JPS6015308B2 - Satsukaromyces cerevisiae FTY (FRI-413) - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to Saccharomyces cerevisiae.
e) Regarding FTY (FRI-413).

More specifically, the present invention provides a method for producing bread from Saccharomyces cerevisiae F which is useful for producing bread that does not suffer from freezing damage, sufficiently expands, and has excellent quality in a frozen dough bread making method.
This relates to TY (FRI-413). Freezing of bun dough is carried out for the purpose of producing fresh bread by thawing it at a desired time. That is, after fermenting the mixed bread dough, it is divided and shaped as necessary, and then stored frozen at a temperature of about -20°C for about 1 to 4 weeks, and the required amount of frozen dough is prepared at a desired time. This is a new bread-making technology that involves thawing bread, fermenting it in a barrel oven, and baking it to produce fresh bread. By introducing this frozen dough baking method, consumers will be able to easily obtain fresh bread, and bakers will not only be able to eliminate the high-mix, low-volume production system, but will also be able to reduce the amount of work done at night and early in the morning. Benefits include the ability to take appropriate labor measures. However, conventional baker's yeast used for bread dough suffers from freezing damage during frozen storage, which significantly delays oven fermentation for expansion after thawing, and tends to cause deterioration in the quality of the bread.

The present inventors have investigated various effective means for increasing the freezing tolerance of yeast, but have not been able to obtain fully satisfactory results. Therefore, in order to find a type of yeast that is resistant to freezing, we focused on various types of naturally fermented bread varieties. As a result, we were able to isolate 4. yeast with high freezing resistance from seeds made by wrapping wheat flour paste in plant leaves and fermenting it naturally.
That is, wrap wheat flour paste in plant leaves (banana leaves), ferment this to make a naturally fermented seed, dissolve this seed in 100M of physiological saline, and mix it with YM agar powder (malt extract 3). In the evening, dissolve 3 portions of yeast, 3 portions of polyveston, and 1 portion of glucose, and adjust the pH to 4.
Add agar 209 as step 6) Pour it on top and add 30oo
The target yeast can be isolated by culturing for 7 hours, picking bacteria from the resulting colonies, and culturing them by Kohei. The mycological properties of the yeast thus isolated by the present inventors are as follows.

○} Morphological properties Streaking culture on wort agar (Difco) slope, wort (D
ifco) culture and slide culture on potato dextrose agar (Nissui Pharmaceutical) medium, observation after 4 to 7 days and 20 days.

a Shape: circular or oval b Size: 2.5 to 9 x 3 to 11 microns (2) Spore formation: Yes Mysterious bacteria pre-cultured on a wort agar slope for 3 days was cultured as Cbrodoko. Column) Cultured on Mr. agar and potato dextrose agar slants, 7 to 3
The presence or absence of spore-forming ability was observed for 08 years.'3} Formation of mechanical hyphae: None {4} Formation of growth: budding■ Biochemical properties a Fermentability of sugar Add 2 sugars to a 3% yeast extract (Difco) solution. % added,
After dispensing into medium test tubes containing Durham tubes and sterilizing them for 3 days, a large amount of the test bacteria was inoculated and the presence or absence of gas generation was observed for 14 days at 25:00.

Fermentability of glucose: Yes Galactose: Yes Sucrose: Yes Fermentability of maltose: Yes (very weak) Raffinose: Yes Melibiose: None Lactose: None b Sugar assimilation Lodder's oxanograph (Au-x
The assimilation of five types of sugars was tested using the a-skin graph method.

The composition of the foundation tower in this test was ammonium sulfate (
N5)2S04)0.5%, acidic potassium phosphate (KH2P
04) 0.1%, magnesium sulfate (MgSO4.7Q
O) 0.05%, agar 2%.

If the results are unclear with this method, use Difco
)'s East Nitrogen Base (Yeastn
using the itrogen port
The test was conducted according to the method of John Kerham.

Glucose assimilability: Yes Galactose: Yes Syucrose 〃: Yes Maltose: Yes Lactose assimilability without soil C Nitrate assimilability: None It was conducted in the same manner as the assimilation of sugar.

Potassium nitrate (KNQ) is used as the nitrate, and the composition of the base material is 2% glucose and 0.0% potassium acid phosphate (KH2P04).
1%, magnesium sulfate (MgS04, 7 days 20) 0.
05% agar and 2%.

The above results indicate that this yeast is Saccharomyces cerevisiae (
Saccharomyces cerevisiae). This bacteria is a common baker's yeast (
Saccharomyces cerevisiae) (
Hereinafter, it will be referred to as "commercial yeast."

) was cultured under the same conditions and compared in terms of yield, permeability, etc., it was found that the bacterial cells were white in color and had good scale properties. When used in bread making, this bacterium has the effect of improving the flavor of bread, and its resistance to wheat flour's anti-yeast protein (purothionin) is much higher than that of commercially available yeast. These properties indicate that this bacterium is extremely easy to use and useful when producing and using it as baker's yeast. However, the greatest characteristic of this bacterium is that it has extremely high freezing resistance, which is not found in general baker's yeast. Next, we will discuss in detail the differences in properties between this bacterium and commercially available yeast.

