A method for culturing low-cadmium, selenium-rich yellow mealworms using cadmium-containing feed and its application.

Abstract

This invention belongs to the field of animal husbandry and deep processing of agricultural products, specifically relating to a method and its application for cultivating low-cadmium, selenium-rich mealworms using cadmium-containing feed. Specifically, this invention involves adding a low concentration of selenium to a cadmium-containing bran and rice bran feed to raise 3rd-4th instar mealworms. In the later stages of rearing, the mealworms are transferred to a selenium-only feed for cadmium removal, ensuring that the cadmium content in the mealworms does not exceed relevant standards and achieving the goal of efficiently treating cadmium-containing agricultural waste and obtaining low-cadmium, selenium-rich mealworm products. Finally, lipids in the mealworm powder are extracted in one step using low-boiling-point petroleum ether to obtain low-cadmium, selenium-rich mealworm protein powder. In summary, this invention is simple, low-cost, and can efficiently process cadmium-containing materials while simultaneously yielding low-cadmium, selenium-rich, high-quality mealworm products and mealworm protein powder, without affecting mealworm yield. It achieves multiple benefits and has good practical application value.

Description

Technical Field

[0001] This invention belongs to the field of animal breeding and deep processing technology of agricultural products, specifically relating to a method for cultivating low-cadmium, selenium-rich yellow mealworms using cadmium-containing feed and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Cadmium (Cd), a heavy metal, is characterized by its high toxicity, persistent degradation, widespread pollution, and difficulty in remediation. It seriously impacts ecosystem stability, food safety, and animal and human health, posing a major threat to ecological environment and biosecurity. Generally, grains such as rice and wheat harvested from Cd-contaminated areas contain a certain amount of Cd, which accumulates in their bran and aleurone layer. Therefore, milling can effectively remove Cd from the edible parts of grains. However, agricultural waste products such as bran or rice bran after hulling are rich in high concentrations of Cd and cannot be effectively utilized. Improper disposal can easily cause environmental pollution and other adverse effects. Therefore, it is necessary to find suitable and efficient methods for treating these heavy metal-containing agricultural wastes.

[0004] Mealworms, also known as yellow mealworms, primarily feed on bran and other organic materials. Their bodies contain 40%-60% crude protein, with a complete range of amino acids, including all 18 essential amino acids required by the human body (their essential amino acid content accounts for 39.14% of the total amino acids, basically meeting the FAO / WHO standard that high-quality protein should contain 40% essential amino acids). They are also rich in crude fat, carbohydrates, vitamins, enzymes, and minerals, making their nutritional value comparable to beef and mutton. They have significant application value in livestock, poultry, and aquatic animals, and can also serve as human food, making them one of the most promising renewable high-protein biological resources currently attracting attention.

[0005] Mealworm farming offers advantages such as high feed conversion rate, low breeding cost, rapid reproduction, short cycle, small space requirement, and low greenhouse gas emissions. Mealworms primarily feed on organic materials such as wheat bran and rice bran, and exhibit a certain tolerance and low accumulation of heavy metals and other pollutants. This makes them suitable for processing waste organic materials such as wheat bran and rice bran contaminated with cadmium (Cd), while simultaneously producing high-protein mealworm products. However, mealworms obtained through this method contain a certain amount of Cd, and effectively reducing the concentration of heavy metals in the insects is a problem that needs to be considered.

[0006] Selenium (Se) is an essential trace element for the growth and development of humans and animals. It participates in the formation of many important functional enzymes in the body, playing a variety of important biological functions such as antioxidation, anti-aging, detoxification, and anti-cancer effects. It plays a vital role in maintaining human health and normal physiological metabolism. Currently, the cultivation method for selenium-enriched mealworms generally involves adding a high concentration of inorganic selenium to the feed. However, long-term exposure to high concentrations of selenium can lead to breed degeneration and a decrease in reproductive rate, limiting cultivation to only one or two generations and making continuous cultivation impossible, thus failing to meet the long-term cultivation and harvesting requirements for selenium-enriched mealworms. Some researchers convert inorganic selenium into organic selenium through plants and then feed it to mealworms to cultivate selenium-enriched mealworms. This method is cumbersome, costly, and time-consuming, and is also not conducive to the efficient breeding and harvesting of selenium-enriched mealworms. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention aims to provide a method for cultivating low-cadmium, selenium-rich yellow mealworms using cadmium-containing feed and its application. Specifically, this invention involves adding a low concentration of selenium to a cadmium-containing bran and rice bran feed to raise 3rd-4th instar yellow mealworms. Later in the rearing process, the mealworms are transferred to a selenium-only feed for further selenium enrichment and cadmium removal, ensuring that the cadmium content in the insects does not exceed relevant standards and achieving efficient treatment of cadmium-containing agricultural waste while obtaining a low-cadmium, selenium-rich yellow mealworm product. Finally, lipids in the mealworm powder are extracted in one step using low-boiling-point petroleum ether to obtain high-quality, low-cadmium, selenium-rich yellow mealworm protein powder. Based on the above research results, this invention is thus completed.

