JP2004313190A - New baker's yeast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a bread suppressed in the growth of mold without adding preservatives, free from impairing quality of bread (swelling, inside foaming, flavor, and the like). <P>SOLUTION: The bread is produced by using a baker's yeast which controls growth of mold by reducing pH of a crumb of the bread produced in a sponge and dough method to less than 5.2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel baker's yeast, a dough containing the baker's yeast, and a method for producing bread using the baker's yeast.

  The bread is baked after mixing flour, water, salt, baker's yeast, dairy products, sugars, oils and fats, fermenting for a certain period of time, and the like. During the fermentation process, baker's yeast fermentes sugars such as maltose contained in flour and sugar added as a raw material to convert most of them into carbon dioxide and ethanol. Also, organic acids, esters, and the like are formed, and these contribute to the flavor of bread. Since baking is usually performed in an oven at about 200 ° C., the outer skin temperature rises to about 160 ° C., and the center of the inner phase also rises to about 100 ° C., and this temperature is maintained for 10 minutes during the baking time. Has been maintained.

  Mold is generally low in heat resistance, so it is known that spores of blue mold die at 82 ° C. for 10 minutes and spores of red mold die at about 70 ° C. for 10 minutes. Immediately after serving, the bread and the inner phase are sterile.

  However, since the bread leaving the oven is cooled on the conveyor for several tens of minutes with the target of the central temperature of 40 ° C., contact with the mold spores in the air is inevitable. Furthermore, mold spores also attach to the bread by the hands of the manufacturing workers due to contact with the slice, slicing, packaging, and the like, which also causes the occurrence of mold in bread (Non-Patent Document 1).

  For this reason, at the bread manufacturing site, the cooling process, the packaging process, the cleaning of dust and bread crumbs at the shipping site, and the spraying of a fungicide are performed, and the number of mold spores is reduced, thereby suppressing the occurrence of mold. Can be obtained, but it is very difficult to make it completely sterile.

  As a countermeasure, in the manufacture of bread, propionic acid and acetic acid are added as a preservative to delay mold generation for about 1 to 2 days, but as the amount added increases, fermentation of baker's yeast is suppressed, resulting in a decrease in bread volume. In addition, there are problems such as deterioration of the inner phase and deterioration of bread, such as generation of acid odor of preservatives.

  In addition, among the organic acids generated during the fermentation process as described above, acetic acid, in particular, has long been known empirically to have a strong antibacterial activity, and it has been known to preserve foods such as sushi, pickled vegetables, mayonnaise, etc. Power is being used.

  The antibacterial action of an organic acid is expressed only when it penetrates the cell membrane of a microorganism and enters the cell, but non-dissociated molecules have higher antibacterial activity because they have higher cell membrane permeability than dissociated molecules. Acetic acid, which has a low dissociation constant, is less likely to dissociate than organic acids such as succinic acid, lactic acid, malic acid, and citric acid, and the proportion of non-dissociated molecules increases, resulting in strong antibacterial activity. Have been.

  Further, since the dissociation of the organic acid is suppressed by lowering the pH, the lower the pH, the higher the concentration of the non-dissociative molecules becomes, and a strong antibacterial action can be exhibited (Non-Patent Document 2). For example, when acetic acid and lactic acid are allowed to act on E. coli simultaneously, rather than maintaining a constant pH of 5 to 6, it is better to control the pH by lactic acid and thereby increase the concentration of non-dissociated molecules of acetic acid without controlling the pH. It has been reported that the inhibitory effect on ATP increases (Non-Patent Document 3). In fact, it is known that the coexistence of lactic acid and acetic acid in soy sauce moromi increases the antibacterial activity by increasing the non-dissociated concentration of acetic acid due to a decrease in the pH of lactic acid (Non-Patent Document 4).

