Protein feed produced by fermenting citrus peel residues as well as preparation method and application of protein feed

Abstract

The invention relates to a protein feed produced by fermenting citrus peel residues as well as a preparation method and application of the protein feed. The preparation method of the protein feed produced by fermentation of the citrus peel residues comprises the following steps: (1) performing microwave enzyme deactivation on the citrus peel residues, drying to obtain dried citrus peel residues, and uniformly spraying fermentation promoting liquid on the dried citrus peel residues to obtain citrus peel residues containing a fermentation promoter; and (2) carrying out anaerobic fermentation on the citrus peel residues containing the fermentation accelerant, then turning piles, humidifying, and carrying out second-stage fermentation to obtain the high-protein feed. The protein feed prepared by the preparation method disclosed by the invention can reduce the pollution of ecological environment, improve the utilization rate of citrus, effectively improve the protein content, reduce the contents of substances such as naringin, limonin and citrus essential oil in the citrus pomace, and is beneficial to the health of animals.

Description

Technical Field

[0001] This invention relates to the field of biofeed technology. Specifically, it relates to a protein feed produced by fermenting citrus peel residue, its preparation method, and its application. Background Technology

[0002] Citrus (Citrus reticulata Blanco), also known as mandarin orange, is a small tree belonging to the genus Citrus in the family Rutaceae. The fruit is typically oblate, nearly spherical. China is a major citrus producer, with an output of 44.6 million tons in 2022, accounting for 28% of global production. Citrus cultivation in China is mainly distributed in Guangxi, Jiangsu, and Hainan provinces. The pulp of citrus is sweet and sour, and can be processed into juice, jam, fruit cakes, and other food products. The fruit, peel, and juice can all be used medicinally. The flowers and fruits of citrus can be used to extract essential oils, while the pomace and peel can be used to extract pectin, citric acid, and other substances.

[0003] In the citrus processing industry, the main waste is the large amount of citrus peel residue generated after juicing. Its components mainly include peel, seeds, pith, and pulp residue. Citrus peel residue is rich in protein, as well as a large amount of minerals, vitamins, and other nutrients, and can be used to process and produce ruminant animal feed.

[0004] With the rapid development of the citrus processing industry, the output of citrus by-products has surged, leading to increasingly serious environmental pollution and resource waste due to insufficient processing capacity. Common disposal methods include open-air dumping, landfilling, use as fertilizer, or disposal as waste or discharge into rivers, severely impacting the ecological environment and air quality. On the other hand, citrus pomace is rich in minerals, sugars, amino acids, and vitamins, as well as pigments, dietary fiber, and flavonoids with strong antioxidant properties. It can serve as a potential good feed resource, alleviating my country's feed shortage, reducing competition for food between humans and livestock, and lowering livestock feed costs. Therefore, fully utilizing my country's abundant citrus pomace resources and developing its use as livestock feed has significant economic and ecological benefits.

[0005] Citrus peel pomace presents several challenges for direct feeding, including high levels of bitter substances, poor palatability, and low protein content. Furthermore, its high anti-nutritional factors and low protein content further limit its application. In addition, citrus peel pomace has an initial moisture content as high as 70-80%, leading to high transportation and storage costs, and it is also susceptible to Aspergillus flavus contamination. Therefore, its effectiveness in animal feeding is not ideal.

[0006] Therefore, it is urgent to improve its bioavailability through appropriate processing techniques and nutritional balance technologies, thereby reducing ecological pollution and resource waste. Summary of the Invention

[0007] To address the aforementioned technical problems, the purpose of this invention is to provide a protein feed produced from citrus peel residue fermentation, its preparation method, and its application. The protein feed prepared using the method of this invention can reduce environmental pollution, improve the utilization rate of citrus, effectively increase protein content while reducing the content of substances such as naringin, limonene, and citrus essential oil in citrus peel residue, which is beneficial to animal health.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: The first objective of this invention is to provide a method for preparing protein feed produced by fermenting citrus peel residue, comprising the following steps: (1) After microwaving and drying the citrus peel residue, dry citrus peel residue is obtained. The fermentation promoter is evenly sprayed onto the dry citrus peel residue to obtain citrus peel residue containing the fermentation promoter. (2) The citrus peel residue containing the fermentation promoter is subjected to anaerobic fermentation, then turned over and humidified for secondary fermentation to obtain high-protein feed.

