JP4349518B2 - Continuous enzyme deactivation method of fruit juice - Google Patents

Description

  The present invention relates to a method for inactivating or reducing enzyme activity in a low acid liquid such as fruit juice or vegetable juice. According to the present invention, it is possible to inactivate various enzymes including enzymes that cause quality degradation during storage, so that it is possible to obtain fruit juice or vegetable juice that retains quality immediately after production for a long period of time. it can.

  Enzymes that cause quality degradation such as oxidation are contained in low acid liquids such as fruit juice and vegetable juice, and the quality degradation progresses even during storage. Low acidic liquids such as fruit juice contain pectin methylesterase and peroxidase, which causes problems such as precipitation due to degradation of pectin and browning due to oxidation. Inactivated the enzyme.

  Enzymes are weak to heat and generally denatured and deactivated easily at 60 ° C. or higher (see, for example, Non-Patent Document 1). Therefore, a heat exchange plate was used to deactivate the enzyme contained in the juice. Inactivation by heating and enzyme inactivation by heat during vacuum heating concentration are generally performed. However, simple heat treatment requires heating at about 90 ° C. for several tens of seconds, and it has not been possible to prevent deterioration of components and aroma due to heating at that time.

  Also, if it takes time to pack the juice from the juice, it may be heated immediately after squeezing to deactivate the enzyme, and may be heated again when packed in the vessel. The quality has deteriorated even in this process. It was.

  On the other hand, as an electrical treatment of a liquid beverage, a method of continuously sterilizing a liquid by flowing it in a high electric field has been proposed. In order to carry out this continuous sterilization, an opening forming a part of a fluid flow path is formed in a wall made of an insulating material, and at least a pair of electrode wires to which an AC voltage is applied are formed in the opening. Is sterilized by applying an AC voltage between at least a pair of electrode wires using a sterilization device stretched across the wire (see, for example, Patent Document 1).

However, the above-described method of passing a liquid through a high-voltage electric field generated between the electrode wires is for sterilizing the liquid, and does not deactivate the enzyme or reduce the enzyme activity.
Japanese Patent No. 2848591 "Chemical Dictionary 3", Kyoritsu Shuppan, 5th, 1971, pages 562-564.

  In the present invention, in view of the above-described state of the art, enzymes in fruit juice and vegetable juice are deactivated by heating to 130 ° C. with a microwave of, for example, 600 W or 10 ° C. in a warm bath at 100 ° C. as in the conventional method. Pay attention to the fact that flavor and quality deterioration are unavoidable when heat treatment is performed for a long time, such as heat treatment for minutes, and enzymes in fruit juices and vegetable juices, especially fruit juices and vegetables, can be obtained by low temperature or high temperature short time treatments. It was made for the purpose of newly developing a method for efficiently deactivating enzymes that cause deterioration and deterioration of juice.

  In order to achieve the above object, as a result of examination from various directions, the present inventors have focused on the energization treatment that has been performed exclusively for the purpose of sterilization. And, when AC voltage was applied to the electrode and the juice was exposed to the high electric field obtained by this, new knowledge that the enzyme was deactivated in a very short treatment within 1 second was not known at all. In addition to the obtained, it was confirmed that the product temperature could be increased without raising the temperature to 100 ° C. or higher, and as a result, it was confirmed for the first time that the juice was not deteriorated or deteriorated in flavor due to heat.

  Thus, it is a new finding that the enzyme in the fruit juice is deactivated by the energization treatment, and the enzyme causing the quality deterioration during storage is deactivated by this treatment, so that the flavor quality of the fruit juice is maintained over a long period of time. Unlike the conventional methods, the enzyme deactivation treatment itself is not a high temperature treatment, so there is no deterioration in flavor and quality due to the high temperature even during the enzyme deactivation treatment. According to the present invention, it is a further new finding that the flavor and quality of fruit juice can be prevented from being deteriorated in general over the storage period from the time of enzyme deactivation treatment (at the time of energization treatment).

  These findings are completely different from sterilization treatment by energization, and are also different from conventional enzyme deactivation treatment by high-temperature heating, which is completely new and useful knowledge. It is.

