Method for culturing hermetia illucens and extracting protein powder by using food waste solids

Abstract

The invention relates to the technical field of biological agriculture, and particularly discloses a method for culturing hermetia illucens and extracting protein powder by using food waste solids. The method comprises the following steps: firstly, performing impurity removal, crushing and solid-liquid separation treatment on the food waste; then light-controlled segmented breeding is implemented, long illumination is adopted in cooperation with blue light in the early stage to promote growth of larvae, short illumination is switched in the later stage, high-protein-induced slow-release gel prepared through food waste liquid fermentation is fed, and automatic regulation and control of illumination and feeding are achieved through a spectrum sensor; and finally, carrying out low-temperature and low-pressure flash wall breaking, vacuum freeze drying and screening treatment to obtain protein powder, synchronously separating grease, and fermenting the breeding residues to prepare the organic fertilizer. According to the method, food waste liquid recycling and hermetia illucens larva protein directional enrichment are synchronously achieved, the breeding regulation and protein extraction technology is optimized, the protein powder quality is improved, full-process resource utilization of food waste is achieved, the technology adaptability is high, by-products can be recycled in a closed-loop mode, and the method has outstanding waste recycling and industrialization application value.

Description

Technical Field

[0001] This application relates to the field of bio-agricultural technology, and more specifically, it relates to a method for extracting protein powder by raising black soldier flies using solid waste from catering. Background Technology

[0002] With the development of the catering industry, the amount of catering waste is increasing year by year. Catering waste is rich in organic matter, and using it to raise black soldier fly larvae and process the larvae into protein powder is an important way to realize the resource utilization of organic waste. Existing technology usually uses catering waste directly as feed after impurity removal and crushing, allowing black soldier fly larvae to feed and grow under natural conditions. After the larvae mature, protein powder is prepared through processes such as drying and crushing, which can achieve preliminary reduction of catering waste and utilization as feed. However, the large amount of liquid generated after solid-liquid separation of catering waste is mostly treated as wastewater, which not only fails to realize resource utilization but also increases the overall disposal cost. At the same time, the natural growth breeding model cannot actively control the metabolic direction of larvae, making it difficult to further improve the protein content and total amino acid content of the protein powder.

[0003] Current technologies for extracting protein powder from black soldier fly larvae do not involve segmented control of lighting during the breeding process, nor do they convert liquid food waste into nutrients that can regulate larval growth. Therefore, they cannot simultaneously achieve the resource utilization of liquid food waste and the targeted enrichment of protein from black soldier fly larvae while processing solid food waste. This problem directly reduces the overall resource utilization efficiency of food waste and also hinders the improvement of protein powder quality. Summary of the Invention

[0004] To address the challenges of resource utilization of liquid food waste and the inability to simultaneously achieve targeted enrichment of proteins from black soldier fly larvae in existing technologies, this application provides a method for extracting protein powder by raising black soldier flies using solid food waste.

[0005] A method for extracting protein powder by raising black soldier flies using food waste solids includes the following steps: S1. Pre-treatment: The collected food waste is sequentially processed through impurity removal, crushing, and solid-liquid separation to obtain food waste solids and food waste liquids respectively; S2. Light-controlled segmented culture: Black soldier fly larvae are inoculated into the food waste solids for culture, and the light conditions are switched according to the culture stage; in the early stage of culture, the first light cycle is used to promote the growth of larvae, and in the later stage of culture, the second light cycle is switched and high protein induction slow-release gel is fed to induce larvae to concentrate protein. S3. Low-temperature extraction: The black soldier fly larvae raised in step S2 are subjected to flash evaporation under low temperature and low pressure conditions to induce cell wall rupture and release oil. Protein powder is obtained after solid-liquid separation. S4. Post-processing: The protein powder obtained in step S3 is dried, and the oil separated in step S3 is collected.

[0006] By adopting the above technical solution, the pretreatment step performs solid-liquid separation of catering waste, realizing the classified disposal and utilization of catering waste. The light-controlled segmented breeding matches the corresponding light conditions according to the larval growth stage, and the high-protein induced slow-release gel provides targeted nutrition to the larvae. Low-temperature and low-pressure flash evaporation completes the cell wall breaking and oil separation of the insect body under mild conditions. The drying treatment maintains the stability of the protein powder composition. The overall technical solution combines the liquid resource utilization of catering waste with the larval protein enrichment process, so that each step is connected and cooperates with each other.

[0007] Preferably, in step S2, the first light cycle is 16 to 20 hours of light and 4 to 8 hours of darkness per day, supplemented by blue light source with a wavelength of 440 to 470 nm; the second light cycle is 4 to 8 hours of light and 16 to 20 hours of darkness per day.

[0008] By adopting the above technical solution, the first photocycle uses a longer photocycle duration combined with blue light irradiation of a specific wavelength, which can act on the larval photoresponse mechanism, improve the larval feeding efficiency and biomass growth rate. The second photocycle uses a shorter photocycle duration, which can change the larval metabolic pathway, causing the larval metabolic process to shift towards protein enrichment. The division of photocycle duration and the selection of blue light wavelength are both adapted to the physiological characteristics of different growth stages of black soldier fly larvae.

[0009] Preferably, in step S2, the early stage of breeding is from day 1 to day 7 after inoculation, and the late stage of breeding is from day 8 to day 12 after inoculation; at the beginning of the late stage of breeding, feeding of food waste solids is stopped and replaced with feeding of high protein induction slow-release gel, with a feeding amount of 5 to 15g per thousand larvae per day.

