Continuous and efficient supercritical CO2 fluid countercurrent sterilization process for blueberry juice

Abstract

The invention provides a continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process. The process comprises the following steps: S1, preparing blueberry juice; s2, sterilizing a supercritical CO2 fluid countercurrent extraction column; s3, performing circulating reflux sterilization; s4, collecting a liquid material; and S5, releasing pressure. According to the continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process provided by the invention, the blueberry juice is sterilized by adopting supercritical CO2 fluid countercurrent extraction column equipment aiming at the defects in the prior art, the blueberry juice can be effectively sterilized, and the sterilization rate reaches 100%; the problems of poor retention of effective components in the blueberry juice, toxicity and harm caused by high temperature and a sterilization medium and the like in a traditional sterilization mode are solved, the continuity of sterilization operation is realized, and the method is suitable for sterilization of large-batch liquid products.

Description

Technical Field

[0001] The invention belongs to the field of blueberry juice sterilization and relates to a continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process. Background Art

[0002] Blueberry fruit has fine texture, moderate sweetness and sourness, rich nutrition, refreshing aroma and unique flavor. Through measurement and analysis, every 100g of blueberry pulp contains 0.5g protein, 0.1g fat, 12.9g carbohydrate, 8mg calcium, 0.2mg iron, 9mg phosphorus, 70mg potassium, 1mg sodium, 0.26mg zinc, 0.1g selenium, 9ug vitamin A, 9mg vitamin C, 1.7mg vitamin E, as well as rich pectin, SOD, flavonoids and other ingredients. Due to its special chemical composition, blueberry fruit has excellent health care functions. It can be eaten fresh and processed into many kinds of food suitable for all ages, so it is deeply loved by consumers. Blueberry made into juice not only tastes fresh and sweet, but also contains rich anthocyanins, which can remove oxygen free radicals, protect eyesight, delay brain nerve aging, and improve memory. Due to the unique effect of blueberry on protecting and enhancing eyesight, blueberry is also called the breakfast of pilots. It is the designated breakfast food for pilots designated by the British and American air forces. At the same time, because blueberries contain a variety of nutrients, microorganisms are easily bred during the processing of blueberry juice, and it is difficult to control the contamination of blueberry juice by microorganisms, which causes the taste and color of blueberry juice to deteriorate, affecting the quality of the finished product. Due to the limitations of traditional sterilization methods for liquid materials, the traditional sterilization methods have long sterilization times and high temperatures, which can easily lead to incomplete sterilization effects, loss and destruction of high-temperature heat-sensitive components, and cannot effectively maintain the effective ingredients of the materials. Therefore, the sterilization process of blueberry juice products before leaving the factory has become a major problem in the industry. It is necessary to study how to achieve a technology that can achieve complete sterilization under continuous operation, while retaining the effective ingredients in blueberry juice from being destroyed, so that the quality of blueberry juice products can be effectively controlled. Summary of the invention

[0003] To solve the above problems, the present invention provides a continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process, which specifically includes the following steps: S1: preparing blueberry juice. In this step, in order to obtain blueberry juice that meets the process requirements, the blueberry fruits are first cleaned, and then the blueberry fruits are put into a juicer for squeezing. The blueberry fruits are squeezed until there is no particle pulp to obtain blueberry juice, and then filtered. The filtered blueberry juice is allowed to stand until the blueberry juice is clear, and the supernatant is taken as blueberry juice for use in the sterilization process.

[0004] S2: Supercritical CO2 fluid countercurrent extraction column sterilization: The blueberry juice prepared in the previous step is introduced into the supercritical CO2 fluid countercurrent extraction column for sterilization. During the sterilization process, the blueberry juice enters from the upper part of the countercurrent extraction column, and the supercritical CO2 fluid enters from the lower part of the countercurrent extraction column. At the same time, ball ring fillers are added to the countercurrent extraction column to increase the contact area between the supercritical CO2 fluid and the blueberry juice during the sterilization process to improve the sterilization effect. During the sterilization process, the feed rate of blueberry juice is set to 3-30L / h, and the ratio of the feed rate of blueberry juice to the supercritical CO2 fluid flow rate is (3-30)L / h: (10-100)kg / h. In order to achieve complete sterilization of blueberry juice, the interior of the countercurrent extraction column is divided into multiple sections, and the temperature of each section is increased from top to bottom to achieve the function of step sterilization.

