JPH04330274A - Lactobacillus cell immobilized to inorganic porous material - Google Patents

Abstract

PURPOSE:To provide lactobacillus cells immobilized to inorganic porous material, repeatedly usable for the preparation of yogurt, pickles, etc., having high preservability and capable of dividing into nearly equal portions to facilitate the handling. CONSTITUTION:The objective lactobacillus immobilized to inorganic porous material can be produced by immobilizing lactobacillus to an inorganic porous material and lyophilizing in vacuum.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lactic acid bacteria immobilized on an inorganic porous material that can be repeatedly used in the preparation of yogurt and the like and has a high shelf life.

0002

[Prior art] Generally, when storing lactic acid bacteria at room temperature,
If left as is, the bacterial cells will be highly active, and the lactic acid bacteria will die under the influence of the organic acids produced. Therefore, acid resistance can be increased by mixing a protective agent such as skim milk powder with bacterial cells, and
The method of preservation is to reduce the activity of lactic acid bacteria by pulverizing it by vacuum freeze-drying.

[0003] However, the above-mentioned preserved bacterial cells cannot be stored at room temperature (2
It does not have a good shelf life at temperatures above 5°C, and only lasts for about 30 days. In addition, when preparing yogurt using these preserved bacterial cells, it is impossible to reuse the bacterial cells, and furthermore, it is inefficient and uneconomical because it is necessary to weigh each time each use. .

0004

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and has been made through intensive research in order to obtain lactic acid bacteria that can be repeatedly used in the preparation of yogurt, etc., and has a long shelf life. I did it. As a result, it was found that the above objective could not be satisfied only by selecting a protective agent. Therefore, we thought of immobilizing lactic acid bacteria in an inorganic porous material, conducted further research, and finally arrived at the present invention.

[0005] That is, the object of the present invention is to
It is an object of the present invention to provide lactic acid bacteria cells immobilized on an inorganic porous material that can be repeatedly used in the preparation of yogurt and the like and have a high preservability.

[0006]

[Means for Solving the Problems] The above object is achieved by an inorganic porous material-immobilized lactic acid bacteria body, which is made by supporting vacuum freeze-dried lactic acid bacteria on an inorganic porous material.

Next, the present invention will be explained in detail. The inorganic porous bodies used in the present invention include ceramic porous bodies such as ceramic foam, ceramic honeycomb, and cotton-like ceramics made of alumina, zirconia, titania, cordierite, mullite, etc., and amorphous ceramics such as porous glass and foam glass. This refers to materials that have many pores in them, such as porous materials. Further, a coated ceramic porous body obtained by coating the ceramic porous body with alumina, zirconia, titania, silica, etc. may be used.

The pores may be closed pores or open pores, but from the viewpoint of lactic acid bacteria activity per unit volume of the porous material, open pores are preferred. In addition, the pore diameter of the porous body is
5 to 100 μm is preferable, more preferably 10 to 60 μm.
It is μm. If the pore size exceeds 100 μm, the leakage of lactic acid bacteria will increase and it will be difficult to withstand reuse.
If it is less than that, the amount of lactic acid bacteria immobilized will be low, and it will be difficult for the fermented material to diffuse into the inside of the porous body.

[0009] Also, the porosity varies depending on the pore diameter, but for example, when the pore diameter is 5 to 100 μm, the porosity is 50 μm.
Setting it to 90% is preferable in terms of immobilization efficiency.

Further, the shape of the inorganic porous material is generally preferably rod-like or plate-like because they are easy to handle. Alternatively, it may be shaped like a cup or bowl that can be used to directly prepare yogurt or the like. Moreover, if the size is too small, it will take time to separate it from fermented products such as yogurt, so it is preferable that the size is such that it can be easily removed. Further, the length of one side of the inorganic porous body is preferably 5 mm or less, more preferably 2 mm or less. If it exceeds 5 mm, the efficiency of immobilizing the microbial cells inside the porous body tends to be poor, and the fermentation efficiency when fermentation is performed using the immobilized microbial cells tends to become poor. Further, the size of the inorganic porous body may be appropriately set according to the amount of the medium so that the entire surface is immersed in the medium.

In the present invention, by using an inorganic porous material, it has excellent stability against heat such as sterilization, physical stability against operations such as vacuum freeze-drying, and chemical stability against solvents, bacteria-produced substances, etc. There is. Therefore, compared to conventional bacterial cell protectants, the durability and storage stability of bacterial cells upon repeated use are improved.

[0012] The lactic acid bacteria used in the present invention are lactic acid bacilli and lactic acid cocci commonly used in the food industry, and specifically, Lactobacillus genus, Leuconostoc genus, Bifidobacterium ( Bifidobacterium
) and Streptococcus
s) Consists of at least one bacterial group selected from the genus, etc.

