological fortification method for selenium-rich edible mushrooms that can effectively improve the yield and selenium conversion efficiency of selenium-rich edible mushrooms. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a biological fortification method for selenium-rich edible mushrooms, which can improve the absorption and conversion efficiency of selenium by edible mushrooms by optimizing the types of selenium sources, addition concentrations, and culture conditions, and obtain edible mushroom products with high yield and high organic selenium content.

[0005] The technical solution of the present invention is as follows: A biological fortification method for selenium-rich edible mushrooms, comprising the following steps: (1) Prepare a culture medium, add a selenium source to the culture medium, and after mixing the selenium source with the culture medium, make it into a mushroom bag and sterilize it; the selenium source includes one or both of a selenium-rich soil nutrient fortifier or potassium selenocyanoacetate; (2) Inoculation: Inoculate the mycelium of the edible mushroom into the culture medium; (3) Cultivation: After inoculation, place the mushroom bag in a mushroom cultivation room for cultivation; (4) Harvesting: Move the mushroom bag into a fruiting room for cultivation and harvest the fruiting bodies.

[0006] Preferably, the selenium source is a selenium-enriched soil nutrient enhancer and potassium selenocyanoacetate; the mass ratio of selenium in the selenium-enriched soil nutrient enhancer to potassium selenocyanoacetate is 1:1. Selecting a composite selenium source can give play to the advantages of different selenium sources and simultaneously improve the conversion efficiency of selenium and the yield of edible fungi.

[0007] Preferably, in step (2), the addition concentration of selenium in the culture medium is 2 mg / kg.

[0008] Preferably, in step (3), the temperature in the mushroom cultivation room is 21 - 22 °C, ventilation is carried out once every 30 minutes for 5 minutes each time to ensure that the maximum-minimum difference in the CO2 concentration in the mushroom cultivation room is 500 ppm.

[0009] When the CO2 concentration is too high, it will inhibit the respiratory function of the mycelium, resulting in slow mycelium growth and decreased vitality. Too low CO2 concentration means excessive ventilation, leading to situations such as too rapid water loss in the cultivation environment and large temperature fluctuations, which are not conducive to mycelium growth. By controlling the CO2 concentration difference to 500 ppm, a relatively stable and suitable gas exchange environment can be created for the mycelium, ensuring the smooth respiratory metabolism of the mycelium, enabling various metabolic pathways to operate coordinately, being beneficial to the absorption and utilization of nutrients by the mycelium, and promoting the growth and development of the mycelium.

[0010] The CO2 concentration is interrelated with other environmental parameters in the mushroom cultivation room, such as temperature and humidity. A stable CO2 concentration difference helps to maintain the stability of the entire cultivation environment, and in synergy with the set temperature of 21 - 22 °C in the mushroom cultivation room and the ventilation time (ventilation once every 30 minutes for 5 minutes each time), etc., provides a stable and suitable growth environment for the edible mushroom mycelium.

[0011] Preferably, in step (3), the cultivation time is at least 30 days.

[0012] Preferably, in step (4), the environmental temperature in the fruiting room is 25 - 28 °C, and the relative humidity is 80% - 90%.

[0013] By precise environmental control to meet the needs of different growth stages of edible fungi, it effectively promotes the growth and development of edible fungi.

[0014] Preferably, by mass percentage, the formula of the culture medium contains: 35% sawdust, 20% wheat bran, 25% cottonseed hulls, 5% soybean meal, 5% corn flour, and 10% corn cob.

[0015] Preferably, the edible fungi include Pleurotus geesteranus, Lentinula edodes, or Flammulina velutipes.

[0016] Preferably, the preparation method of the selenium-enriched soil nutrient enhancer includes the following steps: 1) Crush the selenium-enriched ore and dry it to obtain the dried selenium ore; 2) Grind the dried selenium ore finely to obtain selenium ore powder with a particle size of 160 mesh; 3) Add the activator CaO to the ore powder and mix evenly to obtain a mixture; 4) Place the mixture of the raw materials in a muffle furnace at a temperature of 600 °C and roast for 0.5 h for static conversion; 5) Cool and mix to obtain SeOP.