[0010] By adopting the above technical solution, the time division between the early and late stages of breeding is in line with the developmental pattern of black soldier fly larvae. In the later stage of breeding, feeding solid food waste is stopped and replaced with high-protein induced slow-release gel, which can reduce the interference of miscellaneous nutrients on the directional accumulation of larval protein. The feeding amount is set to match the daily feeding needs of larvae, and a stable nutritional supply is continuously provided for larvae.

[0011] Preferably, in step S2, the high-protein induced sustained-release gel is prepared by the following method: the liquid food waste obtained in step S1 is subjected to microbial fermentation to convert it into a single-cell protein culture medium. The microbial fermentation uses a domesticated compound microbial agent containing yeast and lactic acid bacteria. The domestication is obtained by continuous subculturing in a culture medium containing the liquid food waste. Then, the single-cell protein culture medium is mixed with plant-derived excipients at a mass ratio of 1:0.3 to 1:0.8, and three-dimensional network gel particles are formed through a cross-linking reaction. The particle size of the gel particles is 2 to 5 mm.

[0012] By adopting the above technical solution, the liquid food waste is transformed into a single-cell protein culture medium through microbial fermentation, turning the waste liquid into usable nutrient raw materials. The compound microbial agent, which is continuously cultured, can adapt to the matrix environment of the liquid food waste, thereby improving the fermentation and transformation efficiency. The single-cell protein culture medium and plant-derived auxiliary materials form three-dimensional network gel particles through cross-linking reaction. The gel structure can realize the slow release of nutrients, and the gel particle size is set to facilitate feeding by black soldier fly larvae.

[0013] Preferably, the plant-based adjuvant is at least one of substandard flour, cassava starch, or potato starch; the microbial fermentation temperature is 28 to 35°C, and the fermentation time is 24 to 48 hours.

[0014] By adopting the above technical solutions, substandard flour, cassava starch, or potato starch can be used as plant-based auxiliary materials to provide structural support for gel formation. Different auxiliary materials can be adapted to the forming requirements of gel particles. The limited microbial fermentation temperature and time can ensure that the compound microbial agent maintains normal metabolic activity and successfully completes the conversion process of food waste liquid into single-cell protein.

[0015] Preferably, in step S3, the pressure of the low-temperature and low-pressure flash evaporation treatment is 0.01 to 0.05 MPa, the temperature is 35 to 45°C, and the treatment time is 10 to 30 min.

[0016] By adopting the above technical solution, the limited low-temperature and low-pressure flash evaporation pressure, temperature and time can cause cell wall disruption of insects without damaging the protein structure, promoting the separation of intracellular lipids and protein components. The setting of the treatment parameters takes into account both cell wall disruption efficiency and the integrity of protein components.

[0017] Preferably, in step S2, a spectral sensor is integrated into the breeding device to monitor the reflectance intensity of the black soldier fly larvae's epidermis to the near-infrared spectrum in real time. When the reflectance intensity drops to a preset threshold range, the control system automatically switches the light cycle from the first light cycle to the second light cycle and simultaneously starts feeding the high-protein induced slow-release gel.

[0018] By adopting the above technical solution, the spectral sensor in the breeding device can continuously collect the spectral reflectance signal of the larvae's epidermis. The signal changes can intuitively reflect the larvae's growth state transformation process. Based on the changes in the reflectance signal, the control system can synchronously complete the switching of the light cycle and the initiation of gel feeding, so that the breeding regulation actions are consistent with the actual growth state of the larvae.

[0019] Preferably, the near-infrared band is 850 to 950 nm, and the preset threshold range is when the reflection intensity decreases by 15% to 25% compared to the initial value.

[0020] By adopting the above technical solution, the selected near-infrared band can accurately respond to changes in the tissue characteristics of the black soldier fly larvae's epidermis. The set threshold for the decrease in reflectance intensity corresponds to the transition point of the larvae from the growth increment stage to the protein enrichment stage, ensuring the accuracy of the timing of aquaculture control actions.

[0021] Preferably, in step S2, the composite microbial agent in the high-protein induced slow-release gel continuously metabolizes during the breeding process, adsorbing and degrading the ammonia produced by the larvae; after the breeding is completed, the breeding residue and gel residue are collected, mixed and fermented to produce organic fertilizer.

[0022] By adopting the above technical solution, the compound microbial agent in the high protein-induced slow-release gel can continuously metabolize and adsorb and decompose ammonia in the breeding environment, improve the gas composition of the local breeding environment, and the breeding residue and gel residue can be mixed and fermented to convert the breeding by-products into organic fertilizer, realizing the closed-loop resource utilization of waste.

[0023] Preferably, in step S4, the drying process is carried out by vacuum freeze drying, the drying temperature is -20 to -10°C, the drying time is 6 to 12 hours, and after drying, the product is passed through a 60 to 80 mesh sieve to obtain black soldier fly protein powder.

[0024] By adopting the above technical solution, vacuum freeze drying dries protein powder in a low-temperature environment, avoiding denaturation of protein powder due to heat, maintaining the physicochemical properties of protein components, and the sieving step after drying can remove impurity particles from the protein powder, improving the uniformity of the finished product. Simultaneous collection and separation of oils can achieve full recycling of resources.

