JPH06292546A - Production of fruit juice - Google Patents

Abstract

PURPOSE:To remove bacteria without removing flavoring ingredients by carrying out the sterilizing filtration of a raw fruit juice under pressure with a ceramic filter without using a precoating material. CONSTITUTION:A raw fruit juice is circulated from a tank 1 through a ceramic filter 3 to the tank 1 with a pump 2. The resultant permeated liquid subjected to sterilizing filtration is then filled in a container with a filling device 4 and N2 gas is introduced into the tank 1. The hermetically sealed system is kept under pressure to cool a part of the circulating fruit juice with a shell-and-tube heat exchanger 5.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing fruit juice. More specifically, the present invention relates to a method for producing a fresh juice having a good flavor by preventing heat sterilization from being omitted or simplified by effectively filtering the raw juice and thus preventing the production of off-flavor.

[0002]

2. Description of the Related Art In the production of fruit juice by a conventional method, fresh fruits are squeezed and heat-sterilized. This is to prevent spoilage and deterioration due to bacterial growth during storage or distribution. This heat sterilization is over 65 ℃, usually 9
It is carried out by heating at 0 ° C to 120 ° C, which often produces off-flavor substances. For example, the fruit juice of citrus fruits such as oranges and oranges contains a substance called methylmethionine sulfonium (MMS),
This MMS is changed into dimethylsulfonium (DMS) which is a causative substance of potato odor by heating. Particularly, since the fruit juice of Satsuma mandarin contains a relatively large amount of MMS, when the fruit juice was heated, DMS was produced, and there was a drawback that it had an offensive odor.

For this reason, various methods of producing juice without heat sterilization have been proposed, examples of which include an ultrahigh pressure sterilization method and a membrane separation method. Among them, the ultra-high pressure sterilization method applies a high pressure of 4000 atm, so that the apparatus becomes huge, and continuous processing cannot be performed, which makes mass production difficult. On the other hand, the membrane separation method does not require the use of such an ultrahigh pressure, the apparatus is easy to handle, continuous or semi-continuous processing is possible, and it is suitable for mass production. Therefore, attempts have been made to apply the membrane separation method to sterilization of fruit juice to omit or simplify heat sterilization.

The use of the membrane separation method for the concentration and purification of fruit juice has already been put into practical use. For example, a reverse osmosis membrane is used to concentrate tomato juice, and an ultrafiltration membrane is used to clarify apple juice. In the case of concentrating tomato juice using a reverse osmosis membrane, it is possible to produce high-quality juice having a better color tone and texture and a high residual rate of vitamin C, lycopene pigment, etc., as compared with the atmospheric pressure heating method and vacuum evaporation method. Further, in the case of clarification of apple juice, by using suitable membrane separation conditions, it is possible to remove only pulp and pectin without removing useful components, and when using pectin-degrading enzyme and precoat filtration. In comparison, it is possible to produce high-quality juice that is excellent in transparency and flavor and does not cause secondary precipitation.

[0005]

However, when the sterilization treatment of the fruit juice is carried out by using the membrane separation method, there is an aspect which is quite different from the above-mentioned concentration and clarification, and the above-mentioned practical application is carried out. Membrane separation technology cannot be applied as it is. For example, the concentration of fruit juice removes only water from a multi-component mixture, so the already established reverse osmosis technique should be used to create conditions under which only water is permeated and useful components are not permeated. Setting is basically less difficult (ie except for the need to consider factors such as membrane fouling, physical strength of the membrane or drug resistance). On the other hand, in the clarification of fruit juice, the objects to be removed are suspended substances and macromolecules, and the permeate side is collected as a product, contrary to the above-mentioned concentration of fruit juice, but the suspended matter and colloidal substances are permeated Permeation of smaller molecules together with water without being allowed is within the scope of already established microfiltration or ultrafiltration technology, and it can be said that the basic condition setting thereof is not so difficult. That is, when the juice is concentrated or clarified, the components to be permeated and the components to be retained on the concentrated liquid side can be relatively clearly distinguished due to the difference in molecular size, etc., and the separation characteristics of the membrane are not so sharp. However, it does not matter in practice.