[0013] The inorganic porous material-immobilized lactic acid bacteria cells of the present invention can be produced, for example, as follows. That is, first, an inorganic porous material is placed in a sterilized lactic acid bacteria growth medium, and 106 to 1010 pre-cultured lactic acid bacteria are added thereto.
cc inoculation and culture. Next, after the lactic acid bacteria are immobilized on the inorganic porous material, this is taken out and vacuum freeze-dried.

[0014] As the medium for growing lactic acid bacteria, skim milk powder medium, MRS medium, etc. are used. In addition, the culture conditions may be those for culturing lactic acid bacteria, such as pH 6 to 8 and temperature 30.
What is necessary is to culture at ~40°C for about 24 hours.

[0015] Further, as a method for vacuum freeze-drying, a conventional method may be followed. For example, after freezing an inorganic porous material on which lactic acid bacteria have been immobilized in advance, it is placed in a vacuum freeze-dryer and heated to an upper limit temperature of about 40°C. The water is sublimated and dried.

The amount of lactic acid bacteria immobilized on the inorganic porous material-immobilized lactic acid bacteria cells obtained as described above is approximately the same as the number of bacteria grown in the lactic acid bacteria growth medium, 10 6 to 10 10 cells/cc. Since the amount of immobilized lactic acid bacteria is almost known in this way, there is no need to weigh them each time they are used for fermentation.

The inorganic porous material-immobilized lactic acid bacteria cells of the present invention obtained as described above can be used for preparing yogurt, pickles, and the like. For example, to prepare yogurt, add 5 g of lactic acid bacteria immobilized on an inorganic porous material to 300 cc of sterilized milk or skimmed milk powder, and then
This is done by fermenting for hours.

[0018] The lactic acid bacteria cells immobilized on an inorganic porous material of the present invention have 1
It can be used not only once, but repeatedly several times. That is, the inorganic porous material-immobilized lactic acid bacteria cells used once can be taken out from the fermentation preparation, washed, and used for the next preparation, and can usually be used six times without any disadvantage.

[0019]

As described above, the inorganic porous material-immobilized lactic acid bacteria cells of the present invention can be used to repeatedly prepare yogurt and the like. In addition, the storage stability is higher than that of conventional vacuum freeze-dried preserved bacterial cells. In addition, since the number of immobilized bacteria is approximately known at the time of immobilization, there is no need to measure them each time they are used, which improves production efficiency. Furthermore, it is also possible to package and commercialize the product.

The present invention will be specifically explained below with reference to Examples. [Examples 1 and 2] Lactobacillus bulgaricus (L
actobacillus (hereinafter referred to as L.) bul
garicus) in skim milk powder medium to 107 to 108
cells/cc, and then pre-sterilized 2
0x20x2mm, pore diameter 45-60μm, porosity 65
% open pore alumina coated ceramics (
Skim milk powder medium (10% milk powder aqueous solution) containing approx. 5g) 3
One platinum loopful of the above lactic acid bacteria was inoculated into 00 cc and incubated at 37°C for 2 hours.
It was cultured for 4 hours. Next, the ceramics were washed with a sterilized skim milk powder medium, and then placed in a sterile petri dish and vacuum freeze-dried.

[0021] Example 1 is a lactic acid bacteria body immobilized on a ceramic porous body immediately after vacuum freeze-drying, and the lactic acid bacteria body immobilized on a ceramic porous body immediately after vacuum freeze-drying is filled into a laminated aluminum bag, sealed, and stored at 25°C for 40 days. The stored sample was designated as Example 2.

[Examples 3 and 4] As a lactic acid bacterium, Leuconostoc mesenteroides
c mecenteroides).
A porous ceramic body-immobilized lactic acid bacteria body was prepared in the same manner as in Example 1. Example 3 is a lactic acid bacteria body immobilized on a porous ceramic body immediately after vacuum freeze-drying, and the lactic acid bacteria body immobilized on a porous ceramic body immediately after vacuum freeze-drying was filled into a laminated aluminum bag, sealed, and stored at 25°C for 40 days. was designated as Example 4.

[Examples 5 and 6] Streptococcus thermophilus was used as a lactic acid bacterium.
Ceramic porous material-immobilized lactic acid bacteria cells were prepared in the same manner as in Example 1, except that S. thermophilus was used. Example 5 is lactic acid bacteria cells immobilized on a porous ceramic body immediately after vacuum freeze-drying, and the lactic acid bacteria bodies immobilized on a porous ceramic body immediately after vacuum freeze-drying are filled into a laminated aluminum bag, sealed, and stored at 25°C for 40 days. was designated as Example 6.