[0025] In summary, this application has the following beneficial effects: 1. Because this application adopts a light-controlled segmented breeding method combined with high-protein induced slow-release gel feeding, long light is used in the early stage of breeding to promote the growth and increase of larvae, and short light is switched in the later stage of breeding and gel is fed to induce larvae to accumulate protein in a targeted manner. The gel uses single-cell protein prepared by fermentation of catering waste liquid as raw material, and converts catering waste liquid into nutrient raw materials. Therefore, the effect of targeted accumulation of black soldier fly larvae protein and resource utilization of catering waste liquid are achieved simultaneously, thereby significantly increasing the protein content and total amino acid content in the protein powder.

[0026] 2. In this application, the preferred method is to use a spectral sensor to monitor the near-infrared band reflection intensity of the larvae's epidermis in real time for automatic regulation. Based on the changes in reflection intensity, the light cycle switching and gel feeding initiation are automatically completed, replacing the fixed-time regulation mode. Therefore, the effect of accurately matching the breeding process regulation nodes with the actual growth status of the larvae is achieved.

[0027] 3. The method of this application completes the cell wall disruption and oil separation of black soldier fly larvae through low-temperature and low-pressure flash evaporation. The cell wall disruption operation is performed under the set low-temperature and low-pressure conditions to avoid the influence of high-temperature conditions on the protein structure of the insect body, thus achieving the effect of maintaining the integrity of the protein powder components.

[0028] 4. In this application, a high-protein induced slow-release gel is prepared by using a domesticated compound microbial agent. The agent continuously adsorbs and degrades the ammonia produced by the larvae during the breeding process. The breeding residue is fermented to make organic fertilizer, thus achieving the effects of optimizing the breeding environment and utilizing the resources of breeding by-products.

[0029] 5. The method of this application involves post-processing the protein powder by vacuum freeze-drying, processing the protein powder by low-temperature drying and sieving to obtain the finished product, and collecting the separated oil at the same time. Therefore, it achieves the effect of ensuring the stability of the physicochemical properties of the protein powder and resource recycling. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method for extracting protein powder by raising black soldier flies using food waste solids, as provided in this application. Detailed Implementation

[0031] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0032] Technical Concept: In existing methods for raising black soldier fly larvae using food waste, the liquid portion produced after solid-liquid separation typically lacks effective resource utilization pathways and is often treated as wastewater, increasing disposal costs. Simultaneously, the larval rearing process relies primarily on their natural growth characteristics, making it difficult to actively regulate metabolism to increase protein content. This results in room for improvement in the protein powder's protein content and total amino acid content. The reason for these problems is that current technologies have not yet been able to convert food waste liquid into nutrient raw materials that can directly participate in the metabolic regulation of larvae, and also lack effective means to intervene in the larval metabolic direction through environmental signals.

[0033] This application addresses the aforementioned problems by preparing a single-cell protein culture medium from liquid food waste through microbial fermentation, which is then cross-linked with plant-derived additives to form a high-protein-inducing slow-release gel. In the early stages of rearing, long-day light is used to promote rapid larval growth, while in the later stages, short-day light is applied and the larvae are fed the gel, utilizing light signals to induce larval protein accumulation. By converting waste liquid into a gel nutrient source and synergistically coordinating with photoperiod regulation, the resource utilization of liquid food waste and the targeted accumulation of larval protein are simultaneously achieved, thereby significantly increasing the protein content and total amino acid content in the protein powder.

[0034] Example 1: This example provides a method for extracting protein powder by raising black soldier flies using food waste solids, including the following steps: S1. Pre-treatment: The collected food waste is sequentially processed through impurity removal, crushing, and solid-liquid separation to obtain food waste solids and food waste liquids respectively; The process involves a combination of manual screening and vibrating screens to remove foreign objects such as plastics, metals, and bones from food waste. A high-speed crusher is used for crushing, controlling the particle size of the crushed material to 2-3 mm to facilitate subsequent solid-liquid separation. Solid-liquid separation is performed using a horizontal screw centrifuge at a speed of 2500 r / min for 15 minutes, ensuring the moisture content of the solid waste is controlled at 65-70%. The liquid portion of the food waste is collected separately for later use.

