JPH0576329A - Sterilization of fluid material - Google Patents

Abstract

PURPOSE:To industrially advantageously sterilize a fluid material such as a beverage or a fluid food while keeping its quality by applying a high pressure to the fluid material and then rapidly reducing the pressure for the purpose of cell-crush treatment. CONSTITUTION:The objective sterilization is carried out by applying a high pressure of >=2500kg/cm<2> (preferably 3500-4500kg/cm<2>) to a fluid material (e.g. fluid material mainly composed of milk protein) and then taking out the treated material from the high-pressure treatment tank for the purpose of cell crush by rapid reduction of pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sterilizing beverages, liquid foods, raw materials or semi-finished products thereof, which are liquid, and various other liquids.

[0002]

2. Description of the Related Art Liquid substances such as beverages and liquid seasonings which are required to be stored for a certain period of time after production are treated at any stage of the production process in order to prevent deterioration and spoilage due to the growth of microorganisms. It is common to undergo some sort of sterilization treatment.
In many cases, sterilization of food and drink is performed by subjecting the raw material or the final product to heat treatment. However, although the heat sterilization treatment can achieve the purpose of sterilization relatively easily, it often causes unfavorable alterations such as discoloration due to heat, generation of offensive odor, and destruction of vitamins and amino acids.

As a sterilization method that is less likely to induce deterioration of the quality of the object to be treated, which is often seen in heat sterilization treatment,
In recent years, a sterilization method for killing microorganisms by applying ultrahigh pressure has been developed (for example, Japanese Patent Laid-Open No. 2-312577). This is about 5000 using a hydrostatic pressure device.
By applying a high pressure of kg / cm ² or more, damage to the cell wall, cell membrane, etc. of the microorganism in the object to be treated, and at the same time denaturation of intracellular proteins, try to kill the bacteria. .. However, 5000 kg
It is not easy to apply a high pressure exceeding / cm ² to the object to be processed, not only an expensive ultra-high pressure generator and a high pressure-resistant processing apparatus are required, but it also takes a long time to reach a predetermined ultra-high pressure. There is a drawback that it costs. The pressure that is relatively easy to use for the pressure treatment of the liquid is about 4500 kg / cm ² or less, but at such a pressure, sufficient sterilization cannot be performed unless the treatment is repeated many times.

On the other hand, as a device capable of killing bacterial cells, there is a so-called cell crusher. This is because the suspension of bacteria is pressurized to a pressure of about 2000 kg / cm ² and released all at once into a space at normal pressure and suddenly decompressed. The impact of the sudden decompression and the released suspension are The crushing of microbial cells is carried out by utilizing the impact of collision with a fixed wall surface at high speed. The pressure employed in this method is much lower than in the ultra-high hydrostatic pressure application described above, so the device is also small and can be implemented efficiently. However, the cell crusher is only for crushing cells to take out intracellular components, and is not used for the purpose of sterilization. Further, the cells that can be disrupted by the cell disrupter are limited to some microorganisms, and the treatment effect is insufficient for microorganisms having a rigid cell wall such as yeast and lactic acid bacteria. For example, when Lactobacillus casei is treated once at a treatment pressure of 1000 kg / cm ² , the number of bacteria of 1.0 × 10 ⁷ cells / ml becomes 7.0 × 10 ⁶ cells / ml. Meaning It takes several iterations to reduce the number of bacteria to some extent. Therefore, the treatment by the cell disruptor cannot be an industrially practicable liquid material sterilization method.

[0005]

The object of the present invention is to improve the high-pressure sterilization method, which has many problems as described above in spite of being superior to heat sterilization treatment from the viewpoint of maintaining the quality of food and drink, This is to make it industrially easy to implement and to obtain a sufficient treatment effect.

[0006]

The high-pressure sterilization method according to the present invention comprises a treatment for applying a high pressure of 2500 kg / cm ² or more to the object to be treated (hereinafter referred to as an ultra-high pressure treatment) and a rapid decompression cell crushing treatment from a high pressure. It is characterized by applying. When the ultra-high pressure treatment and the rapid depressurization treatment from the high pressure are performed together, the microorganisms in the liquid substance are crushed more reliably than when either treatment is performed. In addition, ultra-high pressure treatment is easy to carry out from 2500 to
Pressurization of about 4500 kg / cm ² is sufficient.

