Concentrated fruit juice production method

Abstract

To provide a concentrated fruit juice production method which relates to concentrated fruit juice and which is simple in a production process and is excellent in practicality while preserving taste and an aroma of fruit.SOLUTION: A concentrated fruit juice production method includes: performing first water washing of fruit to be concentration-processed, thereafter sterilization washing of the fruit, and also second water washing of the fruit after the sterilization washing; then, removing flesh from the fruit after the second water washing and crushing the flesh to produce fruit juice as a processed ingredient; charging the processed ingredient into a vacuum pot 2, decompressing the interior of the pot, and performing concentration-processing by decompression-heating with a heating temperature of 50°C or more and 60°C or less and a heating time of 2 hour or more and 5 hour or less; and thereafter removing the concentrated processed ingredient from the vacuum pot 2 and sealing the concentrated processed ingredient in a bag which prevents oxidation deterioration to obtain a concentration-processed product.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing concentrated fruit juice, which is simple and practical and capable of retaining the fresh aroma of fruits. [Background technology]

[0002] Regarding the concentration of fruit juice, for example, Patent Document 1 discloses a method for producing a fruit spread, which includes a reduced pressure heating concentration step in which a feed material containing fruits and clarified concentrated fruit juice is concentrated at 65°C or less to obtain a concentrate so that part of the fruit pulp can retain its original shape, a heat sterilization step in which the concentrate is kept at 90°C or higher for 10 minutes or more, and a cooling step in which the concentrate is cooled to 70°C or higher and 85°C or lower within 2 minutes after the completion of the heat sterilization step.

[0003] Patent Document 2 also describes a method for producing a fruit extract, which includes two steps: a concentration step and a heating step (a heating temperature of 100°C is preferred), in which the moisture content of the fruit extract raw material is reduced to 10 to 40% by mass in the concentration step, and then the moisture content is maintained in the heating step, resulting in a high content of mumefural and a simple fruit extract production method that produces a high-quality flavor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7005980 [Patent Document 2] Patent No. 3452263 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional concentration of fruit juice or the like includes a heat sterilization step of the concentrate as shown in Patent Document 1, and also includes a high-temperature heating and pressurization step as shown in Patent Document 2. When the processed material is heated at high temperatures in this way, there is a concern that the taste, aroma, color, nutrients, etc. of the fruit may be lost.

[0006] Furthermore, the manufacturing process in Patent Document 1 includes a reduced pressure heating concentration step and a heat sterilization step, and Patent Document 2 also includes two steps, a concentration step and a heating step, making the manufacturing process complex and large-scale. Generally, known methods for concentrating fruit juice include boiling in a flat pot, vacuum concentration using a large device, and ultrafiltration using a semipermeable membrane. These concentration methods have the problem that the production line becomes large and complicated, resulting in high production and maintenance costs.

[0007] On the other hand, in farms producing fruits such as grapes, peaches, and pears, many fruits are discarded or have no market value. Some of these fruits are processed into juice or jam for further use, but such processing is generally carried out on a large scale in factories. For this reason, it is hoped that a practical production environment will be created in the local areas of fruit-producing farms, etc., to process fruit and produce products that use fruit juice on a relatively small scale and in a simple manner.

[0008] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a method for producing concentrated fruit juice which is simple in production steps, has excellent practicality, and also preserves the taste and aroma of the fruit. [Means for solving the problem]

[0009] In order to solve the above technical problems, the method for producing concentrated fruit juice according to the present invention comprises the steps of: first washing fruits to be concentrated with water; sterilizing and washing the fruits; then conducting a second water wash on the fruits after the sterilizing and washing; then removing the pulp from the fruits after the second water wash and crushing it to produce fruit juice as a processing material; putting the processing material into a vacuum kettle 2, reducing the pressure inside the kettle, setting the heating temperature to 50°C or higher and 60°C or lower for a heating time of 2 hours or higher and 5 hours, and performing concentration processing by reduced pressure heating; thereafter, removing the concentrated processing material from the vacuum kettle 2 and sealing it in a bag that prevents oxidative deterioration to obtain a concentrated processed product.

[0010] The method for producing concentrated fruit juice according to the present invention is configured to reduce the pressure inside the vacuum pot 2 to a pressure that reaches the boiling point of the heating temperature according to the heating temperature, and perform the heating and concentrating process.

[0011] The method for producing concentrated fruit juice according to the present invention is configured to use a double-structure vacuum kettle 2 in which an outer kettle 14 is provided outside an inner kettle 12 in which the processing material is placed, a liquid tank 16 is formed between the two kettle, and the liquid 15 in the liquid tank 16 is heated to maintain the temperature inside the inner kettle 12.

[0012] The method for producing concentrated fruit juice according to the present invention is configured to use an agitator 30 equipped with a Bernoulli flow agitator or a centrifugal agitator as an agitator 32, and to place either of the agitators 32 in the center of the inner kettle 12 of the vacuum kettle 2, thereby agitating the processing material in the vacuum kettle to generate a turbulent flow.

[0013] The method for producing concentrated fruit juice according to the present invention is configured such that punched or unevenly processed baffle plates 40 are arranged vertically on the inner wall of the inner pot 12 of the vacuum pot 2, and the turbulent flow of the processed material caused to flow by the stirring is brought into contact with the baffle plates 40, thereby finely breaking down any air bubbles generated in the processed material.

