Preparation method of quick-frozen fruit pulp

Abstract

The invention relates to the technical field of beverage processing, in particular to a preparation method of quick-frozen fruit pulp. According to the method disclosed by the invention, the pulped fruit pulp is sterilized in a microwave sterilization manner, so that the method is quicker, more efficient, safer and more environment-friendly; meanwhile, according to the method disclosed by the invention, the step of vacuum degassing after traditional sterilization is avoided, and the sterilized fruit pulp is cooled once, so that energy can be effectively extracted; after filling, ultrasonic degassing and secondary cooling are carried out at a low temperature, so that the degassing effect is ensured, the cooling effect is also ensured, tedious operation and possible potential safety hazards of a traditional soaking mode are avoided, and heat extracted by primary cooling and secondary cooling is used for energy consumption during pretreatment; in addition, through an ultraviolet lamp irradiation mode, bacterial pollution is avoided, the fruit pulp is transferred to a refrigeration house for cryopreservation after being packaged, safe and efficient preparation of the quick-frozen fruit pulp is achieved, and meanwhile more energy is saved and more environment friendliness is achieved.

Description

Technical Field

[0001] This invention relates to the field of beverage processing technology, and specifically to a method for preparing quick-frozen fruit pulp. Background Technology

[0002] Quick-frozen fruit pulp is produced by rapidly freezing fruits and vegetables after they have been pulped, in order to preserve their taste and prevent the loss of nutrients. The process involves sterilization, degassing, filling, and quick-freezing to sterilize and rapidly freeze the pulp, ensuring its taste while extending its shelf life.

[0003] Currently, quick-freezing of fruit pulp generally employs a refrigeration unit for rapid freezing. During this process, the filled fruit pulp is immersed in a -35°C brine tank, where it rapidly exchanges heat with the freezing liquid, thus achieving quick freezing. However, in actual production, due to quality differences between batches of packaging bags and variations in quality control during filling, leakage sometimes occurs during quick freezing of the fruit pulp in the freezing liquid. This affects product quality, contaminates the freezing liquid, disrupts continuous and stable production, and poses food safety risks.

[0004] Therefore, this invention proposes a method for preparing quick-frozen fruit pulp, which achieves the quick-freezing process of fruit pulp through a first cooling, a second cooling, and cold storage. On the one hand, it realizes the extraction of heat during the first and second cooling processes, making it more energy-efficient and environmentally friendly; on the other hand, the second cooling adopts a circulating air method, avoiding the traditional method of soaking in freezing liquid, eliminating food safety risks, and facilitating promotion and application. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing quick-frozen fruit pulp, in order to solve the problems that easily occur when quick-frozen fruit pulp is quick-frozen in the brine tank of a refrigeration unit, such as swelling, damage and leakage of the outer packaging, which affects product quality and poses food safety risks.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing quick-frozen fruit pulp, comprising the following steps:

[0007] S1. The pulp prepared by the pulping machine is cooled once after microwave sterilization; The aforementioned cooling process takes place in a first heat pump, in which microwave-sterilized fruit pulp is used as the heat medium and the heat pump working fluid is used as the cold medium. S2. The fruit pulp after the first cooling in S1 is aseptically filled into PET bottles. S3. Under ultrasonic vibration field and ultraviolet light irradiation, the fruit pulp after aseptic filling in S2 is degassed and cooled twice; and under ultraviolet light irradiation, the fruit pulp after the second cooling is packaged and transferred to cold storage for freezing. The secondary cooling process uses the filled fruit pulp as the heat medium and the circulating air as the cold medium. The circulating air exchanges heat with the second heat pump, in which the circulating air is used as the heat medium and the heat pump working fluid is used as the cold medium. The heat extracted by the first and second heat pumps is used for the energy consumption of S1 fruit and vegetable pulping.

[0008] Furthermore, in S1, the pulper includes a double-stage pulper, wherein the screen aperture of the first pulper is 1~2mm and the screen aperture of the second pulper is 0.3~0.8mm; the pulper speed is 800~1200rpm and the pulping temperature is 70~80℃.

[0009] Furthermore, in S1, the fruit pulp includes mango, apple, pear, and tomato.

[0010] Furthermore, in S1, the microwave sterilization power is 700~800W, the time is 60~180s, and the temperature is 70~80℃.

[0011] Furthermore, in S1, the temperature of the fruit pulp after one cooling is controlled at 10~30℃.

[0012] Furthermore, in S2, the filling specification is 1kg±0.01kg.

[0013] Furthermore, in S3, the frequency of the ultrasonic waves in the ultrasonic vibration field is 20~30kHz, and the intensity is 0.5~1W / cm. 2 .

