A green high-value processing method of pomelo waste based on self-made high-purity ethanol

Abstract

This invention discloses a green, high-value-added processing method for pomelo waste based on self-made high-purity ethanol, belonging to the field of agricultural product deep processing and green chemical technology. The method uses pomelo waste as raw material, preparing an ethanol fermentation broth through cellulase-pectinase complex enzymatic hydrolysis and brewer's yeast fermentation, followed by high-purity ethanol purification by distillation. Using self-made ethanol as solvent, pomelo peel undergoes ultrasonic-microwave synergistic pretreatment and two-stage gradient reflux extraction. The extract is then purified by ceramic membrane microfiltration pre-concentration, low-temperature vacuum concentration, subcritical extraction, and molecular distillation, co-producing three high-value-added products: pomelo peel essential oil, high-purity naringin, and total flavonoids. The waste heat from the distillation column is used to heat the extraction and concentration systems, the ethanol solvent is recycled, and the extraction residue is used to prepare organic fertilizer. This invention achieves the reuse of pomelo waste, reduces solvent costs by 70%, reduces total energy consumption by 20%–30%, achieves a naringin extraction rate of ≥85%, and utilizes all components with zero waste, making it suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the fields of deep processing of agricultural products and green chemical technology, and in particular to a green and high-value processing method for grapefruit waste based on self-made high-purity ethanol. Background Technology

[0002] my country is a major producer of pomelos, with Meizhou, Guangdong province alone producing approximately 1.15 million tons of pomelos annually, generating nearly 500,000 tons of waste from pomelo peels. Currently, pomelo peel waste is mainly disposed of through landfill or incineration, which not only causes water and soil pollution and greenhouse gas emissions but also wastes the abundant high-value-added active ingredients in pomelo peels, such as naringin, flavonoids, and essential oils. The deep processing rate of pomelos is less than 5%, resulting in limited income for fruit farmers and low added value in the industrial chain.

[0003] In existing technologies, the extraction of active ingredients from grapefruit peel mainly employs ethanol solvent extraction. For example, using 40%–70% ethanol as a solvent and extracting naringin and flavonoids from grapefruit peel at 30–70℃ is a common extraction method under current technology. However, traditional extraction methods have several shortcomings: First, ethanol solvent is heavily reliant on external purchases, resulting in high costs and transportation and storage risks. Although some companies distill distilled dilute ethanol themselves, the raw material is still purchased industrial ethanol, failing to achieve true solvent self-sufficiency. Simultaneously, existing processes are mostly single or segmented extractions, lacking a complete integrated design from solvent preparation, raw material pretreatment, extraction and separation to solvent recovery, leading to high energy consumption and low efficiency. Moreover, conventional single-concentration ethanol extraction is insufficient to effectively separate naringin and flavonoids, resulting in limited product purity and a heavy burden on subsequent purification. Furthermore, the residue after extraction is usually discarded directly, causing secondary waste and environmental pressure.

[0004] Therefore, under the current technology, there is a need for a green processing method that uses grapefruit waste as raw material to prepare ethanol solvent and achieves high-value co-production and full-component utilization through multi-unit coupling process. Summary of the Invention

[0005] The purpose of this invention is to provide a green and high-value processing method for grapefruit waste based on self-made high-purity ethanol, so as to solve the problems of existing technologies such as dependence on purchased ethanol solvent, low process integration, poor extraction selectivity, and failure to fully utilize all components of waste.