[0014] The method for producing concentrated fruit juice according to the present invention is configured to place a cylindrical body 42 having a punched or meshed cylindrical surface inside the inner pot 12 of the vacuum pot 2 and outside the stirring body 32, and bring the turbulent flow of the processed material caused to flow by the stirring into contact with the cylindrical body 42, thereby finely breaking down any air bubbles generated in the processed material.

[0015] The method for producing concentrated fruit juice according to the present invention is configured such that the concentrated processed material is transported to a quantitative filling machine 6 directly connected to the inner pot of the vacuum pot 2, where it is measured and filled into the bags for sealing.

[0016] The method for producing concentrated fruit juice according to the present invention is configured to use, as the bag, a high gas barrier bag or an oxygen absorbing film bag laminated with an oxygen scavenger so as to be able to remove dissolved oxygen from the contents.

[0017] The method for producing concentrated fruit juice according to the present invention is configured such that all steps, except for washing the fruit, from the subsequent processing steps until the concentrated processed product is removed from the vacuum cooker 2 and packed into the bag, are carried out in an ISO 7-8 clean room or an equivalent clean environment. Effect of the Invention

[0018] According to the method for producing concentrated fruit juice of the present invention, fruits are first washed with water, sterilized and washed with water, and then fruit juice is produced from the fruits after the second water wash as a processing material. The processing material is then placed in a vacuum kettle, the inside of the kettle is reduced in pressure, and the processing is concentrated by heating under reduced pressure at a heating temperature of 50°C to 60°C and a heating time of 2 hours to 5 hours. This is then sealed in a bag that prevents oxidation and deterioration to obtain a concentrated processed product. Since the processing steps are simple, there is no need for a high-temperature processing step due to the reduced pressure, oxidation of the processing material is prevented, and the processing time is short, the taste, aroma, color, nutrients, etc. of the fruit can be maintained. Furthermore, since the production scale is simple, maintenance and management are easy, and the process can be carried out on a small scale, making it practical and economical.

[0019] According to the method for producing concentrated fruit juice of the present invention, the pressure inside the vacuum pot is reduced to a pressure that reaches the boiling point of the heating temperature in accordance with the heating temperature, and the heating and concentration process is carried out. This has the effect of promoting active evaporation and accelerating the concentration of the processed materials, and also contributing to maintaining the quality of the processed materials.

[0020] According to the method for producing concentrated fruit juice of the present invention, a double-structure vacuum kettle is used as the vacuum kettle, in which an outer kettle is provided outside an inner kettle in which the material to be processed is placed, forming a liquid tank between the two kettle, and the liquid in the liquid tank is heated to maintain the temperature inside the inner kettle.This has the advantages that temperature control is easy and the temperature inside the vacuum kettle can be accurately adjusted, the structure is simple and can be operated on a small scale, and it is easy to maintain and control.

[0021] In the method for producing concentrated fruit juice according to the present invention, a stirrer equipped with a Bernoulli flow stirrer or a centrifugal stirrer is used to stir the processing materials in a vacuum kettle to generate turbulent flow. This separates dissolved gas from the processing materials and eliminates air bubbles in a short period of time, thereby preventing bumping, accelerating the evaporation of moisture from the processing materials, and maintaining a constant overall temperature.

[0022] According to the method for producing concentrated fruit juice of the present invention, punched or unevenly processed baffle plates are arranged vertically on the inner wall of the inner kettle of the vacuum kettle, and the turbulent flow of the processing material flowing due to stirring is brought into contact with the baffle plates. This has the effect that air bubbles generated in the processing material come into contact with the small holes and protrusions caused by the punching or uneven processing on the baffle plates and are finely broken up, thereby safely and reliably preventing the processing material from bumping.

[0023] According to the method for producing concentrated fruit juice of the present invention, a cylindrical body having a punched or meshed surface is placed inside the inner kettle of the vacuum kettle and outside the stirrer, and the turbulent flow of the processed material caused to flow by stirring is brought into contact with the cylindrical body. This has the effect that air bubbles generated in the processed material come into contact with small holes etc. caused by the punched or meshed process and are finely broken down, thereby safely and reliably preventing the bumping of the processed material.

[0024] According to the method for producing concentrated fruit juice of the present invention, the concentrated processed material is transported to a fixed quantity filling machine directly connected to the vacuum kettle, where it is measured and filled into bags for sealing. This has the effect of contributing to the production of hygienic and high-quality products, since a fixed amount of concentrated processed product is measured and directly filled into bags for sealing.

[0025] According to the method for producing concentrated fruit juice of the present invention, a bag with high gas barrier properties, or an oxygen absorbing film bag laminated with an oxygen scavenger and capable of removing dissolved oxygen from the contents, or a resin bag with excellent gas and water vapor barrier properties is used as the bag, which has the effect of preventing oxidation and deterioration of the product during storage, distribution, etc., and maintaining its freshness.