[0035] S2. Light-controlled segmented culture: Black soldier fly larvae are inoculated into food waste solids for culture, and the light conditions are switched according to the culture stage. In the early stage of culture, the first light cycle is used to promote the growth of larvae, and in the later stage of culture, the second light cycle is switched and high-protein induction slow-release gel is fed to induce larvae to concentrate protein. The first light cycle consists of 18 hours of light and 6 hours of darkness per day, supplemented by a 455nm blue light source with a power of 30W and an illumination distance of 50cm to ensure uniform light coverage of the breeding area; the second light cycle consists of 6 hours of light and 18 hours of darkness per day, without the addition of an additional blue light source. The early stage of breeding is from day 1 to day 7 after inoculation, and the later stage of breeding is from day 8 to day 12 after inoculation. At the beginning of the later stage of breeding, stop feeding solid food waste and switch to feeding high protein induction slow-release gel. The feeding amount is 10g per thousand larvae per day, divided into 2 feedings per day with an interval of 12 hours to ensure that the larvae feed evenly. The high-protein induced sustained-release gel was prepared by the following method: the liquid food waste obtained in S1 was subjected to microbial fermentation to convert it into a single-cell protein culture medium. The microbial fermentation used a domesticated compound microbial agent containing yeast and lactic acid bacteria. Domestication was achieved by continuous subculturing for 5 generations in a culture medium containing food waste liquid, with the subculturing temperature maintained at the same temperature as the fermentation temperature. Then, the single-cell protein culture medium was mixed with plant-derived excipients at a mass ratio of 1:0.55. The plant-derived excipients were selected as low-grade flour. After mixing, 0.3% sodium alginate was added as a cross-linking agent. Three-dimensional network gel particles were formed through a cross-linking reaction at 35℃. The particle size of the gel particles was 3.5 mm. The microbial fermentation temperature was 32℃, the fermentation time was 36h, and the mixture was stirred every 8h at a speed of 100r / min to ensure uniform fermentation. After fermentation, the mixture was filtered through an 80-mesh sieve to remove impurities and obtain a pure single-cell protein culture medium. A spectral sensor is integrated into the breeding device. The spectral sensor is installed on the top of the breeding device and collects data every 30 minutes to monitor the reflectance intensity of the black soldier fly larvae's epidermis to the near-infrared spectrum in real time. When the reflectance intensity drops to the preset threshold range, the control system automatically switches the light cycle from the first light cycle to the second light cycle and simultaneously starts the automatic feeding device for the high-protein induced slow-release gel. The near-infrared band is 900nm, and the preset threshold range is a 20% decrease in reflectance compared to the initial value; the initial reflectance is the average reflectance collected on the first day of the early breeding period, which is used as the benchmark value and entered into the control system. The compound microbial agent in the high-protein induced slow-release gel continuously metabolizes during the breeding process, adsorbing and degrading the ammonia produced by the larvae, with a degradation efficiency maintained above 85%, thus avoiding the accumulation of ammonia that affects larval growth. After the breeding is completed, the breeding residue and gel residue are collected, mixed, and 5% composting agent is added. The mixture is fermented for 7 days at 30℃ and 70% humidity to produce organic fertilizer. During the fermentation process, the pile is turned regularly to ensure full fermentation.

[0036] S3. Low-temperature extraction: The black soldier fly larvae raised in step S2 are subjected to flash evaporation under low temperature and low pressure conditions to induce cell wall rupture and release oil. Protein powder is obtained after solid-liquid separation. The low-temperature and low-pressure flash evaporation process was carried out using a vacuum flash evaporator at a pressure of 0.03 MPa, a temperature of 40°C, and a processing time of 20 min. Nitrogen gas was continuously introduced during the flash evaporation process at a flow rate of 0.5 L / min to prevent the oxidation of insect protein. The solid-liquid separation was carried out using a high-speed centrifuge at a speed of 3500 r / min and a separation time of 12 min. After separation, the upper layer was oil and the lower layer was protein precipitate, which yielded crude protein powder. The oil and crude protein powder were collected separately.

[0037] S4. Post-processing: The protein powder obtained in step S3 is dried, and the oil separated in step S3 is collected at the same time. The drying process was carried out using a vacuum freeze dryer at a temperature of -15℃ for 9 hours, with the vacuum level maintained at 10Pa during the drying process. After drying, the product was sieved through a 70-mesh sieve to remove any unbroken insect residue, resulting in a uniform and fine black soldier fly protein powder. The collected oil was then filtered and stored in a sealed container for subsequent industrial processing or biodiesel production.

[0038] Example 2: This example provides a method for extracting protein powder by raising black soldier flies using food waste solids, including the following steps: S1. Pre-treatment: The collected food waste is sequentially processed through impurity removal, crushing, and solid-liquid separation to obtain food waste solids and food waste liquids respectively; The process involves a combination of manual screening and vibrating screens to remove foreign objects such as plastics, metals, and bones from food waste. A high-speed crusher is used for crushing, controlling the particle size of the crushed material to 1-2 mm to facilitate subsequent solid-liquid separation. Solid-liquid separation is performed using a horizontal screw centrifuge at a speed of 2000 r / min for 10 minutes, ensuring the moisture content of the solid waste is controlled at 65-70%. The liquid portion of the food waste is collected separately for later use.

