JP4872048B2 - Method for germinating spores and method for sterilizing spores using the same - Google Patents

Description

  The present invention relates to a method for germinating spores formed by spore bacteria contained in liquid eggs or processed egg products, and a method for sterilizing spore bacteria using the same.

  Spores that form spores of the genus Bacillus, such as Bacillus cereus and Bacillus subtilis, and the genus Clostridium, are heat-resistant, pressure-resistant, and dry-resistant. And chemical resistance become extremely high, and sterilization becomes difficult.

  At present, sterilization of spore bacteria present in foods and pharmaceuticals and spores formed by the spore is generally performed by high-temperature heat sterilization methods such as retort treatment, UHT treatment, autoclave treatment, etc. However, there is a problem that quality deterioration (denaturation, coagulation, discoloration, etc.) of foods due to heating is remarkable. For this reason, it is very difficult to sterilize spores and spores contained in liquid eggs such as liquid eggs that easily deteriorate in quality while being maintained.

  Therefore, at present, liquid eggs and egg processed products are often pasteurized by sterilization under a temperature condition of 100 ° C. or less. However, spores formed by spores cannot be killed by pasteurization. . Therefore, for example, by circulating at a low temperature of 10 ° C. or less, germination and proliferation of the remaining spores are suppressed. However, psychrophilic spore bacteria such as Bacillus cereus germinate and proliferate even at a low temperature of 10 ° C. or less. End up. In particular, since Bacillus cereus is a food poisoning bacterium, it can be said that it is a spore bacterium that requires the most attention in sterilization, storage, and distribution of liquid eggs and egg processed products.

  In addition, as a method of sterilizing and removing heat-resistant spores while suppressing quality deterioration of foods and the like due to heating, sterilization methods of spore bacteria using ultra high pressure, sterilization methods using germination of spores, membrane filtration methods Are well known. In addition, additives such as shelf life improvers and preservatives are often added for the purpose of suppressing the growth of remaining spore bacteria.

  The method for sterilizing spore bacteria using ultra-high pressure can reduce the deterioration of quality caused by heating food or the like in the sterilization process of spore bacteria. As a method for sterilizing spore bacteria using ultra-high pressure, for example, there is a high-pressure treatment method for alcoholic beverages described in Patent Document 1. Such a high-pressure treatment method sterilizes an alcoholic beverage with a hydrostatic pressure of 100 MPa or more at room temperature.

  As a sterilization method using germination of spores, an intermittent sterilization method is performed in which food is treated at a temperature from room temperature to about 50 ° C. for about 10 minutes to 2 hours to germinate the spores in the food and then pasteurized. It has been known for a long time. In addition, as described in Patent Document 2, a method of sterilizing bacteria spores at a pressure of 100 MPa or higher after performing germination activation treatment by heating the bacterial spores at 40 ° C. or higher for 1 minute or longer has been reported.

  The germination activation process in the intermittent sterilization method is often performed by a heat treatment of 40 ° C. or higher (substantially 60 to 100 ° C.) as in Patent Document 2.

  On the other hand, there are the following reports as methods for germinating spores using both pressure and heating. For example, Non-Patent Document 1 reports that spore germination in milk was observed by subjecting milk to a pressure treatment of 50 to 200 MPa at 45 to 60 ° C. Non-Patent Document 2 reports that germination was observed by performing a pressure treatment of 20 MPa or more at 50 to 70 ° C.

  A germination method using pressure has also been reported. For example, in Non-Patent Document 3, germination was observed by performing low pressure treatment such as 20 MPa on spore treated at 70 ° C. for 30 minutes in the presence of an amino acid functioning as a germination inducing factor. Has been reported.

JP-A-6-165667 (Claim 1) JP-A-5-227925 (Claims 1 and 2) Kenji Nishi, Ryo Kato, Mamoru Tomita, "Activation and disinfection of Bacillus spore by pressure", Japan Society for Food Science and Technology 41 p.542-549 1994 Aoyama, Y., Shigeta, Y., Okazaki, T., Hagura, Y. and Suzuki, K, “Germination and Inactivation of Bacillus subtilis Spores under Combined Conditions of Hydrostatic Pressure and Medium Temperature”, Food Sci. Technol. Res. , 11 (1), p. 101-105. 2005 J. G. CLOUSTON AND PAMELA A. WILLS, “Initiation of Germination and Inactivation of Bacillus pumilus Spores by Hydrostatic Pressure”, JOURNAL OF BACTERIOLOGY, Feb. 1969, p.684-690

  As described above, the high temperature heat sterilization method has a problem that the quality of foods and the like is significantly deteriorated by heating, and the low temperature sterilization method has a problem that spores formed by spore bacteria cannot be killed. In addition, the addition of additives such as shelf life improvers and preservatives tends to be avoided from consumers, and it is accompanied by a deterioration in taste due to the addition, so reduction of additives is strongly desired.

  The method for sterilizing spore bacteria using ultra-high pressure described in Patent Document 1 and Patent Document 2 requires an extremely high pressure of 100 MPa or more, and actually 300 to 700 MPa. There is a problem that the cost becomes high. In addition, depending on the food, the quality may deteriorate due to the ultra-high pressure treatment itself. In particular, in a liquid egg or processed egg product containing protein, the protein is denatured and coagulated by the ultra-high pressure treatment, so the ultra-high pressure treatment may not be an effective sterilization method.