[0008] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution:

[0009] The first aspect of the present invention provides a method for culturing low-cadmium, selenium-rich mealworms using cadmium-containing feed. The method includes: mixing cadmium-containing wheat bran and cadmium-containing rice bran, adding sodium selenite solution to obtain a first mealworm feed, feeding 3-4 instar mealworms (1-1.2 cm in length) with the first mealworm feed, and then transferring the mealworms to a second mealworm feed containing only selenium and no cadmium for continued feeding and cultivation; the cadmium concentration in the first mealworm feed is 0.5-5 mg / kg; the selenium concentration in both the first and second mealworm feeds is 1-4 mg / kg.

[0010] In a second aspect, the present invention provides the application of the above-mentioned method in the production of high-quality mealworm products and mealworm protein powder that are low in cadmium and rich in organic selenium. The application method includes drying and dehydrating the obtained mealworms, pulverizing them to obtain mealworm powder, and then using petroleum ether extraction to remove the oil from the mealworm powder in one step, so as to increase the proportion of selenium, protein and other nutrients in the mealworm protein powder product and their absorption and utilization efficiency in the body, thereby obtaining high-quality low-cadmium and rich in organic selenium mealworm protein powder.

[0011] The beneficial technical effects of one or more of the above technical solutions are as follows:

[0012] 1) The final harvest yield of yellow mealworms after selenium supplementation was 5.91%-17.05% higher than that of those raised alone with feed containing 0.5-5 mg / kg cadmium, and the mortality rate of yellow mealworms in each treatment group did not exceed 2%.

[0013] 2) After the “cadmium removal” stage, the cadmium concentration in the yellow mealworms is below 1 mg / kg, which does not exceed the standard of ≤2 mg / kg specified in the feed standard. The cadmium content of yellow mealworms raised alone with feed containing 0.5-5 mg / kg is reduced by more than 90%.

[0014] 3) After being fed with selenium, the selenium content of the mealworms reached 1.52-2.38 mg / kg, which met the selenium enrichment standard. This is 5-8 times higher than the selenium content of mealworms raised alone on feed with a cadmium content of 0.5-5 mg / kg.

[0015] 4) After being fed with selenium, the organic selenium content in the yellow mealworms reached 1.37-2.26 mg / kg, accounting for 90.01%-95.62%, which means that the yellow mealworms converted almost all of the inorganic selenium they ingested into organic selenium, with a conversion rate of over 90%.

[0016] 5) After extraction with petroleum ether using Soxhlet extraction technology, the lipid content of the high insect meal was significantly reduced, the selenium content increased to 2.17-3.42 mg / kg, and the protein content was 68.12%-74.23%, which is about 25-30% higher than before degreasing.

[0017] 6) The selenium in the defatted mealworm protein powder mainly consists of two organic selenium compounds: methyl selenocysteine ​​(MeSeCys) and selenomethionine (SeMet).

[0018] In summary, the above-mentioned technical solution is simple and low-cost, and can efficiently process cadmium-containing materials while harvesting high-quality yellow mealworm products and yellow mealworm protein powder that are low in cadmium and rich in organic selenium, without affecting the yield of yellow mealworms. It achieves multiple benefits and therefore has good practical application value. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1This invention uses HPLC-ICP-MS to determine the selenium morphology of defatted yellow mealworms after treatment with 1 and 4 mg Se / kg feed; A, five selenium standard sample solutions with a concentration of 20 mg / L; B, selenium morphology of defatted yellow mealworms after treatment with 4 mg Se / kg feed; C, selenium morphology of defatted yellow mealworms after treatment with 1 mg Se / kg feed; 1, selenocysteine ​​(SeCys2); 2, methylselenocysteine ​​(MeSeCys); 3, sodium selenite (Se(IV)); 4, selenomethionine (SeMet); 5, sodium selenate (Se(VI)). Detailed Implementation