  The present invention has finally been completed as a result of further research based on these useful new findings, and an alternating voltage is applied to the electrode, and a high electric field obtained thereby allows a short time (within 5 seconds, preferably 1). Within a second), the enzyme is deactivated. In the present invention, when the enzyme is deactivated, the effect of the electric field is used in combination to shorten the time of exposure to high temperature as much as possible. The object of the present invention is to provide a method for continuously deactivating an enzyme while suppressing degradation.

  In order to achieve the above object, it can be achieved by providing an energizing unit in a container provided with a liquid supply port and a liquid discharge port. An AC power supply is connected to the electrodes of the energization unit, and the liquid can be deactivated by passing between at least a pair of opposed electrodes inserted with an insulator. Furthermore, it is desirable to have a structure that immediately cools after passing through the energization unit because it is heated by resistance heating by energization. In addition, the energization unit electrode can be energized a plurality of times at a time by stacking a plurality of electrodes inserted with an insulator as required, and is efficient.

  For example, by using the following apparatus, the enzyme can be deactivated efficiently by the energization treatment according to the present invention.

  In a container that can be a pressurized container provided with a supply port and an outlet for fruit juice or vegetable juice (hereinafter also referred to as fruit juice), a current-carrying unit and a storage part that is cooled by cooling water at the lower part thereof It arranges, the upper end part of an electricity supply unit is connected to supply ports, such as fruit juice, and a lower end part is connected to a storage part. Fruit juice and the like after completion of the enzyme deactivation treatment stored in the storage part are taken out of the container from the outlet through a pipe.

  The energization unit is formed with a channel through which fruit juice supplied from a supply port for fruit juice or the like flows, and it is sufficient that at least a pair of electrodes connected to an AC power source face the channel. A plurality of insulators can be stacked and an electrode can be sandwiched between the insulators.

  In addition, when fruit juice is heated by the energization process and its product temperature rises and boils, in order to suppress it, the energization process is performed under the pressurizing condition using the container as a pressurized container. do it. At that time, the pressure in the pressurized container should be 0.1 MPa or more, preferably 0.2 Ppa or more, and there is no particular limitation on the upper limit, but it is usually about 0.5 MPa, and within this range What is necessary is just to determine suitably according to goods temperature. Moreover, if a pressurized container is used, the juice after enzyme deactivation etc. can be easily taken out of a container using a pressure difference by opening the valve of a liquid outlet.

  In the present invention, the relationship between the gap (d: mm) between the pair of electrodes and the applied voltage (H: V) is such that 200 ≦ H / d ≦ 2000, preferably 400 ≦ H / d ≦ 1600. To deactivate. The lower the frequency, the higher the efficiency. Therefore, the frequency is 50 KHz or less, preferably 20 KHz or less. The time for passing the liquid is sufficiently effective within one second.

  As described above, the residence time (from the start of temperature rise to the start of cooling) in the energization unit is sufficiently effective in a short time of 1 second to 0.01 seconds, but the residence time (treatment time) is preferably Is 0.5 to 0.05 seconds, more preferably about 0.3 to 0.1 seconds. When the energization process is performed as in the present invention, for example, the product temperature can be rapidly increased by 50 ° C. in 0.2 seconds. Further, if the power consumption is increased, the time until the product temperature rises is shortened. As described above, since the temperature can be rapidly increased in a short time by applying a voltage, it is presumed that some physical property change occurs in the enzyme in the solution, and the enzyme can be deactivated quickly.

  By the energization treatment, the enzyme present in the fruit juice or the like is deactivated, and the enzyme activity is reduced to 0 to 10%. Enhancing the treatment conditions can further reduce the enzyme activity, but considering general distribution, it is considered that there is virtually no problem if it is in the range of 10% or less. In this way, since the activity of enzymes (pectin methylesterase, peroxidase, etc.) that cause quality degradation during storage of fruit juice or the like is also reduced, quality degradation of fruit juice or the like is suppressed over a long period of time. . In the present invention, the term “inactivation” includes not only the case where the enzyme activity is completely lost (complete inactivation) but also the case where the enzyme activity is reduced although it does not lead to complete inactivation.