[0026] According to the method for producing concentrated fruit juice of the present invention, all the processes from the subsequent processing steps except for washing the fruit to removing the concentrated processed product from the vacuum cooker and packing it into bags are performed in an ISO 7-8 clean room or an equivalent clean environment. This reduces floating and falling bacteria in the production process and prevents the adhesion and infiltration of various germs, thereby contributing to aseptic processing and also contributing to the quality of the concentrated processed product. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of a processing device using a vacuum cooker or the like for concentration processing in relation to the production of concentrated fruit juice. [Diagram 2] FIG. 1 is a schematic diagram showing the inside of a vacuum cooker for producing concentrated fruit juice, in which (a) shows a longitudinal section and a cross section showing the arrangement of an agitator and a baffle plate, and (b) shows a longitudinal section and a cross section showing the arrangement of an agitator and a cylinder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the method for producing concentrated fruit juice according to the present invention will be described. The fruits used here include, for example, grapes, peaches, plums, pears, apples, mandarins, grapefruits, lemons, citrus fruits, plums, apricots, as well as watermelons, melons, pineapples, strawberries, blueberries, bananas, tomatoes, etc., and mainly those that can be processed into fruit juices such as juice.

[0029] In particular, grapes, peaches, plums, pears, and apples are produced in large quantities as fruits, so it is beneficial to use some of these fruits as processed products of concentrated fruit juice in terms of quality, etc. Of course, there is no problem with using other fruits as well, and the juice of these fruits that can be concentrated is used as the processing material, and this is concentrated in a vacuum pot to produce concentrated processed products.

[0030] Also, from the standpoint of sterilization and hygiene, it is effective to carry out all or part of the manufacturing process, from washing the fruit to concentrating and packaging the processed products, in a clean room or an equivalent clean environment. In terms of cleanliness class, this environment should be around ISO 7-8 (USA class 10,000-100,000) according to the International Organization for Standardization (ISO) standard.

[0031] The above-mentioned equivalent clean environment refers to an environment in which it is possible to ensure a level of cleanliness equivalent to that achieved by using the above-mentioned air purifier by thoroughly taking measures such as airtightness of the room, medium-performance filter air intake and exhaust (intake air:exhaust air = 1:0.8), cleaning of floors and equipment, changing clothes and managing behavior, etc., thereby reducing the suspension and generation of fine dust particles. Other types of clean rooms include clean booths, which are partitioned rooms, and modular clean units. Clean rooms generally use air purifiers with built-in filters to circulate the air in the room and maintain a certain level of cleanliness (ISO 7-8, etc.).

[0032] Here, taking into consideration the quality of the product, the cleanliness level is set to ISO 8, 7 or 6. By carrying out the concentration process in a clean environment, it is possible to reduce floating and falling bacteria, prevent the adhesion and infiltration of various germs, and improve the quality of the concentrated processed products. In addition, when maintaining a clean environment (overall process), it is desirable to spray a mist containing hypochlorous acid water either before or after use, or both before and after use.

[0033] The harvested fruit is first washed with water (first water washing) to remove dirt and germs. Next, the washed fruit is washed for sterilization. In this sterilization washing, the fruit that was previously washed with water is immersed in hypochlorous acid water for about 30 seconds to 1 minute to sterilize it. After this, the fruit is taken out and further washed with water (second water washing) to remove impurities.

[0034] The first water washing, sterilization washing, and second water washing correspond to the initial bacteria reduction, and it is believed that these sterilization processes can reduce the number of bacteria to one hundredth of the target (a three-digit reduction). This reduction in the initial bacteria can ensure reliable sterilization and also prevent the proliferation of bacteria in subsequent processes. In the production of this concentrated fruit juice, the subsequent heating and concentration can be carried out at a low temperature because sufficient sterilization has been achieved by the first water washing, sterilization washing, second water washing, etc., and therefore it is not necessary to carry out a high-temperature treatment step for sterilization.

[0035] In addition, all subsequent processing steps, except for the above-mentioned washing steps (first water washing, sterilization washing, and second water washing), are carried out in a clean room, which is effective in preventing the introduction of unwanted bacteria. These processing steps include processing the washed fruit into fruit juice, transporting it to a vacuum cooker, heating and concentrating it in the vacuum cooker, and removing the concentrated processed product from the vacuum cooker and filling it into bags, or vacuum-packing the bags. By carrying out all of these steps in a clean room, there is no risk of contamination by unwanted bacteria during each processing step, and a sterile environment is ensured.

[0036] Next, the skin, seeds, etc. are removed from the washed fruit to extract the pulp. The pulp is then crushed using a juicer or the like, filtered to extract the juice, and this is used as the processed material. Depending on the fruit, the skin, seeds, etc. may not be removed, and the fruit may be crushed as is, and the juice may be extracted by filtering. Alternatively, the pulp may be crushed and not filtered to produce a juice containing some of the pulp, which may then be used as the processed material. This produces a concentrated fruit juice with a different texture. In addition, no additives are added to the processed fruit material in order to preserve the flavor and aroma of the fruit. After this, the fruit juice as the processing material is heated under reduced pressure and concentrated. In this concentration process, the processing material is placed in a vacuum kettle 2, the pressure inside the kettle is reduced, and the processing material is heated and concentrated. This vacuum kettle 2 is used by reducing the pressure inside the kettle to a pressure lower than atmospheric pressure, the pressure inside the kettle is reduced, the processing material is heated, and the concentration process is performed by heating under reduced pressure.

[0037] In principle, the heating and concentrating process in the vacuum cooker 2 utilizes the phenomenon that the boiling point decreases as the air pressure decreases. When the air pressure inside the vacuum cooker 2 is lowered and the processing material (fruit juice) is heated, the processing material can be dehydrated (moisture removed) at a low temperature, that is, the water can evaporate, and the reduced pressure causes the moisture inside the processing material to seep out, so dehydration can be achieved all the way to the inside. In this way, the material to be processed is placed in the vacuum pot 2, decompressed, and heated at a low temperature to concentrate the material. In this concentration process, the material to be processed is heated and concentrated to obtain a concentrated product with a predetermined viscosity.