[0005] In order to ensure the best sterilization effect, the countercurrent extraction column is divided into 4 sections, namely the first stage, the second stage, the third stage and the fourth stage from top to bottom. The temperature of the first stage is set at 40-50°C, the temperature of the second stage is set at 50-60°C, the temperature of the third stage is set at 60-70°C, and the temperature of the fourth stage is set at 70-80°C. During the sterilization process, the pressure in the countercurrent extraction column is maintained at 10-40MPa. By setting the temperature gradient, some easy-to-kill bacteria can be killed first, so that the bacterial content gradually decreases. At the same time, by increasing the temperature, bacteria that are more difficult to kill can be further killed. Setting the highest temperature at the fourth stage can not only achieve an effective sterilization effect, but also reduce the high-temperature contact time of the liquid material, and effectively prevent the loss of heat-sensitive components.

[0006] S3: Circulation reflux sterilization: The blueberry juice sterilized by the supercritical CO2 fluid countercurrent extraction column is introduced into the separation kettle, and then the blueberry juice is circulated back from the separation kettle to the countercurrent extraction column for multiple circulation reflux sterilization to improve the sterilization effect. The number of cycles is 1 to 5 times.

[0007] During the circulation reflux process, the pressure inside the countercurrent extraction column is adjusted and controlled to ensure that the pressure of the countercurrent extraction column in each circulation reflux is higher than that of the previous circulation reflux, and the maximum pressure of the countercurrent extraction column is controlled to be 40MPa.

[0008] S4: Collecting liquid material: taking out the blueberry juice that has been sterilized by circulating reflux from the separation kettle to obtain liquid material to prepare a final sterilized product.

[0009] S5: Pressure relief: The countercurrent extraction column is pressure-relieved to recover CO2. In order to ensure the stability of the pressure relief process, the pressure relief process is carried out slowly with a pressure relief rate of 0.001 to 0.1 MPa / s.

[0010] The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process provided by the present invention aims at the deficiencies of the prior art and adopts a supercritical CO2 fluid countercurrent extraction column device to sterilize blueberry juice. The blueberry juice can be effectively sterilized with a sterilization rate of 100%. The problems of poor retention of effective ingredients in blueberry juice, high temperature and toxic and harmful substances caused by the sterilization medium in the traditional sterilization method are solved, and the continuity of the sterilization operation is achieved. The process is suitable for the sterilization of large quantities of liquid products. DETAILED DESCRIPTION

[0011] To further illustrate the concept of the present invention, the present invention will be further described in detail by specific examples below. The following examples are only for illustrative purposes to illustrate and explain the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the contents of the present invention are included in the scope of protection intended by the present invention.

[0012] First, prepare the blueberry juice. Wash the blueberries and put them into a juicer to squeeze until there is no granular pulp. Then filter and let stand until the blueberry juice is clear, and take the supernatant as the blueberry juice. Embodiment 1

[0013] First, adjust the supercritical CO2 fluid countercurrent extraction column to the start-up state, and adjust the sterilization process parameters to: sterilization pressure 15MPa, CO2 flow 60Kg / h, reflux times 2 times, first-stage countercurrent extraction column sterilization temperature 40℃, second-stage countercurrent extraction column sterilization temperature 45℃, third-stage countercurrent extraction column sterilization temperature 50℃. Fourth-stage countercurrent extraction column sterilization temperature 55℃.