On the other hand, in the case of sterilization filtration of fruit juice,
There is a request that almost 100% of the bacteria in the fruit juice must be removed, and there is a request that useful components that give the taste and aroma peculiar to each fruit juice must be permeated as much as possible. It is not always easy to set filtration conditions that meet the purpose, since bacteria and their components cannot be clearly distinguished due to differences in size and properties. In addition, conventionally, microfiltration has been used for the production of sterile water and the capture and concentration of bacterial cells, but the liquid to be filtered in these cases is generally highly purified water, and has a complicated composition such as fruit juice. It does not selectively remove only the bacteria from the liquid containing. That is, in the sterilization filtration of beverages, a higher degree of selectivity, that is, a sharp separation characteristic is required as compared with the concentration and clarification of fruit juice or the production of sterile water.

If heat sterilization is omitted or simplified by performing sterilization filtration, this sterilization step must be highly reliable. The microfiltration membranes that have been used for the production of sterile water and the capture and concentration of bacterial cells are organic polymer membranes, and the rigidity of the membrane structure is not so large, so continuous filtration is performed on an industrial scale. In that case, the reliability is not necessarily high in terms of absolutely preventing the leakage of bacteria, and the heat resistance of the membrane material is not so great.
There is a drawback that it is difficult to heat sterilize the membrane itself. For this reason, when performing sterilization filtration of fruit juice using a conventional organic membrane, heat sterilization cannot be omitted or simplified, and the advantage of performing sterilization filtration by membrane separation cannot be fully utilized.

If a ceramic film is used instead of the organic film,
Since the membrane has high rigidity and heat resistance, it is expected that the above reliability problem can be solved. For example, it has been proposed to use a ceramic membrane for sterilization filtration of fruit juice (Japanese Patent Application Laid-Open No. 60-184373). . However, with the silica-alumina-based ceramic membrane used therein, it is virtually impossible to obtain an effective bactericidal effect without the precoating method using a filter aid. In that case, in fruit juices such as citrus fruits, the presence form of the flavor component is different from that of the fruit fruits, and the peculiar flavor is lost by precoat filtration, so it is said that this method cannot be applied to such fruit juices. . In general, the precoat method has a feature that it can evenly collect from large particles to considerably small particles due to the adsorption effect and the compaction effect of the precoat layer, but on the other hand, since the separation is not sharp, it is similar to sterilization filtration of fruit juice. It is not always suitable for the purpose of selectively removing only bacteria. After all, if ceramic membranes were used instead of organic membranes simply because of their high mechanical strength and heat resistance, the use of precoat materials was virtually indispensable for effective sterilization, and therefore fruit juice Achieving the intended purpose of permeating as much as possible the active ingredients that bring about the flavor peculiar to each fruit juice in the sterilization filtration of
It can be said that the conventional techniques were generally difficult. That is, in order to simultaneously satisfy the high reliability and high selectivity required for sterilization filtration of fruit juice, a new examination of the filtration conditions centered on the filter medium is necessary.

Further, in order to enhance the effect of suppressing the production of off-flavor substances, it is not enough to carry out effective sterilization filtration to omit or simplify heat sterilization, and it is necessary to suppress heat generation throughout the manufacturing process. There is. For example, when pressurizing the inlet side of the membrane module in order to obtain the differential pressure required for the filtration, pressurizing with a centrifugal pump generates a considerable amount of Joule heat in the pump, thereby generating an off-flavor substance. . It is necessary to circulate the liquid in order to give a flow velocity parallel to the membrane surface, but it is not preferable to use a circulation pump for this purpose because it causes a large heat generation and a large cause of off-taste substances. .