[0038] Fig. 1 shows a processing device for concentrating fruit juice by heating under reduced pressure. This processing device has a vacuum pot 2, a material container 4, a fixed-volume filling machine 6, a vacuum pump 10, etc. The vacuum cooker 2 is made of a metal such as stainless steel, and has a double structure consisting of an inner pot 12 and an outer pot 14 on the outside. A doughnut-shaped space is formed between the inner pot 12 and the outer pot 14, and this space serves as a liquid tank 16 filled with a liquid 15 (water in this case). In this way, the inside of the outer pot 14 is used as the liquid tank 16. An inlet 18 for the liquid 15 is provided between the upper part of the outer pot 14 and the inner pot 12. Here, the cross section of the inner pot 12 of the vacuum cooker 2 is circular, and the cross section of the outer pot 14 is also circular. Therefore, the side of the inner pot 12 is generally cylindrical, the bottom is semispherical (or conical), and the lid is flat (or convex). The outer pot 14 is formed to cover the bottom and sides of the inner pot 12, so that the liquid 15 in the outer pot 14 efficiently heats the material to be processed from the bottom and sides of the inner pot 12.

[0039] A heater (not shown) is placed in the outer pot 14 to heat the liquid 15 in the liquid tank 16 and maintain a predetermined temperature. This temperature management is performed by a control device, which controls the heater so that the inside of the inner pot 12 is maintained at a predetermined temperature. Here, water is used as the liquid 15. In addition to water, antifreeze such as ethylene glycol, propylene glycol, or an aqueous solution of these can also be used as the liquid 15. Antifreeze has heat retention and prevents rust, and is also effective in protecting the vacuum cooker 2. In the reduced pressure heating process using the vacuum cooker 2, the boiling point decreases as the air pressure decreases due to the reduced pressure. By using this phenomenon, the boiling point is reached by heating at a low temperature, thereby accelerating the evaporation of water. In addition, the reduced pressure in the vacuum pot 2 prevents oxidation of the processed materials, which contributes to the quality of the processed products.

[0040] The vacuum cooker 2 used here has an inner pot 12 with a capacity of 50 liters. When using this vacuum cooker 2, about 30 liters of the material to be processed are put in and processed, and the remaining 20 liters are used as a space. In order to provide this space, the diameter of the inner pot 12 and the distance between the liquid level of the material to be processed and the lid are set to be approximately the same (or within a ratio of 1:1 to 1.5). The reason for providing the space is to prevent the processing material from being erroneously sucked out through the exhaust port of the lid. In other words, if the distance of the space is insufficient, the processing material may be discharged from the exhaust port of the lid due to bumping or the like during exhaust from the lid, which may adversely affect equipment such as the vacuum pump. In order to prevent the erroneous suction, it is also effective to take measures to prevent bumping, such as installing an agitator. Additionally, a practical size for the inner pot 12 is about 30 to 80 liters.

[0041] The reason why the liquid 15 is used as the heat source medium for the vacuum cooker 2 is that the temperature for the concentration processing of the material in the vacuum cooker 2 can be accurately and relatively easily ensured, and is therefore suitable for the concentration processing according to the present invention. In addition, compared with a vacuum cooker that uses steam as a general heat source, the structure of the cooker can be simplified, making it practical and economical. The temperature of the liquid in the liquid tank 16 can be easily controlled, and the temperature of the liquid 15 and the temperature inside the inner cooker 12 can be accurately maintained. In this embodiment, no high-temperature processing is performed, but rather low-temperature processing is performed. In this low-temperature processing, a method of controlling the temperature of the liquid 15 in the liquid tank 16 of the vacuum cooker 2 is useful for heating and concentrating the processing material at low temperatures.

[0042] Then, the liquid 15 (here, water) in the liquid tank 16 is heated by a heater provided in the outer pot 14, thereby maintaining the temperature inside the inner pot 12. The temperature of the liquid 15 in the liquid tank 16 is directly reflected in the temperature of the processing material in the inner pot 12. Here, an electric heater is used as the heat generator, and the temperature is controlled by detecting the water temperature with a temperature detector and controlling the electric heater. The temperature of the vacuum cooker 2 (inner cooker 12) is controlled by the temperature of the liquid 15, which allows for accurate temperature control, is easy to control, and is economical. Therefore, the temperature control structure for this vacuum cooker 2 can be implemented in small-scale equipment, which greatly contributes to practical use.

[0043] The material container 4 of the processing device is a container for storing processing materials such as fruit juice. This material container 4 is connected to the inner pot 12 through a pipe A20. A valve for sending and stopping the material is provided in the middle of the pipe A20.

[0044] The inner pot 12 is sealed to reduce the pressure. An exhaust port 8 is formed near the top of the inner pot 12, and the air, steam, etc. inside the inner pot 12 are exhausted from the exhaust port 8 and sent to the vacuum pump 10 through the pipe C24. The vacuum pump 10 sucks the air from inside the inner pot 12, reducing the pressure inside the inner pot 12. A water-sealed vacuum pump is used as the vacuum pump 10.