[0014] Furthermore, in S3, the intensity of the ultraviolet lamp irradiation is 80~100 μW / cm². 2 .

[0015] Furthermore, in S3, the temperature after the secondary cooling is controlled at -20~-10℃.

[0016] Furthermore, in S3, the temperature in the cold storage is controlled at ≤-18℃.

[0017] The beneficial effects of this invention are: 1. The method of the present invention uses microwave sterilization to sterilize the pulped fruit pulp, which is faster, more efficient, safer and more environmentally friendly. 2. The method of the present invention avoids the traditional vacuum degassing steps after sterilization and before filling. The degassing step is transferred to after filling. Through ultrasonic vibration field and secondary cooling, degassing and cooling are carried out at a lower temperature, which ensures both degassing and cooling effects. 3. The method of the present invention uses circulating air to cool the fruit pulp after filling, which avoids the cumbersome operation of the traditional soaking method and the safety hazards such as possible leakage. 4. The method of the present invention uses the heat extracted from the first and second cooling processes for energy consumption during pretreatment, which is more energy-efficient and environmentally friendly. 5. The method of the present invention avoids bacterial contamination by ultraviolet light irradiation, effectively ensuring product safety; and after packaging, it is transferred to a cold storage for freezing, realizing the safe and efficient preparation and storage of quick-frozen fruit pulp. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

[0019] The principle of this invention is as follows: In the process of using the method of this invention, fresh, unrotten, and mold-free fruits and vegetables are selected and steamed. The steaming can be carried out using heat extracted by a first and second heat pump. The pulp is then pulped in a double-stage pulper at a pulping temperature of 70-80℃ and a pulping speed of 800-1200 rpm. The screen aperture of the first pulper is 1-2 mm, and the screen aperture of the second pulper is 0.3-0.8 mm, thereby obtaining fruit pulp.

[0020] The method of this invention sterilizes the fruit pulp obtained after pulping using microwave sterilization. The temperature of the fruit pulp is 70~80℃. Microwave sterilization eliminates the need for additional heating, resulting in lower energy consumption and higher efficiency. The sterilization power is controlled at 700~800W, and the time is 60~180s. The sterilized fruit pulp is then directly used for bottling. Aseptic bottling is used to effectively avoid secondary bacterial contamination of the fruit pulp. It should be noted that this invention uses bottle filling, with bottle material including PET, and the filling specification is 1kg±0.01kg.

[0021] The bottle-filling method facilitates subsequent secondary cooling and degassing processes. In the method of this invention, the fruit pulp after the first cooling is degassed and then cooled again. At lower temperatures, gas solubility is reduced, which is more conducive to degassing. Simultaneously, in the ultrasonic vibration field, the material flow and mass transfer caused by ultrasonic cavitation are more conducive to uniform heat exchange between the fruit pulp and the circulating air, achieving the dual effects of effective degassing and effective cooling. During the degassing and secondary cooling process, the frequency of the ultrasonic waves is controlled at 20~30kHz, and the intensity is 0.5~1W / cm².2 After the second cooling, the temperature of the fruit pulp is controlled at -20~-10℃.

[0022] To prevent secondary bacterial contamination during degassing, secondary cooling, and subsequent bottle sealing, ultraviolet (UV) irradiation is used for sterilization during the operation of this invention, thereby ensuring food hygiene and safety. The intensity of the UV irradiation during the process is 80~100 μW / cm². 2 After packaging, the fruit pulp can be directly transferred to a cold storage at -18℃ or below for freezing.

[0023] Example 1 In this embodiment, apples are pulped to prepare quick-frozen apple pulp.

[0024] Fresh, unrotten, and mold-free apples are selected as raw materials. After core removal, they are steamed and then pulped in a double-stage pulper. The first stage of the double-stage pulper has a screen aperture of 1.5 mm, and the second stage has a screen aperture of 0.5 mm. The pulping is carried out at 70~80℃ and 1000 rpm to obtain fruit pulp. The temperature of the fruit pulp is 70~80℃.

[0025] The obtained fruit pulp is directly sterilized by microwave. In this embodiment, the microwave sterilization is performed at 800W for 120 seconds. After microwave sterilization, the fruit pulp is cooled once by the first heat pump.

[0026] In this embodiment, the fruit pulp and the heat pump working fluid exchange heat in a shell-and-tube heat exchanger. The heat pump working fluid is R134a, with the fruit pulp flowing through the tube side and R134a flowing through the shell side. The temperature of the fruit pulp at the outlet of the shell-and-tube heat exchanger is controlled between 10 and 30°C, and the cooling time is 10 to 20 minutes. The heat extracted by the first heat pump can be exchanged with water to release energy, and the heated water can be used as boiler water, which is more energy-efficient. At the same time, the steam generated by the boiler can be used for cooking the apple raw materials.

