Rapid preparation method of aronia melanocarpa juice freeze-dried powder

Abstract

The invention relates to a rapid preparation method of aronia melanocarpa juice freeze-dried powder, and belongs to the field of food processing. The preparation method comprises the following steps: injecting aronia melanocarpa juice into a closed container, controlling the temperature to be 8-12 DEG C, introducing carbon dioxide gas, controlling the pressure in the container to be 0.38-0.45 MPa, reducing the temperature to-2-0 DEG C, releasing the pressure within 30 seconds to obtain aronia melanocarpa ice, then performing quick-freezing treatment to obtain aronia melanocarpa ice cubes, and finally performing vacuum freeze-drying to obtain the aronia melanocarpa juice freeze-dried powder. The method not only can effectively reduce the loss of anthocyanin of the aronia melanocarpa in the processing process, but also can greatly reduce the treatment time of vacuum freeze drying, and is a simple and rapid processing method of the aronia melanocarpa juice freeze-dried powder.

Description

Technical Field

[0001] The invention relates to a method for quickly preparing freeze-dried powder of berry juice, and belongs to the field of food processing. Background Art

[0002] Aronia nigra, also known as Aronia nigra, is a black-purple berry that is considered to be one of the plant fruits with the richest anthocyanin content. Rich in anthocyanins and other bioactive substances, Aronia nigra has strong antioxidant, anti-inflammatory, antibacterial, and anti-tumor physiological functions. However, anthocyanins are easily degraded during processing, especially their instability at high temperatures, making it difficult to apply the technology of drying them by heat treatment to anthocyanin-rich raw materials such as Aronia nigra. The emergence of vacuum freeze-drying technology allows people to directly sublimate the ice in the raw materials into water vapor at freezing point, and then dry the raw materials. This has led to an increasing use of vacuum freeze-drying technology in the preparation of Aronia nigra juice powder. However, the long preparation cycle and high energy consumption of vacuum freeze-drying have greatly increased the preparation cost, limiting the use of this technology. Summary of the invention

[0003] In order to solve the defects of high energy consumption and reduced product quality caused by the long sample preparation cycle in the vacuum freeze-drying process in the prior art for processing freeze-dried powder of berry juice, the present invention provides a method for quickly preparing freeze-dried powder of berry juice. The present invention uses high-pressure inflation technology to inject carbon dioxide into berry juice, and obtains berry smoothie by increasing the inflation volume (pressure), lowering the temperature, and releasing the pressure in a short time, and then vacuum freeze-drying is performed after quick freezing to obtain freeze-dried powder of berry juice. The present invention can not only effectively reduce the loss of berry anthocyanins during the processing process, but also greatly reduce the processing time of vacuum freeze drying. It is a simple and fast method for processing freeze-dried powder of berry juice.

[0004] The technical solution adopted by the present invention to solve its technical problem is: a method for quickly preparing berry juice freeze-dried powder, which comprises injecting berry juice into a sealed container, controlling the temperature to 8-12°C and then filling with carbon dioxide gas, controlling the pressure in the container to 0.38-0.45MPa, and releasing the pressure within 30 seconds after cooling to -2-0°C to obtain berry smoothie, followed by quick freezing to obtain berry ice cubes, and finally performing vacuum freeze drying to obtain berry juice freeze-dried powder.

[0005] Furthermore, when carbon dioxide gas is injected into the berry juice, the pressure and temperature are controlled so that the berry juice reaches a supercooled state, thereby accelerating the formation time of the smoothie.

[0006] Furthermore, releasing the pressure within 30 seconds is to quickly transform the berry juice from a liquid state to a porous solid smoothie state.

[0007] Furthermore, through high-pressure inflation technology combined with specific pressure and temperature conditions, the berry juice is supercooled and quickly transformed into porous solid shaved ice, which significantly shortens the time it takes to make shaved ice from the berry juice, greatly reduces the particle volume of the shaved ice, increases the surface area of ​​the shaved ice, and significantly increases the water sublimation efficiency during the vacuum freeze-drying process.

[0008] In the rapid preparation method of the lyophilized powder of berry juice of the present invention, the equipment used for charging carbon dioxide gas is all the charging devices disclosed in the prior art, preferably high-pressure charging equipment.