The sterilization method of the present invention will be described in more detail below. Either the ultra-high pressure treatment or the rapid decompression cell crushing treatment from the high pressure may be performed first, but the ultra-high pressure treatment is advantageous in terms of treatment effect. The ultra-high pressure treatment can be easily performed by using a hydrostatic pressure device, but a direct pressure method may be adopted. When the hydrostatic pressure device is used, the liquid material to be treated is first placed in an appropriate container such as a container for a retort pouch and sealed, and hydrostatic pressure is applied. In order to carry out efficient sterilization treatment, the hydrostatic pressure applied should be 2500 kg / cm ² or more. If the hydrostatic pressure is less than 2500 kg / cm ² , long-time treatment is required. In particular, if the object to be treated is mainly composed of milk protein, the treatment effect is less likely to appear than in the case of a product such as fruit juice that does not contain milk protein, so a pressure of about 3500 kg / cm ² or more is used. It is desirable to do. Although there is no upper limit to the hydrostatic pressure to be applied, it is not preferable to use a high pressure exceeding 5000 kg / cm ² because the burden on the apparatus becomes large and the time for pressurization becomes long as described above. Also, since it is contrary to the object of the present invention, it is usually about 3500.
until kg / cm ^2, it is desirable to carry out at any time up to about 4500 kg / cm ² when processing those based on milk proteins. The time for ultra-high pressure treatment may be about 10 minutes each time.

After the ultra-high pressure treatment is finished, the object to be treated is taken out of the treatment container and then 800 to 2500 kg / cm ²
Performing a process of releasing the object to be treated from a state of pressurizing it to a high pressure of about normal pressure or a low pressure atmosphere close to it and rapidly depressurizing it, preferably at that time, fixing the flow of the object to be treated released at high speed By colliding with a wall or the like, a mechanical shock is given to crush the microbial cells. A typical example of an apparatus that can be used for this process is Microfluidizer manufactured by Microfluidics, Inc., USA. This device continuously ejects a high-pressure object to be processed from two facing ejection ports into an atmospheric pressure chamber, and further collides the two flows of the ejected object to be processed with each other from the front. The cells are disrupted by impacting the microorganisms in the material. In addition, for small-scale implementation, a French press cell crusher from SLM-AMINCO in the US, a minilab from Dainippon Pharmaceutical Co., Ltd., etc. Alternatively, a member that collides with a member immediately before the injection port can be used.

The ultrahigh pressure treatment and the rapid depressurization treatment from the high pressure can be repeated twice or more when each treatment is not sufficient. The sterilization method according to the present invention performs rapid depressurization treatment in which a pressurized state is passed through a narrow flow path to release the liquid, so that it can be carried out only on a fluid liquid, but as long as it is a liquid, all It is applicable to foods and drinks, raw materials or semi-finished products thereof, which are liquid, and various other liquids.

[0010]

【Example】

 Example 1 Cultivation of Lactobacillus casei in ILS-lactose medium
Then, the obtained cells were added to 10 mM HEPES at about 3.0 × 10.⁷Pieces / m
Suspended to l. Food and drink containing microorganisms
To the above lactic acid bacteria suspension as a model, 3500 kg / cm²of
Hydrostatic pressure treatment, 800kg using microfluidizer
/cm²Rapid decompression cell lysate treatment from or the same conditions as above
Sterilization of the present invention in which the hydrostatic pressure treatment and the rapid depressurization treatment are successively performed
Treated. The results are shown in Table 1. Table 1Number of hydrostatic pressure treatments Number of sudden decompression treatments Number of surviving bacteria (cells / ml)  Comparative Example 4 4.0 x 10³  Example 2 2 2.0 x 10³  Example 1 3 2.0 × 10³  Comparative Example 0 4 3.0 × 10⁶

Example 2 Lactobacillus casei live cells in 10% skim milk powder solution
10⁷3000kg / cm after adding so that the number becomes 1 / ml²of
Hydrostatic pressure treatment, 800kg using microfluidizer
/cm²Rapid depressurization process from and hydrostatic pressure under the same conditions as above
The sterilization treatment of the present invention is performed by continuously performing the treatment and the rapid depressurization treatment.
It was The results are shown in Table 2. Table 2Number of hydrostatic pressure treatments Number of sudden decompression treatments Number of surviving bacteria (cells / ml)  Comparative Example 4 0 1.0 × 10^Five  Example 2 2 2.0 x 10^Four  Example 1 3 1.0 × 10^Four  Comparative Example 0 4 3.0 × 10⁶

Example 3 3000 kg / cm of unsterilized Valencia orange juice²Still water
2000kg / cm by pressure treatment, French press²Sudden from
Reduced pressure cell disruption and hydrostatic treatment under the same conditions as above
Then, the sterilization treatment of the present invention was performed in which the rapid depressurization treatment was continuously performed.
The results are shown in Table 3. Table 3Number of hydrostatic pressure treatments Number of sudden decompression treatments Number of surviving bacteria (cells / ml)  Comparative Example 4 0 300 Example 2 2 6 Example 1 3 0 Comparative Example 0 4 30

Example 4 Lactobacillus casei was inoculated into 10% skim milk, and 37
The yogurt was incubated at ℃ for 48 hours,
When 1 kg of hydrostatic pressure treatment of kg / cm ² and 6 times of rapid depressurization treatment with a microfluidizer were performed, no lactic acid bacteria remained and no odor of heating was obtained. It was

