Freeze concentration method of fruit and vegetable juice

Abstract

The invention relates to a freeze concentration method of fruit and vegetable juice, and belongs to the technical field of fruit and vegetable juice processing and freeze concentration. According to the fruit and vegetable juice freeze concentration method, fruit and vegetable juice is frozen into ice, heat is transferred to the ice, and the concentration target is achieved through temperature-controlled dissolution. During dissolution, heat is transferred to an ice body in a proper heat transfer mode, and the freezing concentration effect and efficiency can be improved. In the ice body dissolving process, the concentration of the dissolved fruit and vegetable juice is gradually reduced from high to low. And according to the requirement of the target concentration, the solution is preserved in sections, so that the fruit and vegetable juice with different concentrations is obtained. The fruit and vegetable juice meeting the target concentration is transferred to the next link to be stored (utilized). The fruit and vegetable juice which does not conform to the target concentration can be repeatedly frozen and concentrated through the method, and the concentration of the fruit and vegetable juice is continuously increased. The method is simple in equipment and high in efficiency, and can be operated at normal pressure and low temperature, so that heat-sensitive nutrients and flavor substances contained in the fruit and vegetable juice are reserved, and the flavor of the fruit and vegetable juice is greatly improved.

Description

Technical Field

[0001] The invention discloses a method for freezing and concentrating fruit and vegetable juice, belonging to the technical field of fruit and vegetable juice processing and freezing and concentrating. Background Art

[0002] Fruit and vegetable juices are rich in nutrients and have a unique, delicious flavor. Their health benefits have made them a daily necessity for many people. However, the rich nutrients and unique flavor inherent in fruit and vegetable ingredients and juices place higher demands on the concentrated processing of these products. Freeze concentration, which operates at atmospheric pressure and low temperatures, preserves heat-sensitive nutrients and flavors, making it ideal for juice concentration. However, current freeze concentration equipment suffers from complex structures, high production costs, and low efficiency, making it less commonly used in juice production.

[0003] The method of the present invention freezes fruit and vegetable juice into a solid state (hereinafter referred to as ice) and achieves concentration by transferring heat to the ice through temperature-controlled dissolution, effectively improving the freeze-concentration effect and efficiency of fruit and vegetable juice. Furthermore, due to the high water content of the juice, the remaining ice in the final stage of dissolution is primarily water-based ice (crystals), which has a melting point of 0 degrees Celsius. The temperature of the crystals during the heating and dissolution process is maintained at their melting point (0 degrees Celsius), keeping the juice ice at a low temperature throughout the entire heating and dissolution process. This prevents potentially adverse biochemical changes and minimizes loss of aroma, flavor, and nutritional value in the juice. Summary of the Invention

[0004] The present invention is a method for freeze-concentrating fruit and vegetable juices, and belongs to the technical field of fruit and vegetable juice processing and freeze-concentration. A method for freeze-concentrating fruit and vegetable juices is described, wherein the fruit and vegetable juices are frozen into a solid state (hereinafter referred to as an ice body), heat is transferred to the ice body, and the concentration target is achieved by temperature-controlled dissolution. During dissolution, heat is transferred to the ice body using an appropriate heat transfer method, which can improve the effect and efficiency of freeze-concentration. During the dissolution of the ice body, the concentration of the dissolved fruit and vegetable juice gradually decreases from high to low. According to the needs of the target concentration, the solution is retained in sections to obtain fruit and vegetable juices of different concentrations. The fruit and vegetable juices that meet the target concentration are transferred to the next link for storage (utilization). The fruit and vegetable juices that do not meet the target concentration can be repeatedly freeze-concentrated using this method to continue to increase the concentration of the fruit and vegetable juice. This method has simple equipment, high efficiency, and can be operated at normal pressure and low temperature, so that the heat-sensitive nutrients and flavor substances contained in the fruit and vegetable juices are retained, and the flavor of the fruit and vegetable juices is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 It is a schematic cross-sectional view of a cylindrical freeze concentration device;

[0006] Figure 2is a schematic cross-sectional view of another cylindrical freeze concentration device;

[0007] Figure 3 A schematic diagram of a freeze concentration apparatus.

[0008] In the figure, 1- original solution bottle, 2- dilute solution, 3- heating tube, 4- heater chassis groove edge, 5- solution outlet, 6- sealing material, 7- ice body, 8- power socket protective cover, 9- socket, 10- temperature control switch, 11- solution outlet and switch valve. DETAILED DESCRIPTION

[0009] This method is now explained using schematic diagrams. The present method provides an example of a heat source placement: the heat source is positioned toward the ice (from the cooling surface) and perpendicularly away from the "cooling surface" (either inside or outside the ice). The following schematic diagram provides a simple qualitative description of this heat source placement.

