JPS58205481A - Method and apparatus for instantaneous sterilization of fluid - Google Patents

Abstract

PURPOSE:To carry out the sterilization of a highly viscous substance, by mixing the substance with steam, thereby heating at a high temperature in a short time. CONSTITUTION:A highly viscous fluid such as jam is introduced through the inlet 23 into the thin space 22 between a pair of porous plates 21 having a number of minute pores for blasting steam. The fluid is transferred at a rate of 0.05- 1.5m/sec in the space. In the course of transfer, high temperature steam is blasted through the minute pores of the porous plates 21 at a rate of 10-550m/sec to raise the temperature of the fluid to a predetermined sterilization temperature (e.g. 100-150 deg.C). The fluid is maintained at the temperature for several seconds, and water is evaporated under reduced pressure to effect the cooling of the fluid and the removal of water corresponding to the introduced stream. The thermal sterilization and the cooling can be carried out instantaneously by this method, and accordingly, the influence of heat of the fluid during the sterilization process can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultra-high temperature instantaneous (hereinafter abbreviated as UHT) sterilization method in which a highly viscous substance is mixed with water vapor and heated to a high temperature for a short period of time to sterilize the mixture.

Many of the fluids that require sterilization treatment are affected to a greater or lesser degree by heat treatment, and deterioration in quality cannot be avoided.

For this reason, a heat treatment sterilization method with a small thermal history is desired, and a direct heating UHT sterilization method has been developed as one of the methods. However, the conventional direct heating UHT sterilization method was developed for fluids with relatively low viscosity such as milk, and this method instantly sterilizes the fluid by injecting the fluid to be treated with steam and atomizing it. The temperature is raised to a desired temperature and held at that temperature for a short period of time for sterilization. In such a method, when the viscosity of the fluid to be treated is as high as several thousand to hundreds of thousands of centipoises, extremely high pressure is required to atomize the fluid, and uniform atomization is difficult. It was not possible to raise the temperature uniformly and instantaneously. For this reason, the direct heating UHT sterilization method developed for conventional low viscosity fluids has not been applied to high viscosity fluids.

For heat sterilization of highly viscous fluids, there is only an indirect heating method using a scraped heat exchanger.

An example of this scraped formation heat exchanger will be explained with reference to the drawings. FIG. 1 (OL) is an external view of the scraped formation heat exchanger. FIG. 1(b) is a cross-sectional view taken along the line A-A in FIG. 1(cL), showing the inside of the cylinder 1 through which the fluid to be treated passes. It is being In this scraped heat exchanger, the fluid is 5
The water vapor or heat is introduced into the cylinder 1 through 7, is introduced into the jacket 2 provided outside the cylinder 1, and is discharged through 8, heated by the steam or heat, and then discharged through 6. At this time, the scraper 9 is rotated by the drive motor 4 in order to prevent the fluid from adhering to the inner wall of the cylinder 1.

A flow sheet of a fluid sterilization treatment apparatus using such a scraped heat exchanger is shown in FIG.

In FIG. 2, 11 is a supply tank for the fluid to be treated;
It is sent to a heating heat exchanger 13 by a pump 12. Two heating heat exchangers 13 are provided to prevent the fluid from burning due to rapid temperature rise. First, the first heating heat exchanger raises the temperature with hot water, and then the second heating heat exchanger Raise the temperature to the specified temperature using steam in a container. After this is held for a certain period of time in the high temperature holding section 14, it is cooled in two stages in the cooling heat exchanger 15. 16 is a hot water line, 17 is a steam line.

18 is a cooling water line, and 19 is a product tank.

As is clear from this process, in the indirect heating method using a scraped heat exchanger, it takes a long time to raise the temperature of all parts of the fluid to the sterilization temperature, and it takes a long time to cool it down. The thermal history that it undergoes is large, and the fluid changes, for example,
When the processing fluid is food, deterioration of its color tone, flavor, and nutritional value is a major problem.

The present invention provides a heat sterilization method and apparatus capable of directly heating UHT sterilization using water vapor even for highly viscous fluids in order to solve the above-mentioned problems, that is, the problems caused by the poor thermal history. be.