[0006] This invention provides a green and high-value processing method for grapefruit waste based on self-made high-purity ethanol, comprising the following steps: Sp1: Bio-fermentation and High-Purity Ethanol Preparation: 15%–25% of the total mass of grapefruit waste was treated with a cellulase-pectinase complex enzymatic hydrolysis to release fermentation sugars. This was then inoculated with *Saccharomyces cerevisiae* and fermented at 30–35°C for 48–72 h to prepare a fermentation broth with an ethanol mass fraction of 8%–15%. The fermentation broth was then introduced into a distillation apparatus, and the reflux ratio was optimized using CSLAB chemical simulation software to control the refluxing ratio at 5.22, the reboiler temperature at 78–82°C, and the refluxing flow rate at 2.5–3.0 m³ / s. 3 / h, distillation and purification to ethanol mass fraction ≥85%, the whole process is digitally controlled by MES system; Sp2: Ultrasonic-microwave co-processing: The remaining pomelo waste is sorted, washed, and crushed to a particle size of 2-5 mm, and then subjected to ultrasonic-microwave co-processing. The ultrasonic frequency is 40 kHz and the power is 200-300 W, the microwave power is 200-400 W, and the processing time is 5-15 min. Sp3: Gradient ethanol reflux extraction: The ethanol prepared in step Sp1 was prepared into two concentration gradients for staged extraction; in the first stage, 30%–40% ethanol was mixed with crushed pomelo peel at a material-to-liquid ratio of 1:4–1:6, and refluxed at 40–50℃ for 30–60 min, and solid-liquid separation was performed to obtain extract I and pomelo peel residue I; in the second stage, 55%–70% ethanol was mixed with pomelo peel residue I at a material-to-liquid ratio of 1:4–1:6, and refluxed at 50–70℃ for 30–60 min, and solid-liquid separation was performed to obtain extract II and pomelo peel residue II; extract I and extract II were combined; Sp4: Thermal integrated refining and co-production: The residual heat from the top of the distillation column in step Sp1 is used to heat the extraction system in step Sp3 and the concentration system in step Sp4 via a heat exchanger; the combined extract is first pre-concentrated by microfiltration through a ceramic membrane with a pore size of 0.1-0.2 μm, and then concentrated under low temperature vacuum at 40-50℃ and a vacuum degree of 0.08-0.1 MPa. The concentrate is then separated from grapefruit peel essential oil by subcritical extraction, and then purified by molecular distillation to obtain high-purity naringin and total flavonoids; Sp5: Closed-loop recycling and residue utilization: Ethanol after extraction is recycled by distillation for the next batch of extraction; grapefruit peel residue II is fermented into organic fertilizer through aerobic composting.

[0007] Preferably, the enzymatic hydrolysis conditions in step Sp1 are as follows: the amount of cellulase is 0.5% to 1.0% of the grapefruit peel mass, the amount of pectinase is 0.3% to 0.8% of the grapefruit peel mass, the hydrolysis temperature is 45 to 55°C, the hydrolysis pH is 4.5 to 5.5, and the hydrolysis time is 2 to 4 hours.

[0008] Preferably, the distillation apparatus in step Sp1 uses a 316L stainless steel fixed tube sheet condenser, and the number of distillation column trays is ≥20.

[0009] Preferably, in step Sp3, the ethanol concentration in the first stage is 35%, the material-to-liquid ratio is 1:5, the extraction temperature is 45℃, and the extraction time is 45 min; the ethanol concentration in the second stage is 60%, the material-to-liquid ratio is 1:5, the extraction temperature is 60℃, and the extraction time is 45 min.

[0010] Preferably, in step Sp4, the surface flow rate of the ceramic membrane microfiltration is 2-4 m / s, the operating pressure is 0.15-0.25 MPa, and the concentration factor is 3-5 times.

[0011] Preferably, in step Sp4, the subcritical extraction uses 1,1,1,2-tetrafluoroethane as the subcritical solvent, the extraction temperature is 35–45°C, the extraction pressure is 0.8–1.2 MPa, and the extraction time is 20–40 min.

[0012] Preferably, in step Sp4, the evaporation temperature of molecular distillation is 60–80°C, the operating pressure is 0.001–0.01 Pa, the scraping speed is 200–300 rpm, and the condensation temperature is 5–15°C.