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] In a typical embodiment of the present invention, a method for culturing low-cadmium, selenium-enriched mealworms using cadmium-containing feed is provided. The method includes: mixing cadmium-containing wheat bran and cadmium-containing rice bran, adding sodium selenite solution to obtain a first feed for mealworms, feeding and culturing 3-4 instar mealworms (1-1.2 cm in length) with the first feed, and then transferring the mealworms to a second feed containing only selenium and no cadmium for continued feeding and culturing; the cadmium concentration in the first feed is 0.5-5 mg / kg; the selenium concentration in both the first and second feeds is 1-4 mg / kg.

[0024] In the first feed for yellow mealworms, the mass ratio of cadmium-containing wheat bran to cadmium-containing rice bran is 4:1-1:1.

[0025] The preparation method of the second feed for yellow mealworms is the same as that of the first feed for yellow mealworms, the only difference being that the bran and rice bran used are clean and pollution-free and do not contain cadmium; specifically, the preparation method of the second feed for yellow mealworms is as follows: after mixing bran and rice bran in a mass ratio of 4:1 to 1:1, sodium selenite solution is added to it.

[0026] In another specific embodiment of the present invention, the moisture content of the first and second feeds for yellow mealworms is controlled at 8-15%, which is the optimal moisture content for yellow mealworm food.

[0027] The specific feeding and breeding method is as follows: the stocking density is 3000-5000 insects per square meter, and fruits and vegetables (such as carrots, pumpkins, etc.) are added every 1-2 days to provide them with extra nutrition and water. The insect droppings are cleaned and the same feed is added every 3-4 days. They are raised in a dim environment with a temperature of 25-30℃, humidity of 50-70%, and light intensity of 0-300lx.

[0028] In another specific embodiment of the present invention, the culture time for feeding mealworms with the first feed is controlled to be 15-22 days; the culture time for feeding mealworms with the second feed is controlled to be 7-12 days, and the total culture time is 22-34 days.

[0029] By adopting the above feeding method, not only can the overall yield of yellow mealworms and the selenium content in yellow mealworms be effectively increased, but the cadmium content in yellow mealworms can also be effectively reduced.

[0030] In another specific embodiment of the present invention, the method further includes drying and dehydrating the obtained mealworms, pulverizing them to obtain mealworm powder, and then using petroleum ether extraction to remove the oil in the mealworm powder in one step, so as to increase the proportion of selenium, protein and other nutrients in the mealworm protein powder product and their absorption and utilization efficiency in the body, thereby obtaining high-quality low-cadmium selenium-enriched mealworm protein powder.

[0031] The drying process employs freeze-drying technology; Soxhlet extraction technology is used with low-boiling-point petroleum ether as the extractant; and the extraction time is controlled to be 3-5 hours.

[0032] In another specific embodiment of the present invention, the above method is provided for use in the production of low-cadmium, selenium-rich, high-quality mealworm products and mealworm protein powder.

[0033] This invention innovates the method of raising selenium-enriched yellow mealworms, which involves using cadmium-contaminated feed to raise yellow mealworms, thereby achieving the goal of reusing heavy metal pollutants and obtaining high-quality yellow mealworm protein powder to a certain extent.

[0034] Specifically, the present invention can achieve at least the following technical effects:

[0035] 1) This invention proposes a biological treatment technology for agricultural waste such as cadmium-containing bran and rice bran using mealworms, which can efficiently promote the recycling of waste and prevent environmental pollution;

[0036] 2) Using 3rd-4th instar mealworms with a certain degree of resistance to adversity instead of newly hatched larvae to treat cadmium-containing materials results in a high feeding rate, which enhances the material decomposition efficiency without affecting the normal growth of mealworms.

[0037] 3) Adding an appropriate amount of selenium directly to cadmium-containing materials can promote the growth and development of mealworms and inhibit the absorption of cadmium by mealworms or promote its excretion through antagonism, thereby reducing its net accumulation in the insect body. At the same time, mealworms can accumulate and transform selenium through feeding to achieve the purpose of selenium biofortification, thus obtaining selenium-rich mealworms. The method is simple and efficient.