[0045] The fixed-volume filling machine 6 measures and measures a fixed amount of the concentrated processed material and fills it into a bag. The fixed-volume filling machine 6 is directly connected to the inner pot 12 through a pipe B22. A valve is provided midway through the pipe B22. The processed material concentrated in the inner pot 12 is sent directly to the fixed-volume filling machine 6 through the pipe B22. The fixed-volume filling machine 6 weighs out a fixed amount of the processed material and fills it into a bag as a concentrated processed product. The bag is then manually set in a vacuum packaging machine, and the concentrated processed product is vacuum-packed. Therefore, the concentrated processed product processed in the inner pot 12 is sent directly to the quantitative filling machine 6 without being touched by human hands and filled into bags for sealing, thereby obtaining a hygienic product of good quality. The bags are bags for shipping, and after vacuum packing, the products are boxed and shipped as they are.

[0046] Here, the heating temperature in the inner pot 12 serving as the vacuum pot 2 is adjusted to a temperature of 50 degrees Celsius (50° C.) or higher and 60 degrees Celsius (60° C.) or lower, and the processing material is heated and concentrated at this temperature. If the heating temperature in the inner pot 12 is set below 50°C, a long heating time is required to concentrate the processed materials, which may affect the freshness of the processed materials and is not favorable in terms of production efficiency. For this reason, the heating temperature is set to 50°C or higher.

[0047] Furthermore, if the heating temperature is set to 60°C or higher, there is a concern that the enzymes in the fruit will be denatured and inactivated, reducing their activity, and it will be difficult to maintain freshness. Normally, concentration is carried out at high temperatures (60°C to 80°C) under reduced pressure, but this impairs the aroma and flavor. For these reasons, the heating temperature is set to 60°C or lower (or less than 60°C). After the sterilization, the concentration process is carried out at a relatively low temperature of 60°C or less for a treatment time of 2 to 5 hours, which has a sterilizing effect and contributes to sterility.

[0048] Thus, heat sterilization at high temperatures such as 75°C to 120°C is not performed here. The above-mentioned concentration process at a relatively low temperature prevents oxidation and thermal deterioration of the fruit, and maintains the flavor and freshness of the fruit. In addition, the above-mentioned process of reducing the initial bacteria such as washing allows the subsequent processing to be performed in a sterile condition, which contributes to the heat concentration at a low temperature. Depending on the type of fruit used for processing, pears and peaches have a high water content, while grapes and apples have relatively low water content. Therefore, by adjusting the concentration time according to the type of fruit used for concentration processing, the appropriate sugar content and viscosity can be obtained in the concentrated processed product. Similarly, the heating temperature is adjusted slightly if the sugar content or water content differs depending on the type of fruit used (watermelon, grapes, etc.).

[0049] In order to perform the concentration process by lowering the temperature in the vacuum cooker 2, the internal air pressure in the vacuum cooker 2 is lowered to lower the boiling point of the material to be processed. Then, the air pressure in the inner pot 12 of the vacuum cooker 2 is reduced by using the vacuum pump 10. Lowering the internal air pressure within the vacuum cooker 2 also contributes to preventing oxidation of the processed materials, and the color and flavor of the fruit juice as the processed materials can be maintained in good condition.

[0050] For example, the saturated water vapor pressure at a temperature of 50°C is 12.3 kPa, and at a temperature of 60°C it is 19.9 kPa. For this reason, when evaporating the moisture in the processing material, in the reduced pressure heating concentration, if the pressure (atmospheric pressure) in the inner pot 12 is reduced to 12.3 kPa, the boiling point will drop to 50°C, and if the pressure in the inner pot 12 is reduced to 19.9 kPa, the boiling point will be 60°C. Therefore, depending on the heating temperature of the material to be processed, the pressure inside the inner pot 12 is reduced and adjusted to the boiling point of that temperature.

[0051] In this case, for example, when the heating temperature is set to 55°C, if the pressure inside the inner pot 12 is set to the same as the steam pressure, there is no margin at the boundary of the boiling point. Therefore, to allow for margin of error, etc., and to maintain a constant boiling state, the pressure is set slightly lower (by a few percent). When the air pressure inside the inner pot 12 is reduced to the boiling point of the temperature inside the pot, the material to be processed boils due to heating, and vaporization begins from inside the material to promote evaporation of water, thereby enabling effective heating and concentration.

[0052] In the above-mentioned heating and concentration, if the pressure is appropriately reduced, the material will reach a boiling state at this temperature. In this case, the boiling point of the material to be processed will be slightly elevated due to the influence of impurities, etc., and the boiling point will be slightly higher than that of water. In practice, it is sufficient to determine the relationship between the heating temperature and the pressure at which the material to be processed boils by testing, etc. Even if the material to be processed does not reach its boiling point under reduced pressure, the water will evaporate and heating and concentration can be achieved as long as the heating temperature is appropriately adjusted, although the heating time will be longer.

[0053] Here, the heating temperature of the material to be processed is set to 50°C or higher and 60°C or lower, so that evaporation by boiling starts at the temperature with the internal pressure reduced, and the evaporation rate of the water increases. In other words, the internal pressure is adjusted to obtain the boiling point corresponding to each temperature from 50°C to 60°C or lower. Therefore, when the heating temperature is from 50°C to 60°C or lower and the material is concentrated by reduced pressure heating, if the pressure inside the inner pot 12 is reduced to the pressure at which the material boils at the temperature, evaporation is promoted by vaporization from the inside of the material, and the material can be concentrated efficiently. Here, the heating temperature is determined, the pressure inside the inner pot 12 is reduced so that the vapor pressure becomes the boiling pressure at this temperature, and the processing material is heated and concentrated in a boiling state to promote evaporation of water.