[0039] S2. Light-controlled segmented culture: Black soldier fly larvae are inoculated into food waste solids for culture, and the light conditions are switched according to the culture stage. In the early stage of culture, the first light cycle is used to promote the growth of larvae, and in the later stage of culture, the second light cycle is switched and high-protein induction slow-release gel is fed to induce larvae to concentrate protein. The first lighting cycle consists of 16 hours of light and 4 hours of darkness per day, supplemented by a 440nm blue light source with a power of 20W and an illumination distance of 40cm to ensure uniform light coverage of the breeding area; the second lighting cycle consists of 4 hours of light and 16 hours of darkness per day, without the addition of an additional blue light source. The early stage of breeding is from day 1 to day 7 after inoculation, and the later stage of breeding is from day 8 to day 12 after inoculation. At the beginning of the later stage of breeding, stop feeding solid food waste and switch to feeding high protein induction slow-release gel. The feeding amount is 5g per thousand larvae per day, divided into 2 feedings per day with an interval of 12 hours to ensure that the larvae feed evenly. The high-protein induced sustained-release gel was prepared by the following method: the liquid food waste obtained in S1 was subjected to microbial fermentation to convert it into a single-cell protein culture medium. The microbial fermentation used a domesticated compound microbial agent containing yeast and lactic acid bacteria. Domestication was achieved by continuous subculturing for 3 generations in a culture medium containing food waste liquid, with the subculturing temperature maintained at the same temperature as the fermentation temperature. Then, the single-cell protein culture medium was mixed with plant-derived excipients at a mass ratio of 1:0.3. The plant-derived excipient was cassava starch. After mixing, 0.1% sodium alginate was added as a cross-linking agent. Three-dimensional network gel particles were formed through a cross-linking reaction at 30℃, with a particle size of 2 mm. The microbial fermentation temperature was 28℃, the fermentation time was 24h, and the mixture was stirred every 8h at a speed of 80r / min to ensure uniform fermentation. After fermentation, the mixture was filtered through an 80-mesh sieve to remove impurities and obtain a pure single-cell protein culture medium. A spectral sensor is integrated into the breeding device. The spectral sensor is installed on the top of the breeding device and collects data every 30 minutes to monitor the reflectance intensity of the black soldier fly larvae's epidermis to the near-infrared spectrum in real time. When the reflectance intensity drops to the preset threshold range, the control system automatically switches the light cycle from the first light cycle to the second light cycle and simultaneously starts the automatic feeding device for the high-protein induced slow-release gel. The near-infrared band is 850nm, and the preset threshold range is a 15% decrease in reflectance compared to the initial value; the initial reflectance is the average reflectance collected on the first day of the early breeding period, which is used as the benchmark value and entered into the control system. The compound microbial agent in the high-protein induced slow-release gel continuously metabolizes during the breeding process, adsorbing and degrading the ammonia produced by the larvae, with a degradation efficiency maintained above 75%, thus avoiding the accumulation of ammonia that affects larval growth. After the breeding is completed, the breeding residue and gel residue are collected, mixed, and 3% composting agent is added. The mixture is fermented for 5 days at 28℃ and 65% humidity to produce organic fertilizer. During the fermentation process, the pile is turned regularly to ensure full fermentation.

[0040] S3. Low-temperature extraction: The black soldier fly larvae raised in step S2 are subjected to flash evaporation under low temperature and low pressure conditions to induce cell wall rupture and release oil. Protein powder is obtained after solid-liquid separation. The low-temperature and low-pressure flash evaporation process was carried out using a vacuum flash evaporator at a pressure of 0.01 MPa, a temperature of 35°C, and a processing time of 10 min. Nitrogen gas was continuously introduced during the flash evaporation process at a flow rate of 0.3 L / min to prevent the oxidation of insect protein. The solid-liquid separation was carried out using a high-speed centrifuge at a speed of 3000 r / min and a separation time of 10 min. After separation, the upper layer was oil and the lower layer was protein precipitate, which yielded crude protein powder. The oil and crude protein powder were collected separately.

[0041] S4. Post-processing: The protein powder obtained in step S3 is dried, and the oil separated in step S3 is collected at the same time. The drying process was carried out using a vacuum freeze dryer at a temperature of -20℃ for 6 hours, with the vacuum level maintained at 8Pa during the drying process. After drying, the product was sieved through a 60-mesh sieve to remove any unbroken insect residue, resulting in a uniform and fine black soldier fly protein powder. The collected oil was then filtered and stored in a sealed container for subsequent industrial processing or biodiesel production.

[0042] Example 3: This example provides a method for extracting protein powder by raising black soldier flies using food waste solids, including the following steps: S1. Pre-treatment: The collected food waste is sequentially processed through impurity removal, crushing, and solid-liquid separation to obtain food waste solids and food waste liquids respectively; The process involves a combination of manual screening and vibrating screens to remove foreign objects such as plastics, metals, and bones from food waste. A high-speed crusher is used for crushing, controlling the particle size of the crushed material to 3-4 mm to facilitate subsequent solid-liquid separation. Solid-liquid separation is performed using a horizontal screw centrifuge at a speed of 3000 r / min for 20 minutes, ensuring the moisture content of the solid waste is controlled at 65-70%. The liquid portion of the food waste is collected separately for later use.