In recent years, the use of synthetic compounds in bread making has been shunned due to the growing tendency toward nature, and the use of natural products and the elimination of preservatives have tended to increase commercial value. However, no baker's yeast has produced acetic acid in an amount that exhibits sufficient antibacterial properties in the fermentation process and lowers the pH of crumb.
Korin, “The Science of Baking (1) The Science of Baking Process”, 1991, pp. 263-271 Gihodo Shuppan, "Food Microbiology Handbook", 1995, 522 pages J. Appl. Bacteriol. 1983, 54, 383. Jokyo, 1981, 76, 701

  In the present invention, it is an object of the present invention to enable the production of bread without adding a preservative, suppressing the generation of mold and not impairing the quality of bread (bread swelling, inner phase dust, flavor, etc.). .

  The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, produced bread having a lower pH of bread crumb and a higher acetic acid concentration as compared with the case of using conventional baker's yeast. The present inventors have found that the use of baker's yeast that can do so delays the occurrence of mold, and has completed the next invention.

  That is, the first aspect of the present invention relates to a baker's yeast characterized by lowering the pH of crumb of bread prepared by the bread seed method to 5.2 or less. In a preferred embodiment, the baker's yeast described above, wherein the acetic acid concentration in crumb is 250 ppm or more, more preferably, the baker's yeast is a strain KSY290 belonging to Saccharomyces cerevisiae (deposit number: FERM P- 18863). A second aspect of the present invention relates to a dough containing the above-described baker's yeast. A third aspect of the present invention relates to a method for producing bread using the above-described baker's yeast.

  When bread is produced using the baker's yeast of the present invention, the bread has a lower pH and a higher acetic acid concentration than bread produced using conventional baker's yeast, and as a result, the antibacterial activity is enhanced. In the conventional baker's yeast, mold is controlled by a method of adding a preservative, but in the baker's yeast of the present invention, mold can be suppressed by fermentation alone, and the use of the preservative can be prevented from affecting the bread quality.

  Hereinafter, the present invention will be described in more detail. The terms used in the present specification have the same meanings as those generally used in the art, except where specifically described below.

  In the present specification, the ratio (%) of sugar, salt, and other bread making ingredients refers to the weight ratio to flour. For example, a sugar content of 6% means that 6 g of sugar is used for 100 g of flour in bread dough. In the present specification, "other bread making auxiliary materials" refers to ingredients used for bread making other than flour, salt and water, for example, sugar, isomerized sugar, dairy products, fats and oils, and the like. It is not limited to.

  The baker's yeast of the present invention has a slower mold generation than the bread produced using the conventional baker's yeast, i.e., the bread produced using the baker's yeast of the present invention has It is characterized in that mold generation is suppressed. Here, the difficulty of mold generation in bread is referred to as mold resistance.

  The bread loaf seed method is a general bread making method and includes the following steps. 70% of the total amount of flour used for bread production is mixed with yeast and water to make a sponge dough, fermented at 27 ° C for about 4 hours, and then returned to the mixer, where the remaining flour and sugar are added to the sponge dough. , Fats and oils, dairy products and an appropriate amount of water, kneading, fermentation, and finally baking.

The bread crumb pH and acetic acid concentration were measured by the following methods. 20 g of the crumb portion of the cooled bread was mixed with 80 ml of distilled water, and crushed with a homogenizer at 12,000 rpm for 5 minutes to obtain a crushed liquid. The pH of the crushed liquid was measured with a pH meter and determined as crumb pH. 50 ml of the crushed liquid was centrifuged for 10 minutes at a gravitational acceleration of 17000 × g, 4.5 ml of the supernatant was collected, 0.5 ml of 10% perchloric acid was added and mixed well, and then centrifuged at a gravitational acceleration of 17000 × g for 10 minutes. Then, the supernatant was filtered through a syringe filter having a pore size of 0.45 μm to obtain a sample solution. The sample solution was subjected to measurement of the acetic acid concentration in bread crumb by high performance liquid chromatography (HPLC). The analysis conditions by HPLC are as follows.
HPLC: SHIMAZU LC10A
Column: SCR101H
Column temperature: 60 ° C
Detector: SPD10A (475 nm)
Flow rate: 1 ml / min
Mobile phase: Perchloric acid solution (pH 2.2)

  The bread crumb pH of bread prepared using the baker's yeast of the present invention by the sponge method is preferably in the range of 5.2 or less. If the pH is within this range, bread having reduced mold generation without impairing swelling is prepared. it can. The bread crumb preferably has a pH of 4.0 to 5.2, and more preferably 4.5 to 5.2. When the pH of the crumb of the bread is less than 4.0, the leavening of the bread may be reduced or the flavor may be impaired.