  In addition, the product temperature such as fruit juice does not rise more than necessary by processing in a short time even by energization treatment, and the product temperature is 100 ° C. or less and is in a temperature range of 100 to 50 ° C., usually 90 It is about ~ 65 ° C. When the target product temperature is reached by the energization process, cooling of the processed fruit juice or the like is started immediately. Therefore, according to the energization process, it is not necessary to perform a high temperature and long time treatment as in the case of the conventional enzyme inactivation, and therefore, quality deterioration of fruit juice and the like during the inactivation process is prevented. Furthermore, in the present invention, the enzyme activity such as fruit juice is zeroed or reduced by energization, and then immediately cooled (for example, in a cooled storage section provided at the lower part of the energization unit). Is further prevented.

  The juice that passes through the energizing unit is not particularly limited in terms of the method of squeezing.

  Moreover, all the fruit juices, such as the straight fruit juice, the freeze-concentrated fruit juice, and the concentrated and reduced fruit juice, can be used for the fruit juice to pass.

  The juice that has been squeezed is preferably subjected to pulp removal.

  Candidate juices such as oranges and lemons, apples, grapes, peaches, pineapples, strawberries, tomatoes, none, bananas, melons, vegetable juices such as carrots and radishes can be used as target solutions It is. These liquids are preferably unheated.

  The passed fruit juice, etc. can be filled and sealed as it is in the container, but the fruit juice after passing the liquid is immediately cooled and then filled in the container and sealed to prevent further deterioration in quality during storage. . Therefore, the present invention not only provides an efficient new method for inactivating or reducing enzyme activity contained in fruit juice etc., but also the fruit juices obtained by this method in which deterioration of flavor and quality is prevented. Various beverages manufactured according to conventional methods using these fruit juices as raw materials are also included in the present invention.

  In the present invention, fruit juice or the like is passed through an energization unit for a short time, and at that time, a high electric field is applied to deactivate the enzyme. Since the method of the present invention does not perform heating at a high temperature for a long period of time as in a normal heating method, it is less likely to cause fragrance deterioration or component alteration than the heat-treated fruit juice, and the juice is more freshly squeezed. Can be manufactured.

  Examples of the present invention and comparative examples will be described below.

  From 10 kg of lemon fresh fruit, 2.9 kg of lemon fruit juice was squeezed with an in-line juicer. The juice was filtered through 200 mesh, passed through a current-carrying unit, and then immediately cooled to measure pectin methylesterase activity.

  As processing conditions, a voltage of 20 KHz and 5.50 KV / cm was applied, and the processing time was set to 0.2 seconds. The product temperature at that time was 70.5 ° C.

  4 kg of lemon juice was squeezed from 10 kg of fresh lemon fruit using an in-line juicer. The juice was filtered through 200 mesh, passed through a current-carrying unit, cooled immediately thereafter, and the reduced vitamin C content was measured by the iodine method.

  As processing conditions, a voltage of 20 KHz and 4.00 KV / cm was applied, and the processing time was 0.2 sec. The product temperature at that time was 72 ° C.

  4 kg of lemon juice was squeezed from 10 kg of fresh lemon fruit using an in-line juicer. The juice was filtered through 200 mesh, passed through an energization unit, and then immediately cooled to measure pectin methylesterase activity. Moreover, the reduced vitamin C content was measured by the iodine method.