Example 5 Lactobacillus casei was cultured in an ILS-lactose medium, and the obtained cells were suspended in sterilized Valencia orange juice at a concentration of about 3.0 × 10 ⁷ cells / ml. This juice was subjected to hydrostatic pressure treatment and rapid decompression cell disruption treatment using a minilab or French press, either alone or in combination. Tables 4 to 7 show the results of examining the number of treatments required to reduce the viable cell count to a desired level by changing the treatment pressure and the treatment time. In the case of the combination of the hydrostatic pressure treatment and the rapid depressurization treatment from the high pressure, the hydrostatic pressure treatment was once and the number of the rapid depressurization treatment from the high pressure was changed.

Table 4: Hydrostatic pressure treatment: 3500 kg / cm², 10 minutes Minilab processing pressure: 800kg / cm²  Number of hydrostatic pressure treatments Minilab processing times Number of surviving bacteria (cells / ml)  Comparative Example 5 2.0 x 10³  Example 1 3 2.0 × 10³  Comparative Example 0 18 2.0 × 10³

Table 5: Hydrostatic pressure treatment: 2500 kg / cm², 60 minutes Minilab processing pressure: 800kg / cm²  Number of hydrostatic pressure treatments Minilab processing times Number of surviving bacteria (cells / ml)  Comparative Example 5 0 1.0 × 10^Four  Example 1 3 1.0 × 10^Four  Comparative Example 0 16 1.0 × 10^Four

Table 6: Hydrostatic pressure treatment: 3500 kg / cm², 10 minutes French press processing pressure: 2000kg / cm²  Number of hydrostatic pressure treatments Number of French press treatments Number of surviving bacteria (cells / ml)  Comparative Example 7 0 3.0 x 10²  Example 1 3 3.0 x 10²  Comparative Example 0 8 3.0 × 10²

Table 7: Hydrostatic pressure treatment: 2500 kg / cm², 60 minutes French press processing pressure: 2000kg / cm²  Number of hydrostatic pressure treatments Number of French press treatments Number of surviving bacteria (cells / ml)  Comparative Example 7 8.0 × 10²  Example 1 3 8.0 × 10²  Comparative Example 0 7 8.0 × 10²

Example 6 Lactobacillus Streptococcus lactis was added to a heated extract of oolong tea as a contamination model bacterium solution so that the concentration was 10 ³ / ml, and the mixture was treated once with a hydrostatic pressure of 3000 kg / cm ² and then 800 kg using a microfluidizer. When the treatment of suddenly reducing the pressure from / cm ² was repeated, the number of bacteria became 0 / ml after the treatment with the microfluidizer twice. 3000 for comparison
When only hydrostatic pressure treatment of kg / cm ² was repeated, the number of bacteria was 0.
Five treatments were required to reach the count / ml.

[0020]

EFFECTS OF THE INVENTION The sterilization method of the present invention, which performs both ultra-high pressure treatment and rapid decompression cell crushing treatment from high pressure, requires a high pressure of about 5000 kg / cm ² or more in the conventional high-pressure sterilization method. By comparison, the pressure in ultra-high pressure treatment is 2500-45
Since it only requires about 00 kg / cm ² , it has the feature of being much simpler and more efficient. In addition, the number of ultra-high pressure treatments that require a long time for pressurization and depressurization is small, and sterilization can be completed in a short time. Furthermore, compared with the rapid depressurization sterilization method using only a cell crusher, there is a feature that most microorganisms including yeasts and lactic acid bacteria, which are difficult to kill only by the rapid depressurization treatment, can be killed. Therefore, according to the present invention, it becomes possible to carry out a high-pressure sterilization method that does not impair the flavor and nutritional value more easily and at a lower cost than conventional methods.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location A23L 2/16 9162-4B (72) Inventor Koichiro Sonoe 1-1-Higashishimbashi, Minato-ku, Tokyo 19 Yakult Honsha Co., Ltd. (72) Inventor Yoshio Kimura 1-1-19 Higashishimbashi, Minato-ku, Tokyo Yakult Honsha Co., Ltd. (72) Masami Ishihara 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa New Japan (72) Inventor Kenji Fukumoto, 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Shin-Nippon Steel Engineering Co., Ltd.

Claims (2)

[Claims] 1. A method for sterilizing a liquid material, which comprises applying a high pressure of 2500 kg / cm ² or more to the liquid material and subjecting the liquid material to rapid cell decompression from a high pressure. 2. A milk protein, wherein a rapid decompression cell disruption process from the process and the high pressure in the liquid containing the milk protein as the main component added pressure of 3500kg / cm ² ~4500kg / cm ² applied mainly A method for sterilizing a liquid material as an ingredient.