[0038] 4) In the later stages of rearing, they are transferred to a selenium-containing feed for "cadmium removal" to ensure that the cadmium content in the insect body does not exceed the relevant standards;

[0039] 5) A one-step method using petroleum ether is adopted to remove the oil from the mealworm powder, thereby increasing the proportion of selenium, protein and other nutrients in the powder and their absorption and utilization efficiency in the body, and obtaining high-quality, low-cadmium, organic selenium-rich mealworm protein powder.

[0040] The present invention will be further described below with reference to embodiments. The present invention is further illustrated by means of embodiments, but this does not limit the present invention to the scope of the embodiments described. Based on the embodiments of the present invention, any changes to the present invention by those skilled in the art without inventive step are within the protection scope of the present invention. Furthermore, in the embodiments of the present invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0041] Example 1

[0042] A method for culturing low-cadmium, selenium-enriched yellow mealworms using cadmium-containing feed includes:

[0043] 1) Preparation of cadmium-containing bran and rice bran feed: Mix cadmium-containing bran and rice bran in a 1:1 ratio and use the same proportion of the two clean and pollution-free materials to fully mix and adjust the feed so that the final cadmium concentration of the feed reaches 0.5 mg / kg.

[0044] 2) Selenium-containing feed preparation: Add a certain amount of sodium selenite solution prepared with deionized water to the above-mentioned cadmium-containing mixed feed to make the selenium content of the feed 2mg / kg. Place this prepared selenium-cadmium-containing feed in the sun to dry until its moisture content is about 8%. At the same time, use clean and pollution-free materials to prepare feed with a selenium concentration of only 2mg / kg, and dry it for later use.

[0045] 3) Use 3-4 instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the selenium-cadmium-containing material mentioned in 2) above. The stocking density is 3000-5000 mealworms per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the insect feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 25℃, humidity of 70% and light intensity of 100lx for 15 days.

[0046] 4) Transfer the yellow mealworms from 3) above to the feed containing only 2 mg / kg selenium from 2) and continue to cultivate for 7 days to promote further selenium enrichment in the yellow mealworms and excrete the heavy metal cadmium from the insects, thereby ensuring that the cadmium content in the insects does not exceed the relevant standards. The management method and breeding environment are the same as in 3).

[0047] 5) The harvested mealworms were dehydrated by freeze-drying and ground into powder. Then, they were continuously extracted with petroleum ether using Soxhlet extraction technology for 3 hours to remove the oil in the mealworm powder in one step, so as to improve the proportion of selenium, protein and other nutrients in the mealworm powder and their absorption and utilization efficiency in the body, and obtain high-quality low cadmium and organic selenium-rich mealworm protein powder.

[0048] Example 2

[0049] A method for culturing low-cadmium, selenium-enriched yellow mealworms using cadmium-containing feed includes:

[0050] 1) Preparation of cadmium-containing bran and rice bran feed: Mix cadmium-containing bran and rice bran in a 2:1 ratio and use the same proportion of the two clean and pollution-free materials to fully mix and adjust the feed so that the final cadmium concentration of the feed reaches 2mg / kg.

[0051] 2) Selenium-containing feed preparation: Add a certain amount of sodium selenite solution prepared with deionized water to the above-mentioned cadmium-containing mixed feed to make the selenium content of the feed 1 mg / kg. Place this prepared selenium-cadmium-containing feed in the sun to dry until its moisture content is 12%. At the same time, use clean and pollution-free materials to prepare feed with a selenium concentration of only 1 mg / kg, and dry it for later use.

[0052] 3) Use 3-4 instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the selenium-cadmium-containing material mentioned in 2) above. The stocking density is 3000-5000 mealworms per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the insect feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 28℃, humidity of 60% and light intensity of 200lx for 18 days.

[0053] 4) Transfer the yellow mealworms from 3) to the feed containing only 1 mg / kg selenium from 2) and continue to cultivate for 10 days to promote further selenium enrichment in the yellow mealworms and excrete the heavy metal cadmium from the insects, thereby ensuring that the cadmium content in the insects does not exceed the relevant standards. The management method and breeding environment are the same as in 3).

[0054] 5) The harvested mealworms were dehydrated and ground into powder using freeze-drying technology. Then, they were continuously extracted with petroleum ether using Soxhlet extraction technology for 4 hours to remove the oil in the mealworm powder in one step. This improved the proportion of selenium, protein and other nutrients in the mealworm powder and their absorption and utilization efficiency in the body, resulting in high-quality, low-cadmium, organic selenium-rich mealworm protein powder.