[0014] The blueberry juice is transported to the material barrel above the screw pump, and the plunger metering pump and the screw pump are started. The feed rate of the blueberry juice material is set to 15L / h. When the feed rate reaches the set value, the screw pump and the plunger metering pump are closed, and the material outlet valve on the fourth stage of the countercurrent column is opened to the separation kettle. The valve of the material storage tank connected to the separation kettle on the countercurrent extraction column is opened. When the material flows completely into the material storage tank, the valve between the material storage tank and the material inlet at the upper end of the countercurrent extraction column is opened, and the reflux metering pump is started to start the second reflux sterilization. The reflux pressure is 20MPa, and the reflux flow rate of the blueberry juice material is 20L / h. During the reflux, the sterilization temperature of the four levels of the countercurrent extraction column remains unchanged. After the sterilization is completed, the liquid material is collected by a sterile collector, and the liquid material is sealed and stored for microbial testing, and then the pressure pump is stopped to balance the pressure of the countercurrent column and the pressure of the intermediate storage tank, and the pressure relief begins. During the pressure relief process, the pressure relief rate in the countercurrent extraction column is 0.001MPa / s. Embodiment 2

[0015] First, adjust the supercritical CO2 fluid countercurrent extraction column to the start-up state, and adjust the sterilization process parameters to: sterilization pressure 20MPa, CO2 flow 80Kg / h, reflux times 3 times, first-stage countercurrent extraction column sterilization temperature 45℃, second-stage countercurrent extraction column sterilization temperature 50℃, third-stage countercurrent extraction column sterilization temperature 55℃. Fourth-stage countercurrent extraction column sterilization temperature 60℃.

[0016] The blueberry juice is conveyed to the material barrel above the screw conveying pump, and the plunger metering pump and the screw conveying pump are started. The feed rate of the blueberry juice material is set to 25L / h. When the feed rate reaches the set value, the screw conveying pump and the plunger metering pump are closed, and the material outlet valve on the fourth stage of the countercurrent column is opened to the separation kettle. The valve of the material storage tank connected to the separation kettle on the countercurrent extraction column is opened. After the material completely flows into the material storage tank, the valve between the material storage tank and the material inlet at the upper end of the countercurrent extraction column is opened, and the reflux metering pump is started to start the second reflux sterilization. The reflux pressure is 20MPa, and the reflux flow rate of the blueberry juice material is 20L / h. During reflux, the sterilization temperature of the four levels of the countercurrent extraction column remains unchanged. After the second reflux sterilization, the third reflux sterilization is carried out, with a reflux pressure of 30MPa and a material reflux flow rate of 30L / h. During reflux, the sterilization temperature of the four levels of the countercurrent extraction column remains unchanged. After sterilization, a sterile collector is used to collect the liquid material, and the liquid material is sealed and stored for microbial testing. The pressure pump is then stopped to balance the pressure of the countercurrent column with the pressure of the intermediate storage tank and begin to release the pressure. During the pressure release process, the pressure release rate in the countercurrent extraction column is 0.01 MPa / s. Embodiment 3

[0017] First, adjust the supercritical CO2 fluid countercurrent extraction column to the start-up state, and adjust the sterilization process parameters to: sterilization pressure 25MPa, CO2 flow rate 100Kg / h, reflux times 3 times, first-stage countercurrent extraction column sterilization temperature 50℃, second-stage countercurrent extraction column sterilization temperature 55℃, third-stage countercurrent extraction column sterilization temperature 65℃. Fourth-stage countercurrent extraction column sterilization temperature 65℃.

[0018] The blueberry juice is conveyed to the material barrel above the screw conveying pump, and the plunger metering pump and the screw conveying pump are started. The feed rate of the blueberry juice material is set to 30L / h. When the feed rate reaches the set value, the screw conveying pump and the plunger metering pump are closed, and the material outlet valve on the fourth stage of the countercurrent column is opened to the separation kettle. The valve of the material storage tank connected to the separation kettle on the countercurrent extraction column is opened. After the material completely flows into the material storage tank, the valve between the material storage tank and the material inlet at the upper end of the countercurrent extraction column is opened, and the reflux metering pump is started to start the second reflux sterilization. The reflux pressure is 30MPa, and the reflux flow rate of the blueberry juice material is 30L / h. During reflux, the sterilization temperature of the four levels of the countercurrent extraction column remains unchanged. After the second reflux sterilization, the third reflux sterilization is carried out, with a reflux pressure of 35MPa and a material reflux flow rate of 40L / h. During reflux, the sterilization temperature of the four levels of the countercurrent extraction column remains unchanged. After sterilization, a sterile collector is used to collect the liquid material, and the liquid material is sealed and stored for microbial testing. The pressure pump is then stopped to balance the pressure of the countercurrent column with the pressure of the intermediate storage tank and begin to release the pressure. During the pressure release process, the pressure release rate in the countercurrent extraction column is 0.1 MPa / s.