As processing conditions, a voltage of 20 KHz and 4.50 KV / cm was applied, and the processing time was 0.2 sec. The product temperature at that time was 79 ° C.
(Comparative Example 1)
From 10 kg of fresh lemon fruit, 2.9 kg of lemon fruit juice was squeezed with an in-line juicer. The squeezed juice was filtered through 200 mesh, and pectinmethylesterase activity was measured. Moreover, the reduced vitamin C content by the iodine method was measured.
(Comparative Example 2)
4 kg of lemon juice was squeezed from 10 kg of fresh lemon fruit using an in-line juicer. The juice was filtered through 200 mesh, heat-treated in a water bath at 80 ° C. for 30 seconds, and pectin methylesterase activity was measured. Moreover, the reduced vitamin C content was measured by the iodine method.
Method for measuring pectin methylesterase activity:
4 ml of 1M NaCl is added to 25 ml of lemon juice, pH is adjusted to 7.5 with 1N NaOH, and the volume is adjusted to 40 ml. (Lemon juice that had been heated at 100 ° C. for 15 minutes in advance was used as a blank.) As a substrate, 1% citrus pectin was dissolved in 0.1 M NaCl, and the pH was adjusted to 7.5 with NaOH. The adjusted one was used. For the activity measurement, after pre-incubating in 5 ml of enzyme solution at 30 ° C. for 10 minutes, 20 ml of substrate was added and reacted at 30 ° C. for 3 hours, and then the reaction was stopped by heating at 100 ° C. for 15 minutes. The activity was measured by titration with 0.02M NaOH. The enzyme activity was calculated from the following formula.
Pectin methylesterase activity (Unit / ml)
= [(Titration amount × Factor) / (Reaction time × Enzyme amount × Dilution ratio)] × 10000
The results of measuring pectin methylesterase activity are shown in Table 1 below, and the results of measuring reduced vitamin C content are shown in Table 2 below.
(Table 1)
Pectin methylesterase activity measurement results
Residual activity (%)
────────────────────
Example 1 4.0
Example 3 0.0
Comparative Example 1 100.0
Comparative Example 2 0.1
────────────────────
(Table 2)
Reduced vitamin C content
Vitamin C content (mg%)
────────────────────
Example 2 54.93
Example 3 54.06
Comparative Example 1 57.20
Comparative Example 2 53.18
────────────────────
As is clear from the above results, it was demonstrated that the pectin methylesterase in the fruit juice can be inactivated (Table 1) and that the component decomposition is also suppressed (Table 2) by the liquid passing treatment.

  3.6 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The juice was filtered through 200 mesh, passed through a current-carrying unit, and then immediately cooled to measure pectin methylesterase activity.

  As processing conditions, a voltage of 20 KHz and 5.50 KV / cm was applied, and the processing time was 0.2 sec. The product temperature at that time was 69.7 ° C.

  3.9 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The juice was filtered through 200 mesh, passed through a current-carrying unit, and then immediately cooled to measure pectin methylesterase activity.

As processing conditions, a voltage of 20 KHz and 7.0 KV / cm was applied, and the processing time was set to 0.2 sec. The product temperature at that time was 79 ° C.
(Comparative Example 3)
3.9 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The juice was filtered through 200 mesh and pectin methylesterase activity was measured.
(Comparative Example 4)
3.9 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The squeezed liquid was filtered with 200 mesh and heat-treated at 70 ° C. for 30 seconds. Pectin methylesterase activity was measured.
(Comparative Example 5)
3.9 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The juice was filtered through 200 mesh and heat-treated at 80 ° C. for 30 seconds. Pectin methylesterase activity was measured.

Pectin methylesterase activity was performed in the same manner as in Example 1. The obtained results are shown in Table 3.
(Table 3)
Pectin methylesterase activity measurement results
Residual activity (%)
────────────────────
Example 4 10.0
Example 5 0.0
Comparative Example 3 100.0
Comparative Example 4 11.0
Comparative Example 5 11.0
───────────────────
From the above, it was found that the energization treatment was effective in deactivating the enzyme, and the enzyme could be deactivated by heating for a very short time.

  Furthermore, compared with the comparative example 4 and the comparative example 5 which heat-processed, Example 4 and Example 5 had the tendency for there was little heating odor (potato odor) and the aftertaste was clear.

  3.7 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The juice was filtered through 200 mesh, passed through a current-carrying unit, and then cooled immediately to measure peroxidase activity.