[0055] Example 3

[0056] A method for culturing low-cadmium, selenium-enriched yellow mealworms using cadmium-containing feed includes:

[0057] 1) Preparation of cadmium-containing bran and rice bran feed: Mix cadmium-containing bran and rice bran in a 4:1 ratio and use the same proportion of the two clean and pollution-free materials to fully mix and adjust the feed so that the final cadmium concentration of the feed reaches 5mg / kg.

[0058] 2) Selenium-containing feed preparation: Add a certain amount of sodium selenite solution prepared with deionized water to the above cadmium-containing mixed feed to make the selenium content of the feed 4 mg / kg. Place this prepared selenium-containing cadmium feed in the sun to dry until its moisture content is 15%. At the same time, use clean and pollution-free materials to prepare feed with a selenium concentration of only 4 mg / kg, and dry it for later use.

[0059] 3) Use 3-4 instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the selenium-cadmium-containing material mentioned in 2) above. The stocking density is 3000-5000 mealworms per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the insect feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 30℃, humidity of 50% and light intensity of 300lx for 22 days.

[0060] 4) Transfer the yellow mealworms from 3) to the feed containing only 4 mg / kg selenium from 2) and continue to cultivate them for 12 days to promote further selenium enrichment in the yellow mealworms and excrete the heavy metal cadmium from the insects, thereby ensuring that the cadmium content in the insects does not exceed the relevant standards. The management method and breeding environment are the same as in 3).

[0061] 5) The harvested mealworms are dehydrated and ground into powder using freeze-drying technology. Then, they are continuously extracted with petroleum ether using Soxhlet extraction technology for 5 hours to remove the oil in the mealworm powder in one step. This improves the proportion of selenium, protein and other nutrients in the mealworm powder and their absorption and utilization efficiency in the body, resulting in high-quality, low-cadmium, organic selenium-rich mealworm protein powder 3.

[0062] Comparative Example 1

[0063] A method for culturing mealworms using cadmium-containing feed includes:

[0064] 1) Preparation of cadmium-containing bran and rice bran feed: Mix cadmium-containing bran and rice bran in a 1:1 ratio and use the same proportion of two clean and pollution-free materials to fully mix and adjust the feed so that the final cadmium concentration of the feed reaches 0.5 mg / kg. Place this prepared cadmium-containing feed in the sun to dry until its moisture content is about 8% and set aside for later use.

[0065] 2) Use 3rd-4th instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the cadmium-containing material in 2) above. The stocking density is 3000-5000 mealworms per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the insect feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 25℃, humidity of 70% and light intensity of 100lx for 22 days (corresponding to the total culture time in Example 1).

[0066] 3) The harvested mealworms were dehydrated by freeze-drying and ground into powder. Then, they were extracted with petroleum ether using Soxhlet extraction technology for 3 hours to remove the oil from the mealworm powder in one step, thus obtaining mealworm protein powder 1.

[0067] Comparative Example 2

[0068] A method for culturing mealworms using cadmium-containing feed includes:

[0069] 1) Preparation of cadmium-containing bran and rice bran feed: Mix cadmium-containing bran and rice bran in a 2:1 ratio and use the same proportion of two clean and pollution-free materials to fully mix and adjust the feed so that the final cadmium concentration of the feed reaches 2mg / kg. Place this prepared cadmium-containing feed in the sun to dry until its moisture content is about 12% and set aside.

[0070] 2) Use 3-4 instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the cadmium-containing material in 2) above. The stocking density is 3000-5000 mealworms per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the insect feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 28℃, humidity of 60% and light intensity of 200lx for 28 days (corresponding to the total culture time in Example 2).

[0071] 3) The harvested mealworms were dehydrated by freeze-drying and ground into powder. Then, they were continuously extracted with petroleum ether using Soxhlet extraction technology for 4 hours to remove the oil from the mealworm powder in one step, thus obtaining mealworm protein powder 2.

[0072] Comparative Example 3

[0073] A method for culturing mealworms using cadmium-containing feed includes:

[0074] 1) Preparation of cadmium-containing bran and rice bran feed: Mix cadmium-containing bran and rice bran in a 4:1 ratio and use the same proportion of two clean and pollution-free materials to fully mix and adjust the feed so that the final cadmium concentration of the feed reaches 5mg / kg. Place this prepared cadmium-containing feed in the sun to dry until its moisture content is about 15% and set aside.