[0009] In the rapid preparation method of the lyophilized powder of berry juice of the present invention, the cooling process is carried out in an existing cooling device, preferably a cold storage.

[0010] In the rapid preparation method of the lyophilized powder of the berry juice of the present invention, the berry juice can be obtained by the following steps: washing the berry fruits, squeezing and crushing them, passing them through a 200-mesh sieve, performing high-pressure homogenization and heat sterilization treatment, and obtaining the berry juice.

[0011] Furthermore, the berry fruit is preferably fresh and non-rotten berry fruit.

[0012] Furthermore, the pressure during the high-pressure homogenization process is 30 MPa.

[0013] Furthermore, the heat sterilization treatment condition is heating at 72-79° C. for 10-15 minutes.

[0014] In the rapid preparation method of the lyophilized powder of berry juice of the present invention, the quick freezing treatment condition is quick freezing at -30 to -35°C for 15 to 30 minutes, and the core temperature is below -18°C.

[0015] In the rapid preparation method of the lyophilized powder of berry juice of the present invention, the quick freezing treatment is carried out in a quick freezing device.

[0016] Furthermore, the quick freezing is to transform the berry smoothie into solid berry ice cubes, and the vacuum freeze-drying time is reduced by pre-freezing treatment.

[0017] In the rapid preparation method of the lyophilized powder of berry juice of the present invention, the vacuum freeze-drying conditions are freeze-drying at -30 to -35°C for 24 to 36 hours and the vacuum degree is below 100 Pa.

[0018] Furthermore, the vacuum freeze-drying is to sublime the water in the berry ice cubes from a solid state to a gaseous state, so as to remove the water and obtain berry freeze-dried powder.

[0019] The present invention uses high-pressure gas charging equipment to charge carbon dioxide into the berry juice, combines pressure, temperature and other conditions to quickly reduce it to below freezing point and uses vacuum freeze-drying technology for drying. The invention can quickly change the berry juice from liquid to low-temperature loose solid. This short-term treatment is more suitable for rapid industrial production, with low energy consumption and high efficiency. In addition, by making it into a loose solid, the surface area of ​​the sample is greatly increased, the water sublimation efficiency is effectively increased, and the processing time of vacuum freeze-drying is reduced. This will greatly improve the high energy consumption and long cycle of vacuum freeze-drying technology, and is more suitable for rapid industrial production.

[0020] Beneficial effects of the present invention:

[0021] 1. Improve production efficiency: Through high-pressure inflation technology combined with specific pressure and temperature conditions, the berry juice is supercooled and quickly transformed into a porous solid smoothie. This step significantly shortens the time of making berry juice into smoothies, greatly reduces the particle volume of the smoothies, increases the surface area of ​​the smoothies, and significantly increases the water sublimation efficiency during the vacuum freeze-drying process.

[0022] 2. Reduce energy consumption: The present invention can quickly solidify the berry juice, increase the surface area of ​​the sample, and improve the water sublimation efficiency, thereby reducing the energy consumption required in the vacuum freeze-drying process. Compared with the traditional method, the present invention reduces energy consumption while maintaining product quality.

[0023] 3. Protect the stability of anthocyanins: Anthocyanins in berry are important biologically active substances, but they are easily degraded during processing. The present invention effectively reduces the loss of berry anthocyanins through rapid solidification and low-temperature treatment, ensures the anthocyanin content in the final product, and thus retains the functional activity of berry anthocyanins.

[0024] 4. Applicable to industrial production: The preparation method of the present invention is simple and easy to control, and the required equipment is relatively easy to obtain, so it is very suitable for industrial production. By optimizing the process parameters, large-scale, high-quality and rapid preparation of lyophilized berry juice powder can be achieved. DETAILED DESCRIPTION

[0025] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0026] The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0027] The rapid preparation method of the lyophilized powder of berry juice described in the following embodiment can be carried out according to the following process route diagram:

[0028] Berry fruit → cleaning → pressing → filtering → high-pressure homogenization → thermal sterilization → berry juice → high-pressure aeration → precise cooling → pressure reduction → quick freezing → vacuum freeze drying → berry juice freeze-dried powder

[0029] One of the specific implementations:

