JP3104887B2 - Liquid food continuous treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating liquid foods and feeds (hereinafter simply referred to as foods) in a continuous manner.

[0002]

2. Description of the Related Art As is well known, it is preferable that, for example, vegetable juices and the like are subjected to heat sterilization treatment, and that, for example, fish feeds and the like are similarly sterilized and then dried and sold as powdery granules.

However, a liquid containing a large amount of plant cells, whether vegetable juice or fish feed, is released at a temperature of about 55 ° C. under atmospheric pressure, because carbon dioxide and oxygen gas contained in the cells are expanded and released. The cell wall is destroyed, and the cells are damaged by prolonged heating at 85 ° C. or higher, which is effective for sterilization, and the main components in the cells flow out. As a result, the components change due to oxidation, decomposition, and the like. Also,
For example, it becomes a colloidal liquid, causing sedimentation or separation, or a chloroplast browning, carotene blackening, and other appearance changes, resulting in inconveniences such as a decrease in quality and a decrease in nutritional value.

In recent years, with the development of biotechnology, there has been known a technique for producing a liquid obtained by cutting cell tissues using enzymes or extracting cells with enzymes. However,
Even in such a case, if the enzyme is not deactivated as in the above-mentioned sterilization operation, a change due to the remaining enzyme occurs during storage, which is inconvenient.

[0005] Heat treatment is required in both cases of sterilization and enzyme inactivation, but this results in destruction or damage of cell walls, and the prior art could not satisfy both.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for treating a liquid food which can sterilize and deactivate enzymes properly without causing cell destruction.

[0007]

[Knowledge] As a result of various studies, the present inventor has found that rapid heating and rapid cooling of a liquid food in a short time can sufficiently achieve sterilization and enzyme inactivation without destroying plant cells. I found it. However, it is difficult to rapidly heat and cool the liquid because the liquid is usually heated and cooled by convection. Therefore, when one elongated tube-shaped flow path is heated or cooled under pressure, the liquid flowing in the flow path is directly heated or cooled by heat conduction from the wall surface of the flow path. It has been found that a stream is generated, so that the whole is uniformly heated and cooled. In addition, processing in one flow path can be performed in a regular flow, the temperature can be raised and cooled within a fixed time, and continuous processing can be performed, thereby improving processing efficiency.

[0008]

According to the present invention, there is provided a method for continuously treating a liquid food which is sterilized by heating under pressure.
The liquid food is allowed to flow into a single flow path while being pressurized with a pressure of ² kg / cm ² G or more, and the liquid food is heated to a sterilization temperature of 85 ° C. to 120 ° C. in 7 seconds to 15 seconds. The liquid food is cooled to 10 ° C. to 0 ° C. in 10 seconds to 20 seconds by raising the temperature, maintaining the temperature at the sterilization temperature for 3 seconds to 10 seconds, and then cooling the channel, and reducing the pressure in the channel. It is designed to return to atmospheric pressure.

[0009]

[Explanation of the operation and effect] The pressurization is performed at a pressure of 2 kg / cm ² G or more. Usually, for example, vegetable juices and the like generate gas (carbon dioxide gas, oxygen gas) when heated to 50 ° C or higher,
Gas generation can be prevented by pressurization. Therefore, pressurization is performed at a pressure that can prevent generation of gas.

As described above, the heating time is preferably short.
The heat treatment temperature is 85 ° C. to 120 ° C., and this temperature is suitable as a temperature for sterilization and enzyme inactivation. If the retention time is too short, the bacteria will not be killed and the enzyme will not be deactivated. If the heating time and the holding time are too long, the cells are adversely affected.

If the cooling rate is too long, the time at the high temperature becomes longer and adversely affects the cells. Therefore, it is preferable to set the cooling time within 20 seconds. Of course, a shorter time is preferable. Then, at least about 10 seconds are required.

Therefore, the time from the start of heating to the completion of cooling is at most 45 seconds, preferably about 25 seconds.
In this case, the preferable flow rate of the heating and cooling channels is 1.
5 to 2.5 m / sec, and the tube inner diameter of the channel is, for example, 8 mm to 30 mm.

[0013] Thus, in a single channel under pressure,
Since the liquid food is processed, no stagnation occurs in the flow path, and the turbulent flow in the flow path heats and cools the liquid food by heat transfer directly from the wall of the flow path instead of convection. Therefore, partial heating or the like does not occur, heating and cooling are performed uniformly, and the liquid food can be completely processed. As a result, a high quality liquid food can be obtained.

[0014]

EXPERIMENTAL EXAMPLES In order to better understand the present invention, various experimental examples by the present inventors will be described.