[0009] The beneficial effects of this invention are: the protein feed prepared by the method of this invention can reduce pollution of the ecological environment, improve the utilization rate of citrus, effectively increase the protein content while reducing the content of substances such as naringin, limonene, and citrus essential oil in citrus peel residue, which is beneficial to animal health.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the microwave blanching time is 1-2 minutes, the power is 3kw, and the drying method is natural air drying.

[0012] Furthermore, in step (1), the fermentation promoter liquid includes the following raw materials: sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, and guar gum.

[0013] The beneficial effects of adopting the above-mentioned further scheme are as follows: Citrus peel residue, especially citrus peel, contains a certain amount of essential oil compounds, which makes it unfavorable for microbial fermentation during anaerobic fermentation. The fermentation promoting liquid of this application is sprayed onto the surface of the citrus peel residue, at which time the surface of the citrus peel residue still has a certain degree of hydrophobicity. During the sealed fermentation process, the compound microbial agent in the promoting liquid accumulates on the surface of the citrus peel residue. At the same time, the glucose and betaine hydrochloride added to the fermentation promoting liquid can promote the compound microbial agent to produce more active substances such as proteins, enzymes, and polysaccharides, which then adhere to the surface of the citrus peel residue, accelerating the decomposition of the citrus peel residue and the decomposition of essential oils. In addition, the compound microbial agent itself will also produce active substances such as organic acids during the fermentation process. In order to prevent the inhibitory effect of metabolites on the compound microbial agent, sorbitol is added to maintain the integrity of the cell membrane structure by adjusting the osmotic pressure and reducing the loss of activity. Meanwhile, in the early stage of fermentation, adding guar gum can minimize moisture loss and ensure the aggregation of microorganisms on the surface of citrus peel residue. In the later stage of fermentation, turning the pile introduces an appropriate amount of air, and then sealing it to continue fermentation. The compound microbial agent assimilates non-protein nitrogen and converts it into microbial protein to increase the true protein rate. At this time, guar gum has also been utilized or degraded, and this hydrophobic effect is eliminated, entering a high-speed decomposition and fermentation process. The added bran participates in the fermentation of citrus peel residue, which can further increase protein production.

[0014] Furthermore, the mass ratio of the sorbitol, the wheat bran, the compound microbial agent, the glucose, the betaine hydrochloride, and the guar gum in the fermentation promoter is 10~30:40~55:1~3:3~5:1~2:5~7.

[0015] Furthermore, the compound microbial agent includes yeast and Bacillus subtilis.

[0016] Furthermore, the total number of viable yeast cells in the compound microbial agent is 8 × 10⁻⁶. 12 ~10×10 12 CFU / g, the total viable count of the Bacillus subtilis is 2×10⁻⁶. 10 ~4×10 10 CFU / g.

[0017] Furthermore, the amount of fermentation promoter liquid sprayed in step (1) is 20% to 35% of the mass of the dried citrus peel residue.

[0018] Furthermore, the anaerobic fermentation temperature in step (2) is 45℃~60℃, and the time is 2~3 days.

[0019] Furthermore, the humidity in the humidified fermentation environment described in step (2) is 65%~90%; the temperature of the second-stage fermentation is 45℃~60℃; and fermentation continues until the citrus peel residue no longer raises its temperature on its own.

[0020] The second objective of this invention is to provide a protein feed produced by fermenting citrus peel residue.

[0021] The third objective of this invention is to provide an application of protein feed produced by fermenting citrus peel residue, which is then used in piglet feed. Detailed Implementation

[0022] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1: Preparation of protein feed produced by fermentation of citrus peel residue Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, guar gum, and water were mixed in a mass ratio of 20:48:2:4:1.5:6:45 to obtain a fermentation promoter. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of the yeast in the compound microbial agent was 9 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 3×10⁻⁶. 10 CFU / g.

[0024] Preparation of protein feed: (1) After blanching the citrus peel residue in a 3kW microwave for 1-2 minutes, the citrus peel residue is naturally dried to obtain dried citrus peel residue. 27% of the fermentation promoter liquid of the citrus peel residue is evenly sprayed onto the dried citrus peel residue to obtain citrus peel residue containing fermentation promoter. (2) The citrus peel residue containing fermentation promoter was sealed and anaerobic fermented at a temperature of 55°C for 2 days. Then, the pile was turned over and humidified. The humidity in the fermentation environment after humidification was 77%. The second stage of fermentation was carried out until the temperature no longer rose, and high-protein feed was obtained.

