Method for preparing graded debittered navel orange powder

Abstract

The application discloses a preparation method of a graded debittered navel orange powder and belongs to the technical field of deep processing of navel orange agricultural products. The raw materials are selected from at least one of navel orange fresh fruits, navel orange small fruits and navel orange juice residue. Different debittering treatments are adopted according to the characteristics of different raw materials. The residue raw material is directly subjected to vacuum low-temperature composite enzymolysis debittering. The fresh fruit and small fruit raw materials are first subjected to physical grinding to remove the epidermal oil cell layer and then subjected to vacuum low-temperature composite enzymolysis debittering. After unified debittering, the navel orange powder is prepared by low-temperature drying process to obtain a basic navel orange powder and by vacuum freeze-drying process to obtain a high-end debittered navel orange powder according to application scenarios. The basic powder is suitable for navel orange rice products, navel orange noodles, feed and organic enzymes. The high-end powder is suitable for nutritional meal replacement, functional food and export raw materials. The application realizes resource utilization of navel orange small fruits and residue, and is free of external additives in the whole process. The application truly realizes "eating all and utilizing all" of a navel orange.

Description

Technical Field

[0001] This invention belongs to the technical field of deep processing of navel orange agricultural products and resource utilization of fruit and vegetable by-products. Specifically, it relates to a process for preparing graded and debittered navel orange powder using fresh navel oranges, smaller navel oranges, and navel orange juice residue. Background Technology