[0030] Step 1: Wash and crush fresh and non-rotten berry fruits, pass through a 200-mesh sieve, perform high-pressure homogenization at a pressure of 30 MPa, and perform heat sterilization at 72-79° C. for 10-15 minutes to obtain berry juice;

[0031] Step 2: inject the above-obtained berry juice into a sealed container, control the temperature to 8-12°C, then fill in carbon dioxide gas, control the pressure in the container to 0.38-0.45MPa, cool to -2-0°C, release the pressure within 30s, and obtain berry smoothie;

[0032] Step 3: Quickly freeze the obtained berry smoothie at -30 to -35°C for 15 to 30 minutes to obtain berry ice cubes, and finally freeze-dry them at -30 to -35°C in a vacuum state for 24 to 36 hours, wherein the vacuum degree is below 100 Pa, to obtain berry juice freeze-dried powder.

[0033] Example 1

[0034] A method for rapidly preparing lyophilized powder of berry juice comprises the following steps:

[0035] Step 1: Take 500g of fresh berry fruits, wash them, squeeze them, pass them through a 200-mesh sieve, and perform high-pressure homogenization at a pressure of 30MPa. After thermal sterilization at 75°C for 10 minutes, obtain berry juice;

[0036] Step 2: inject the obtained berry juice into a sealed container and lower the temperature to 12°C, then fill the container with carbon dioxide gas through a high-pressure gas filling device until the pressure in the tank reaches 0.38MPa; after the gasified berry juice is cooled to 0°C in a cold storage, the pressure in the container is released within 30 seconds to obtain berry smoothie;

[0037] Step 3: Place the obtained berry smoothie into a quick-freezing device, lower the temperature to -30°C and quick-freeze for 15 minutes to obtain berry ice cubes. Then place the obtained berry ice cubes into a vacuum freeze-drying device and dry them for 24 hours. The bottom plate temperature is -30°C and the vacuum degree is 50Pa to obtain berry juice freeze-dried powder, in which the anthocyanin retention rate is 95%.

[0038] Example 2

[0039] A method for rapidly preparing lyophilized powder of berry juice comprises the following steps:

[0040] Step 1: Take 2000g of fresh berry fruits, wash them, squeeze them, pass them through a 200-mesh sieve, and perform high-pressure homogenization at a pressure of 30MPa. Then, sterilize them at 78℃ for 12min to obtain berry juice.

[0041] Step 2: inject the obtained berry juice into a sealed container and lower the temperature to 8°C, then fill the container with carbon dioxide gas through a high-pressure gas filling device until the pressure in the tank reaches 0.40MPa; after the gas-filled berry juice is cooled to -2°C in a cold storage, the pressure in the container is released within 30 seconds to obtain berry smoothie;

[0042] Step 3: Place the obtained berry smoothie into a quick-freezing device, lower the temperature to -35°C and quick-freeze for 18 minutes to obtain berry ice cubes. Then place the obtained berry ice cubes into a vacuum freeze-drying device and dry them for 28 hours. The bottom plate temperature is -35°C and the vacuum degree is 100Pa to obtain berry juice freeze-dried powder, in which the anthocyanin retention rate is 94%.

[0043] Example 3

[0044] A method for rapidly preparing lyophilized powder of berry juice comprises the following steps:

[0045] Step 1: Take 5000g of fresh berry fruits, wash them and squeeze them, pass them through a 200-mesh sieve, and then perform high-pressure homogenization at a pressure of 30MPa, and sterilize them at 78℃ for 15min to obtain berry juice;

[0046] Step 2: inject the obtained berry juice into a sealed container and lower the temperature to 12°C, then fill the container with carbon dioxide gas through a high-pressure gas filling device until the pressure in the tank reaches 0.45MPa; after the gas-filled berry juice is cooled to -2°C in a cold storage, release the pressure in the container within 30 seconds to obtain berry smoothie;

[0047] Step 3: Place the obtained berry smoothie into a quick-freezing device, lower the temperature to -35°C and quick-freeze for 25 minutes to obtain berry ice cubes. Then place the obtained berry ice cubes into a vacuum freeze-drying device and dry for 36 hours. The bottom plate temperature is -35°C and the vacuum degree is 70Pa to obtain berry juice freeze-dried powder, in which the anthocyanin retention rate is 95%.