  In addition, the intermittent sterilization method has a problem that the sterilization effect is low and not only lacks stability, but also takes time and time, so that productivity is poor. In the membrane filtration method, the object to be treated must easily pass through the membrane, and liquid eggs and egg processed products cannot be membrane-filtered.

  When the germination activation treatment is performed by heat treatment as in Patent Document 2, since the heating temperature is high, the protein is easily coagulated and denatured, and there is a risk of quality deterioration.

  In addition, when non-patent literature 1 performs germination activation treatment at relatively low temperature conditions and relatively high pressure conditions, or relatively high temperature conditions and relatively low pressure conditions as in non-patent literature 2. When the germination activation treatment is carried out, the coagulation / denaturation of the protein may still occur, which may cause quality deterioration.

  In addition, although the pressurization conditions are low as in Non-Patent Document 3, when heating is performed at a relatively high temperature in the pretreatment before pressurization, protein coagulation / denaturation occurs, which may cause quality degradation.

  The present invention has been made in view of the above-mentioned problems, and a spore germination method for sterilizing spores contained in a liquid egg or processed egg product or spores formed by the method without spoiling quality, An object is to provide a sterilization method.

(1) The spore germination method according to the present invention that solves the above-mentioned problems is achieved by reducing the spore formed by the spore bacteria contained in the liquid egg or egg processed product without deteriorating the quality of the liquid egg or egg processed product. A method for germinating a spore to germinate, characterized in that the liquid egg or the processed egg product is subjected to a pressure treatment with a hydrostatic pressure of 10 MPa to 200 MPa at a temperature of 5 ° C. to less than 60 ° C. for 1 minute to 120 minutes. To do.

  Under such pressure conditions, it is possible to perform processing without deteriorating the quality of the liquid egg or processed egg product due to pressure. Furthermore, it is possible to suppress the quality deterioration of the liquid egg or egg processed product by heating by processing under such specific pressure conditions. That is, the optimal temperature range for germination of spore is 30 ° C to 60 ° C. If a liquid egg or processed egg product is left at such a temperature for 10 minutes to 2 hours required for germination of the spore, liquid egg or egg The processed product will deteriorate in quality. Further, when a pressure of 300 to 700 MPa necessary for spore sterilization is applied, the quality of the liquid egg or processed egg product deteriorates due to the pressure. However, according to the pressure treatment under the specific conditions described above, the pressure acts to protect against the deterioration of the quality of the liquid egg or processed egg product, and the liquid egg or processed egg product deteriorates at normal pressure. It is possible to prevent the quality of the liquid egg or egg processed product from deteriorating even at a temperature of 30 to 60 ° C. Furthermore, spore germination can be significantly accelerated by pressure and temperature.

(2) In the spore germination method of the present invention, at least one of a shelf life improver and a preservative may be added to the liquid egg or the processed egg product in an amount of 0.1% to 3% in terms of weight. In this way, the shelf life after sterilization can be further improved with a shelf life improver and / or a preservative with a smaller amount of addition than is usually added.

(3) The method for sterilizing a spore according to the present invention is a sterilization treatment for sterilizing the spore after germination of the spore contained in the liquid egg or the processed egg product by the spore germination method. It is characterized by performing.
When the spore is germinated by the spore germination method according to the present invention, the heat resistance and pressure resistance are remarkably lowered. Therefore, the spore germ and the spore formed thereby can be effectively sterilized by performing sterilization treatment after germination. Can do.

(4) The method for sterilizing a spore according to the present invention is to germinate the spore contained in the liquid egg or the processed egg product by the spore germination method described above, and at a temperature of room temperature to 60 ° C. for 10 minutes to 120 minutes. The spore is allowed to stand under normal pressure and then sterilized to sterilize the germinated spores.
After spore germination by pressure treatment, the spore can be germinated more reliably by leaving it under such specific conditions. And by sterilizing this, it becomes possible to sterilize spores (spore bacteria) effectively.

(5) In the method for sterilizing spore bacteria of the present invention, the sterilization treatment is performed by performing at least one of a heat treatment at 40 ° C. to 100 ° C. and a pressure treatment at 100 MPa to 500 MPa for 1 second to 120 minutes. Is preferred. When heat treatment and / or pressure treatment are performed under such conditions, spore bacteria and spores formed by the spore bacteria can be more effectively sterilized.

(6) Further, in the method for sterilizing spore bacteria according to the present invention, the sterilization treatment is more preferably at least one of a heat treatment of 40 ° C. to 60 ° C. and a pressure treatment of 100 MPa to 200 MPa. . Heat treatment and / or pressure treatment under such conditions not only can effectively sterilize spore bacteria and the spores formed by the spore bacteria, but also do not coagulate or denature proteins in liquid eggs or egg products. For example, the liquid egg after sterilization can be maintained in a raw state.

  According to the spore germination method of the present invention, since the protein is not coagulated / denatured, the spore contained in the liquid egg or egg processed product can be germinated without deteriorating the quality.