[0054] It has been experimentally confirmed that in the inner pot 12, in terms of the relationship between the surface area of ​​the liquid surface of the material to be processed and the liquid volume of the material to be processed (depth inside the pot), the greater the ratio of the surface area to the liquid volume, the shorter the concentration processing time. It has also been confirmed that in terms of the relationship between the spatial area inside the pot (height from the liquid surface to the upper lid body) and the liquid volume, the smaller the ratio of the spatial area to the liquid volume, the shorter the concentration processing time. From this, it can be considered that the processing time, etc. will be affected to some extent by the structure of the inner pot (horizontal cross-sectional area and height of the pot) and the amount of processing materials added, etc.

[0055] When the processing material is heated and concentrated inside the inner pot 12 of the vacuum pot 2, the movement of the processing material (fruit juice) is small due to thermal convection alone, and uniform temperature control of the entire processing material is desired. Furthermore, when the pressure inside the sealed inner pot 12 is reduced and heated, the air pressure drops and the temperature rises, and the gas dissolved in the liquid processing material (fruit juice) separates, generating a large amount of bubbles. In addition, in the case of processing materials (aqueous solutions) containing sugar and other ingredients, the surface tension is high, and the movement of the processing materials is small due to thermal convection alone. For this reason, a sudden large boil occurs due to stimuli such as vibration (bumping phenomenon), which hinders the concentration process and efficiency. In particular, when bumping occurs, the processing materials are sucked out from the outlet of the lid, which may have a negative effect on equipment such as vacuum pumps.

[0056] For this reason, we decided to use a stirrer to stir the processed material (fruit juice) in the kettle, which would cause the dissolved gas to separate and destroy the bubbles that would be generated. This stirring prevents the processed material from bumping and also keeps the temperature of the processed material constant. Furthermore, stirring causes the processed material to flow inside the sealed kettle, which separates the dissolved gas and quickly eliminates the bubbles that are generated when boiling. When boiling water to concentrate it, it is desirable for the bubbles to disappear in a short time.

[0057] As the agitator used for agitation, here we used an agitator 30 equipped with a Bernoulli flow agitator or a centrifugal agitator that utilizes centrifugal force. Note that a propeller-type agitator is not suitable because it creates a vortex up to the liquid surface and takes in gas from the air. 2(a) and (b), the agitator 30 is composed of an agitator 32 and an external motor 34, and for example, the agitator 30 is attached to a lid 36 on the top of the vacuum pot 2 (inner pot 12). This lid 36 is configured to be detachable from the periphery of the top of the inner pot 12, and when attached, the inside is sealed. An agitator 32 is placed inside the inner pot 12 of the vacuum pot 2, and is driven by an external motor 34 through a shaft 38 of the agitator 32, which is attached to a lid 36 equipped with a mechanical seal made of airtight packing. In addition, edible oil is used at the point on the lid 36 where the shaft 38 passes, to ensure safety.

[0058] When the agitator 30 using centrifugal force, such as the Bernoulli flow agitator, is used as the agitator 32, a turbulent flow is generated in the processed material (fruit juice) that is a mixture of ascending, descending, and horizontal flows, etc., due to the agitation caused by the rotation of the agitator 32. Furthermore, the agitator 30 is structurally capable of performing good agitation regardless of the degree of viscosity of the processed material (fruit juice). In addition, the agitator 32 separates dissolved gases by making the processing material flow inside the inner pot 12, reduces and eliminates bubbles that are generated when boiling, and suppresses bumping. In addition, agitation also promotes the evaporation of moisture from the processing material. In the heat concentration process here, the viscosity of the processed fruit juice increases gradually with the degree of concentration, and the mixer 30 is optimal because it can perform mixing that is adapted to this.

[0059] Here, in order to further enhance the effect of stirring by the stirrer 30, as shown in Fig. 2(a), a baffle plate 40 is disposed facing up and down on the inner wall of the inner pot 12 of the vacuum pot 2. This baffle plate 40 is a long and thin plate material (baffle plate) that is provided with holes (small holes), punchings formed by punching out shapes, or uneven protrusions all over the plate material. A plurality of baffle plates 40, for example 4 to 10, are attached vertically to the inner wall of the inner kettle 12. Here, eight baffle plates 40 are attached at equal intervals.

[0060] When the agitator 32 is rotated in the vacuum pot 2, the liquid surface of the processing material is not rippled due to the control action of the baffle plate 40, so the intake of gas is suppressed. Furthermore, by rotating the agitator 32, the processing material (fruit juice) is vigorously mixed and comes into contact with the small holes and protrusions of the baffle plate 40, turning the air bubbles into finer bubbles and suppressing bumping. Therefore, the bumping phenomenon of the processed material (fruit juice) is safely prevented by the baffle plate 40. Also, the water vapor that pops off the liquid surface smoothly moves toward the exhaust port 8 and is discharged by the vacuum pump 10. By suppressing the bumping phenomenon in this way, adverse effects on equipment such as the vacuum pump can also be prevented.