[0002] Navel oranges are fruits belonging to the Rutaceae family and the Citrus genus. They are rich in vitamin C, flavonoids, dietary fiber, limonene compounds, and other active ingredients. Southern Jiangxi is a world-renowned region for navel orange production, boasting a large planting area and high yields. However, during the cultivation of navel oranges, a considerable proportion of small and substandard fruits are produced each year (these fruits mature at the same time as marketable fruits, have no difference in internal quality, and only do not meet the sales standards for marketable fruits due to their size or appearance). In addition, the juicing process of navel oranges generates a large amount of fruit residue (including peel, pulp, and pith). For a long time, these by-products have been mainly disposed of through landfill or cheap animal feed, which not only causes a huge waste of biomass resources, but also places a heavy burden on the environment because the residue has a high water content and is prone to decay and odor. Directly drying and grinding fruit pomace, small fruits, or second-grade fruits into powder presents the following technical challenges: First, the high content of bitter substances. The bitter substances in navel orange peel, such as naringin and limonene, are the main obstacle limiting its food application. Directly grinding it into powder results in a bitter taste, making it unsuitable as a food ingredient. Second, the product forms are limited. Existing fruit powder preparation technologies mostly use a single drying method, which cannot meet the needs of different application scenarios: basic hot air dried powder is low-cost, suitable for mass production, and can be widely used in rice and flour product ingredients, feed, organic enzymes, and other fields; freeze-dried powder has high quality and good nutrient retention, making it suitable for functional beverages and high-end meal replacement foods. Existing technologies fail to achieve graded utilization and make the most of resources. Third, the issue of additives. Existing fruit powder preparation technologies often involve the addition of chemical additives such as color protectants and antioxidants, which limits the application of the product in the high-end market. Summary of the Invention 3. Purpose of the Invention: To address the shortcomings of existing technologies, this invention provides a method for preparing graded debittered navel orange powder. Differentiated debittering treatments are employed based on the characteristics of different raw materials. After unified debittering, two separate production lines are used for low-temperature drying and vacuum freeze-drying, depending on the end-use. These lines produce basic powder suitable for rice and flour products and animal feed, and high-end powder suitable for functional foods, respectively, achieving graded and efficient utilization of navel orange resources. 3.2 Technical Solution The raw materials used in this invention are all from the navel orange itself: fresh navel oranges, smaller navel oranges, and navel orange juice pulp, without any external additives. Raw material description: Navel orange pulp is the solid residue remaining after juicing navel oranges, including peel, pulp, and segments, with a moisture content of 60%-80%. Differentiated debittering treatment: (1) For fresh navel oranges and smaller navel oranges: Since the fruit is intact, the oil cell layer (the main source of bitterness) on the peel can be removed by physical grinding to reduce the introduction of bitter substances from the source. Then, under vacuum conditions of 0.06-0.08 MPa and temperature of 38-42℃, naringin and cellulase are mixed in a mass ratio of 2:3 and enzymatically hydrolyzed for 45-60 minutes to degrade the residual naringin and limonene. (2) For navel orange juice pomace: Since the pomace cannot be physically ground, it is directly enzymatically hydrolyzed for 45-60 minutes using a mixture of naringinase and cellulase at a mass ratio of 2:3 under vacuum conditions of 0.06-0.08 MPa and temperature of 38-42℃. This enzymatic hydrolysis removes bitter substances. Graded drying: (1) Low-temperature drying process: The drying temperature is 50-60℃, the moisture content of the finished product is ≤5.0%, and it is pulverized through 200 mesh to obtain basic navel orange powder. This powder has low cost and is suitable for mass production. It is applicable to the deep processing of staple foods such as navel orange rice products and navel orange noodles, as well as non-food fields such as feed additives and organic enzyme raw materials. (2) Vacuum freeze-drying process: Pre-freezing temperature -38℃ to -42℃, freeze-drying time 18-22h, finished product moisture content ≤3.0%, ultra-fine pulverization to 200-250 mesh to obtain high-end navel orange powder. The powder retains the complete heat-sensitive nutrients such as vitamin C, and is suitable for nutritional meal replacements, functional foods, solid beverages and export food raw materials. No artificial flavors, synthetic colors, or chemical preservatives are added throughout the entire process. 3.3 Beneficial Effects 1. Make full use of the smaller fruits of navel oranges and the pulp from juicing to solve the problem of waste of navel orange by-products and improve the comprehensive utilization rate of local navel orange resources. 2. Differentiated debittering treatments are adopted for different raw material characteristics: Fresh fruit and smaller fruit are debittered by a combination of physical grinding and enzymatic hydrolysis, resulting in higher quality; fruit pomace is directly debittered by enzymatic hydrolysis, which simplifies the process and keeps costs under control. 3. After standardizing the debittering process, a dual-process graded production method is adopted to precisely match different application scenarios: the basic powder has low cost and is suitable for staple foods such as rice and flour, feed, and enzymes, with a focus on volume sales; the high-end powder retains better nutrition and is suitable for functional foods and export markets, with a focus on price sales. Graded utilization ensures that resources are used to their fullest potential. 4. The base powder can be used in various fields such as rice and flour products, feed additives, and organic enzymes, thus broadening the application range of fruit pomace and maximizing its economic value. 5. The high-end freeze-dried powder retains ≥92% of vitamin C and has complete preservation of active nutrients, making it suitable for the functional food and export markets. 6. No chemical additives are used throughout the entire process, ensuring high product safety and complying with clean label consumer trends and export food raw material production standards. 7. It is fully compatible with the patented processes of navel orange rice products and navel orange noodles, forming a complete patent protection system for upstream raw materials and midstream products. Detailed Implementation Example 1: Fruit pomace raw material + low-temperature drying (basic powder) Collect the pomace (including peel, pulp, and segments, with a moisture content of approximately 75%) remaining after juicing navel oranges, and wash to remove impurities. Directly transfer the pomace into a vacuum enzymatic hydrolysis tank at a vacuum of 0.07 MPa and a temperature of 40°C. Add a compound debittering enzyme preparation (a mixture of naringinase and cellulase in a 2:3 ratio, added at 0.08% of the total crude pulp mass), and stir at low speed for 50 minutes for enzymatic hydrolysis. After enzymatic hydrolysis, cool to 22°C and undergo primary homogenization at 18 MPa and secondary homogenization at 32 MPa. Spread the modified pulp to a thickness of 6 mm, dry with hot air at 55°C until the moisture content reaches 4.8%, air-jet pulverize to 200 mesh, sieve, and seal for packaging. The basic navel orange powder prepared in this embodiment has a naringin removal rate of ≥88%, no bitter taste, and dissolves rapidly in cold water in 3-5 seconds. It is suitable for the deep processing of staple foods such as navel orange rice products and navel orange noodles, as well as feed additives and organic enzyme raw materials. Example 2: Small navel oranges + vacuum freeze-drying (high-end powder) Smaller navel oranges that mature at the same time as commercial navel oranges but do not meet the fresh fruit sales standards due to their smaller size or less appealing appearance are selected. The outer oil cell layer of the peel is first removed by physical grinding, followed by peeling, pulp extraction, and crushing to obtain a coarse pulp. The coarse pulp is then fed into a vacuum enzymatic hydrolysis tank at a vacuum of 0.07 MPa and a temperature of 40°C, where a compound debittering enzyme is added, and enzymatic hydrolysis is performed for 50 minutes. The temperature is then lowered to 22°C, and the pulp undergoes primary homogenization at 18 MPa and secondary homogenization at 32 MPa under high pressure. The modified pulp is spread to a thickness of 7 mm and pre-frozen at -40°C for 3 hours; then freeze-dried at a cold trap temperature of -52°C and a vacuum of 20 Pa for 20 hours, achieving a final moisture content of 2.8%; finally, it is pulverized to 220 mesh under a low-temperature nitrogen environment and sealed in nitrogen-sealed packaging. The high-end navel orange powder prepared in this embodiment has a naringin removal rate of ≥90%, a vitamin C retention rate of ≥92%, and the finished product is loose and porous, dissolves quickly in cold water, has a golden color, and an orange aroma close to that of fresh navel oranges. It is suitable for nutritional meal replacements, functional foods, solid beverages, and as a raw material for export foods.