[0043] S2. Light-controlled segmented culture: Black soldier fly larvae are inoculated into food waste solids for culture, and the light conditions are switched according to the culture stage. In the early stage of culture, the first light cycle is used to promote the growth of larvae, and in the later stage of culture, the second light cycle is switched and high-protein induction slow-release gel is fed to induce larvae to concentrate protein. The first light cycle consists of 20 hours of light and 8 hours of darkness per day, supplemented by a 470nm blue light source with a power of 40W and an illumination distance of 60cm to ensure uniform light coverage of the breeding area; the second light cycle consists of 8 hours of light and 16 hours of darkness per day, without the addition of an additional blue light source. The early stage of breeding is from day 1 to day 7 after inoculation, and the later stage of breeding is from day 8 to day 12 after inoculation. At the beginning of the later stage of breeding, stop feeding solid food waste and switch to feeding high protein induction slow-release gel. The feeding amount is 15g per thousand larvae per day, divided into 3 feedings per day with an interval of 8 hours to ensure that the larvae feed evenly. The high-protein induced sustained-release gel was prepared by the following method: the liquid food waste obtained in S1 was subjected to microbial fermentation to convert it into a single-cell protein culture medium. The microbial fermentation used a domesticated compound microbial agent containing yeast and lactic acid bacteria. Domestication was achieved by continuous subculturing for 7 generations in a culture medium containing food waste liquid, with the subculturing temperature maintained at the same temperature as the fermentation temperature. Then, the single-cell protein culture medium was mixed with plant-derived excipients at a mass ratio of 1:0.8. Potato starch was selected as the plant-derived excipient. After mixing, 0.5% sodium alginate was added as a cross-linking agent. Three-dimensional network gel particles were formed through a cross-linking reaction at 40℃, with a particle size of 5 mm. The microbial fermentation temperature was 35℃, the fermentation time was 48h, and the mixture was stirred every 6h at a speed of 120r / min to ensure uniform fermentation. After fermentation, the mixture was filtered through a 100-mesh sieve to remove impurities and obtain a pure single-cell protein culture medium. A spectral sensor is integrated into the breeding device. The spectral sensor is installed on the top of the breeding device and collects data every 20 minutes to monitor the reflectance intensity of the black soldier fly larvae's epidermis to the near-infrared spectrum in real time. When the reflectance intensity drops to the preset threshold range, the control system automatically switches the light cycle from the first light cycle to the second light cycle and simultaneously starts the automatic feeding device for the high-protein induced slow-release gel. The near-infrared band is 950nm, and the preset threshold range is a 25% decrease in reflectance compared to the initial value; the initial reflectance is the average reflectance collected on the first day of the early breeding period, which is used as the baseline value and entered into the control system. The compound microbial agent in the high-protein induced slow-release gel continuously metabolizes during the breeding process, adsorbing and degrading the ammonia produced by the larvae, with a degradation efficiency maintained above 90%, thus avoiding the accumulation of ammonia that affects larval growth. After the breeding is completed, the breeding residue and gel residue are collected, mixed, and 8% composting agent is added. The mixture is fermented for 10 days at 32℃ and 75% humidity to produce organic fertilizer. During the fermentation process, the pile is turned regularly to ensure full fermentation.

[0044] S3. Low-temperature extraction: The black soldier fly larvae raised in step S2 are subjected to flash evaporation under low temperature and low pressure conditions to induce cell wall rupture and release oil. Protein powder is obtained after solid-liquid separation. The low-temperature and low-pressure flash evaporation process was carried out using a vacuum flash evaporator at a pressure of 0.05 MPa, a temperature of 45°C, and a processing time of 30 min. Nitrogen gas was continuously introduced during the flash evaporation process at a flow rate of 0.8 L / min to prevent the oxidation of insect protein. The solid-liquid separation was carried out using a high-speed centrifuge at a speed of 4000 r / min and a separation time of 15 min. After separation, the upper layer was oil and the lower layer was protein precipitate, which yielded crude protein powder. The oil and crude protein powder were collected separately.

[0045] S4. Post-processing: The protein powder obtained in step S3 is dried, and the oil separated in step S3 is collected at the same time. The drying process was carried out using a vacuum freeze dryer at a temperature of -10℃ for 12 hours, with the vacuum level maintained at 15Pa during the drying process. After drying, the product was sieved through an 80-mesh sieve to remove any unbroken insect residue, resulting in a uniform and fine black soldier fly protein powder. The collected oil was then filtered and stored in a sealed container for subsequent industrial processing or biodiesel production.

[0046] Comparative Example 1: The only difference between this comparative example and Example 1 is that the high-protein induced sustained-release gel fed in step S2 was prepared by the following method: directly using purchased yeast protein powder and plant-derived excipients mixed at a mass ratio of 1:0.55, without going through the liquid microbial fermentation step of catering waste; the remaining operation steps and parameters are exactly the same as those in Example 1.

[0047] Comparative Example 2: The only difference between this comparative example and Example 1 is that in step S2, the entire breeding process adopts the first light cycle with a daily light duration of 18 hours and a dark duration of 6 hours, without switching to the second light cycle; the other operating steps and parameters are exactly the same as in Example 1.

[0048] Comparative Example 3: The only difference between this comparative example and Example 1 is that in step S3, the temperature of the low-temperature and low-pressure flash evaporation treatment is 75°C; the other operating steps and parameters are exactly the same as in Example 1.

[0049] Comparative Example 4: The only difference between this comparative example and Example 1 is that: in step S2, no spectral sensor is set up for monitoring, and the switching of light cycle and feeding of high protein-induced sustained-release gel are carried out at a fixed time, that is, at 0:00 on the 8th day after inoculation; the other operation steps and parameters are exactly the same as those in Example 1.

[0050] Comparative Example 5: The only difference between this comparative example and Example 1 is that the preparation method of Example 1 is not used. Instead, commercially available common black soldier fly protein powder is directly selected as the control. This protein powder is prepared by conventional breeding methods, and the raw material is common black soldier fly larvae. It has not undergone special light regulation and gel feeding treatment. The other detection and treatment methods used for comparison are exactly the same as those in Example 1.

[0051] Test Item 1: Determination of the purity of black soldier fly protein powder. The test was conducted in accordance with GB / T5009.5-2016 "Determination of Protein in Food". The test materials included the finished black soldier fly protein powder prepared in Examples 1, 2 and 3, and the black soldier fly protein powder samples of Comparative Examples 1, 2, 3, 4 and 5. The test instruments used included a Kjeldahl nitrogen analyzer, electronic balance, digestion furnace, distillation apparatus, burette, etc., and all instruments were calibrated and qualified. Before the experiment, all samples were dried to constant weight in a 105℃ oven to remove moisture. After drying, the samples were pulverized and passed through a 100-mesh sieve. 0.2g of the sample was accurately weighed and placed in a digestion tube. 3g of catalyst and 10mL of concentrated sulfuric acid were added. The digestion tube was placed in a digestion furnace, and the digestion temperature was set to 420℃. Digestion continued until the sample turned a transparent blue-green color without any precipitate. The sample was then removed and cooled. The cooled digest was transferred to a distillation apparatus, and 20mL of sodium hydroxide solution was added for distillation. The distilled ammonia was absorbed with boric acid solution, and then titrated with a standard hydrochloric acid solution until the solution turned grayish-red and did not fade within 30 seconds, which was the titration endpoint. A blank test was performed to account for reagent errors. Each sample was measured three times. The titration volumes for Examples 1, 2, 3, and Comparative Examples 1 to 5 were recorded. The protein purity of each sample was calculated using the Kjeldahl nitrogen determination formula, and the average of the three measurements was taken as the final purity data.