  According to the method for sterilizing spore bacteria according to the present invention, proteins are not coagulated / denatured, so that spore bacteria contained in liquid eggs or egg processed products and spores formed thereby can be sterilized without deteriorating quality. it can.

  Next, the best mode for carrying out the spore germination method and the spore germicidal method using the spore germination method according to the present invention will be described in detail.

First, the spore germination method according to the present invention will be described.
A spore germination method according to the present invention is a spore germination method for germinating a spore formed by a spore bacterium contained in a liquid egg or egg processed product without degrading the quality of the liquid egg or egg processed product, A liquid egg or processed egg product is subjected to a pressure treatment of 10 MPa or more and 200 MPa or less at a temperature of 5 ° C. or more and less than 60 ° C. for 1 minute to 120 minutes.

Here, the liquid egg generally refers to whole egg, egg yolk, egg white obtained by removing the shell from the egg, but in the present invention, the liquid material has a shelf life improver, a preservative, a seasoning, or For example, processing raw materials to which ingredients such as salmon meat, poultry meat, salmon, and auxiliary materials such as starch are added are also included.
The processed egg product refers to a product that has been subjected to processing such as boiling or baking using eggs, such as boiled egg, fried egg, egg tofu and tea fumigation. It goes without saying that a shelf life improver, a preservative, a seasoning and the like may be added to the processed egg product.

The shelf life improver and the preservative can be used alone or in combination.
As the shelf life improver and preservative, for example, sodium acetate, glycine, phosphates and the like can be used alone, or these can be used in combination.
When at least one of the shelf life improver and the preservative is used, these can be added in an extremely small amount that cannot normally exhibit the shelf life extension effect, for example, 0.1% to 3% in terms of weight. . When a shelf life improver and / or a preservative is added within this range, the shelf life after sterilization by the spore germ killing method described later can be further improved. If the amount of the shelf life improving agent and / or preservative added is less than 0.1% in terms of weight, the shelf life after sterilization is not improved so much and it is meaningless. On the other hand, if the addition amount of the shelf life improver and / or the preservative exceeds 3% in terms of weight, the taste may be deteriorated, which is not preferable.

  In addition, spore bacteria to be germinated refer to general spore bacteria contained in fresh foods, for example, Bacillus genus such as Bacillus cereus and Bacillus subtilis, Clostridium -The genus Clostridium such as Clostridium botulinum and Clostridium perfringens can be mentioned.

  In the spore germination method according to the present invention, the liquid egg or processed egg product is subjected to a pressure treatment of 10 MPa or more and 200 MPa or less at a temperature of 5 ° C. or more and less than 60 ° C. for 1 to 120 minutes. This is to promote germination by applying pressure to the spores under an appropriate temperature condition without causing protein denaturation or coagulation as much as possible.

In such a pressure treatment, if the temperature condition is less than 5 ° C. or the pressure condition is less than 10 MPa, germination of spores cannot be promoted sufficiently, and sterilization may be insufficient. On the other hand, if the temperature condition exceeds 60 ° C. in the pressure treatment, the protein in the liquid egg or egg processed product may be denatured or coagulated. In addition, the present inventors have confirmed that if the upper limit of the pressurizing condition is 500 MPa or less, more preferably 200 MPa or less, the protein of the liquid egg or egg processed product does not denature or coagulate.
The pressure treatment in the spore germination method of the present invention may be performed at a temperature condition of 5 ° C. or more and less than 50 ° C. from the viewpoint of cost reduction or the like. The upper limit of the pressurizing condition may be less than 100 MPa or less than 20 MPa. The pressing time may be 1 minute to 60 minutes.

  The pressurization conditions required for germination of the above-mentioned spores are very low as compared with the conventional sterilization conditions by ultra-high pressure treatment, and are not accompanied by deterioration of the quality of the liquid egg or egg processed product by the ultra-high pressure treatment. Furthermore, under such pressurization conditions, it is possible to suppress deterioration of quality due to heating by pressure. Furthermore, by lowering the pressure, it is possible to keep down the equipment cost and processing cost for sterilization.

In addition, liquid eggs and egg processed products may be directly put into a treatment tank of a pressurizing apparatus and subjected to pressurization, or may be filled after being sealed in a plastic container and sealed and then subjected to pressurization.
The pressurization method is preferably based on hydrostatic pressure, but pressure via a medium such as gas pressure or hydraulic pressure can also be used.
It is desirable that the liquid egg or processed egg product and the pressure medium are not in direct contact with each other. However, if the pressure medium is water, gas or the like having cleanliness that can be used as a food, the pressure medium is applied to the liquid egg or processed egg product. May be injected directly.
Various materials such as polyethylene and fluororesin can be used for the filling container. Further, as long as at least a part of the filling container has plasticity, the shape and the sealing method are not limited.
The pressurization method may be any conventionally known batch method, semi-batch method, continuous method, or the like.
The same applies to the method for sterilizing spores described later.

  As described above, according to the spore germination method of the present invention, by applying a specific pressure and temperature, the spore is germinated without denaturing or coagulating the protein of the liquid egg or processed egg product. be able to.