[0017] Preferably, the mass of the activator is 50% of the mass of the selenium ore powder.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: By selecting a selenium source, optimizing the addition concentration, and the environmental conditions during the cultivation process, the present invention significantly improves the absorption and conversion efficiency of selenium by edible fungi. Compared with the case without adding a selenium source, the selenium content of the edible fungi is increased by 17 times. Compared with the traditional addition of a selenium source, the proportion of organic selenium reaches 99%, effectively reducing the waste of the selenium source and environmental pollution.

[0019] The present invention further finds that by using a composite selenium source SeOP + PSeCA with a selenium mass ratio of 1:1, the advantages of different selenium sources can be exerted, synchronously improving the conversion efficiency of selenium and the yield of edible fungi.

[0020] The method of the present invention is simple to operate and low in cost, suitable for large-scale production of selenium-enriched edible fungi, and has broad application prospects. Specific Embodiments

[0021] To enable those skilled in the art to better understand the technical content of the present invention, the present invention will be further described below with reference to specific embodiments.

[0022] The SeOP in the present invention is a selenium-enriched soil nutrient enhancer. The SeOP can be a commercially available product or a self-made product. In the following examples, the SeOP is prepared by the method in the reference patent document CN106905000A. The specific preparation method is as follows: A preparation method of a selenium-enriched soil nutrient enhancer, comprising the following steps: 1) Crush the selenium-enriched ore with a selenium content of 121 mg / kg, dry it to obtain dried selenium ore; 2) Grind the dried selenium ore finely to obtain selenium ore powder with a particle size of 160 mesh; 3) Add the activator CaO to the ore powder and mix evenly to obtain a mixture; wherein, the mass of the activator is 50% of the mass of the selenium ore powder; 4) Place the mixture of the raw materials in a muffle furnace at a temperature of 600 °C and roast for 0.5 h for static conversion; 5) Cool and mix to obtain SeOP.

[0023] The PSeCA in the present invention is potassium selenocyanatoacetate.

[0024] Example 1: Production of Pleurotus geesteranus A method for biofortifying selenium-enriched edible fungi, comprising the following steps: 1. Preparation of culture medium Prepare an edible fungi culture medium, and the formula of the culture medium is (by mass percentage): sawdust 35%, wheat bran 20%, cottonseed hulls 25%, soybean meal 5%, corn flour 5%, and corncob 10.00%. Adjust the pH of the culture medium to 8.5 - 9 with lime (water content 65%). Add a selenium source to the culture medium to make the selenium concentration 2 mg / kg. After the selenium source and the culture medium are fully mixed, bag them to make fungus bags, each bag weighing 1.35 - 1.40 kg, and sterilize at 121 °C under high pressure for 2 hours.

[0025] The selenium source is SeOP and PSeCA (Se mass ratio 1:1).

[0026] 2. Inoculation: After the fungus bags are sterilized and cooled to room temperature, Pleurotus geesteranus carry out mycelium inoculation (20 mL of mycelium culture solution).

[0027] 3. Cultivation: After inoculation, place it in a mycelium cultivation room for cultivation. The temperature of the mycelium cultivation room is 21 - 22 °C, ventilate once every 30 minutes for 5 minutes each time to ensure that the maximum and minimum difference in the CO2 concentration in the mycelium cultivation room is 500 ppm, and the mycelium cultivation room is completely dark.

[0028] 4. Harvest: After the mycelium is completely colonized on the substrate (about 55 - 60 days), move the fungus bags to the fruiting room for fruiting cultivation. The environmental conditions are 25 - 28 °C and the relative humidity is 80% - 90%. Start harvesting the fruiting bodies on the 5th - 6th day of fruiting (only harvest one flush), weigh them and detect the selenium content.

[0029] Example 2: Production of Pleurotus geesteranus The cultivation process of the edible fungi is the same as that in Example 1, except that: Only PSeCA is added as the selenium source , make the selenium concentration in the culture medium 2 mg / kg.

[0030] Example 3: Production of Pleurotus geesteranus The cultivation process of the edible fungi is the same as that in Example 1, except that: Only SeOP is added as the selenium source , make the selenium concentration in the culture medium 2 mg / kg.