[0019] The liquid material prepared in the above embodiment was subjected to microbial detection to detect the total number of bacterial colonies, yeast, coliform bacteria, mold and other microorganisms contained therein. The detection results of the blueberry juice before sterilization are shown in Table 1: Table 1: Microbiological test results of blueberry juice before sterilization

[0020] The results of the blank sample microbial test are shown in Table 2: Table 2: Blank sample microbial test results

[0021] The results of microbial detection in liquid materials after countercurrent sterilization are shown in Table 3: Table 3: Microbiological test results in liquid materials after countercurrent sterilization

[0022] By conducting microbial detection on the sterilized liquid material in the embodiment, it can be seen that the present invention provides a continuous and efficient supercritical CO2 fluid countercurrent sterilization process for blueberry juice. The total colony count, yeast, coliform group, and mold detection results after sterilization are all undetectable, and the sterilization rate reaches 100%. The taste and color of the obtained finished blueberry juice do not change, achieving the effect of complete sterilization while effectively preserving the taste of the finished blueberry juice.

[0023] There are many methods and approaches to implement the technical solutions of the present invention, and the above are only preferred implementations provided by way of example. Those skilled in the art may think of many changes, modifications and substitutions without departing from the present invention. It should be understood that various alternatives to the implementations of the present invention described herein may be adopted in the practice of the present invention. The attached claims are intended to limit the scope of the present invention and therefore cover methods within the scope of these claims and their equivalents. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

Claims

1. A continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process, characterized by: The following steps are involved: S1: preparing blueberry juice; S2: Supercritical CO2 fluid countercurrent extraction column sterilization: blueberry juice is introduced into a supercritical CO2 fluid countercurrent extraction column, the blueberry juice enters from the upper part of the countercurrent extraction column, and the supercritical CO2 fluid enters from the lower part of the countercurrent extraction column. The countercurrent extraction column is divided into multiple sections, and the temperature of each section increases from top to bottom; S3: Circulation reflux sterilization: the blueberry juice sterilized by the supercritical CO2 fluid countercurrent extraction column is introduced into the separation kettle, and then the blueberry juice is circulated back from the separation kettle to the countercurrent extraction column for circulation reflux sterilization, and the cycle is repeated 1 to 5 times; S4: collecting liquid material: taking out the blueberry juice that has been sterilized by circulating reflux from the separation kettle to obtain a liquid material; S5: Pressure relief: Pressure relief of the countercurrent extraction column.

2. The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process according to claim 1 is characterized in that: The countercurrent extraction column in step S2 is divided into four sections, namely the first stage, the second stage, the third stage and the fourth stage from top to bottom. The temperature of the first stage is 40-50°C, the temperature of the second stage is 50-60°C, the temperature of the third stage is 60-70°C, and the temperature of the fourth stage is 70-80°C; the pressure in the countercurrent extraction column is 10-40MPa.

3. The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process according to claim 2 is characterized by: The blueberry juice feed rate is 3-30 L / h, and the ratio of the blueberry juice feed rate to the supercritical CO2 fluid flow rate is (3-30) L / h: (10-100) kg / h.

4. The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process according to claim 3 is characterized by: In step S3, during the circulation reflux process, the pressure of the countercurrent extraction column in each circulation reflux is higher than that in the previous circulation reflux, and the maximum pressure of the countercurrent extraction column is 40 MPa.

5. The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process according to claim 1 is characterized by: Ball ring filler is added in the countercurrent extraction column.

6. The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process according to claim 1 is characterized by: The pressure relief rate in step S5 is 0.001-0.1 MPa / s.

7. The continuous and efficient blueberry juice supercritical CO2 fluid countercurrent sterilization process according to claim 1 is characterized by: In step S1, the blueberry fruits are first cleaned, and a juicer is used to squeeze the blueberry fruits until there is no particle pulp to obtain blueberry juice. The blueberry juice is filtered and then allowed to stand. When the blueberry juice is clear, the supernatant is taken as blueberry juice for later use.

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