[0048] Comparative Example 1

[0049] A method for preparing lyophilized berry juice powder comprises the following steps:

[0050] Step 1: Take 500g of fresh berry fruits, wash them, squeeze them, pass them through a 200-mesh sieve, and then perform high-pressure homogenization at a pressure of 30MPa. Then, perform heat sterilization at 75°C for 10min to obtain berry juice;

[0051] Step 2: Place the obtained berry juice into a quick-freezing device, lower the temperature to -30°C and quick-freeze for 15 minutes to obtain berry ice cubes. Then place the obtained berry ice cubes into a vacuum freeze-drying device and dry them for 60 hours (consistent with the moisture content of the berry juice freeze-dried powder in Example 1). The bottom plate temperature is -30°C and the vacuum degree is 50Pa to obtain berry juice freeze-dried powder, in which the anthocyanin retention rate is 90%.

[0052] The difference between Comparative Example 1 and Example 1 is that high-pressure inflation and cooling steps are not performed in step 2, and other experimental conditions are the same as those in Example 1, such as the shape and placement of the sample during the freezing process.

[0053] The anthocyanin content was determined by the pH differential method, and the specific steps are as follows:

[0054] Two 1 mL samples were transferred into test tubes, and 9 mL of buffer solutions of pH = 1.0 and pH = 4.5 were added respectively. After being placed away from light for 1 h, the absorbance was measured at wavelengths of 520 nm and 700 nm using a UV-visible spectrophotometer.

[0055] Preparation method of pH=1.0 buffer solution: Mix 125mL potassium chloride solution with 375mL 0.2M hydrochloric acid solution, wherein the potassium chloride solution is obtained by diluting 3g potassium chloride to 200mL; 0.2M hydrochloric acid solution is obtained by diluting 43mL concentrated hydrochloric acid to 500mL to obtain 1M hydrochloric acid solution, and then take 100mL 1M hydrochloric acid solution and dilute to 500mL to obtain 0.2M hydrochloric acid solution. Preparation method of pH=4.5 buffer solution: Mix 500mL sodium acetate solution, 300mL 1M hydrochloric acid and 450mL water, wherein the sodium acetate solution is obtained by diluting 41g sodium acetate to 500mL.

[0056] The absorbance obtained above was substituted into the following formula to calculate the anthocyanin content, wherein the total anthocyanin in the sample was expressed as cyanidin-3-O-glucoside equivalent, TAC was the total anthocyanin concentration (mg), Mw was the relative molecular mass of cyanidin-3-O-glucoside (449), DF was the dilution factor, ε was the molar extinction coefficient of cyanidin-3-O-glucoside (26900), and L was the optical path (1 cm).

[0057]

[0058] Test results:

[0059] Table 1 Comparison of vacuum freeze drying time and anthocyanin retention rate in Example 1 and Comparative Example 1

[0060]

Claims

1. A method for rapidly preparing freeze-dried powder of berry juice, characterized in that: Inject the berry juice into a sealed container, control the temperature to 8-12°C, then fill in carbon dioxide gas, control the pressure in the container to 0.38-0.45MPa, cool to -2-0°C and release the pressure within 30 seconds to obtain berry smoothie, then perform quick freezing to obtain berry ice cubes, and finally perform vacuum freeze-drying to obtain berry juice freeze-dried powder.

2. The method according to claim 1, characterized in that: The temperature of the quick freezing treatment is -30 to -35°C, the core temperature is below -18°C, and the quick freezing time is 15 to 30 minutes.

3. The method according to claim 1, characterized in that: The vacuum freeze drying conditions are freeze drying at -30 to -35°C for 24 to 36 hours, with a vacuum degree of less than 100 Pa.

4. The method according to claim 1, characterized in that: The berry juice can be obtained by the following steps: washing the berry fruits, squeezing and crushing them, passing them through a 200-mesh sieve, and performing high-pressure homogenization and heat sterilization to obtain the berry juice.

5. The method according to claim 1 or 4, characterized in that: The pressure during the high-pressure homogenization process is 30 MPa.

6. The method according to claim 1 or 4, characterized in that: The heat sterilization treatment condition is heating at 72-79° C. for 10-15 minutes.

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