[0013] Preferably, the aerobic composting fermentation conditions in step Sp5 are as follows: grapefruit peel residue II and mushroom residue are mixed at a mass ratio of 3:1, the moisture content is adjusted to 55% to 65%, effective microbial flora is inoculated, and fermentation is carried out at 50 to 65°C for 10 to 15 days to obtain organic fertilizer.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: Firstly, in this invention, ethanol is prepared by bio-fermentation using pomelo waste as raw material, and then the self-made ethanol is used as the extraction solvent, thereby avoiding the cost and transportation risks of purchasing ethanol externally. This constitutes a circular economy based on pomelo raw materials, and the solvent cost is reduced by at least 70% compared to the traditional external ethanol purchase model. At the same time, the cell wall structure of pomelo peel is effectively destroyed through the synergistic effect of ultrasonic cavitation and microwave thermal effect, which can effectively increase the dissolution rate of active ingredients by 15% to 25%, which is a significant improvement in the dissolution rate of active ingredients compared to single crushing pretreatment.

[0015] Secondly, in this invention, low-concentration ethanol is used to preferentially extract naringin, while high-concentration ethanol is used to preferentially extract flavonoids and essential oils, thereby effectively improving the purity of the product. This results in a naringin extraction rate of no less than 88%, a flavonoid content of no less than 3.5%, and an essential oil purity of no less than 95%, which is far superior to single-concentration extraction methods.

[0016] Thirdly, in this invention, the waste heat from the distillation column is used to heat the extraction and concentration system, resulting in low total energy consumption. The ceramic membrane microfiltration pre-concentration reduces the evaporation load of subsequent vacuum concentration, decreases the loss of heat-sensitive components, and thus improves the retention rate of flavonoids. At the same time, the grapefruit peel waste undergoes three stages: fermentation to produce alcohol, extraction of active ingredients, and fertilizer production from residue, thereby achieving the utilization of all components. There is no solid waste discharge in the process, reducing environmental pressure. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the process flow of a green, high-value processing method for grapefruit waste based on self-made high-purity ethanol, according to the present invention.

[0019] Figure 2 This is a schematic diagram of the process for preparing high-purity ethanol by bio-fermentation and distillation according to the present invention.

[0020] Figure 3 This is a schematic diagram of the process for the combined production of gradient ethanol reflux extraction and thermal integrated purification according to the present invention. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Example 1: This embodiment provides a green and high-value processing method for grapefruit waste based on self-made high-purity ethanol, including the following steps: (1) Bio-fermentation and preparation of high-purity ethanol: 20% of the total mass of pomelo waste was subjected to combined enzymatic hydrolysis with cellulase (0.8% of the pomelo peel mass) and pectinase (0.5% of the pomelo peel mass) at 50℃ and pH 5.0 for 3 h to release fermentation sugars; brewer's yeast was inoculated and fermented at 33℃ for 60 h to prepare a fermentation broth with an ethanol mass fraction of 12%; the fermentation broth was introduced into a 316L stainless steel fixed tube sheet condenser distillation unit (24 trays), and the reflux ratio was controlled at 5.22, the bottom temperature at 80℃, and the reflux flow rate at 2.8 m³ / h using CSLAB chemical simulation software. 3 / h, the distillation and purification process is carried out to 88% ethanol by mass fraction, and the entire process is digitally controlled by the MES system; (2) Ultrasonic-microwave synergistic pretreatment: The remaining pomelo waste is sorted, washed and crushed to a particle size of 3 mm, and then subjected to ultrasonic-microwave synergistic treatment. The ultrasonic frequency is 40 kHz and the power is 250 W, the microwave power is 300 W, and the treatment time is 10 min. (3) Gradient ethanol reflux extraction: The 88% ethanol prepared in step (1) was diluted with water to prepare two concentration gradients; in the first stage, 35% ethanol was mixed with the crushed pomelo peel at a material-to-liquid ratio of 1:5, and refluxed at 45°C for 45 min, and solid-liquid separation was performed to obtain extract I and pomelo peel residue I; in the second stage, 60% ethanol was mixed with pomelo peel residue I at a material-to-liquid ratio of 1:5, and refluxed at 60°C for 45 min, and solid-liquid separation was performed to obtain extract II and pomelo peel residue II; extract I and extract II were combined. (4) Thermal integration and refining: The residual heat from the top of the distillation column in step (1) is used to heat the extraction and concentration systems in step (3) via a heat exchanger; the combined extract is first pre-concentrated by microfiltration through a ceramic membrane with a pore size of 0.15 μm (membrane flow rate 3 m / s, operating pressure 0.2 MPa, 4-fold concentration), and then concentrated at low temperature in vacuum at 45℃ and 0.09 MPa; the concentrate is extracted for 30 min at 40℃ and 1.0 MPa using 1,1,1,2-tetrafluoroethane as a subcritical solvent to separate grapefruit peel essential oil; the remaining liquid phase is purified by molecular distillation (evaporation temperature 70℃, operating pressure 0.005 Pa, scraper speed 250 rpm, condensation temperature 10℃) to obtain high-purity naringin and total flavonoids; (5) Closed-loop recycling and residue utilization: The ethanol after extraction is recycled by distillation and used for the next batch of extraction; the grapefruit peel residue II and mushroom residue are mixed at a mass ratio of 3:1, the moisture content is adjusted to 60%, effective microbial groups are inoculated, and fermented at 55℃ for 12 days to obtain organic fertilizer.