[0075] 2) Use 3-4 instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the cadmium-containing material in 2) above. The stocking density is 3000-5000 mealworms per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the insect feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 30℃, humidity of 50% and light intensity of 300lx for 34 days (corresponding to the total culture time in Example 3).

[0076] 3) The harvested mealworms were dehydrated by freeze-drying and ground into powder. Then, they were continuously extracted with petroleum ether using Soxhlet extraction technology for 5 hours to remove the oil from the mealworm powder in one step, thus obtaining mealworm protein powder 3.

[0077] Comparative Example 4

[0078] A method for culturing mealworms using common feed includes:

[0079] 1) Preparation of wheat bran and rice bran feed: Mix wheat bran and rice bran in a ratio of 4:1 and use the same proportion of the two clean and uncontaminated materials to fully mix and adjust. Place this prepared feed in the sun to dry until its moisture content is about 15% and set aside.

[0080] 2) Use 3rd-4th instar mealworms (1-1.2cm long) instead of newly hatched larvae to treat the material in 2) above. The stocking density is 3000-5000 larvae per square meter. Add carrots, pumpkins and other fruits and vegetables every 1-2 days to provide them with extra nutrition and water. Clean the larvae feces and add the same feed every 3-4 days. Keep them in a dark environment with a temperature of 30℃, humidity of 50% and light intensity of 300lx for 34 days (corresponding to the total culture time in Example 3).

[0081] 3) The harvested mealworms were dehydrated by freeze-drying and ground into powder. Then, they were continuously extracted with petroleum ether using Soxhlet extraction technology for 4 hours to remove the oil from the mealworm powder in one step, thus obtaining mealworm protein powder 4.

[0082] Effect verification

[0083] Table 1

[0084]

[0085] The results are shown in Table 1. The mealworms obtained by the cultivation method of the present invention have low mortality and high yield. At the same time, the mealworm powder has a high selenium concentration and a significantly reduced cadmium content. In addition, the lipid content of the mealworm powder is reduced and the protein content is significantly increased, which has good application value.

[0086] It should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the given examples, those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention as needed, without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for culturing low-cadmium, selenium-rich yellow mealworms using cadmium-containing feed, characterized in that, The method includes: mixing cadmium-containing wheat bran and cadmium-containing rice bran, adding sodium selenite solution to obtain a first feed for yellow mealworms, feeding and culturing 3-4 instar yellow mealworms with the first feed, and then transferring the yellow mealworms to a second feed containing only selenium and no cadmium for continued feeding and culturing; the cadmium concentration in the first feed is 0.5-5 mg / kg; the selenium concentration in both the first and second feeds is 1-4 mg / kg.

2. The method as described in claim 1, characterized in that, In the first feed for yellow mealworms, the mass ratio of cadmium-containing wheat bran to cadmium-containing rice bran is 4:1 to 1:

1.

3. The method as described in claim 1, characterized in that, The second feed for yellow mealworms is prepared as follows: clean, uncontaminated wheat bran and rice bran are mixed in a mass ratio of 4:1 to 1:1, and then sodium selenite solution is added to the mixture.

4. The method as described in claim 1, characterized in that, The moisture content of the first and second feeds for yellow mealworms is controlled at 8-15%.

5. The method as described in claim 1, characterized in that, The specific feeding and breeding method is as follows: the stocking density is 3000-5000 insects per square meter, fruits and vegetables are added every 1-2 days, insect droppings are cleaned and the same feed is added every 3-4 days, and the insects are raised in a dim environment with a temperature of 25-30℃, humidity of 50-70%, and light intensity of 0-300lx.

6. The method as described in claim 1, characterized in that, The culture time for feeding yellow mealworms with the first feed should be controlled at 15-22 days; the culture time for feeding yellow mealworms with the second feed should be controlled at 7-12 days.

7. The method as described in claim 1, characterized in that, The method also includes drying and dehydrating the obtained mealworms, pulverizing them to obtain mealworm powder, and then extracting it with petroleum ether.

8. The method as described in claim 7, characterized in that, The drying process employs freeze-drying technology.

9. The method as described in claim 7, characterized in that, Soxhlet extraction was performed using petroleum ether; the extraction time was controlled to be 3-5 hours.

10. The application of the method according to any one of claims 1-9 in the production of low-cadmium, selenium-enriched, high-quality mealworm products and mealworm protein powder.

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