  In the bread prepared using the baker's yeast of the present invention and having a crumb pH of 5.2 or less, the acetic acid concentration in the crumb is preferably 250 ppm or more. Further, the acetic acid concentration in the crumb is preferably 250 to 4000 ppm. More preferably, it is 300 to 4000 ppm. When the acetic acid concentration in the breadcrumb is 250 ppm or more, sufficient mold prevention is obtained. If it exceeds 4000 ppm, a smell peculiar to acetic acid is felt and the commercial value of bread is impaired.

  The method for evaluating the fungicide resistance in the present invention is as follows. First, the prepared bread was allowed to stand in the air for one day, then sealed in a nylon bag, allowed to stand at 25 ° C. for 10 days, and 0.3 g of bread having sufficient mold growth was weighed and suspended in 10 ml of sterilized water. The initial concentration. Furthermore, a suspension was prepared by diluting the suspension having the initial concentration with another sterilized water 10 times to 100000 times.

  For the mold generation test, a bread of the target sample was sliced at a thickness of 2 cm, and 30 μl of the prepared four-level mold suspensions of 100 times, 1000 times, 10000 times and 100000 times were crumbed with n number = 4. After applying to the part, it is sealed with a nylon bag and allowed to stand at 25 ° C for 4 days to prevent mold from the difference in the dilution ratio of the mold suspension from which mold begins to develop on the crumb surface and the difference in mold growth thereafter. Sex was determined.

  Although the present invention has been described with reference to an example using a medium bread loaf bread, the bread yeast of the present invention also exerts the fungicidal effect of bread prepared by a method other than bread.

  In the present invention, it is preferable to select baker's yeast belonging to Saccharomyces cerevisiae in order to make the pH of crumb of bread produced by the bread loaf seeding method to 5.2 or less, and cross obtained from them. Of the strains, the KSY290 strain is more preferred.

  This strain KSY290 was identified as Saccharomyces cerevisiae, and this strain was identified as FERM P-18863 on May 17, 2002 by the Patent Organism Depositary, National Institute of Advanced Industrial Science and Technology (1-1-1 Higashi, Tsukuba, Ibaraki, Japan). No. 6).

  Hereinafter, examples of the present invention will be described. However, these examples are merely illustrative of the present invention, and the present invention is not limited to these examples. In addition, as for the materials used in the following examples, "Camelia" (manufactured by Nisshin Flour Milling Co., Ltd.) was used as flour, and "East Food C" (manufactured by Kanegafuchi Chemical Industry Co., Ltd.) was used as yeast food. The shortening used "Snow Light" (manufactured by Kanegafuchi Chemical Industry Co., Ltd.). As the emulsifier, "Panmac 200B" (manufactured by Riken Vitamin Co., Ltd.) was used. Other baking ingredients and baking ingredients used were those available from general retailers. As control strains, two commercially available baker's yeast strains (conventional baker's yeast A (product name: RED yeast, manufactured by Kaneka Chemical Industry Co., Ltd.) and conventional baker's yeast B (product name: GA yeast, Kanekachi Chemical Industry ( Co., Ltd.)) was used.

<Specific volume evaluation method in bread making test>
Breads produced based on the Examples and Comparative Examples were measured for volume (ml) by the rapeseed replacement method, and this value was divided by weight (g), and the value was used as a specific volume for comparison.

<Evaluation method of mold development>
From the top of the sliced bread, four mold suspensions with a dilution ratio of 100, 1000, 10,000, and 100,000 were applied at four points, and four samples coated with the same mold suspension were arranged side by side in the horizontal direction. After culturing at 4 ° C. for 4 days, the dilution ratio of the mold suspension in which mold had developed was visually evaluated.