[0031] Example 4: Production of Lentinula edodes A method for biofortifying selenium-enriched edible fungi, comprising the following steps: 1. Preparation of culture medium Prepare an edible mushroom culture medium. The formula of the culture medium is (by mass percentage): sawdust 35%, wheat bran 20%, cottonseed hulls 25%, soybean meal 5%, corn flour 5%, and corn cob 10.00%. Adjust the pH of the culture medium to 8.5 - 9 with lime (water content 65%). Add a selenium source to the culture medium to make the selenium concentration 2 mg / kg. After thoroughly mixing the selenium source with the culture medium matrix, bag it to make mushroom bags, each bag weighing 1.35 - 1.40 kg, and sterilize at 121 °C for 2 hours.

[0032] The selenium source is SeOP and PSeCA (Se mass ratio 1:1).

[0033] 2. Inoculation: After the mushroom bags are sterilized and cooled to room temperature, Lentinula edodes carry out mycelium inoculation (20 mL of mycelium culture solution).

[0034] 3. Cultivation: After inoculation, place it in a mushroom cultivation room for cultivation. The temperature of the mushroom cultivation room is 21 - 22 °C, ventilate once every 30 minutes for 5 minutes each time to ensure that the maximum - minimum difference in the CO2 concentration in the mushroom cultivation room is 500 ppm, and the mushroom cultivation room is completely dark.

[0035] 4. Harvest: After the mycelium is completely colonized on the matrix (about 55 - 60 days), transfer the mushroom bags to the fruiting room for fruiting cultivation. The environmental conditions are 25 - 28 °C and the relative humidity is 80% - 90%. Start harvesting the fruiting bodies on the 5th - 6th day of fruiting (only harvest one flush), weigh them and detect the selenium content.

[0036] The results show that: the yield of Lentinula edodes reaches 245.64 g / mushroom bag, the selenium content is 12.24 mg / kg (dry weight), and the proportion of organic selenium is 93%.

[0037] Example 5: Production of Flammulina velutipes A biological fortification method for selenium - rich edible mushrooms, comprising the following steps: 1. Culture medium preparation Prepare an edible mushroom culture medium. The formula of the culture medium is (by mass percentage): sawdust 35%, wheat bran 20%, cottonseed hulls 25%, soybean meal 5%, corn flour 5%, and corn cob 10.00%. Adjust the pH of the culture medium to 8.5 - 9 with lime (water content 65%). Add a selenium source to the culture medium to make the selenium concentration 2 mg / kg. After thoroughly mixing the selenium source with the culture medium matrix, bag it to make mushroom bags, each bag weighing 1.35 - 1.40 kg, and sterilize at 121 °C for 2 hours.

[0038] The selenium source is SeOP and PSeCA (Se mass ratio 1:1).

[0039] 2. Inoculation: After the mushroom bags are sterilized and cooled to room temperature, Flammulina velutipesMycelium inoculation (20 mL mycelium culture solution).

[0040] 3. Cultivation: After inoculation, place it in a mycelium cultivation room for cultivation. The temperature in the mycelium cultivation room is 21 - 22 °C, ventilate once every 30 minutes for 5 minutes each time to ensure that the maximum and minimum difference in CO2 concentration in the mycelium cultivation room is 500 ppm, and keep the mycelium cultivation room completely dark.

[0041] 4. Harvest: After the mycelium is completely colonized on the substrate (about 30 - 35 days), transfer the mushroom bag to the fruiting room for fruiting cultivation. The environmental conditions are 25 - 28 °C and the relative humidity is 80% - 90%. Start harvesting the fruiting bodies on the 5th - 6th day of fruiting (only harvest one flush), weigh them and detect the selenium content.

[0042] The results show that: The yield of Flammulina velutipes reaches 258 g / mushroom bag, the selenium content is 21.32 mg / kg (dry weight), and the proportion of organic selenium is 91%.

[0043] Comparative Example 1 (blank control group): The cultivation process of the edible mushroom is the same as that in Example 1, except that: Neither SeOP nor PSeCA is added.