Next, the method for sterilizing spores according to the present invention will be described.
The method for sterilizing spore bacteria according to the present invention is to perform sterilization by sterilizing germinated spores after germination of spores contained in a liquid egg or processed egg product by the germination method of spores according to the present invention described above. It is.

  As the spore fungus forms a spore, as it is called a durable type, it has extremely high heat resistance, pressure resistance, drought resistance, chemical resistance and the like. For example, it can be sterilized by heating at about 60 ° C. Although it is impossible, germination and normal growth / metabolism (referred to as vegetative type) cause a significant decrease in heat resistance, pressure resistance, etc. For example, spore bacteria can be sterilized within a short time even when heating at about 60 ° C. The present invention utilizes this phenomenon to sterilize spores and spores.

The sterilization treatment for sterilizing the germinated spore bacteria is preferably at least one of heat treatment and pressure treatment. This is because it is easy to set and adjust conditions that are unlikely to cause deterioration of quality, and sufficient sterilization can be performed.
The heat treatment for sterilizing the germinated spore bacteria is preferably performed at 40 ° C. or higher and 100 ° C. or lower, and the pressure treatment is preferably performed at 100 MPa or higher and 500 MPa or lower. Such conditions can be applied to processed egg products in which deterioration of quality is difficult to manifest since the upper limit is relatively severe.
In this case, if the heat treatment is less than 40 ° C. or the pressure treatment is less than 100 MPa, sterilization may not be performed sufficiently. On the other hand, if the heat treatment exceeds 100 ° C. or the pressure treatment exceeds 500 MPa, the protein in the liquid egg or egg processed product may be denatured or coagulated, and the quality may be deteriorated. Moreover, the expense concerning a sterilization process will become great.
When heat treatment and pressure treatment are used in combination, sterilization may be possible under milder conditions than the above heating and pressure conditions.

The heat treatment for sterilizing the germinated spore bacteria can be performed at 40 ° C. or more and 60 ° C. or less, and the pressure treatment can be performed at 100 MPa or more and 200 MPa or less. Such conditions can be suitably applied to liquid eggs where deterioration of quality is likely to be manifested because the upper limit is a relatively loose condition.
In this case, if the heat treatment is less than 40 ° C. or the pressure treatment is less than 100 MPa, sterilization may not be sufficiently performed as described above. On the other hand, if the heat treatment exceeds 60 ° C. or the pressure treatment exceeds 200 MPa, when the liquid egg is used, the protein may be denatured or coagulated, and the raw state may not be maintained. . That is, the quality of the liquid egg may be deteriorated.
When heat treatment and pressure treatment are used in combination, sterilization may be possible under milder conditions than the above heating and pressure conditions.

  And, as the treatment time of the sterilization treatment is generally increased, the effect of extending the shelf life is enhanced. However, the treatment time of the sterilization treatment in the present invention can be applied without any problem as long as it is from 1 second to 120 minutes. In addition, from the viewpoint of sterilization cost, sterilization efficiency, and the like, the sterilization treatment time may be 1 minute to 120 minutes or 30 minutes to 60 minutes. If the treatment time for the sterilization treatment is less than 1 second, the sterilization effect may not be sufficient.

  In addition, in the spore germination method according to the present invention, when the treatment is performed at 40 ° C. or higher, it is conceivable that spore bacteria germinated at the same time as germination are killed. In such a case, the sterilization treatment performed following the germination method of the spore according to the present invention can be omitted, or the conditions of the sterilization treatment can be made more gentle than those described above.

  In addition, the sterilization process in the spore germicidal method according to the present invention is not limited to the above-described process. For example, any treatment such as treatment by a conventionally known pasteurization method or treatment by a chemical sterilization method such as hypochlorous acid or ozone may be used. Moreover, the heat-resistant spore in the liquid egg or egg processed product may be germinated according to the present invention, and then sterilized in a heating step related to processing.

The spore germicidal method according to the present invention is a germination method of the spore according to the present invention described above, wherein the spore contained in the liquid egg or egg product is germinated, and the temperature is from room temperature to 60 ° C. for 10 minutes to 120 minutes. It is preferable to perform a sterilization treatment for sterilizing germinated spores after being left under normal pressure. If the spore is allowed to stand under such conditions, the spore can be germinated more reliably, so that the spore (spore bacterium) can be effectively sterilized.
If the temperature to be left is less than room temperature or the time to be left is less than 10 minutes, spores may not be allowed to germinate. On the other hand, if the leaving temperature exceeds 60 ° C. or the standing time exceeds 120 minutes, the sterilization efficiency of the spores may be reduced, spores may be formed again, or microorganisms may grow.

  According to the spore germicidal method according to the present invention described above, germination is performed on the germination method according to the present invention, and spore germs in a state in which heat resistance, pressure resistance and the like are significantly reduced are sterilized. This can be sterilized reliably. Moreover, since the conditions for such sterilization treatment can be set relatively gently, spore bacteria can be sterilized without denaturing or coagulating the protein of the liquid egg or egg processed product.

  Next, an example in which the effect of the spore germination method of the present invention and the spore germicidal method using the spore germination method is confirmed will be described.