First, an experiment was conducted on the effects of pressure and temperature on the quality of vegetable juice, and as a result, Table 1 was obtained.

[0016] In this experiment, the time from the room temperature to the heat treatment temperature was 25 seconds, and the cooling temperature was 30 ° C.

[0017] The browning is a five-point evaluation in which what can be clearly discriminated visually is a maximum of five, and the separation is a percentage of the supernatant of the upper layer of the two-layer separated liquid after standing for 10 minutes. It is. In each case, the smaller the value, the higher the commercial value. As can be seen from this table, when the temperature is 50 ° C. or higher, the quality deteriorates. The reason is that the gas contained in the cells expands,
This is because the cell membrane is destroyed and gas is released, and as a result, the color component and the component change are caused by the outflow of the dye component together with the vacuoles and cell nuclei supported by the cell membrane, and the quality of the processed product is deteriorated.

It turns out that it is preferable to apply pressure at a pressure of 2 kg / cm ² G or more.

Further, the vegetable juice is separated into two layers by the heat treatment, but the upper layer liquid is a brown transparent liquid, and a precipitate is formed in the lower layer. The larger the ratio of the two-layer separation, the larger the lower layer precipitate is. Although it becomes a cotton lump, such a defect can be removed by applying a pressure of ² kg / cm ² G or more.

Next, an experiment was conducted on the relationship between the two-layer separation or browning and the treatment time as described above, and the results are shown in Tables 2 and 3.

[0021] Here, the graph created from Table 2 is shown in FIG. 2, and the graph created from Table 3 is shown in FIG.

In this experiment, the pressure was 2 kg / cm ² G
And As can be seen from Table 2, short heating time and cooling time and low cooling temperature are extremely preferable in terms of quality.

Finally, the effect of sterilization on Escherichia coli and general bacteria was tested in relation to the heating temperature. The results are shown in Table 4.

[0024] In Table 4, for the coliform bacteria group, the positive was indicated by + and the negative was indicated by-using the fermentation tube method. In this experiment, the rise time for the heat treatment was 13.3 seconds, the cooling time was 16 seconds, and the cooling temperature was 5 ° C.

As can be seen from Table 3, a temperature of 85 ° C. or more and 120
A sufficient sterilization effect can be obtained by performing a heat treatment at a temperature of not more than 5 ° C. for 5 seconds.

Further, it is known that the enzyme used for converting a single plant into a single cell is inactivated at 85 ° C., and the enzyme can be inactivated simultaneously with the sterilization treatment. Therefore, the present invention is also effective in the case of vegetable juice produced by the enzymatic method.

[0027]

FIG. 1 shows an example of a processing apparatus for carrying out the present invention. In FIG. 1, a liquid food at an ambient temperature (about 20 ° C.) is pressurized to ² kg / cm ² G or more by a pump 1 and sent to a heating device 2 through a line L1. This heating device 2 performs rapid heating in a single flow path,
For the heating, the heat medium of the heat medium source is sent to the heating device 2 by the circulation pump 4. The temperature of this heating medium is 88-124 ° C., so that the line L
The liquid food flowing from 1 into the heating device 2 is heated to 85 to 120 ° C. in 7 to 15 seconds while flowing through a single flow path.
Therefore, since the rate of temperature rise is proportional to the length of the flow path, that is, time, the flow path is lengthened when the temperature is high,
If the temperature is low, shorten the flow path. The heated liquid food is held at that temperature for 3 to 10 seconds while flowing through the holding unit 5.

Next, the liquid food that has flowed into the cooling device 6 is cooled by the temperature supplied from the cooling medium source 7 by the circulation pump 8.
It is rapidly cooled by a cooling medium at 5 to -15C for 10 to 20 seconds and flows out to the line L2 at a temperature of 0 to 10C.
The structure of the cooling device 6 is substantially the same as the structure of the heating device 2.

A pressure sensor 9 is provided on the line L2.
A signal from the pressure sensor 9 is input to a control unit 10 including a pressure controller, and the control unit 10 controls the valve drive unit 12 of the pressure control valve 11 based on the signal to control the line L.
The pressure of 1 to L2 is maintained at a predetermined pressure, for example, 2 kg / cm ² G. A line L3 is provided downstream of the pressure control valve 11.
The line L3 returns to the atmospheric pressure.

[0030]

Next, a specific example of the present invention will be described.