[0010] Figure 1 This is a schematic diagram of a cross section of a cylindrical freeze concentration device. Fruit and vegetable juice is frozen into ice in this device. Figure 1 In (2), when the fruit and vegetable juice is frozen into a cylindrical ice body, the "central axis area" of the ice body is in the direction away from the "cooling surface". A heat source (heating rod) or multiple heat sources (multiple heat source rods) can be set in this area. Figure 1 Chinese (3).

[0011] Figure 2 This is a cross-sectional diagram of another cylindrical freeze concentration device. In this device, the refrigerant passes through the device from the central axis through a sealed pipe. Figure 2 (1). When freezing fruit and vegetable juice, the "cooling surface" is the outer wall of the refrigerant pipe. The heat source can be set in the ice body in the area close to the outer wall of the container (in the direction away from the "cooling surface"), or it can be set outside the container (outside the ice body), see Figure 2 Chinese (2).

[0012] Figure 3 This is a freeze concentration device made according to the method of the present invention. The device consists of a stock solution bottle and a heater. The heater is installed on the bottle cap of the stock solution bottle. The bottle cap has a solution outlet valve 11. Figure 3 Chinese (1) Figure 3 Chinese (2) Figure 3 Chinese (3).

[0013] The specific operation is as follows: inject the dilute solution into the original liquid bottle 1, cover the bottle cap, keep the bottle mouth facing upward and send the device into the freezer. After the dilute solution is frozen into a solid state (hereinafter referred to as ice body), move the device out of the cold storage and place it on the platform with the bottle mouth facing downward. Open the power socket protective cover 8, connect the power supply through the power socket 9, and set the heating temperature through the thermostat 10. Turn on the power switch, control the temperature and dissolve the ice body, and collect the solution in sections from the outlet valve 11 to obtain solutions of different concentrations. Solutions that meet the target concentration will proceed to the next working link. For solutions that do not meet the target concentration, this device can continue to freeze and concentrate to increase the concentration of the liquid.

[0014] Based on the above device and method, we compared the freeze concentration of two groups of thorny grape juice.

[0015] (1) Use three 60-liter barrels to load 56 liters of thorn grape juice (14.3% brix content) into each device. Name the barrels in each device A, B, and C. Use one 30-liter barrel to load 25 liters of thorn grape juice (14.3% brix content) into each device. Name the barrel in this device D. Transfer the barrels (devices) of thorn grape juice (A, B, C, and D) to the freezer.

[0016] After the thorny grape juice is frozen into ice, the thorny grape juice ice in four devices (four barrels) is moved out of the freezer, and then a comparative experiment on the dissolution and concentration effect is conducted.

[0017] (1) Bucket A (not heated) uses natural dissolution.

[0018] (2) Tanks B, C, and D are heated and dissolved according to the above-mentioned method. Tank B is heated to 45 degrees Celsius (the temperature of the heating rod), and Tanks C and D are heated to 65 degrees Celsius (the temperature of the heating rod) to dissolve the ice. As the ice dissolves, the outflowing solution temperature is monitored to remain below 0 degrees Celsius.

[0019] Two target concentrations were set for recording: the first target concentration was 30% sugar (refractive index), and the second target concentration was 18% sugar (refractive index). The liquid effluent from the ice melt in buckets A, B, C, and D was collected. The experimental results are recorded in Tables 1, 2, 3, and 4.

[0020] Table 1: Data recorded for barrel A (56L juice, original refractive index 14.3%), natural dissolution

[0021]

[0022] Table 2: Data recorded for bucket B (56L volume, original refractive index of juice, 14.3%), heating temperature (45°C)

[0023]

[0024] Table 3: Data recorded for barrel C (56L volume, original refractive index of juice, 14.3%), heating temperature (65°C)

[0025]

[0026] Table 4: Data recorded for bucket D (25L juice, original refractive index 14.3%), heating temperature (45°C)

[0027]

[0028] (1) Comparison of the recorded data of buckets A, B, and C:

[0029] (1) The volumes of the three barrels of thorn grape juice obtained at the first target concentration (refractive sugar content 30%) were 0.5 L, 14.1 L, and 13.2 L, respectively, accounting for 4.5%, 25.18%, and 23.6% of the original solution volume, respectively. It can be seen that the concentration effect of the method of the present invention is significantly superior to that of the natural dissolution method (the existing "ice slip" technology) in the high-concentration range: the volume of the high-concentration solution obtained by the method of the present invention is 26 times that of the existing method (the natural dissolution method).