First, the experimental apparatus used in the examples will be described.
FIG. 1 is a schematic diagram of an experimental apparatus. This experimental apparatus includes a pressure vessel 1. The pressure vessel 1 is a cylindrical sealed vessel having an inner diameter of 100 mm, for example, and the wall thickness dimension is set to 150 mm. In the pressure resistant container 1, a food container, that is, a liquid egg or processed egg product is sealed in a flexible container. Next, the pressure vessel 1 is filled with fresh water. A heater 2 for heating is disposed on the outer surface of the pressure vessel 1. The heater 2 can raise the temperature in the pressure vessel 1 to 90 ° C., and can set the pressure vessel 1 to an arbitrary temperature. A pressure pump 3 is connected to the pressure vessel 1. The pressure pump 3 can adjust the pressure vessel 1 to an arbitrary pressure up to 500 MPa. Further, a temperature sensor 4 and a pressure gauge 5 are attached to the pressure vessel 1. The temperature sensor 4 detects and displays the temperature in the pressure vessel 1, and the pressure gauge 5 detects the pressure in the pressure vessel 1. And display.

[1] Evaluation of quality of raw whole liquid egg after heat treatment and pressure treatment Raw whole liquid egg was hermetically filled in a polyethylene pouch, and as shown in Table 1 below, a temperature condition of 5 to 70 ° C. And each was processed for 30 minutes under pressure conditions of 0.1 to 300 MPa.
Table 1 shows the results of evaluating the quality of raw whole liquid eggs after heat treatment and pressure treatment. In Table 1, “◯” indicates that the quality (raw state) was not affected (the quality was not deteriorated), and “△” indicates that the quality (raw state) is slightly affected. “X” indicates that the quality (raw state) was affected (quality was deteriorated).

Further, as described above, the fried egg was hermetically filled in a polyethylene pouch, and as shown in Table 2 below, each was treated for 30 minutes under a temperature condition of 5 to 70 ° C. and a pressure condition of 0.1 to 500 MPa.
Table 2 shows the results of evaluating the quality of the fried eggs after the heat treatment and pressure treatment. In Table 2, “◯” indicates that the quality was not affected (the quality was not deteriorated), and “△” slightly affected the quality (the quality was slightly deteriorated). “X” indicates that the quality was affected (the quality was deteriorated).

  As shown in Table 1, in the pressure treatment of raw whole liquid eggs, the quality deteriorated somewhat at 50 ° C. at 0.1 MPa, and the quality deteriorated at 60 ° C. because the protein in the raw whole liquid eggs was denatured and coagulated. . On the other hand, in the pressure treatment of 10 to 100 MPa, the quality did not deteriorate at 5 to 50 ° C., and further, at 0.1 MPa, the protein was only slightly denatured even at 60 ° C. where the protein was denatured or coagulated. When the pressure was 200 MPa, the quality was slightly modified (the quality was slightly deteriorated), but the quality could be generally maintained at 5 to 60 ° C. Furthermore, when the pressure was set to 300 MPa, it was completely denatured (quality deteriorated). In other words, it was found that the liquid egg can be maintained in a substantially raw state under conditions of 10 to 200 MPa and 5 to 60 ° C. In particular, no deterioration in quality was observed at 20 to 100 MPa and 5 to 50 ° C.

  Further, as shown in Table 2, no significant change was observed in the quality of the fried egg in the pressure treatment of fried egg at 5 to 60 ° C. and 10 to 500 MPa. That is, the quality of the fried egg did not deteriorate.

[2] Spore germination effect (pressure treatment condition (1))
Table 3 shows the germination effect of spores when raw whole liquid eggs were treated under conditions of 10 to 200 MPa, 40 ° C., and 30 minutes. Specifically, Bacillus cereus 1510 (Japan Canning Association) spore was added to raw whole liquid eggs so as to be 10 ⁶ CFU / g, and 8 g each was aseptically sealed and filled in a polyethylene pouch as shown in FIG. The pressure treatment was carried out in a pressurizing and heating apparatus (manufactured by Hikari Kouhiki Co., Ltd.). Subsequently, heat treatment was performed at 60 ° C. for 20 minutes to germinate the germinated spore bacteria. The germination rate of the spores by the pressure treatment and the subsequent heat treatment was determined. The germination rate was determined by the following formula [1]. For this reason, the result of germination rate is better for “-4” than for “−1”. In addition, the germinated spore bacteria here are spore bacteria sterilized by pressure treatment and heat treatment. Therefore, the germination rate here can also be called a sterilization rate.

Germination rate = Log ₁₀ (number of remaining spores after pressure treatment and heat treatment / number of spores before pressure treatment) ... [1]

  As shown in Table 3, an effective germination effect was obtained at 10 to 200 MPa, particularly 40 to 200 MPa. Note that the germination rate of the spores did not change much even at a pressure of 100 MPa or more. Based on the results in Table 1, it was found that the conditions of the pressure treatment in the spore germination method according to the present invention can be applied without problems if the conditions are 10 to 200 MPa. In addition, it turned out that it has a germination effect even if the conditions of a more preferable pressurization process are 20-100 MPa and 10 MPa or more and less than 20 MPa.