In addition, it is important to prevent contact between fruit juice and oxygen in the entire manufacturing process. Vitamin C is generally contained in fruit juice, but since this vitamin C is easily oxidized, excessive contact with oxygen significantly reduces the content of vitamin C in the product juice. In addition, since the fruit juice of pome fruit causes browning in the presence of oxygen, it is necessary to suppress contact with oxygen as much as possible.

[0011]

Means for Solving the Problems The present inventors have been able to perform effective sterilization filtration without using a precoat material by using a certain type of ceramic membrane, and in such a manner, removal of fruit juice can be performed. We have found the condition that bacteria that cause spoilage and deterioration can be selectively removed without removing the aroma component peculiar to various fruit juices by filtering the bacteria. This makes it possible to omit or simplify the heat sterilization in the fruit juice production process, and suppress or prevent the generation of off-flavor components and sediment due to heating.

In this case, it is preferable to seal the entire process including the sterilization filtration step with a gas that does not contain oxygen, which prevents bacteria from entering the system from the air and eliminates the bacteria to be removed. Since only the juice originally contained in the juice, hygiene control of the process is facilitated and the oxidation of the juice is suppressed. Further, by suppressing the heat generation in the circulation pump by supplying the differential pressure necessary for sterilization filtration by gas pressurization, it is more effective to suppress the generation of off-flavor components, in addition to omitting or simplifying the heat sterilization. is there. In addition, if the residual pressure in the filtration step is used for the filling step, the entire step is further simplified.

[0013]

The present invention is characterized in that the raw fruit juice is directly filtered through the ceramic membrane without using the precoat material. When precoat filtration is performed using the precoat material, most of the suspended particles of bacteria and other substances are trapped in the precoat layer, so even if a ceramic membrane is used, it functions as a simple support. Only. On the other hand, in the method of the present invention, since the precoat material is not used, the ceramic film itself captures bacteria. In order to effectively remove bacteria, the pore size of the ceramic membrane is said to be 0.45 micron or less. When the precoat material is used, a wide range of particles including bacteria are captured due to the compaction effect and the adsorption effect of the precoat material.
Direct filtration through a specific ceramic membrane having a pore size of 0.45 micron selectively traps microorganisms and permeates almost all flavor components specific to various juices without removal. Although the optimum value of the pore size is slightly different depending on the type of fruit juice to be targeted, generally, the one having the pore size (nominal value) of about 0.1 to 0.2 μm is most preferable.

In principle, the method of the present invention surely prevents the growth of bacteria in the fruit juice of the product without heat sterilization. Therefore, it is necessary to prevent inadvertent contamination of bacteria into the system. Therefore, it is preferable to seal the whole process with gas. As a gas for this purpose, a gas containing no oxygen is used from the viewpoint of preventing oxidation, but nitrogen gas is particularly preferable from the viewpoint of physicochemical characteristics and availability.
In particular, since the fruit juice of pome fruit has a property that browning proceeds due to the presence of oxygen, it is necessary to take care not to mix oxygen when the fruit juice of pome fruit is contained.

The differential pressure required for filtration depends on the pore size and its distribution, the viscosity of fruit juice, or the filtration rate. When the required differential pressure is small, a suction filtration method in which the inlet side is set to atmospheric pressure and the permeate side is depressurized may be used, but this method cannot obtain a differential pressure above atmospheric pressure, so normally the inlet side is pressurized. Uses pressure filtration method. In the case of a pressure filtration system, a pump for pressurization can be used as a means for applying a necessary pressure, but if a spiral pump is used, for example, the flow rate will necessarily be reduced to enlarge the head,
As a result, the flow velocity parallel to the membrane surface cannot be kept high, which causes the accumulation of suspended matter near the membrane surface, and causes significant heat generation and cavitation in the pump. On the other hand, when a plunger type pump is used as the pressurizing pump, a higher pressure is generally obtained as compared with the spiral type, but pulsation is unavoidable and it is generally difficult to obtain a large flow rate. There is. Therefore, it is preferable to use gas pressurization as the pressurizing means. By using a means other than the pump as the pressurizing means, the pump is used only for the purpose of circulation, and thus a large head is not required. Therefore, even if the flow rate is large, the power required for the pump is small and the heat generation in the pump is small.