[0061] The baffle plate 40 is fixed to the inner wall of the vacuum cooker 2, but since the baffle plate 40 protrudes into the inner cooker 12, some consideration is required regarding the type and capacity of the processed material, the effort required for cleaning, etc. For this reason, a mechanism with a different form from the baffle plate 40 was considered, and as a result, a control method using a cylinder 42 was devised. As shown in Fig. 2(b), the cylindrical body 42 is concentrically disposed between the inner wall of the inner pot 12 of the vacuum pot 2 and the stirrer 32. In a test using this cylindrical body 42, it was confirmed that it had the same effect as the baffle plate 40.

[0062] The cylinder 42 is made of a plate-shaped material with a circular cross section, and this plate is made of a metal material that is finely punched all over, or a metal mesh material that is meshed all over. Therefore, the surface of the cylinder 42 is uneven with small holes formed all over. The cylinder 42 is placed inside the inner kettle 12, and for example, legs are provided on the lower side and fixed to the bottom of the inner kettle 12.

[0063] In this way, by disposing the cylinder 42 outside the agitator 32 and inside the inner pot 12, air bubbles contained in the processed material (fruit juice) vigorously mixed by the agitator 32 come into contact with the small holes in the punching or netting process and are broken down into fine air bubbles, suppressing bumping. Therefore, the bumping phenomenon of the processed material (fruit juice) is safely and reliably prevented, and the popped water vapor is smoothly discharged from the exhaust port 8 and sucked out by the vacuum pump 10.

[0064] In this heat concentration process, the processing material is stirred by the stirrer 32, so that the entire processing material, which has become viscous due to concentration, is mixed, the temperature is kept uniform, and the bumping phenomenon of the boiling processing material is suppressed. Furthermore, by placing a baffle plate 40 on the inner wall of the inner pot 12 of the vacuum pot 2, or by placing a cylindrical body 42 between the inner pot 12 and the stirrer 32, rippling of the surface of the processed material is suppressed, and the air bubbles in the processed material are finely broken down to prevent and suppress the phenomenon of bumping, so that the heating and concentration processing can be carried out in a good environment.

[0065] Next, the heating time is related to the heating temperature, and here the heating time is set to 2 to 5 hours. Usually, the lower the temperature in the pot, the longer the heating time will be, and the higher the temperature, the shorter the heating time will be. The heating time also differs depending on the fruit used. In essence, the relationship between heating time and temperature determines the quality of the product when the processed ingredients are concentrated, so the heating time is determined so as to obtain a product with the right sugar content and viscosity.

[0066] If the heating time is less than 2 hours, the degree of concentration of the processed materials will be insufficient, and shortening the time will require accelerating the concentration process. For this reason, if the heating temperature is unnecessarily high, it will affect the quality and will not be effective. The heating time is set to 5 hours or less because, while a heating time of more than 5 hours may damage the flavor (taste, aroma), color, nutrients, etc. of the fruit, about 5 hours is necessary to ensure a sugar content (Brix in the case of fruit juice, etc.) of 55% or more, and because an unnecessarily long heating time also reduces production efficiency, the heating time is set to 5 hours or less. Therefore, in cases where a slight decrease in the sugar content is acceptable, the heating time may be set to 4 hours or less.

[0067] As the heating time increases during the concentration process, the processed material gradually changes to a viscous paste-like state, that is, a semi-solid, semi-liquid state, soft and smooth. Usually, when the heating time is about 2 hours, the viscosity of the processed product is low and it becomes soft, and when the heating time is 4 to 5 hours, the viscosity of the processed product becomes high and it becomes hard.

[0068] In addition, the market is expected to require a viscosity for this concentrated processed product depending on the purpose of use. Therefore, the heating time is adjusted here so that the processed product can have an appropriate viscosity. In this way, the viscosity of the concentrated processed product can be appropriately adjusted by the simple method of adjusting the heating time. The concentrated processed product can be used as it is or after being diluted a little, in cakes such as pancakes and apple cakes, in sweets such as puddings and jellies, or mixed into chocolate, ice cream, etc. It can also be diluted with water and used as a beverage or juice.

[0069] In concentration processing, appropriate heating temperature and heating time are required to concentrate the processing material (fruit juice) well and to maintain the flavor of the processing material. Reducing the air pressure inside the vacuum kettle (inner kettle) is a means for maintaining the heating temperature and heating time at an appropriate level. The heating temperature and heating time have been derived based on experience in order to concentrate the processing material and obtain an appropriate sugar content and concentration without compromising the fruit flavor in the product. In this way, by heating and concentrating the materials in the pot under reduced pressure and at low temperatures, the flavor, aroma, color, etc. of the materials can be maintained, and the reduced pressure reduces the oxygen content, so the materials can be kept fresh and sufficiently preserved. In addition, even in the heating temperature environment of 50°C to 60°C during the concentration process, bacteria can be killed and reduced.

[0070] In this method for producing concentrated fruit juice, sterilization is carried out by reducing the initial bacteria through the first water wash, sterilization wash, and second water wash, etc., and the production process is carried out in a clean environment such as a clean room, which ensures a sterile state. Furthermore, sterility is achieved for the product produced through this concentration process by carrying out the concentration process at a temperature of 50°C to 60°C for a processing time of 2 to 5 hours.