[3] Spore germination effect (pressure treatment condition (2))
Table 4 shows the germination effect of the spore when the fried egg was processed under conditions of 10 to 500 MPa, 40 ° C., and 30 minutes. That is, Bacillus cereus 1510 (Japan Canning Association) spore was added to egg-cooked so that it would be 10 ⁶ CFU / g, and 8 g each in a polyethylene pouch was aseptically sealed and filled. The product was subjected to pressure treatment. Subsequently, heat treatment was performed at 60 ° C. for 20 minutes to germinate germinated spores. The germination rate of the spores by the pressure treatment and the subsequent heat treatment was determined. In addition, the germination rate was calculated | required by said Formula [1].

  As shown in Table 4, an effective germination effect was obtained at 10 to 500 MPa, particularly 40 to 500 MPa. Note that the germination rate of the spores did not change much even at a pressure of 100 MPa or more. Based on the results in Table 2, it was found that the pressure treatment conditions in the spore germination method according to the present invention were 10 to 500 MPa and could be applied without any problem. In addition, it turned out that it has a germination effect even if the conditions of a more preferable pressurization process are 20-250 MPa and 10 MPa or more and less than 20 MPa.

[4] Germination effect of spore (conditions for heat treatment)
Table 5 shows the germination effect of spores when raw whole liquid eggs and fried eggs were treated under conditions of 60 MPa, 20 to 60 ° C., and 30 minutes. That is, Bacillus cereus 1510 (Japan Canning Association) spores were added to the whole liquid egg so that it would be 10 ⁶ CFU / g, and 8 g of each pouch made of polyethylene was aseptically sealed and filled. It was put in a high-pressure device (trade name) and pressure-treated. Subsequently, heat treatment was performed at 60 ° C. for 20 minutes to germinate germinated spores. The germination rate of spore bacteria by the pressure treatment and the subsequent heat treatment was determined. In addition, the germination rate was calculated | required by said Formula [1].

As shown in Table 5, an effective germination effect was observed at 5 to 60 ° C., particularly 20 to 60 ° C., for raw whole liquid eggs and fried eggs. Moreover, as shown in Table 1, since the egg quality did not deteriorate particularly at 20 to 50 ° C., there was no problem if the heat treatment conditions in the spore germination method according to the present invention were 20 to 60 ° C. I found it applicable. In addition, it has been found that more preferable heat treatment conditions are 30 to 50 ° C., and that a sterilizing effect is obtained even at 5 ° C. or more and less than 50 ° C.
Moreover, as shown in Table 2, since the quality of the fried egg did not change at any temperature, it was found that the heat treatment conditions in the spore germination method according to the present invention can be applied without problems at 5 to 60 ° C. It was. In addition, it turned out that the more preferable heat processing conditions are 20-60 degreeC, and it has a germination effect also at 5 degreeC or more and less than 50 degreeC similarly to the case of whole liquid eggs.

[5] Growth behavior of Bacillus cereus after germination and sterilization
Bacillus cereus 1510 (Japan Canning Association) was added to glucose broth medium (pH 7.0, 3 g / L meat extract (Oxoid, England), 3 g / L yeast extract (Nihon-Seiyaku, Tokyo), 10 g / L Bacto-peptone (Difco Laboratories , USA), 5 g / L NaCl, and 5 g / L glucose) and suspended at 10 ⁵ CFU / mL, and treated under conditions of 60 MPa, 40 ° C., and 1 to 120 minutes. Then, the germination rate of the microbe at the time of heat-processing on 60 degreeC and the conditions for 20 minutes is shown in Table 6. In addition, the germination rate was calculated | required by said Formula [1].
Moreover, the change (namely, growth curve) of a viable count when the suspension of the spore which carried out the pressure process and heat processing on the said conditions was cultured at 35 degreeC for 0 to 16 hours is shown in FIG. In FIG. 2, the horizontal axis represents the processing time (hours), and the vertical axis represents the absorbance (OD 600) at a wavelength of 600 nm. As an absorptiometer, BIO PHOTORECORDER TVS 062CA manufactured by ADVANTEC was used.

  As shown in Table 6, the germination rate increased as the treatment time was increased, but it was found that there was no significant increase in the germination rate even after 60 minutes or longer. On the other hand, as shown in FIG. 2, it can be seen that the time required for the growth of spore bacteria (Bacillus cereus) increases as the treatment time is extended. That is, the longer the shelf life is, the longer the germination treatment time is. It turned out that it can apply without a problem if the processing time of the germination process in this invention is 1-120 minutes. In addition, when the expense concerning a germination process was considered, it turned out that the processing time of a more preferable germination process is 30 to 60 minutes.

[6] Bactericidal treatment of germinating spores of Bacillus cereus (1)
Bacillus cereus 1510 (Japan Canning Association) was suspended in a raw whole liquid egg at 10 ⁶ CFU / mL and treated under conditions of 60 MPa, 40 ° C., 30 minutes to germinate spores. After pressure treatment, 80 ° C. The sterilization rate of the bacteria when heat-treated for 1 second to 120 minutes was determined by the following formula [2]. Table 7 shows the sterilization rate.