In the present invention, high-viscosity fluid is heated to 100°C by injecting high-temperature steam.
A method of uniformly raising the temperature of all parts of the fluid to a predetermined sterilization temperature of ~150°C within a few seconds, as well as removing an amount of water equivalent to the injected steam and cooling it to the original temperature in a short time. and equipment. Therefore, in the present invention,
While moving a high viscosity fluid at a speed of 105 to 1.5 η into a thin layer space surrounded on both sides by a member having an approximately even number of water vapor injection pores, It is a sterilization method in which high-temperature steam is injected at 10 to ssom +, uniformly raising the temperature of all parts of the fluid to a predetermined temperature in a short period of time, and maintaining this temperature for several seconds. The amount of water is evaporated under reduced pressure and cooled at the same time.

FIG. 3 shows a schematic cross-sectional view of an example of an apparatus used for raising the temperature in carrying out the present invention. Figure 3 α' is a cross-sectional view in the moving direction of the fluid, and Figure 3 is a BB-B cross-sectional view of α. A thin layer is formed, and the porous member 21 has pores through which water vapor is injected into the thin layer. The diameter of the pore through which water vapor is injected is CL1 to 4fi, preferably 0.4 to 2B.
It is. Further, the dimensions of the thin layer space formed by the two porous members 21 are appropriately set in consideration of the viscosity of the fluid to be treated, the difficulty of deterioration, etc. When the thin layer space 22 is large, the amount of treatment increases, which is preferable, but if the fluid to be treated has a high viscosity, as the clearance becomes narrower, it becomes difficult for water vapor to reach the center of the thin fluid layer. In many cases, the number is preferably 1 to 15 dragons, preferably 2 to 101 tanuki. The length of this porous member, that is, the length of the steam injection part, is sufficient as long as it is sufficient to raise the temperature of the fluid, and is determined by the thickness of the fluid thin layer and the flow rate, but the length that the fluid passes through within 2 seconds is sufficient. preferable. The overspeed of water vapor from the pores provided in the porous member 21 is set to 10 to 550 degrees. Note that when the viscosity of the fluid is high, such as several thousand centipoise or more, the Reynolds number in the thin layer space 22 becomes extremely low and the fluid becomes a completely laminar flow, so self-mixing between the fluids can hardly be expected. Therefore, in order to uniformly heat all parts of the fluid to be treated, it is necessary to uniformly arrange pores with uniform diameters, and also to ensure that water vapor is mixed into all parts of the fluid passing through the thin layer space 22. In addition, at least one pore must exist in any part in the direction perpendicular to the fluid passage direction. Further, the number of pores in the porous member may be determined from the pore overvelocity of water vapor and the pore diameter.

In the present invention, the fluid thin layer in the temperature increasing region 22 does not necessarily have to be flat. FIG. 4 shows another aspect of the temperature increasing region. FIG. 4 shows a case where the space 22 is formed in a circular shape, FIG. 4 α is a sectional view in the fluid passage direction, and FIG. 4 is a CC sectional view of FIG. .

FIG. 5 shows a flow sheet of a sterilization treatment apparatus using the above-mentioned temperature raising apparatus. In FIG. 5, ■ is a supply tank for the fluid to be treated, ■ is the instantaneous temperature raising section, I is a high temperature holding section, ■ is a cooling vacuum dewatering section, a VID product tank, and ■ is a condenser.

■ indicates a condensed water tank, and ■ indicates a vacuum pump. The fluid to be treated is sent from the tank (■) to the temperature increasing section (■).

In the temperature increasing section (see FIG. 6), the fluid is introduced from an inlet 23 into a thin layer space 22, which is a temperature increasing region, and passes therethrough in the form of a thin layer. Water vapor for heating is introduced into the jacket part 25 from 24 and is injected into the fluid to be treated through the pores of the porous member 21, and the fluid to be treated is instantly heated to 100 to 150''C.Predetermined sterilization temperature. The fluid to be treated, whose temperature has been raised to It is considered a completed item.

A reduced pressure evaporator is used to perform this cooling and water removal instantaneously. In addition, the high temperature holding section (■) may use a pipe line connecting the temperature raising section (■) and the cooling outside to the water capital (■).The present invention can instantaneously raise and cool the temperature of the sterilization reservoir, so The model number due to heat of the fluid to be treated can be suppressed to a minimum.

The small thermal history of the fluid to be treated in the present invention is also clear from FIG. 6, which shows the thermal history in Examples and Comparative Examples, which will be described later.