Maltose fermentation ability and adaptation The maltose fermentation ability of commercially available yeast cultured in molasses and this fungus was determined using the Mycel method (using a Mycel fermentation tube, containing 0.25 liters each of acidic potassium phosphate and diammonium phosphate). solution 1ow' and distilled water 20 skin containing maltose,
Add 20 parts of distilled water containing 1.5 parts of acid base, ferment at 30 qo for 5 hours, and then measure the amount of gas generated gravimetrically.

) The results of the measurements are shown in Table 1. In addition, maltose adaptation treatment (adding a large amount of nitrogen source, maltose and
Culture with shaking for 4 hours in a complete synthesis tower to which 1/1 amount of glucose was added. ) The ability to adapt to maltose is also shown in Table 1. As is clear from Table 1, the maltose fermentation ability of this bacterium is extremely weak compared to commercially available yeast, and even when maltose adaptation treatment was applied, almost no adaptation occurred.

{B' Purothionin Sensitivity Sensitivity to the anti-yeast protein purothionin contained in wheat was investigated for its effect on fermentation (5% sucrose solution).

As a result, as shown in FIG. 1, commercially available yeast was severely inhibited in fermentation as the amount of purothionin added increased, whereas this fungus was not affected in any way.
In addition, yeast was suspended in a purothionine aqueous solution and -2
After 7 days of frozen storage at 000, the yeast was thawed, washed with water, and the separated yeast was examined for residual fermentation ability, and the results are shown in FIG. As is clear from Figure 2, activated bacterial cells of commercially available yeast (
While the bacterial cells in the logarithmic growth phase were strongly affected by purothionin, this bacteria was hardly affected in this case as well. {C} Freezing tolerance-1) Leakage of glutathione due to freezing A suspension of molasses cultured bacterial cells in distilled water was stored frozen, and the amount of glutathione leaked and the amount remaining in the bacterial cells after thawing was measured, and the results were used in the third experiment. Shown in the figure.

At the same time, the bacterial cell survival rate was also illustrated. As is clear from this result, in the case of commercially available yeast, more than half of the yeast die after 2 days and most of the glutathione leaks into the external fluid, whereas with this bacterium, there is little increase in the number of dead and sterilized cells. Despite the high glutathione content within the bacterial cells, there is almost no leakage into external fluids. Glutathione leaking from yeast cells has the effect of weakening bread dough, so a small amount of leakage is a great practical advantage in bread making. (
C-2) Bread dough containing frozen dough-resistant bread was prepared, and 15
(2) The fermented dough was stored frozen at -20q0 for 7 days, and the remaining fermentation ability after thawing was measured.

Figure 4 shows the results. It is known that if frozen dough is frozen immediately after it is healthy, freezing damage will not occur to the yeast, but severe freezing damage will occur only when fermented dough is frozen. The present experimental results show that this is true for commercially available yeast, and a significant decrease in residual fermentation capacity was observed as the fermentation time increased. In bread making, it generally takes 120 to 150 minutes to complete the fermentation process or finish the finishing process, but at this point frozen dough has lost 80 to 90% of its fermentation ability. On the other hand, this bacterium exhibits a completely opposite tendency, and exhibits a distinctive feature in that the more it is frozen after sufficient fermentation, the higher the fermentation capacity after thawing becomes.

This result is directly reflected in the quality of bread. That is, FIG. 5 shows a cross section of bread made from these frozen doughs. As is clear from the figure, even with frozen dough made using commercially available yeast and fermented for 60 minutes, the bread collapses and the inner layer becomes rough due to the reduced fermentation ability of the yeast and the damage caused by leaked glutathione. becomes more significant as the fermentation time increases. On the other hand, when using this bacteria, the bread becomes better as the fermentation time increases. As mentioned above, this bacterium has an extremely low fermentation ability and adaptation capacity for maltose, is almost insensitive to purothionine, and is a logarithmic growth phase active subtype bacterium that exhibits extremely high freezing tolerance. For these reasons, it is not appropriate to attribute this bacterium as it is to Saccharomyces cerevisiae, and it is considered that it should be a mutant strain.

Therefore, the present inventors named this bacterium Saccharomyces cerevisiae FTY (FRI-413). This bacterium has been deposited with the Institute of Microbial Technology, Agency of Industrial Science and Technology as FERM-P6363. This bacterium is extremely effective when used in frozen bread dough, and its impact on the bread-making industry is immeasurable.

Furthermore, by utilizing the above-mentioned characteristics of this bacterium, it is expected that it will be used in other microbial industrial fields.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing the purothionine sensitivity of yeast. Figure 3 is a graph showing glutathione leakage and survival rate during frozen storage of yeast suspension, Figure 4 is a glass graph showing the relationship between bread dough fermentation time and yeast fermentation ability after thawing the frozen dough. The figure shows the relationship between the fermentation time of bread dough and the quality of frozen dough bread; the upper row shows the case when commercially available yeast was used, and the lower row shows the case when the present bacteria were used. In addition, the numbers shown at the bottom of the figure are the volume of bread (CC) in the upper row.
, the lower row shows the quality score (based on a 100-point scoring system, scoring 5 items for interior appearance and 5 items for appearance). Lacquer 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 Satucharomyces cerevisiae FTY (FRI-41
3).