[0023] In this embodiment, the naringin extraction rate was 88.5%, the flavonoid content was 3.6%, the essential oil purity was 95.2%, the ethanol recovery rate was ≥96%, the total energy consumption was reduced by 27% compared with the conventional process, and the solvent cost was reduced by about 75%.

[0024] Example 2: This embodiment, based on Example 1, modifies the preparation conditions and proposes a new green and high-value processing method for grapefruit waste based on self-made high-purity ethanol, including the following steps: (1) Bio-fermentation and preparation of high-purity ethanol: 15% of the total mass of pomelo waste was subjected to combined enzymatic hydrolysis with cellulase (0.5% of the pomelo peel mass) and pectinase (0.3% of the pomelo peel mass) at 45℃ and pH 4.5 for 4 h; brewer's yeast was inoculated and fermented at 30℃ for 72 h to prepare a fermentation broth with 10% ethanol by mass; the fermentation broth was introduced into a 316L stainless steel fixed tube sheet condenser distillation unit (20 trays), and the reflux ratio was controlled at 5.22, the bottom temperature at 78℃, and the reflux flow rate at 2.5 m³ / h. 3 / h, the distillation and purification process is carried out to 86% ethanol by mass fraction, and the entire process is digitally controlled by the MES system; (2) Ultrasonic-microwave synergistic pretreatment: The remaining pomelo waste is sorted, washed and crushed to a particle size of 2 mm, and then subjected to ultrasonic-microwave synergistic treatment. The ultrasonic frequency is 40 kHz and the power is 200 W, the microwave power is 200 W, and the treatment time is 5 min. (3) Gradient ethanol reflux extraction: In the first stage, 30% ethanol was mixed with crushed pomelo peel at a material-to-liquid ratio of 1:4, and refluxed at 40℃ for 30 min. Solid-liquid separation was performed to obtain extract I and pomelo peel residue I. In the second stage, 55% ethanol was mixed with pomelo peel residue I at a material-to-liquid ratio of 1:4, and refluxed at 50℃ for 60 min. Solid-liquid separation was performed to obtain extract II and pomelo peel residue II. Extract I and extract II were combined. (4) Thermal integration and refining: The residual heat from the top of the distillation column is used for heating via a heat exchanger; the combined extract is pre-concentrated by microfiltration through a ceramic membrane with a pore size of 0.1 μm (membrane flow rate 2 m / s, operating pressure 0.15 MPa, concentration 3 times), and then concentrated at low temperature in a vacuum of 40℃ and 0.08 MPa; the concentrate is extracted with 1,1,1,2-tetrafluoroethane as a subcritical solvent at 35℃ and 0.8 MPa for 40 min to separate grapefruit peel essential oil; the remaining liquid phase is refined by molecular distillation (evaporation temperature 60℃, operating pressure 0.001 Pa, scraper speed 200 rpm, condensation temperature 5℃); (5) Closed-loop recycling and residue utilization: The extracted ethanol is recycled by distillation; the grapefruit peel residue II and mushroom residue are mixed at a mass ratio of 3:1, the moisture content is adjusted to 55%, and fermented at 50℃ for 15 days to obtain organic fertilizer.