Furthermore, unlike the conventional direct heat sterilization method, the present invention does not require the step of turning the fluid to be treated into fine particles, and does not require the high pressure needed to turn the fluid into fine particles. Therefore, according to the present invention, ultrahigh temperature instant sterilization can be applied extremely easily to highly viscous fluids, for example, high viscosity fluids with a viscosity of several thousand to several hundred thousand centipoise, to which conventional direct heating ultrahigh temperature instant sterilization methods cannot be applied. Of course, the present invention is equally applicable to fluids with a viscosity of less than 1,000 centivoids.

Specific examples of highly viscous fluids that can be applied to the invention include jam, miso, dressing, ketchup, sauce, curry roux, fruit juice, baby food, soy milk, processed cheese, sugar, and soup.

Pastes, such foods, toothpaste, creams.

Cosmetics such as emulsion, lipstick, and backing agents are available.

Example Tomato paste (viscosity 220.ODD centiboise at 10°C) was sterilized using the apparatus shown in FIG. The instantaneous heating section used in this example has a groove as shown in Fig. 3, and the thickness of the thin layer space 22 through which the tomato paste passes is 2111. Board) 2 has a width of 551m and a length of 11m.
00a, the porosity ratio I] is 5%.

Using the above-mentioned apparatus, tomato paste is passed through the thin layer space 22 at a passing speed of 0.2 m, and water vapor (
Inject 3 (m saturated steam) into 6 and 5 through the pores of the perforated plate,
After being sterilized under the conditions listed in Table 1, it was sent to the cooling vacuum dewatering section (2), where an amount of water corresponding to the injected steam was evaporated and cooled to obtain a kimono product. Table 1 shows the sterilization conditions and the number of viable bacteria in the raw tomato paste and the product tomato base.

＼ Furthermore, when we visually compared the tomato paste before and after sterilization with respect to color change, almost no change was observed under all the sterilization conditions shown in Table 1.

Comparative example The scraped heat exchanger shown in Fig. 1 (fluid passage diameter 1
501ft+! , length 450 mm) using the apparatus shown in Figure 2 at a sterilization temperature of 125° under the sterilization conditions shown in the example.
The same tomato paste as in the example was sterilized under conditions that matched the C1 retention time to 4 seconds. (See Figure 6)
In this case, it took 180 seconds to heat up and 180 seconds to cool down, and because the tomato paste had a long thermal history, the color after sterilization was clearly changed by visual inspection, and the original red color was not as vivid. The umbrella had become dull.

[Brief explanation of the drawing]

Figure 1 (α) is an external view of a conventional scraped heat exchanger, (
b) is an AA sectional view of (α), and Figure 2 is a 70-sheet of a sterilization treatment apparatus using a scraped heat exchanger,
(L) is a 1-circle diagram of the heating part used in the Immortal-Kyuei-Gou sequence, (
b) is a dB cross-sectional view of (α), FIG.
-C cross-sectional view, FIG. 5 is a flow sheet of the sterilization processing apparatus of the present invention, and FIG. 6 is a graph showing the thermal history of fluids in Examples and Comparative Examples. 21... Porous member, 22... Thin layer space, 23...
Fluid inlet, 24... water vapor inlet, 25... jacket part. ■... Supply tank for the fluid to be treated, ■... Instantaneous temperature rise section, ■--High temperature holding section, ■... Cooling, vacuum water removal section, ■...
・・Product tank, ■・Condenser, ■・Condensed water tank, ■・Vacuum pump. Above, ``''''□-'-1 Agent Kiyose Sanbe - Same Takuo Adachi, ゛-= 1≧- Also, 8-8, age 1 figure (a) (b) age '2 figure, +3 times ;?4 leap J

Claims (1)

[Claims] il), while moving a fluid at a rate of CLO5 to t5 m/sec into a thin space surrounded on both sides by a porous member having a large number of steam injection pores, high-temperature steam is released from both sides of the fluid. Water is injected through the pores of the porous member at a rate of 10 to 550 l/sec to raise the temperature to a predetermined sterilization temperature, and after holding at this temperature for several seconds, the pressure is reduced to cool and remove an amount of water equivalent to the injected water vapor. A method for instant sterilization of fluids characterized by evaporation. (2) The method for instant sterilization of a fluid according to claim 1, wherein the fluid has a viscosity of centiboise or more. (3) A thin layer space surrounded on both sides by a 11N porous member with a large number of steam injection holes, through which the fluid to be treated passes, and an instantaneous heating section and depressurization section having a jacket section that introduces high temperature steam to the outside of the core porous member. A fluid sterilization device characterized by cooling by evaporation and having a high temperature holding section connected to a reduced pressure water removal section.