Bactericidal rate = Log ₁₀ (number of remaining spores after pressure treatment and heat treatment / number of viable bacteria after pressure treatment) [2]

  As shown in Table 7, it was found that the spore bacteria germinated by the germination method of the present invention are very easily killed and can be sufficiently sterilized by heating at 80 ° C. for 1 second or longer. In consideration of the cost for sterilization treatment and deterioration of egg quality due to heating, the preferred heating time after pressure treatment is 1 second to 120 minutes.

[7] Bactericidal treatment of germinating spores of Bacillus cereus (2)
Bacillus cereus 1510 (Japan Canning Association) is suspended in a raw whole liquid egg at 10 ⁶ CFU / mL, treated at 60 MPa, 40 ° C. for 30 minutes to germinate spores, and subsequently 40 ° C. to 100 ° C. The sterilization rate of the bacterium when heat-treated at 30 ° C. for 30 minutes was determined by the above formula [2]. Table 8 shows the sterilization rate.

  As shown in Table 8, it was found that the spore bacteria germinated by the germination method of the present invention can be sterilized by heating at 40 ° C to 100 ° C.

[8] Bactericidal treatment of germinating spores of Bacillus cereus (3)
Bacillus cereus 1510 (Japan Canning Association) was suspended in a raw whole liquid egg at 10 ⁶ CFU / mL and treated under conditions of 60 MPa, 40 ° C., 30 minutes to germinate spores, followed by 40 ° C., 0 ° The sterilization rate of the bacteria when heat-treated for 30 minutes at 1 to 500 MPa was determined by the above formula [2]. Table 9 shows the sterilization rate.

  As shown in Table 9, it was found that the spore bacteria germinated by the germination method of the present invention can be sterilized by further applying a pressure of 100 to 500 MPa.

  [6] Bactericidal treatment of germinated spores of Bacillus cereus (1), [7] Bactericidal treatment of germinated spores of Bacillus cereus (2), [8] Bactericidal treatment of germinated spores of Bacillus cereus (3) It was found that the spore bacteria germinated by the germination method of the invention can be sterilized by either heat treatment or pressure treatment. In consideration of sterilization efficiency and egg quality deterioration due to sterilization treatment, the sterilization condition is 40 ° C. to 60 ° C. or 10 to 200 MPa, more preferably 50 ° C. to 60 ° C. For egg processed products that are relatively stable with respect to heating, 40 ° C to 100 ° C or 100 to 500 MPa, more preferably 50 ° C to 100 ° C or 100 to 500 MPa. Of course, the sterilization of the spore bacteria germinated by the germination method of the present invention may be carried out in combination with the heat treatment and the pressure treatment described above. In some cases, it may be moderate.

[9] Storage test (1)
Bacillus cereus, which has been identified from food, is added to the whole liquid egg containing the seasoning liquid, etc. so that it becomes 10 ⁴ CFU / g, and pressure treatment is performed at 60 MPa, 40 ° C. for 30 minutes to germinate spores. The egg was processed as a fried egg and subjected to pasteurization at 90 ° C. for 10 minutes, followed by a storage test at 10 ° C., and the number of viable bacteria was measured (pressure treatment + pasteurization treatment). The results are shown in Table 8. As a comparative control, the number of general viable bacteria of a sample subjected to only pasteurization treatment at 90 ° C. for 10 minutes was also measured.

  As shown in Table 10, in the case where the pressure treatment and pasteurization treatment were performed (pressure treatment + pasteurization treatment), the growth of the number of general viable bacteria was remarkably suppressed even after storage for 15 days. On the other hand, in the case where only pasteurization treatment was performed, the bacteria grew during the storage for 12 days and decayed.

[10] Storage test (2)
Prepare whole egg containing seasoning liquid etc. without sodium acetate (made by Yoneyama Chemical Co., Ltd.) (0%) and 0.5% added (0.5%). Bacillus cereus used in [9] above was added to 10 ⁴ CFU / g. These were pressure treated under conditions of 60 MPa, 40 ° C., 30 minutes to germinate spores, then processed as fried eggs, and pasteurized at 90 ° C. for 10 minutes. And the preservation | save test was done at 30 degreeC and the number of the general viable bacteria was measured (pressurization process + pasteurization process). The results are shown in Table 11. As a comparative control, the number of general viable bacteria of a sample subjected to only pasteurization treatment at 90 ° C. for 10 minutes was also measured.

As shown in Table 11, in the case where only pasteurization treatment was performed, the bacteria proliferated and decayed after storage for 24 hours, but those subjected to pressure treatment and pasteurization treatment (pressure treatment + pasteurization) In the treatment), the number of bacteria did not grow so much even after storage for 24 hours and did not rot. In addition, the number of bacteria did not increase at all even after 48 hours of storage in which 0.5% sodium acetate was added and subjected to pressure treatment and pasteurization treatment.
On the other hand, in the case of adding 0.5% sodium acetate and performing only pasteurization treatment, it was 3,000,000 CFU / g or more after storage for 24 hours, and the growth of bacteria could not be suppressed at all.