Alternatively, as means for suppressing a temperature rise due to heat generation in the pump, a heat exchanger may be provided in the circulation path of the membrane module to cool the fruit juice in the circulation path. By doing so, some heat generation in the pump is allowed, so that it is possible to cover all or part of the differential pressure required for filtration by pressurizing the pump. That is, since the temperature of the fruit juice in the circulation path reaches equilibrium when the balance between the amount of heat generated by the pump and the amount of heat released (cooled) by the heat exchanger is reached, changing the cooling capacity of the heat exchanger The temperature can be controlled. Of course, if all of the differential pressure is applied by gas pressurization and the heat generated by the circulation pump is removed by cooling with a heat exchanger, the temperature rise of the fruit juice can be suppressed to the maximum. It is preferable that the gas used for pressurization also does not contain oxygen gas, and the gas for sealing the whole process can be used as the gas for that purpose.

The sterilized and filtered fruit juice is blended as it is or after being blended as needed, and then filled in a container to obtain a product. When directly filling the container, the residual pressure remaining in the permeated liquid that has undergone the sterilization filtration step can be used in the filling step. In this case, it is possible to consistently perform the steps from the sterilization filtration to the filling step in a predetermined gas atmosphere.

Alternatively, oxygen dissolved in the fruit juice may be removed by performing deaeration before filling the juice-filtered fruit juice into a container. By adding a deaeration step, oxidation of vitamin C and browning of fruit juice of pome fruit can be considerably suppressed as a whole process without performing sterile filtration in a strictly inert gas atmosphere. In addition, since the oxygen originally contained in the raw juice itself can be removed, there is an effect that the oxidation after this process is further prevented. Of course, it is most preferable to perform sterilization filtration under an inert gas atmosphere and provide a deaeration step from the viewpoint of preventing oxidation and browning.

As the degassing method, various means such as vacuum degassing can be used. However, in vacuum degassing, the residual pressure after that becomes zero, and therefore, when the container is filled with the filtered fruit juice, it must be pressurized again. As a measure to solve this point, there is a membrane degassing method using a gas separation membrane. This method is a method of drawing a vacuum through a gas separation membrane that allows only dissolved gas molecules to pass through without allowing liquid to pass through. According to this method, only gas molecules are removed while the liquid pressure is maintained. As the pressure for supplying the permeated liquid to the membrane deaerator, the residual pressure after sterilization filtration can be used. In addition, since the permeated liquid from which solids have already been removed by the ceramic membrane is subject to membrane degassing, it is not necessary to provide a special prefilter for the membrane degassing device, and a hollow fiber type gas separator with high degassing efficiency is also provided. Membranes can be used.

The fruit juice to which the method of the present invention is applied includes
It mainly contains citrus fruits such as Satsuma mandarin oranges, oranges and grapefruits, apples, pears and other fruit fruits, and fruit juices such as grapes, kiwis, strawberries and peaches that produce off-flavor components when heated. Needless to say, the method of the present invention can be applied to the production of any beverage product that has been required to be heat sterilized, but is not limited thereto. In addition, the method of the present invention is not only provided to consumers in the form of being filled in a container along a distribution channel, but also a beverage product that is provided to customers in a restaurant or the like as it is after sterile filtration. Is also targeted.

[0021]

EXAMPLE 1 FIG. 1 shows an example of the process flow of a suitable apparatus for carrying out the method of the present invention. In FIG. 1, a stock solution obtained by squeezing fruits is put in a stock solution tank 1, and is circulated again through a circulation pump 2 and a ceramic membrane filter 3 to return to the stock solution tank. In the ceramic membrane filter 3, the stock solution is sterilized and filtered,
The permeated liquid is filled in a container by the filling device 4 to form a product. In addition, a part of the undiluted solution circulating through the circulation path passes through the shell-and-tube heat exchanger 5 and is cooled. The circulation passage and the passage of the permeated liquid from the ceramic membrane filter 3 to the filling device 4 are closed, and nitrogen gas is introduced into the stock solution tank 1 to keep the closed system under pressure. Since this device does not use heat-sensitive members, it is possible to sterilize the entire device with steam.