[0025] Example 2: Preparation of protein feed produced by fermentation of citrus peel residue Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, guar gum, and water were mixed in a mass ratio of 10:40:1:3:1:5:40 to obtain a fermentation promoter. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of the yeast in the compound microbial agent was 8 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 2×10⁻⁶. 10 CFU / g.

[0026] Preparation of protein feed: (1) After blanching the citrus peel residue in a 3kW microwave for 1-2 minutes, the citrus peel residue is naturally dried to obtain dried citrus peel residue. 20% of the fermentation promoter liquid of the citrus peel residue is evenly sprayed onto the dried citrus peel residue to obtain citrus peel residue containing fermentation promoter. (2) The citrus peel residue containing fermentation promoter was sealed and anaerobic fermented at a temperature of 45°C for 2 days. Then, the pile was turned over and humidified. The humidity in the fermentation environment after humidification was 65%. The second stage of fermentation was carried out until the temperature no longer rose, and high-protein feed was obtained.

[0027] Example 3: Preparation of protein feed produced by fermentation of citrus peel residue Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, guar gum, and water were mixed in a mass ratio of 30:55:3:5:2:7:50 to obtain a fermentation promoter. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of the yeast in the compound microbial agent was 10 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 4 × 10⁻⁶. 10 CFU / g.

[0028] Preparation of protein feed: (1) After blanching the citrus peel residue in a 3kW microwave for 1-2 minutes, the residue is naturally dried to obtain dried citrus peel residue. 35% of the mass of the citrus peel residue is evenly sprayed onto the dried citrus peel residue to obtain citrus peel residue containing fermentation promoter. (2) The citrus peel residue containing fermentation promoter was sealed and anaerobic fermented at a temperature of 60°C for 2 days. Then, the pile was turned over and humidified. The humidity of the fermentation environment after humidification was 90%. The second stage of fermentation was carried out until the temperature no longer rose, and high-protein feed was obtained.

[0029] Comparative Example 1: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, guar gum, and water were mixed in a mass ratio of 20:48:2:4:6:45 to obtain a fermentation promoter. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of the yeast in the compound microbial agent was 9 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 3×10⁻⁶. 10 CFU / g.

[0030] Preparation of protein feed: Same as in Example 1.

[0031] Comparative Example 2: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, and water were mixed in a mass ratio of 20:48:2:4:1.5:45 to obtain a fermentation promoter. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of the yeast in the compound microbial agent was 9 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 3×10⁻⁶. 10 CFU / g.

[0032] Preparation of protein feed: Same as in Example 1.

[0033] Comparative Example 3: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, guar gum, and water were mixed in a mass ratio of 20:48:2:4:1.5:6:45 to obtain a fermentation promoter. The compound microbial agent included yeast; the total viable count of yeast in the compound microbial agent was 9 × 10⁻⁶. 12 CFU / g.

[0034] Preparation of protein feed: Same as in Example 1.

[0035] Comparative Example 4: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of fermentation accelerator broth: Wheat bran, compound microbial agent, betaine hydrochloride, guar gum, and water were mixed in a mass ratio of 48:2:1.5:6:45. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of yeast in the compound microbial agent was 9 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 3×10⁻⁶. 10 CFU / g.

[0036] Preparation of protein feed: Same as in Example 1.

[0037] Comparative Example 5: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of fermentation accelerator broth: Sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, and water were mixed in a mass ratio of 20:48:2:4:1.5:6:45 to obtain a fermentation promoter. The compound microbial agent included yeast and Bacillus subtilis; the total viable count of the yeast in the compound microbial agent was 9 × 10⁻⁶. 12 CFU / g, the total viable count of Bacillus subtilis was 3×10⁻⁶. 10 CFU / g.

[0038] Preparation of protein feed: Same as in Example 1.