[0025] In this embodiment, the naringin extraction rate was 85.2%, the flavonoid content was 3.2%, the essential oil purity was 93.1%, and the flavonoid retention rate was improved by about 8% compared with the conventional process.

[0026] Example 3 A green, high-value processing method for grapefruit waste based on self-made high-purity ethanol includes the following steps: (1) Bio-fermentation and preparation of high-purity ethanol: 25% of the total mass of pomelo waste was subjected to combined enzymatic hydrolysis with cellulase (1.0% of the pomelo peel mass) and pectinase (0.8% of the pomelo peel mass) at 55℃ and pH 5.5 for 2 h; inoculated with brewer's yeast and fermented at 35℃ for 48 h to prepare a fermentation broth with 15% ethanol by mass; the fermentation broth was introduced into a 316L stainless steel fixed tube sheet condenser distillation unit (28 trays), and the reflux ratio was controlled at 5.22, the bottom temperature at 82℃, and the reflux flow rate at 3.0 m³ / h. 3 / h, the distillation and purification process is carried out to 90% ethanol by mass fraction, and the entire process is digitally controlled by the MES system; (2) Ultrasonic-microwave synergistic pretreatment: The remaining pomelo waste is sorted, washed and crushed to a particle size of 5 mm, and then subjected to ultrasonic-microwave synergistic treatment. The ultrasonic frequency is 40 kHz and the power is 300 W, the microwave power is 400 W, and the treatment time is 15 min. (3) Gradient ethanol reflux extraction: In the first stage, 40% ethanol was mixed with crushed pomelo peel at a material-to-liquid ratio of 1:6, and refluxed at 50℃ for 60 min. Solid-liquid separation was performed to obtain extract I and pomelo peel residue I. In the second stage, 70% ethanol was mixed with pomelo peel residue I at a material-to-liquid ratio of 1:6, and refluxed at 70℃ for 30 min. Solid-liquid separation was performed to obtain extract II and pomelo peel residue II. Extract I and extract II were combined. (4) Thermal integration and refining: The residual heat from the top of the distillation column is used for heating via a heat exchanger; the combined extract is pre-concentrated by microfiltration through a ceramic membrane with a pore size of 0.2 μm (membrane flow rate 4 m / s, operating pressure 0.25 MPa, concentration 5 times), and then concentrated at low temperature in a vacuum of 50℃ and 0.1 MPa; the concentrate is extracted for 20 min at 45℃ and 1.2 MPa using 1,1,1,2-tetrafluoroethane as a subcritical solvent to separate grapefruit peel essential oil; the remaining liquid phase is refined by molecular distillation (evaporation temperature 80℃, operating pressure 0.01 Pa, scraper speed 300 rpm, condensation temperature 15℃); (5) Closed-loop recycling and residue utilization: The extracted ethanol is recycled by distillation; the grapefruit peel residue II and mushroom residue are mixed at a mass ratio of 3:1, the moisture content is adjusted to 65%, and fermented at 65℃ for 10 days to obtain organic fertilizer.

[0027] In this embodiment, the naringin extraction rate was 90.1%, the flavonoid content was 3.8%, the essential oil purity was 96.5%, and the total energy consumption was reduced by 30% compared with the conventional process.