Example 2 FIG. 2 shows another example of the process flow of a suitable apparatus for carrying out the method of the present invention. This device is shown in Figure 1.
In the above device, a degassing device 6 for the permeated liquid is further provided. The deaerator 6 is preferably a membrane deaerator using a hollow fiber type gas separation membrane, and the permeate side of the membrane is evacuated by a vacuum pump 7.

Example 3 FIG. 3 shows another example of the process flow of a suitable apparatus for carrying out the method of the present invention. This device is shown in Figure 1.
In the above apparatus, pump pressurization is used instead of nitrogen gas pressurization. Therefore, nitrogen gas is used only for the purpose of sealing, and the differential pressure required for sterilization filtration is the circulating pump
Supplied by In this case, since the circulation pump generates heat, the cooling capacity of the heat exchanger 5 must generally be made larger than that of the device of FIG. 1 in order to suppress generation of off-flavor due to heat.

Example 4 FIG. 4 shows another example of the process flow of a suitable apparatus for carrying out the method of the present invention. This device is shown in Figure 3.
2 is provided with a degassing device 6 for the permeated liquid and a vacuum pump 7 as in the case of the device of FIG.

Example 5 FIG. 5 shows another example of the process flow of a suitable apparatus for carrying out the method of the present invention. This device omits the sealing with nitrogen gas and removes dissolved oxygen by the degassing device 6. In this case, it cannot be expected to reduce the amount of dissolved oxygen in the fruit juice in the steps up to the sterilization filtration step,
It is not suitable for fruit juices such as pome fruits that are particularly reluctant to contact with oxygen, but can be used when the demand for antioxidant is not so strict.

Example 6 FIG. 6 shows another example of the process flow of a suitable apparatus for carrying out the method of the present invention. This device omits not only the sealing by nitrogen gas but also the deaeration device. Therefore, it can be used only when there is no request for antioxidant, or when the original juice does not contain oxygen and there is almost no penetration of oxygen into the system.

Example 7 According to the following conditions, the apple juice immediately after being squeezed was filtered by nitrogen pressure by a membrane separation method to remove bacteria, and the permeated juice of 100 ml in internal volume was directly added in a nitrogen atmosphere without heat sterilization. Fill into a glass jar. Stock solution tank: 50 liter Membrane filter: Made by Nippon Insulator Material Alumina monolith type, length 1000 mm, outer diameter 30 mmφ inner diameter 3 mmφ × 37 pieces Membrane area 0.35 m ² Operating pressure: 170 kPa Membrane surface velocity: 3 m / s Membrane pore diameter: 0 .1 micron Regarding the permeated fruit juice, the number of general bacteria was counted by a plate method using a standard agar medium, the number of lactic acid bacteria was counted by a plate method using an MRS medium, and the number of yeasts was counted on a potato dextrose medium. Not detected.

[Table 1] Further, when the permeated juice was analyzed for the concentration of hydroxymethylfurfural (HMF), which is known as an impurity synthesized from fructose and having a bad taste, by a liquid chromatography apparatus manufactured by Shimadzu Corporation, HMF was not detected. On the other hand, 4.7 ppm HMF was detected in commercially available concentrated and reduced 100% apple juice,
6.4 ppm HMF was detected in apple juice. The analysis results including other components are shown in Table 2.

[Table 2]

[0028]

EFFECTS OF THE INVENTION According to the present invention, it is possible to remove bacteria from a fruit juice having a complicated composition with high reliability, and the heat sterilization treatment of the fruit juice is omitted or simplified. The production of off-flavor substances due to is suppressed or prevented, and since a precoat material is not used, components imparting the aroma and flavor peculiar to each fruit juice are not removed, and it is possible to produce a fruit juice with a fresh flavor that has never existed before. it can.