[Specific Example 1] Using the apparatus shown in FIG. 1, while heating spinach juice at a pressure of 2 kg / cm ² , the temperature was raised to 110 ° C. for 12 seconds by a heating apparatus 2 (flow path length: 21 m).
And hold it in the holding unit for 5 seconds,
Then, after cooling to a temperature of 5 ° C. for 15 seconds, the pressure was returned to atmospheric pressure. The resulting product had a browning of 1 on a 5-point scale and a separation of 5% or less, indicating high commercial value. This was sealed in a can and inspected two months later. As a result, the quality was not changed at all.

[Specific Example 2] Carrot juice was pressed at a pressure of 2.
While pressurizing at 5 kg / cm ² , the temperature was set to 120 ° C. in 12 seconds by the heating device 2 (flow path length: 21 m), and this was held for 5 seconds by the holding unit, and then cooled to 5 ° C. in 15 seconds. The pressure was returned to atmospheric pressure. The resulting product has no discoloration and a separation of less than 5%,
Product value was high. This was sealed in a can and inspected two months later. As a result, there was no change in the quality.

[Specific Example 3] Using algae (diatom community) to produce fish feed, while pressurizing at a pressure of 2.5 kg / cm ² , the temperature was increased for 12 seconds by a heating device 2 (flow path length 21 m). 115 ° C., which was held in the holding unit for 5 seconds, and then cooled to 10 ° C. in 15 seconds,
The pressure was returned to atmospheric pressure. The obtained product had no change in color and fragrance and had a separation of 5% or less. As a result of a bacterial test, the number of bacteria in the undiluted solution before heat treatment was 2.5 ×
The viable cell count after heat treatment was 10 ⁵ cells / ml
Was individual.

[Comparative Example 1] Spinach juice was applied at a pressure of 2
While pressurizing at kg / cm ² , heating device 2 (flow path length 2
1m) for 24 seconds to a temperature of 110 ° C., which was held in a holding unit for 5 seconds, and then cooled to a temperature of 10 ° C. for 30 seconds, after which the pressure was returned to atmospheric pressure. The obtained product is browning (approximately 3 on a scale of 5), with a separation of 28%
The commercial value was low, and in the evaluation after 24 hours, the browning was 4 on a 5-point scale and the separation was 45%.

[Comparative Example 2] While the spinach juice was pressurized at a pressure of 2.5 kg / cm ² , the temperature was raised to 110 ° C. for 12 seconds by the heating device 2 (flow path length: 21 m), and the temperature was reduced to 5 by a holding unit. Hold for 15 seconds, then 15
After cooling to a temperature of 35 ° C. in seconds, the pressure was returned to atmospheric pressure. The resulting product had a browning rating of 2 on a 5-point scale and a separation of 18%. However, according to the result of the inspection again one hour later, the browning was 3 on a scale of 5 and the separation was 30.
%. Further inspection after 24 hours showed that browning was 4 on a 5-point scale and the separation was 45%. As described above, when the final cooling temperature was high (35 ° C. in this experiment), the quality of the spinach juice after treatment continued to deteriorate, resulting in a bad result.

[0036]

As described above, according to the present invention, the following excellent effects can be obtained.

(1) Destruction of cells can be prevented at the same time as sterilization and deactivation of enzymes, and high quality can be obtained.

(2) No browning or precipitation occurs.

(3) Since heat treatment is performed in a single channel under pressure, uniform heat treatment can be performed in a short time.

(4) Since continuous processing can be performed, productivity is high and work efficiency is good.

(5) It can be applied to practically most liquid foods (or feeds), and has wide versatility.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing an example of an apparatus for implementing the present invention.

FIG. 2 shows the relationship between two-layer separation and browning and processing time.
FIG.

FIG. 3 shows the relationship between two-layer separation and browning and processing time.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pump 2 ... Heating device 3 ... Heat medium supply source 4 ... Circulation pump 5 ... Holding unit 6 ... Cooling device 7 ... Cooling medium supply source 8 ... Circulation Pump 9 ... Pressure sensor 10 ... Control unit 11 ... Pressure control valve 12 ... Valve drive unit L1, L2, L3 ... Line

Claims (1)

(57) [Claims] 1. A method for continuously treating a liquid food to be sterilized by heating under a pressure, wherein the liquid food is caused to flow into a single flow path while being pressurized at a pressure of ² kg / cm ² G or more, and the flow path is heated. To make the liquid food 85 to 7 to 15 seconds.
C. to a sterilization temperature of 120 to 120.degree. C., hold at the sterilization temperature for 3 to 10 seconds, and then cool the flow path to cool the liquid food for 10 to 20 seconds.
A method for continuously treating a liquid food, comprising cooling to a temperature of 0 ° C. and returning the pressure in the flow path to atmospheric pressure.