[0039] Comparative Example 6: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of protein feed: (1) After blanching the citrus peel residue in a 3kW microwave for 1-2 minutes, it is naturally dried to obtain dried citrus peel residue. 27% of the mass of the citrus peel residue is evenly sprayed onto the dried citrus peel residue to obtain citrus peel residue containing fermentation promoter. (2) The citrus peel residue containing fermentation promoter was sealed and anaerobic fermented at a temperature of 55°C for 2 days. Then, the pile was turned over and humidified. The humidity in the fermentation environment after humidification was 77%. The second stage of fermentation was carried out until the temperature no longer rose, and high-protein feed was obtained.

[0040] Comparative Example 7: Preparation of Protein Feed Produced from Citrus Peel Residue Fermentation Preparation of fermentation promoter: Same as in Example 1.

[0041] Preparation of protein feed: (1) After blanching the citrus peel residue in a 3kW microwave for 1-2 minutes, the citrus peel residue is naturally dried to obtain dried citrus peel residue. 27% of the fermentation promoter liquid of the citrus peel residue is evenly sprayed onto the dried citrus peel residue to obtain citrus peel residue containing fermentation promoter. (2) Citrus peel residue containing fermentation promoter was sealed and anaerobic fermented at a temperature of 55°C for 2 days to obtain high-protein feed.

[0042] Performance testing: The feeding value of the protein feeds prepared in Example 1 and Comparative Examples 1-7 was evaluated. There were 7 groups of 6 pigs each, and the average starting weight of each group was measured. 15 wt% of the protein feeds prepared in Example 1 and Comparative Examples 1-7 were added to the basal diet of each pig, and the mixture was thoroughly combined before feeding. During the growing pig rearing process, the pigs had free access to feed and water, and the average daily feed intake and average daily weight gain were measured daily. After 2 months of feeding, the average final weight of each group was measured, as shown in Table 1. Table 1 From Table 1, we can obtain: The protein feed prepared using the method of this invention can reduce environmental pollution, improve the utilization rate of citrus fruits, effectively increase protein content while reducing the content of substances such as naringin, limonene, and citrus essential oil in citrus peel residue, thereby improving nutritional value and palatability of the feed and benefiting animal health.

[0043] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing protein feed from citrus peel residue fermentation, characterized in that, Includes the following steps: (1) After microwaving and drying the citrus peel residue, dry citrus peel residue is obtained. The fermentation promoter is evenly sprayed onto the dry citrus peel residue to obtain citrus peel residue containing the fermentation promoter. (2) The citrus peel residue containing the fermentation promoter is subjected to anaerobic fermentation, then turned over and humidified for secondary fermentation to obtain high-protein feed.

2. The method for preparing protein feed from citrus peel residue fermentation according to claim 1, characterized in that, In step (1), the fermentation promoter liquid includes the following raw materials: sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, and guar gum.

3. The method for preparing protein feed from citrus peel residue fermentation according to claim 2, characterized in that, The mass ratio of sorbitol, wheat bran, compound microbial agent, glucose, betaine hydrochloride, and guar gum in the fermentation promoter is 10~30:40~55:1~3:3~5:1~2:5~7.

4. The method for preparing protein feed from citrus peel residue fermentation according to claim 2, characterized in that, The compound microbial agent includes yeast and Bacillus subtilis.

5. The method for preparing protein feed from citrus peel residue fermentation according to claim 4, characterized in that, The total viable count of the yeast in the compound microbial agent is 8 × 10⁻⁶. 12 ~10×10 12 CFU / g, the total viable count of the Bacillus subtilis is 2×10⁻⁶. 10 ~4×10 10 CFU / g.

6. The method for preparing protein feed from citrus peel residue fermentation according to claim 1, characterized in that, The amount of fermentation promoter liquid sprayed in step (1) is 20% to 35% of the mass of the dried citrus peel residue.

7. The method for preparing protein feed from citrus peel residue fermentation according to claim 1, characterized in that, The anaerobic fermentation in step (2) is carried out at a temperature of 45℃~60℃ for 2~3 days.

8. The method for preparing protein feed from citrus peel residue fermentation according to claim 1, characterized in that, The humidity in the fermentation environment after humidification in step (2) is 65%~90%; the temperature of the second stage fermentation is 45℃~60℃.

9. A protein feed produced by fermenting citrus peel residue, characterized in that, The protein feed is prepared by the preparation method according to any one of claims 1 to 8.

10. An application of a protein feed produced by fermenting citrus peel residue, characterized in that, The protein feed according to claim 9 is used in piglet feed.

Images