<Evaluation method of mold growth condition>
From the top of the sliced bread, four mold suspensions with a dilution ratio of 100, 1000, 10,000, and 100,000 were applied at four points, and four samples coated with the same mold suspension were arranged side by side in the horizontal direction. The growth state of the mold after culturing at 3 ° C. for 3 or 4 days was visually evaluated. The evaluation criteria at that time are as follows. ：: growth is worse than conventional baker's yeast A, ×: equivalent to the growth state of conventional baker's yeast A.

<Method for determining mold resistance>
In the "mold development evaluation method" and "mold growth state evaluation method" described above, the mold suspension dilution rate at which mold starts to develop on the crumb surface after standing for 4 days (mold development evaluation) , And mold growth (evaluation of mold growth state) was used to determine the overall antifungal properties. The evaluation criteria at that time are as follows. ：: The dilution ratio of the part where the occurrence of mold was observed most slowly was 10,000 times or less 4 days after the mold application. Further, when the mold density is visually compared at the same dilution ratio, the mold density is lower than that of the conventional baker's yeast, and the spread of the mold is smaller. The evaluation criteria at that time are as follows. ×: The dilution ratio of the part where the occurrence of mold was observed most slowly was 100,000 times or more 4 days after the mold application. In addition, the mold density and spread at the same dilution ratio should be visually comparable to conventional baker's yeast.

(Example 1) Preparation of baker's yeast cells Saccharomyces cerevisiae-preserved strains owned by the present applicant were cultured by the following method.
-Batch culture The medium of the composition of Table 1 was dispensed into 5 ml / large test tubes and 50 ml / 500 ml Sakaguchi flasks, sterilized by autoclave, and used for culture.
Batch-inoculated whole hybrid breeding strain 1 inoculated in a large test tube, shake-cultured at 30 ° C for 1 day, subcultured into a 500 ml Sakaguchi flask, and further cultured at 30 ° C for 1 day in a tube shake culture. Was subjected to the following 5 L jar seed culture.

5 L Jar Seed Culture 2 L of the medium having the composition shown in Table 2 was placed in a 5 L jar, and after sterilization in an autoclave, cells of five 500 ml Sakaguchi flasks were inoculated and seed culture was carried out under the conditions shown in Table 3.

The starting culture volume of the 5 L jar was changed to the medium composition shown in Table 4, and 50 g of the seed cells cultured in the 5 L jar were added as wet cells, and the main culture was carried out under the conditions shown in Table 5.

  Culture was carried out for 13 hours, and sugar was added in portions during the culture for 12 hours. Immediately after the completion of the culturing, the 5-L jar cultured cells were centrifuged, and dehydrated by suction with a Nutsche to produce wet cells, which were used in the following Examples. When used in experiments, the moisture content of the wet cells was measured, and the amount used was converted to 65% moisture.

  Using the above cultured cells, bread was made by the seed method of bread, and the pH and acetic acid concentration of crumb were selected as indices to obtain the KSY290 strain of the present invention.

(Example 2) Evaluation of KSY290 strain In the dough composition shown in Table 6, and in the process shown in Table 7, a medium bread test was performed on KSY290. Table 8 shows the measurement results of the crumb pH and the acetic acid concentration of the prepared bread. FIG. 1 shows the growth state of the mold in the evaluation of fungicidal properties. In FIG. 1, the growth state of the mold after coating at four points with 100 times, 1000 times, 10000 times, and 100,000 times the mold suspension in order from the top and culturing at 25 ° C. for 4 days is shown.

(Comparative Example 1) Evaluation of Conventional Baker's Yeast A Strain Except for using conventional baker's yeast A as the baker's yeast, the medium-type bread making test and the evaluation of mold resistance were performed in the same manner as in Example 2. Table 8 shows the measurement results of the crumb pH and the acetic acid concentration of the prepared bread. FIG. 1 shows the growth state of the mold in the evaluation of fungicidal properties.