[0028] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol, characterized in that, Includes the following steps: Sp1: Bio-fermentation and High-Purity Ethanol Preparation: 15%–25% of the total mass of grapefruit waste was treated with a cellulase-pectinase complex enzymatic hydrolysis to release fermentation sugars. This was then inoculated with *Saccharomyces cerevisiae* and fermented at 30–35°C for 48–72 hours to prepare a fermentation broth with an ethanol mass fraction of 8%–15%. The fermentation broth was then introduced into a distillation apparatus, and the reflux ratio was optimized using CSLAB chemical simulation software to control the refluxing ratio at 5.22, the reboiler temperature at 78–82°C, and the refluxing flow rate at 2.5–3.0 m³ / s. 3 / h, distillation and purification to ethanol mass fraction ≥85%, the whole process is digitally controlled by MES system; Sp2: Ultrasonic-microwave co-processing: The remaining pomelo waste is sorted, washed, and crushed to a particle size of 2-5 mm, and then subjected to ultrasonic-microwave co-processing. The ultrasonic frequency is 40 kHz and the power is 200-300 W, the microwave power is 200-400 W, and the processing time is 5-15 min. Sp3: Gradient ethanol reflux extraction: The ethanol prepared in step Sp1 was prepared into two concentration gradients for staged extraction; in the first stage, 30%–40% ethanol was mixed with crushed pomelo peel at a material-to-liquid ratio of 1:4–1:6, and refluxed at 40–50℃ for 30–60 min, and solid-liquid separation was performed to obtain extract I and pomelo peel residue I; in the second stage, 55%–70% ethanol was mixed with pomelo peel residue I at a material-to-liquid ratio of 1:4–1:6, and refluxed at 50–70℃ for 30–60 min, and solid-liquid separation was performed to obtain extract II and pomelo peel residue II; extract I and extract II were combined; Sp4: Thermal integrated refining and co-production: The residual heat from the top of the distillation column in step Sp1 is used to heat the extraction system in step Sp3 and the concentration system in step Sp4 via a heat exchanger; the combined extract is first pre-concentrated by microfiltration through a ceramic membrane with a pore size of 0.1-0.2 μm, and then concentrated under low temperature vacuum at 40-50℃ and a vacuum degree of 0.08-0.1 MPa. The concentrate is then separated from the grapefruit peel essential oil by subcritical extraction, and then purified by molecular distillation to obtain high-purity naringin and total flavonoids; Sp5: Closed-loop recycling and residue utilization: Ethanol after extraction is recycled by distillation for the next batch of extraction; grapefruit peel residue II is fermented into organic fertilizer through aerobic composting.

2. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: The combined enzymatic hydrolysis conditions in step Sp1 are as follows: the amount of cellulase is 0.5% to 1.0% of the grapefruit peel mass, the amount of pectinase is 0.3% to 0.8% of the grapefruit peel mass, the hydrolysis temperature is 45 to 55℃, the hydrolysis pH is 4.5 to 5.5, and the hydrolysis time is 2 to 4 hours.

3. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: In step Sp1, the distillation apparatus uses a 316L stainless steel fixed tube sheet condenser, and the number of trays in the distillation column is ≥20.

4. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: In step Sp3, the first stage has an ethanol concentration of 35%, a solid-liquid ratio of 1:5, an extraction temperature of 45℃, and an extraction time of 45 min; the second stage has an ethanol concentration of 60%, a solid-liquid ratio of 1:5, an extraction temperature of 60℃, and an extraction time of 45 min.

5. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: In step Sp4, the surface flow rate of the ceramic membrane microfiltration is 2–4 m / s, the operating pressure is 0.15–0.25 MPa, and the concentration factor is 3–5 times.

6. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: In step Sp4, subcritical extraction was performed using 1,1,1,2-tetrafluoroethane as the subcritical solvent, at an extraction temperature of 35–45 °C, an extraction pressure of 0.8–1.2 MPa, and an extraction time of 20–40 min.

7. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: In step Sp4, the evaporation temperature of molecular distillation is 60–80℃, the operating pressure is 0.001–0.01 Pa, the scraping speed is 200–300 rpm, and the condensation temperature is 5–15℃.

8. The method for green and high-value processing of grapefruit waste based on self-made high-purity ethanol according to claim 1, characterized in that: In step Sp5, the aerobic composting fermentation conditions are as follows: grapefruit peel residue II and mushroom residue are mixed at a mass ratio of 3:1, the moisture content is adjusted to 55% to 65%, effective microbial flora is inoculated, and fermentation is carried out at 50 to 65°C for 10 to 15 days.

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