[0052] Test Item 2: Determination of total amino acid content in black soldier fly protein powder. The test was conducted in accordance with GB / T5009.124-2016 "Determination of Amino Acids in Food". The test materials were the same as those in Test Item 1, namely the finished black soldier fly protein powder products prepared in Examples 1, 2, and 3, and the black soldier fly protein powder samples of Comparative Examples 1 to 5. The test instruments used included a high performance liquid chromatograph, an automatic amino acid analyzer, a vacuum drying oven, hydrolysis tubes, and a centrifuge. Accurately weigh 0.1 g of the dried and pulverized sample and place it in a hydrolysis tube. Add 10 mL of 6 mol / L hydrochloric acid solution, purge with nitrogen to remove air, and seal the hydrolysis tube. Place the hydrolysis tube in a 110℃ constant temperature drying oven for 22 h for hydrolysis. After hydrolysis, remove and cool the sample. Filter the hydrolysate into a 50 mL volumetric flask. Wash the hydrolysis tube and filter paper several times with deionized water. Add the washings to the volumetric flask and dilute to the mark. Shake well and take 10 mL of the hydrolysate into a centrifuge tube. Add an equal volume of 0.1 mol / L sodium hydroxide solution to neutralize. Centrifuge to remove the precipitate and take the supernatant. Filter the supernatant through a 0.22 μm filter membrane for later use. The processed sample was injected into the automated amino acid analyzer. The detection conditions were set as follows: column temperature 50℃, mobile phase citrate buffer-acetonitrile gradient elution, detection wavelength 254nm, flow rate 1mL / min. At the same time, a standard curve was plotted using amino acid standards. The content of 17 essential and non-essential amino acids in each sample was calculated based on the standard curve. The total amino acid content was obtained by summing the results. Each sample was measured three times, and the average value was taken as the final total amino acid content data.

[0053] Test Item 3: Determination of ammonia degradation efficiency during aquaculture. The test was conducted according to HJ533-2009 "Determination of Ammonia in Ambient Air and Exhaust Gas - Nessler's Reagent Spectrophotometric Method". The test subjects were the aquaculture systems of Examples 1, 2, and 3, and Comparative Examples 1, 2, and 4. Comparative Examples 3 and 5 did not involve aquaculture and were not tested in this item. The test instruments included an atmospheric sampler, a UV-Vis spectrophotometer, volumetric flasks, pipettes, and cuvettes. The test reagents included Nessler's reagent, potassium sodium tartrate solution, and ammonia standard stock solution. At the start of the experiment, one sampling point was set at the middle and one at the top of each aquaculture device, 10 cm above the surface of the aquaculture material. Gas samples were collected from each device using an atmospheric sampler on the 3rd day of the early aquaculture stage and the 10th day of the late aquaculture stage. The sampling flow rate was 0.5 L / min, and the sampling time was 20 min. The collected gas samples were passed into an absorption tube containing an absorption liquid. After absorption, potassium sodium tartrate solution was added to eliminate interference, followed by Nessler's reagent and shaking. After standing for 10 min, the absorbance was measured at a wavelength of 420 nm. Simultaneously, a series of standard solutions were prepared using ammonia standard stock solution, and a standard curve was plotted. The ammonia concentration of each sample was calculated based on the standard curve. The ammonia degradation efficiency was calculated for each aquaculture system in the early and late stages of aquaculture. Ammonia degradation efficiency = (ammonia concentration in the early stage of aquaculture - ammonia concentration in the late stage of aquaculture) / ammonia concentration in the early stage of aquaculture × 100%. Each aquaculture system was measured three times, and the average value was taken as the final degradation efficiency data.

[0054] Table 1: Key Performance Test Data of Examples 1-3 and Comparative Examples 1-5

[0055] Note: In the table above, " / " indicates that there is no test data for this item.

[0056] Based on Examples 1-3 and Comparative Example 1, and in conjunction with Table 1, it can be seen that using liquid food waste to prepare single-cell protein culture medium through microbial fermentation as the protein source for high-protein induced slow-release gel is directly related to the metabolic effects of the compound microbial agents in the gel and the protein enrichment process after larvae ingestion. This raw material preparation method will affect the nutrient supply efficiency during larval growth and the gas component regulation effect of the breeding system, thereby affecting the protein synthesis and accumulation process in larvae.

[0057] Based on Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, it can be seen that performing the light cycle switching operation during the rearing stage will affect the physiological metabolic process of larvae by changing the light environment conditions for larval growth. The segmented setting of the light cycle matches the protein-directed enrichment process at different growth stages of larvae, and the regulation of the light environment directly affects the synthesis and distribution of proteins in the larvae.