[11] Storage test (3)
Prepare whole egg containing seasoning liquid etc. without glycine (manufactured by Showa Denko KK) (0%) and 1% addition (1%). The Bacillus cereus used was added to 10 ⁴ CFU / g. These were pressure-treated at 60 MPa and 40 ° C. for 30 minutes to germinate spores, processed as fried eggs, and pasteurized under the conditions described in [9] above. And the preservation | save test was done at 30 degreeC and the number of the general viable bacteria was measured (pressurization process + pasteurization process). The results are shown in Table 12. As a comparative control, the number of viable bacteria was also measured at the same time for the sample that was only pasteurized.

As shown in Table 12, in the case where only pasteurization treatment was performed, the bacteria proliferated and decayed after storage for 24 hours, but those subjected to pressure treatment and pasteurization treatment (pressure treatment + pasteurization) In the treatment), the number of bacteria did not grow so much even after 24 hours of storage and did not rot. Moreover, having been subjected to 1% added to pressure treatment and pasteurization glycine did not increase at all the number of bacteria even after 48 hours Maho exist. In contrast, 1% glycine added and only pasteurized was 3,000,000 CFU / g after storage for 24 hours, and the growth of bacteria could not be suppressed at all.

  [10] From the results of the storage test (2) and [11] storage test (3), the shelf life extension effect is significantly extended by using a shelf life improver containing at least one of sodium acetate and glycine and pressure treatment. I found out that Furthermore, it was found that sodium acetate and glycine used in combination are usually sufficient in an extremely small amount so that the shelf life extension effect cannot be exhibited. It was also found that sodium acetate and glycine do not inhibit the shelf life extension effect by pressure treatment. By using pressurization treatment together with shelf life improvers or preservatives such as sodium acetate and glycine, the sterilization effect of heat resistant spores and the shelf life extension effect in liquid eggs, liquid egg processed raw materials, and egg processed products are significantly enhanced. I found out that

[12] Storage test (4)
Bacillus cereus used in [9] above was added to the whole liquid egg containing the seasoning liquid and the like so as to be 10 ³ CFU / g. These were pressure-treated at 60 MPa and 40 ° C. for 30 minutes to germinate spores, then processed as fried eggs, and pasteurized under the above-mentioned conditions [9] (pressure treatment). In addition, after the pressure treatment, it was left under normal pressure at 25 ° C. for 40 minutes, and then processed as an omelet and pasteurized under the condition [9] described above (pressure treatment + normal pressure treatment). Each sample was subjected to a storage test at 30 ° C., and the number of viable bacteria was measured (pressure treatment). The results are shown in Table 13.

  As shown in Table 13, the number of viable bacteria after treatment is less when the pasteurization treatment is carried out after being left under normal pressure after the pressure treatment, and stored for 24 hours than the case where only the pressure treatment is performed. The number of viable bacteria later was also small. From the above results, it was found that the spore sterilizing effect was further enhanced by leaving the sample under normal pressure after the pressure treatment.

  As mentioned above, the spore germination method of the present invention and the spore germicidal method using the spore germination method have been specifically described by the best mode and examples for carrying out the invention, but the gist of the present invention is described in these descriptions. It is not intended to be limiting, and should be interpreted broadly based on the claims. Needless to say, various changes and modifications based on these descriptions are also included in the spirit of the present invention.

It is a schematic diagram of an experimental apparatus. It is a graph which shows the change of viable cell count when the suspension of the spore which carried out the pressure process and heat processing on predetermined conditions was cultured at 35 degreeC for 0 to 16 hours. In the figure, the horizontal axis represents the processing time (hours), and the vertical axis represents the absorbance (OD600) at a wavelength of 600 nm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure-resistant container 2 Heater 3 Pressure pump 4 Temperature sensor 5 Pressure gauge

Claims (6)

A spore germination method for germinating spores formed by spore bacteria contained in a liquid egg or processed egg product without degrading the quality of the liquid egg or processed egg product,
A method for germinating a spore, wherein the liquid egg or the processed egg product is subjected to a pressure treatment at a temperature of 5 to 60 ° C. with a hydrostatic pressure of 10 to 200 MPa for 1 to 120 minutes.   The spore germination method according to claim 1, wherein at least one of a shelf life improver and a preservative is added to the liquid egg or the processed egg product in an amount of 0.1% to 3% by weight.   The germination method according to claim 1 or 2, wherein germination of the germinated spores is performed after germination of the spores contained in the liquid egg or the processed egg product. To sterilize spores.   3. The spore germination method according to claim 1 or 2, wherein the spore contained in the liquid egg or the processed egg product is germinated and left at a temperature of room temperature to 60 ° C. for 10 minutes to 120 minutes under normal pressure. A sterilizing method for spore bacteria characterized by performing a sterilizing treatment for sterilizing the germinated spores later.   The said sterilization process performs at least one among the heat processing of 40 degreeC or more and 100 degrees C or less, and the pressurization process of 100 MPa or more and 500 MPa or less for 1 second to 120 minutes, The claim 3 or 4 characterized by the above-mentioned. To sterilize spore bacteria.   5. The sterilization treatment is performed by performing at least one of a heat treatment of 40 ° C. or more and 60 ° C. or less and a pressure treatment of 100 MPa or more and 200 MPa or less for 1 second to 120 minutes. To sterilize spore bacteria.

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