[0044] Comparative Example 2: The cultivation process of the edible mushroom is the same as that in Example 1, except that: Only sodium selenite is added as the selenium source , so that the selenium concentration in the culture medium is 2 mg / kg.

[0045] Detect the yields and selenium contents of the edible mushrooms obtained in each example and comparative example. Conduct 3 parallel experiments and take the average value. The results are shown in Table 1.

[0046] Detect the selenium content according to the hydride generation atomic fluorescence spectrometry method in "GB 5009.93—2017". Determine the ratio of (SeCys2 + MeSeCys + SeMet) / (SeCys2 + MeSeCys + Se(IV) + SeMet + Se(VI)) by HPLC - ICP - MS as the proportion of organic selenium.

[0047] Table 1

[0048] The results showed that the yield of the blank control group was 242.98 g / bag of mushroom, and the selenium content was 0.70 mg / kg. When potassium selenocyanatoacetate (PSeCA) was added as the selenium source, the yield increased by 17.80%, and the selenium content increased to 12.86 mg / kg, with organic selenium accounting for 97.37%. When selenium-rich soil nutrient enhancer (SeOP) was added as the selenium source, the yield increased by 18.25%, and the selenium content increased to 9.83 mg / kg, with organic selenium accounting for 98.60%. When SeOP + PSeCA (Se ratio 1:1) was added simultaneously as the selenium source, the yield increased by 19.60%, and the selenium content increased to 10.80 mg / kg, with organic selenium accounting for 99.68%. It can be seen that when SeOP and PSeCA are used as selenium sources, the yield of edible mushrooms and the conversion rate of organic selenium are effectively improved.

[0049] The specific embodiments described above are only partial embodiments of the present invention and are not intended to limit the present invention. Any equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for biofortification of selenium-enriched edible fungi, characterized in that: The following steps are involved: (1) preparing a culture medium, adding a selenium source to the culture medium, mixing the selenium source with the culture medium, making a bacterial bag, and sterilizing; the selenium source includes one or both of a selenium-rich soil nutrient enhancer or potassium selenocyanoacetate; (2) Inoculation: inoculating edible fungus mycelium into the culture medium; (3) Cultivation: After inoculation, the bacteria bag is placed in the bacteria culture room for cultivation; (4) Harvest: Move the mushroom bags into the fruiting room for cultivation and harvest the fruiting bodies.

2. The method according to claim 1, characterized in that The selenium sources are selenium-rich soil nutrient enhancer and potassium selenocyanoacetate.

3. The method according to claim 2, characterized in that The selenium mass ratio of selenium-rich soil nutrient enhancer and potassium selenocyanoacetate is 1:

1.

4. The method according to claim 1, characterized in that: In step (2), the concentration of selenium added to the culture medium is 2 mg / kg.

5. The method according to claim 1, characterized in that In step (3), the temperature of the culture room is 21-22°C, and ventilation is performed every 30 minutes for 5 minutes to ensure that the difference between the highest and lowest CO2 concentrations in the culture room is 500 ppm.

6. The method according to claim 1, characterized in that In step (3), the culture time is at least 30 days.

7. The method according to claim 1, characterized in that Step (4), the ambient temperature of the mushroom room is 25-28°C, and the relative humidity is 80%-90%.

8. The method according to claim 1, characterized in that Calculated by mass percentage, the formula of the culture medium contains: 35% sawdust, 20% wheat bran, 25% cottonseed hull, 5% soybean meal, 5% corn flour and 10% corn cob.

9. The method according to claim 1, characterized in that: The edible fungi include Pleurotus geesteranus, Lentinula edodes or Flammulina velutipes.

10. The method according to claim 1, characterized in that The preparation method of the selenium-enriched soil nutrient enhancer comprises the following steps: 1) crushing and drying the selenium-rich ore to obtain dried selenium ore; 2) finely grinding the dried selenium ore to obtain selenium ore powder with a particle size of 160 mesh; 3) Add activator CaO to the mineral powder, mix evenly, and obtain a mixture; the mass of the activator is 50% of the mass of the selenium mineral powder. 4) The mixed material of the raw materials is placed in a muffle furnace at a temperature of 600° C. and calcined for static conversion for 0.5 h; 5) Cool and mix to obtain SeOP.

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