[Brief description of drawings]

1 shows an example of a process flow of a suitable apparatus for carrying out the method of the invention.

FIG. 2 shows an example of a process flow of a suitable apparatus for carrying out the method of the present invention.

FIG. 3 shows an example of a process flow of a suitable apparatus for carrying out the method of the present invention.

FIG. 4 shows an example of a process flow of a suitable apparatus for carrying out the method of the present invention.

FIG. 5 shows an example of a process flow of a suitable apparatus for carrying out the method of the present invention.

FIG. 6 shows an example of a process flow of a suitable apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 1 stock solution tank 2 circulation pump 3 ceramic membrane filter 4 filling device 5 multi-tube heat exchanger 6 degassing device 7 vacuum pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location B01D 19/00 H 61/14 500 8014-4D 63/02 6953-4D (71) Applicant 592069470 Gold Pack Co., Ltd. 2-24-1, Shibuya, Shibuya-ku, Tokyo (72) Inventor Sowa Nakamura 2-12-1, Tsurumi-Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Corporation (72) Inventor Jun Hasegawa Kanagawa 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi Chiyoda Kako Construction Co., Ltd. Kobayashi 515-1 (72) Inventor Tetsuya Katsunishi 2892 Ishikawa, Fujisawa-shi, Kanagawa Imperial Shonan Nibankan 101 (72) Inventor Saburo Harada Yokohama, Kanagawa Minami-ku, Konandai 2-chome No. 2 2-204 (72) inventor Minoru Sato Matsumoto, Nagano Prefecture Sasabe 3-8-13 (72) inventor Kiyohide Takahashi Nagano Prefecture Minamiazumi District, Nagano Azusagawa Oaza Azusa 3072-14

Claims (14)

[Claims] 1. A method for producing a fruit juice, which comprises subjecting the original fruit juice to a sterilization filtration under pressure with a ceramic membrane filter without using a precoat material, thus removing bacteria to obtain a sterile fresh fruit juice. 2. A sterile fresh fruit juice is obtained by removing the bacteria from the original fruit juice by pressure sterilization filtration with a ceramic membrane filter without using a precoat material, and then deaeration of oxygen in the permeated fruit juice. A method for producing fruit juice, which comprises: 3. The raw fruit juice is subjected to pressure sterilization filtration under a gas atmosphere containing no oxygen by a ceramic membrane filter without using a precoat material, and thus bacteria are removed to obtain a sterile raw fruit juice. Method for producing fruit juice. 4. The raw fruit juice is subjected to pressure sterilization filtration in a gas atmosphere containing no oxygen with a ceramic membrane filter without using a precoat material to remove bacteria, and further oxygen in the permeated juice is deaerated and removed. A method for producing a fruit juice, which comprises: 5. The method according to any one of claims 1 to 4, wherein pressure sterilization filtration is performed by pressurizing gas. 6. The method according to claim 1, wherein the juice is cooled by providing a heat exchanger in the circulation path on the inlet side of the filter. 7. The method according to claim 1, wherein the sterilized and filtered fruit juice is pressure-filled in a container by utilizing residual pressure. 8. The method according to claim 2, wherein oxygen is deaerated by membrane deaeration. 9. The method according to claim 8, wherein the membrane degassing is performed using a hollow fiber type gas separation membrane. 10. The method according to claim 8, wherein membrane deaeration is performed by utilizing the residual pressure of the fruit juice that has been sterilized and filtered. 11. The method according to claim 3, wherein the oxygen-free gas is nitrogen gas. 12. The pressurized gas is nitrogen gas.
The method described. 13. The method according to claim 1, wherein the original fruit juice contains citrus fruit juice. 14. The original fruit juice contains a fruit juice of a pome fruit.
13. The method according to any one of 1 to 12.