[0071] After concentration in the vacuum pot 2, the concentrated juice is filled into bags by a quantitative filling machine 6, and the bags are vacuum-packed by a vacuum packaging machine. The bags are thin, plastic bags made of a synthetic resin film, which prevents the processed product from oxidizing and deteriorating. In the above-mentioned concentration process using reduced pressure and heating, oxidation of the processed materials is prevented by the concentration process using reduced pressure. In addition, the use of bags that prevent oxidation deterioration of the processed products contributes to maintaining the quality of the processed products. For example, there is an oxygen absorbing film bag that can remove dissolved oxygen from the contents by laminating an oxygen absorbing agent on the packaging material, and this uses a film that is difficult for oxygen to pass through. In addition, a high gas barrier resin bag that has excellent gas and water vapor barrier properties may also be used.

[0072] The high gas barrier bag is, for example, a laminated product such as aluminum foil or aluminum, alumina oxide, silicon dioxide (silica) or other inorganic vapor deposition film, and has an oxygen barrier property (barrier property) of 20 ml / m 2 Examples include the following: / 24hr / atm. Since the vacuum cooker 2 is almost in a vacuum state, the use of the oxygen absorbing film bag is effective because the oxygen absorber in the packaging material can further remove dissolved oxygen from the contents. The high gas barrier bag is used for vacuum packaging and gas-filled packaging, and has excellent gas and water vapor barrier properties, making it effective for storage, etc.

[0073] By using these bags, it is possible to prevent oxidation deterioration of concentrated fruit juice during the manufacturing, distribution and storage processes. Here, high gas barrier film bags with excellent gas barrier properties are used. There are also resin bags that have both oxygen removal and gas and water vapor barrier properties, so using these is also effective.

[0074] As described above, according to the method for producing concentrated fruit juice of this embodiment, the production scale is simple and the number of production steps is small, making it easy to maintain and manage, and since it can be implemented in small-scale equipment, it is practical and has the effect of contributing to the development of fruit-producing regions. Furthermore, by controlling the temperature, time, and air pressure in the vacuum kettle used for producing this concentrated fruit juice, it is possible to carry out heating and concentration processing at relatively low temperatures, which prevents oxidation and thermal deterioration of the fruit used as a processing material, and also has the effect of preserving the flavor of the fruit, and maintaining the taste, aroma, color, nutrients, etc. [Explanation of symbols]

[0075] 2. Vacuum Cooker 4 Material container 6 Quantitative filling machine 10 Vacuum Pump 12 Inner pot 14 Outer pot 15 liquid 16 Liquid tank 30 Stirrer 32 Stirring body 40 Baffle plate 42 Cylinder

Claims

1. After the first water washing of the fruit for concentration processing, the fruit is disinfected and washed, and then the fruit after the disinfection and washing is washed with water for a second time; Next, the pulp is removed from the fruit after the second water washing and crushed to produce fruit juice as a processed material; The material to be processed is put into a vacuum cooker, the pressure inside the cooker is reduced, the heating temperature is set to 50° C. or more and 60° C. or less, and the heating time is set to 2 hours or more and 5 hours or less, and the material is concentrated by heating under reduced pressure; Thereafter, the concentrated processed material is removed from the vacuum kettle and sealed in a bag that prevents oxidation and deterioration to obtain a concentrated processed product.

2. 2. The method for producing concentrated fruit juice according to claim 1, wherein the pressure inside the vacuum pot is reduced to a pressure that reaches the boiling point of the heating temperature according to the heating temperature, and the heat concentration process is carried out.

3. The method for producing concentrated fruit juice according to claim 1 or 2, characterized in that the vacuum kettle is a double-structure vacuum kettle in which an outer kettle is provided outside an inner kettle in which the processing material is placed, a liquid tank is formed between the two kettle, and the liquid in the liquid tank is heated to maintain the temperature inside the inner kettle.

4. The method for producing concentrated fruit juice according to claim 3, characterized in that a stirrer equipped with a Bernoulli flow stirrer or a centrifugal stirrer is used as the stirrer, either of the stirrers is placed in the center of the inner kettle of the vacuum kettle, and the processed material in the vacuum kettle is stirred to generate turbulence.

5. The method for producing concentrated fruit juice according to claim 4, characterized in that a baffle plate having a punching or uneven surface is arranged vertically on the inner wall of the inner pot of the vacuum pot, and the turbulent flow of the processing material caused to flow by the stirring is brought into contact with the baffle plate, thereby finely breaking down air bubbles generated in the processing material.

6. The method for producing concentrated fruit juice according to claim 4, characterized in that a cylindrical body having a punched or meshed cylindrical surface is placed inside the inner pot of the vacuum pot and outside the stirring body, and the turbulent flow of the processing material caused to flow by the stirring is brought into contact with the cylindrical body, thereby finely breaking down air bubbles generated in the processing material.

7. 5. The method for producing concentrated fruit juice according to claim 4, wherein the concentrated processed material is transported to a quantitative filling machine directly connected to the inner pot of the vacuum pot, where the concentrated processed material is measured and filled into the bags for sealing.

8. The method for producing concentrated fruit juice according to claim 7, characterized in that the bag is a high gas barrier bag or an oxygen absorbing film bag laminated with an oxygen scavenger so as to remove dissolved oxygen from the contents.

9. The method for producing concentrated fruit juice according to claim 7, characterized in that all steps from the subsequent processing steps, except for washing the fruit, to removing the concentrated processed product from the vacuum cooker and packing it into the bag are carried out in an ISO 7-8 clean room or an equivalent clean environment.

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