[0030] (2) Comparison of ice dissolution and separation rates (L / hour): 0.5 L / hour, 1.47 L / hour, and 1.65 L / hour. The ice dissolution and separation rate of the present method in the high-concentration range is more than 2.94 times that of the existing method (natural dissolution method).

[0031] (3) The data of the sugar content (refractive index) below 5% in the three barrels are: 19.6%, 49.46%, and 44.8%. In other words, it can be seen that the concentration and separation effect of the present invention is significantly higher than that of the natural dissolution method, exceeding 2.3 times.

[0032] (2) Comparing the recorded data of buckets B, C, and D

[0033] (4) Comparing the data from buckets B and C, it can be seen that: for the same ice volume, the higher the heater temperature, the faster the ice dissolves and separates. The outlet temperature of the solution is all below 0 degrees Celsius. (5) Comparing the data from buckets B and D, it can be seen that: for a constant heating temperature, the smaller the ice volume, the faster the ice dissolves and separates.

[0034] It can be seen that after the thorn grape juice is frozen into ice, heat is transferred to the ice to dissolve it, which greatly improves the efficiency of freeze concentration. This method has the advantages of simple equipment, low cost, easy operation, high efficiency and low production cost.

[0035] The above embodiment is only one example and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the protection of the present invention.

Claims

1. A method for freeze-concentrating fruit and vegetable juice, characterized in that: A method for freeze-concentrating fruit and vegetable juices is to freeze the fruit and vegetable juice into a solid state (hereinafter referred to as ice body), transfer heat to the ice body, and achieve the concentration goal by temperature-controlled dissolution. During dissolution, using an appropriate heat transfer method to transfer heat to the ice body can improve the effect and efficiency of freeze concentration. During the dissolution of the ice body, the concentration of the dissolved fruit and vegetable juice gradually changes from high to low. According to the needs of the target concentration, the solution is retained in sections to obtain fruit and vegetable juices of different concentrations. Fruit and vegetable juices that meet the target concentration are transferred to the next link for storage (utilization). Fruit and vegetable juices that do not meet the target concentration can be repeatedly freeze-concentrated using this method to continue to increase the concentration of the fruit and vegetable juice. This method has simple equipment and high efficiency, and can be operated at normal pressure and low temperature, so that the heat-sensitive nutrients and flavor substances contained in the fruit and vegetable juice are retained, and the flavor of the fruit and vegetable juice is greatly improved.

2. The method for freeze-concentrating fruit and vegetable juice according to claim 1, characterized in that: After the fruit and vegetable juice is frozen into a solid state (hereinafter referred to as ice body), heat is transferred to the ice body to melt it. The heat transfer method includes (but is not limited to the listed methods): directly heating the ice body, heating the ice body after crushing it, or setting a heat source at a specific location inside or outside the ice body for heating, etc.

3. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: The "specific direction" where the heat source is set is a directional area. For example, when looking at the "cooling surface" during freezing, the "specific direction" is the direction perpendicularly away from the "cooling surface" (hereinafter referred to as the direction away from the "cooling surface"), toward the ice body (from the "cooling surface"). This area can be inside or outside the ice body, at the direction farthest from the "cooling surface" or at a relatively distant location. When fruit and vegetable juice is frozen into ice, based on the solute content of the ice body, the "specific direction" is a directional direction from an area with low solute content (near the "cooling surface") toward an area with high solute content. This area can be the direction with the highest solute content in the ice body or a relatively high direction; it can be inside or outside the ice body. These two directions refer to the same area.

4. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: One or more heat sources can be set as needed.

5. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: The fruit and vegetable juice can be placed in a container that is pre-equipped with a heat source device, and then frozen into ice. The setting requirements of the heat source in the device are: when the fruit and vegetable juice is frozen into ice, the heat source is located away from the "cooling surface".

6. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: After the fruit and vegetable juice is frozen into ice in the container, the heat source can be installed away from the "cooling surface" by drilling holes in the ice (or other mechanical methods).

7. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: When transferring heat to the ice body, gradually increasing the temperature of the heat source from a low temperature (slightly above the "eutectic point" temperature) can improve the freeze concentration effect and efficiency.

8. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: Under the same heat transfer conditions, changing the size and shape of the fruit and vegetable juice container of the freeze concentration device can affect the concentration enhancement effect and efficiency.

9. The method for freeze-concentrating fruit and vegetable juice according to claim 1, wherein: Suitable for various fruit juices, various vegetable juices, and frozen concentration of fruit and vegetable juices.

Images