(Comparative Example 2) Evaluation of conventional baker's yeast B strain A middle-class bread-making test and evaluation of fungicide resistance were performed in the same manner as in Example 2, except that conventional baker's yeast B was used as baker's yeast. Table 8 shows the measurement results of the crumb pH and the acetic acid concentration of the prepared bread. FIG. 1 shows the growth state of the mold in the evaluation of fungicidal properties.

  Bread crumbs produced using KSY290 were characterized by low pH and high acetic acid concentration. As for the growth of mold, only KSY290 can be seen only up to the 10,000-fold dilution, but in the case of the preserved strain and the conventional baker's yeast, the growth of the mold has progressed up to 100,000-fold. KSY290 is thinner. As described above, mold generation was suppressed as compared with the bread produced using the stock strain or the conventional baker's yeast.

(Example 3) Evaluation of mold growth state of KSY290 strain In the dough composition shown in Table 9, and in the steps shown in Table 10, a medium-type bread making test was performed on KSY290. Table 11 shows the measurement results of the crumb pH and the acetic acid concentration of the produced bread. After the mold was applied, its growth was observed for 3 days and 4 days. The result is shown in FIG. FIG. 2 shows the growth state of the mold after 4 times application of a mold suspension having a dilution ratio of 100 times, 1000 times, 10000 times, and 100000 times from the top of the bread and culturing at 25 ° C. for 3 or 4 days.

(Comparative Example 3) Evaluation of mold growth state of conventional baker's yeast A strain Except for using baker's yeast A as a baker's yeast, a middle-class bread making test and evaluation of mold resistance were performed in the same manner as in Example 3. Table 11 shows the measurement results of the crumb pH and the acetic acid concentration of the produced bread. FIG. 2 shows the growth state of the mold in the evaluation of mold resistance.

  Bread crumbs produced using KSY290 were characterized by low pH and high acetic acid concentration. With respect to the growth of the mold, the mold development of the conventional baker's yeast A had progressed to the application portion with a dilution rate of 1000 times three days after application, but the KSY290 had a mold occurrence only up to the dilution rate of 100 times. Four days after the application, the mold development of the conventional baker's yeast A had progressed to the application portion with a dilution ratio of 100,000, whereas the occurrence of mold with KSY290 was only up to the dilution ratio of 10,000. In addition, KSY290 had a lower mold density than the conventional baker's yeast A even at the same dilution ratio. KSY290 suppressed the development of mold every day compared to the conventional baker's yeast. Therefore, it can be said that KSY290 has a high antifungal property.

Fig. 4 shows the occurrence of mold and growth in bread after culturing at 25 ° C for 4 days. Left: conventional baker's yeast A, middle: conventional baker's yeast B, right: KSY290. In one slice pan, four mold suspensions with a dilution ratio of 100 times, 1000 times, 10,000 times, and 100,000 times were applied in order from the top, and a sample to which the same mold suspension was applied in the horizontal direction was applied. It is a dot arrangement. Fig. 4 shows the occurrence and growth of mold on bread after culturing at 25 ° C for 3 or 4 days. Upper left: KSY290-3 days, lower left: KSY290-4 days, upper right: conventional baker's yeast A-3 days, lower right: conventional baker's yeast A-4 days. In one slice pan, four mold suspensions with a dilution ratio of 100 times, 1000 times, 10,000 times, and 100,000 times were applied in order from the top, and a sample to which the same mold suspension was applied in the horizontal direction was applied. It is a dot arrangement.

Claims (5)

  A baker's yeast, which lowers the pH of crumb of bread prepared by the bread seed method to 5.2 or less.   The baker's yeast according to claim 1, wherein the acetic acid concentration in the crumb is 250 ppm or more.   The baker's yeast according to claim 1 or 2, wherein the baker's yeast is a KSY290 strain belonging to Saccharomyces cerevisiae (deposit number: FERM P-18863).   A dough containing the baker's yeast according to any one of claims 1 to 3.   A method for producing bread using the baker's yeast according to claim 1.