Claims

1. A method for preparing graded debittered navel orange powder, characterized in that, The raw materials are selected from at least one of fresh navel oranges, small navel oranges, and navel orange juice residue; the navel orange juice residue is the solid residue remaining after juicing navel oranges, including peel, pulp, and pith. The preparation process includes, in sequence, raw material pretreatment, debittering treatment, grading and drying, and pulverization and sieving; The debittering treatment is performed using one of the following two methods depending on the type of raw material: (1) For fresh navel oranges and smaller navel oranges: first, remove the oil cell layer of the peel by physical grinding, and then enzymatically hydrolyze it for 45-60 minutes by mixing naringinase and cellulase at a mass ratio of 2:3 under vacuum conditions of 0.06-0.08MPa and temperature of 38-42℃. (2) For navel orange juice pomace: directly enzymatically hydrolyze it for 45-60 min under vacuum of 0.06-0.08 MPa and temperature of 38-42℃ using a mixture of naringinase and cellulase at a mass ratio of 2:3; The graded drying process includes low-temperature drying and vacuum freeze-drying processes, which respectively produce navel orange powder suitable for different application scenarios.

2. The preparation method according to claim 1, characterized in that, The physical grinding process removes the epidermal oil cell layer, thus removing some of the bitter substances from the source.

3. The preparation method according to claim 1, characterized in that, Basic navel orange powder was prepared using a low-temperature drying process: drying temperature 50-60℃, finished product moisture content ≤5.0%, and pulverized through 200 mesh.

4. The preparation method according to claim 1, characterized in that, High-end navel orange powder is prepared using a vacuum freeze-drying process: pre-freezing temperature -38℃ to -42℃, freeze-drying time 18-22h, finished product moisture content ≤3.0%, and ultra-fine pulverization to 200-250 mesh.

5. The preparation method according to claim 3, characterized in that, The basic navel orange powder is suitable for navel orange rice products, navel orange noodles, feed additives, and organic enzyme raw materials.

6. The preparation method according to claim 4, characterized in that, The high-end navel orange powder is suitable for use as a raw material in nutritional meal replacements, functional foods, solid beverages, and exported foods.

7. The preparation method according to claim 1, characterized in that, No artificial flavors, synthetic colors, or chemical preservatives are added throughout the entire process.

8. A graded debittered navel orange powder prepared by the method according to any one of claims 1 to 7.