[0058] Based on Examples 1-3 and Comparative Example 3, and in conjunction with Table 1, it can be seen that the temperature control conditions of low-temperature and low-pressure flash evaporation treatment affect the state of the cell wall disruption process of the insect body and the structural stability of the insect body protein. The temperature parameter settings of the extraction process are directly related to the degree of protein component retention, and changes in temperature conditions will alter the integrity of components during the protein extraction process.

[0059] As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, real-time monitoring of the near-infrared reflectance intensity of the larval epidermis by a spectral sensor and execution of automatic control can improve the control accuracy of light cycle switching and gel feeding nodes. This monitoring and control method is adapted to the real-time changes in the larval growth state. Precise control operation will affect the timing of nutrient supply and environmental switching adaptability during the larval growth process.

[0060] As can be seen from Examples 1-3 and Comparative Example 5 and Table 1, the combined technical means of pretreatment, light-controlled segmented culture, low-temperature extraction, post-treatment and environmental control of the culture system in this application are significantly different from the technical path of conventional culture and extraction processes. The synergistic cooperation of the technical means in each link of the overall technical solution will affect the overall execution effect of the larval culture process and the protein extraction process.

[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for extracting protein powder by raising black soldier flies using food waste solids, characterized in that, Includes the following steps: S1. Pre-treatment: The collected food waste is sequentially treated by impurity removal, crushing and solid-liquid separation to obtain food waste solids and food waste liquids respectively; S2. Light-controlled segmented culture: Black soldier fly larvae are inoculated into the food waste solids for culture, and the light conditions are switched according to the culture stage; in the early stage of culture, the first light cycle is used to promote the growth of larvae, and in the later stage of culture, the second light cycle is switched and high protein induction slow-release gel is fed to induce larvae to concentrate protein. S3. Low-temperature extraction: The black soldier fly larvae raised in step S2 are subjected to flash evaporation under low temperature and low pressure conditions to induce cell wall rupture and release oil. Protein powder is obtained after solid-liquid separation. S4. Post-processing: The protein powder obtained in step S3 is dried, and the oil separated in step S3 is collected.

2. The method for extracting protein powder from black soldier flies using food waste solids according to claim 1, characterized in that: In step S2, the first light cycle consists of 16 to 20 hours of light and 4 to 8 hours of darkness per day, supplemented by blue light source with a wavelength of 440 to 470 nm; the second light cycle consists of 4 to 8 hours of light and 16 to 20 hours of darkness per day.

3. The method for extracting protein powder from black soldier flies using food waste solids according to claim 1, characterized in that: In step S2, the early stage of rearing is from day 1 to day 7 after inoculation, and the late stage of rearing is from day 8 to day 12 after inoculation. At the beginning of the late stage of rearing, stop feeding solid food waste and switch to feeding high-protein induction slow-release gel, with a feeding amount of 5 to 15g per thousand larvae per day.

4. The method for extracting protein powder from black soldier flies using food waste solids according to claim 1, characterized in that: In step S2, the high-protein induced sustained-release gel is prepared by the following method: the liquid food waste obtained in step S1 is subjected to microbial fermentation to convert it into a single-cell protein culture medium. The microbial fermentation uses a domesticated compound microbial agent containing yeast and lactic acid bacteria. The domestication is obtained by continuous subculturing in a culture medium containing the liquid food waste. Then, the single-cell protein culture medium is mixed with plant-derived excipients at a mass ratio of 1:0.3 to 1:0.8, and three-dimensional network gel particles are formed through a cross-linking reaction. The particle size of the gel particles is 2 to 5 mm.

5. The method for extracting protein powder from black soldier flies using food waste solids according to claim 4, characterized in that: The plant-based auxiliary material is at least one of substandard flour, cassava starch, or potato starch; the microbial fermentation temperature is 28 to 35°C, and the fermentation time is 24 to 48 hours.

6. The method for extracting protein powder from black soldier flies using food waste solids according to claim 1, characterized in that: In step S3, the pressure of the low-temperature and low-pressure flash evaporation treatment is 0.01 to 0.05 MPa, the temperature is 35 to 45°C, and the treatment time is 10 to 30 min.

7. The method for extracting protein powder from black soldier flies using food waste solids according to claim 1, characterized in that: In step S2, a spectral sensor is integrated into the breeding device to monitor the reflectance intensity of the black soldier fly larvae's epidermis to the near-infrared spectrum in real time. When the reflectance intensity drops to a preset threshold range, the control system automatically switches the light cycle from the first light cycle to the second light cycle and simultaneously starts feeding the high-protein induced slow-release gel.

8. The method for extracting protein powder from black soldier flies using food waste solids according to claim 7, characterized in that: The near-infrared band is 850 to 950 nm, and the preset threshold range is when the reflection intensity decreases by 15% to 25% compared to the initial value.

9. The method for extracting protein powder from black soldier flies using food waste solids according to claim 4, characterized in that: In step S2, the composite microbial agent in the high-protein induced slow-release gel continuously metabolizes during the breeding process, adsorbing and degrading the ammonia produced by the larvae; after the breeding is completed, the breeding residue and gel residue are collected, mixed and fermented to produce organic fertilizer.

10. The method for extracting protein powder from black soldier flies using food waste solids according to claim 1, characterized in that: In step S4, the drying process is carried out by vacuum freeze drying at a temperature of -20 to -10°C for 6 to 12 hours. After drying, the product is passed through a 60 to 80 mesh sieve to obtain black soldier fly protein powder.

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