[0027] After initial cooling, the fruit pulp is sent to the filling section for aseptic filling. During this process, key parts of the filling equipment are disinfected to prevent secondary bacterial contamination of the pulp. PET bottles are used for filling, with a filling size of 1kg ± 0.1kg. After filling, the pulp is sent to an ultrasonic vibration field for degassing and secondary cooling.

[0028] In an ultrasonic vibration field, the pulp temperature is lower after the first cooling, making degassing easier. Simultaneously, the mass transfer of the pulp within the PET bottle caused by ultrasonic cavitation facilitates a more thorough secondary cooling process. Furthermore, ultraviolet irradiation helps prevent secondary bacterial contamination. The ultrasonic frequency during the process is 25 kHz, and the intensity is 0.5 W / cm². 2The ultraviolet radiation intensity is 100 μW / cm. 2 .

[0029] In this embodiment, circulating air is used for secondary cooling of the fruit pulp. During the process, the fruit pulp after filling is transported by a chain conveyor. A shell is installed on the outside of the entire chain conveyor. Inlet and outlet are set on both sides of the shell and baffles are installed (the baffles do not interfere with the entry and exit of the fruit pulp). In this embodiment, the length of the chain conveyor is 40m and the running speed is 0.5m / min. A 5m blank section is left on each side of the shell. Ultrasonic generators and ultraviolet lamps are evenly distributed in the middle 30m of the shell. The circulating air enters from the bottom of the middle part of the chain conveyor shell after passing through a filter. After being distributed by the air distribution plate with screen holes, it is blown upward and drawn out from the top of the shell and collected, thereby realizing the secondary cooling process of the fruit pulp.

[0030] After the circulating air is heated, it exchanges heat with the heat pump working fluid in the second heat pump, releasing heat. The working fluid in the second heat pump is R22, and the temperature of the fruit pulp after secondary cooling is controlled between -20°C and -10°C. The heat extracted by the second heat pump can be exchanged with water to release energy, and the heated water can be used as boiler water, which is more energy-efficient. Simultaneously, the steam generated by the boiler can be used for cooking the apple raw materials. After secondary cooling, the fruit pulp is capped by a capping machine and then directly sent to a cold storage for freezing. Ultraviolet irradiation is used during the capping process, with an intensity of 80 μW / cm². 2 The temperature of the cold storage shall not be lower than -18℃.

[0031] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes made to their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for the preparation of a quick-frozen fruit pulp, characterized in that, Includes the following steps: S1. The pulp prepared by the pulping machine is cooled once after microwave sterilization; The aforementioned cooling process takes place in a first heat pump, in which microwave-sterilized fruit pulp is used as the heat medium and the heat pump working fluid is used as the cold medium. S2. The fruit pulp after the first cooling in S1 is aseptically filled into PET bottles. S3. Under ultrasonic vibration field and ultraviolet light irradiation, the fruit pulp after aseptic filling in S2 is degassed and cooled twice; and under ultraviolet light irradiation, the fruit pulp after the second cooling is packaged and transferred to cold storage for freezing. The secondary cooling process uses the filled fruit pulp as the heat medium and the circulating air as the cold medium. The circulating air exchanges heat with the second heat pump, in which the circulating air is used as the heat medium and the heat pump working fluid is used as the cold medium. The heat extracted by the first and second heat pumps is used for the energy consumption of S1 fruit and vegetable pulping.

2. The method for preparing quick-frozen fruit pulp according to claim 1, characterized in that: In S1, the pulping machine includes a double-stage pulping machine. The screen aperture of the first pulping machine is 1-2 mm, and the screen aperture of the second pulping machine is 0.3-0.8 mm. The pulping machine rotates at 800-1200 rpm, and the pulping temperature is 70-80℃.

3. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: In S1, the fruit pulp includes mango, apple, pear, and tomato.

4. A process for the preparation of quick-frozen fruit pulp as claimed in claim 1, wherein: In S1, the microwave sterilization power is 700~800W, the time is 60~180s, and the temperature is 70~80℃.

5. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: In S1, the temperature of the fruit pulp after one cooling is controlled at 10~30℃.

6. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: In S2, the filling specification is 1kg±0.01kg.

7. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: The frequency of the ultrasonic vibration field is 20-30 kHz and the intensity is 0.5-1 W / cm 2 .

8. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: The intensity of the ultraviolet lamp irradiation in the S3 is 80-100 μW / cm 2 .

9. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: In S3, the temperature after the second cooling is controlled at -20~-10℃.

10. A method of preparing a quick-frozen fruit pulp according to claim 1, characterized in that: In S3, the temperature in the cold storage is controlled at ≤-18℃.