[Comparative Examples 1 and 2] Lactic acid bacteria were immobilized in the same manner as in Example 1, but vacuum freeze-drying was not performed, and 5 m
Comparative Example 1 was obtained by drying the sample for 3 days by blowing air at /sec. Moreover, this was stored at 25° C. for 40 days as Comparative Example 2.

[Comparative Examples 3 and 4] Lactobacillus bulgaricus (L. bulgaricus) as lactic acid bacteria
After pre-culture in skim milk powder medium, pre-sterilized 2G
One platinum loopful was inoculated into YP medium, cultured at 37°C for 1 day, and after centrifugation, the bacterial cells were dispersed in a skim milk powder medium that had been sterilized in advance and vacuum freeze-dried. The powder immediately after vacuum freeze-drying was designated as Comparative Example 3, and the powder immediately after vacuum freeze-drying was filled into a laminated aluminum bag, sealed, and stored at 25° C. for 40 days as Comparative Example 4.

[0026] 300 c of milk sterilized using immobilized or non-immobilized lactic acid bacteria bodies of Examples 1 to 6 and Comparative Examples 1 to 4.
Yogurt was prepared at 37° C. by adding 5 g to C, and the time required to form a curd, the time until the acidity reached 0.8%, and the flavor of the obtained yogurt were investigated.

The results are shown in Table 1. In addition, the sensory evaluation of the flavor of the yogurt was shown by the score when Comparative Example 3 was set as 0, and also by the average score of 13 panelists according to the following evaluation criteria. 0...Good, -1...Slightly bad,
-2...Poor, -3...Very poor

[0028]

[Table 1]

From the results shown in Table 1, when fermentation was carried out using the immobilized lactic acid bacteria cells of Examples, the activity of the lactic acid bacteria was high and the flavor of the resulting yogurt was also good. On the other hand, in the case of the lactic acid bacteria cells of Comparative Examples 1 and 3, the lactic acid bacteria cells of Comparative Examples 1 and 3 were used immediately after preparation, so the lactic acid bacteria cells of Comparative Examples 1 and 3 were used. 2 bodies each
The lactic acid bacteria cells of Comparative Examples 2 and 4 that were stored at 5°C for 40 days were undesirable because the activity of the lactic acid bacteria decreased, fermentation took time, and the resulting yogurt had a bad flavor.

[Example 7] Yogurt was repeatedly prepared using the immobilized lactic acid bacteria of Example 1, and the flavor of the yogurt was sensory evaluated each time. At this time, the immobilized lactic acid bacteria bodies are
Each time yogurt was prepared, the surface was lightly washed with previously sterilized milk. The results are shown in Table 2. In addition,
As described above, the sensory evaluation was based on the first preparation as 0, and was expressed as the average score of the 13 panelists.

[0031]

[Table 2]

From the results in Table 2, it is possible to repeatedly prepare yogurt using the same immobilized lactic acid bacteria, and
Up to the 6th time, yogurt was obtained which had a good flavor and was no different from the yogurt prepared at the 1st time.

[Examples 8 to 12] Inorganic porous material having a rectangular plate shape of 20 mm on each side and 1.5 mm in thickness with different pore diameters
using alumina ceramics of Example 1.
Immobilized lactic acid bacteria cells were prepared in the same manner as above, yogurt was prepared using the same, and the flavor was evaluated. The results are shown in Table 3. The sensory evaluation criteria were the same as described above, and the average score of 13 panelists was used.

[0034]

[Table 3]

From the results in Table 3, when the average pore diameter is 5 μm, the amount of lactic acid bacteria immobilized is low, and it is difficult for the air to diffuse into the inside of the porous material, and when the average pore diameter is 100 μm, there is a lot of lactic acid bacteria leaking out. It affected the flavor of the yogurt.

[Examples 13 to 16] Average pore diameter 45μ,
Lactobacillus bulgaricus (L. bulgaricus) was grown in the same manner as in Example 1 on four kinds of porous ceramics of zirconia, titania, cordierite, and lurite with a porosity of 65%.
ricus) was immobilized and vacuum freeze-dried to obtain immobilized lactic acid bacteria cells. Milk sterilized with this immobilized lactic acid bacteria body 300
cc was added to prepare yogurt at 37°C. At this time, the curd-forming time, the time until the acidity reached 0.8%, and the sensory evaluation of the obtained yogurt were performed. The sensory evaluation method was performed in the same manner as described above. The results are shown in Table 4.

[0037]

[Table 4]

Claims (1)

[Claims] 1. An inorganic porous material-immobilized lactic acid bacteria body, which is obtained by supporting vacuum freeze-dried lactic acid bacteria on an inorganic porous material.