As processing conditions, a voltage of 20 KHz and 4.5 KV / cm was applied, and the processing time was 0.2 sec. The product temperature at that time was 88 ° C.
(Comparative Example 6)
3.7 kg of orange juice was squeezed from 10 kg of fresh Valencia orange fruit with an in-line juicer. The juice was filtered through 200 mesh and the peroxidase activity was measured.
Peroxidase activity measurement method:
1 ml of 0.1% guaiacol was added to 10 ml of 1/15 M acetate buffer (pH 5.0), 5 ml of distilled water was added to 10 ml of orange juice, and 1 ml of 0.1% hydrogen peroxide was added, and the reaction was carried out at 30 ° C. . The reaction was stopped by heating at 100 ° C. for 15 minutes, and ethanol was added to a final concentration of 50%. Thereafter, the enzyme activity was measured by the absorbance at 470 nm of the supernatant after centrifugation at 1500 rpm for 10 minutes.

  In addition, the fruit juice heated beforehand at 100 degreeC for 15 minutes was used as a blank.

The results obtained are shown in Table 4 below.
(Table 4)
Peroxidase activity measurement results
Absorbance at 470 nm
Reaction 60 minutes Reaction 120 minutes ───────────────────────────
Example 6 0.014 0.014
Comparative Example 6 0.028 0.040
Blank 0.014 0.014
────────────────────────────
From the above, it was found that peroxidase can be inactivated.

  4.75 kg of orange juice was squeezed from 10 kg of Valencia orange fresh fruit with an in-line juicer. The juice was filtered through 200 mesh, passed through a current-carrying unit and then immediately cooled to measure pectin methylesterase activity. The method for measuring pectin methylesterase activity was as described above.

  As processing conditions, a voltage of 20 KHz and 6.0 KV / cm was applied, and the processing time was 0.2 sec. The pressure in the electrode during the treatment was changed to 0, 0.1, and 0.2 MPa with carbon dioxide gas. The product temperature at that time was changed to 70, 65, and 60 ° C., respectively.

The results of measuring the activity of pectin methylesterase are shown in Table 5, Table 6 and Table 7 below, with the enzyme activity during normal pressure treatment being taken as 100%.
(Table 5)
Effect of pressure at processing temperature of 70 ℃ ───────────────────
Pressure (MPa) Enzyme activity (%)
───────────────────
0 100
0.1 46.9
0.2 33.8
───────────────────
(Table 6)
Effect of pressure at a processing temperature of 65 ℃ ───────────────────
Pressure (MPa) Enzyme activity (%)
───────────────────
0 100
0.1 95.9
0.2 86.9
───────────────────
(Table 7)
Effect of pressure when the processing temperature is 60 ℃ ───────────────────
Pressure (MPa) Enzyme activity (%)
───────────────────
0 100
0.1 91.0
0.2 89.3
───────────────────
From the above results, when the liquid is passed through the energization unit, it is possible to suppress the enzyme activity by applying the pressure treatment at the same time. Moreover, it turns out that the effect of a pressurizing process increases, so that process temperature becomes high.

Claims (6)

  Unheated fruit juice or unheated vegetable juice is continuously passed through a device equipped with an energization unit facing at least a pair of electrodes, using an AC power source at a frequency of 20 to 50 KHz and an applied electric field of 4000 V / cm. It is contained in the fruit juice or vegetable juice characterized by heating the product temperature of fruit juice or vegetable juice to 50-100 degreeC within 0.5 second by the above energization process, and cooling as soon as possible after that. A method of deactivating an enzyme or reducing enzyme activity.   The method according to claim 1, wherein the energization treatment is performed in an environment in which the pressure in the electrode during the treatment is increased to 0.1 to 0.5 MPa.   3. The method according to claim 1, wherein the relationship between the distance between the pair of electrodes (d: mm) and the applied voltage (H: V) is 200 ≦ H / d ≦ 2000.   The method according to any one of claims 1 to 3, wherein the enzyme is an enzyme that causes quality deterioration during storage of fruit juice or vegetable juice.   The method according to claim 4, wherein the enzyme is pectin methylesterase or peroxidase.   The method according to any one of claims 1 to 5, wherein the enzyme activity is deactivated or reduced to 0 to 10%.