JPH0716401B2 - Culture method of baker's yeast - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for culturing sucrose non-fermentable baker's yeast used for producing bread containing fructooligosaccharide.

In general, fructooligosaccharide has 1 to 1% of fructose of sucrose.
Three molecules of fructose are β-bonded at the positions of C1 and C2, and their chemical structural formulas are as follows.

These fructooligosaccharides are widely distributed in nature in higher plants, and are known to be contained in, for example, asparagus, onions, Jerusalem artichoke, and honey. However, recently, with the establishment of a technique for producing a large amount of fructooligosaccharides from sucrose by a microbial enzyme, the physical properties and physiological actions of these fructooligosaccharides have been investigated, and fructooligosaccharides are indigestible sugars, Has been found to have a bifidobacteria growth-promoting effect, an effect of improving lipid metabolism of cholesterol and the like, an excellent physiological effect such as carious caries, and also has a sweetness similar to that of sugar. The usefulness as one of the materials has become clear.

In order to bring about such an excellent physiological effect of maintaining the health of fructooligosaccharide, it is preferable to continuously ingest the fructooligosaccharide. For that purpose, it is appropriate to mix fructooligosaccharides into foods that are eaten daily, and the amount thereof is about 5 g per day.

Bread is a typical food that meets these conditions. Bread usually has a large amount of sucrose added to its dough, but it is possible to use all or part of this sucrose with fructooligosaccharides.

However, baker's yeast currently used for bread making is sucrose fermentable and has invertase activity,
There is a problem that the fructooligosaccharide added with care is decomposed by invertase and becomes meaningless.

Prior to the present invention, a sucrose non-fermenting and baker-suitable crossing strain was investigated, and as a result, Saccharomyces cerevisiae IL-1 having the characteristics was created.
This strain has been deposited with MIC as FERM BP-3191.

Next, the mycological properties of Saccharomyces cerevisiae IL-1 are shown.

1. Growth condition MY Good growth in liquid medium Cell shape Spherical to oval 3 to 7 × 4 to 8 μM Agar medium Good growth colony (white glossy smooth) 2. Ascospores Formed in potassium acetate medium Ascospore shape spherical 3. Physiological properties Optimal growth conditions Temperature 28-32 ℃ PH4.5-6.5 Growth range Temperature 0-40 ℃ PH2.5-8.0 Nitrate assimilation None Lipolysis No carotenoid formation No significant organic acid formation None Vitamin Requirement Biotin and pantothenic acid 4. Fermentability and assimilation of carbon source Fermentability Assimilation D. Glucose ＋ + D. Galactose ＋ ＋ Maltose ＋ ＋ Sucrose － － 1-Kestose (GF2) － － Nistose (GF3) － -Lactose --- Raffinose --- Mellibiose --- Trehalose --- Merezitose --- α-Methyl-D glucoside --- Dextrin ++ Cellobiose --- D-Ribose --- D Xylo S-L arabinose- Ethanol + DL lactate + Glycerin + And, when Saccharomyces cerevisiae IL-1 which is a non-fermentative sucrose baker's yeast is used, most of the fructooligosaccharides added to the bread-making ingredients remain without being decomposed. And, as for bread, it is possible to obtain excellent bread with good quality.

Next, sucrose non-fermentable baker's yeast is mass-cultured using molasses, which is a general carbon source, but it is low because sucrose non-fermentable baker's yeast cannot assimilate sucrose in molasses. The problem arises that the cell yield will increase.

First, the first conceivable thing is to convert sucrose in molasses by invertase, but this pretreatment step involves adjustment of invertase, molasses treatment by invertase, removal or inactivation of invertase for a considerable time. There is a drawback that requires labor.

The present inventors have earnestly studied for a method for effectively culturing sucrose non-fermentable baker's yeast by using molasses as a carbon source, and it can be solved by mixed culture of sucrose fermentable baker's yeast. did it.

The present invention is a method for culturing baker's yeast, which comprises culturing sucrose-fermentable baker's yeast in a mixed manner when culturing sucrose non-fermentable baker's yeast using molasses as a carbon source.

Saccharomyces cerevisiae IL-1 and FERM BP-3191 are exemplified as sucrose non-fermenting baker's yeast.

Sucrose non-fermenting yeasts such as Saccharomyces cerevisiae IL-1 and sucrose fermenting yeasts such as commercial baker's yeast have almost the same growth rate in a medium containing glucose as a sugar source. When such a sucrose non-fermentative yeast and a sucrose fermentative yeast are appropriately mixed and inoculated, and cultured with molasses as a nutrient source, sucrose in molasses is converted to glucose and fructose by the invertase of the sucrose fermentative yeast. The sucrose non-fermentative yeast grows well using this invert sugar. It was also found that the strain ratios of the sucrose non-fermenting yeast and the sucrose fermenting yeast at the time of inoculation were maintained as they were, and hardly changed at the end of the culture.

Therefore, by changing the ratio of the inoculum of sucrose non-fermentable yeast and sucrose fermentable yeast can be obtained yeast of any invertase activity, for example invertase 30 units / g
Dry yeast The following yeasts hardly decompose fructooligosaccharides and are therefore useful for producing fructooligosaccharide-containing bread.

In the present invention, the amount of yeast inoculum may be sucrose non-fermenting yeast: sucrose-fermenting commercial baker's yeast = about 100: 0.5, but the amount of invertase produced varies considerably depending on the type of sucrose-fermenting yeast. Therefore, it is advisable to determine the amount of inoculum cells on the basis of invertase 30 units / g dry yeast product or less.

Next, examples, test examples and reference examples of the present invention will be shown.

The method for measuring the invertase activity and the liquid fermenting power test used here are as follows.

(Method of measuring invertase activity) 0.5 ml of a 15% sucrose solution (pH 4.5 acetate buffer) was added with 0.5 ml of a yeast suspension and reacted at 30 ° C for 3 minutes, and then a DNS reagent was added to stop the reaction. Obtain the amount of reducing sugar by the DNS reagent method. One unit of invertase activity represents the activity of producing 1 mg of reducing sugar per minute.

(Liquid fermentability test) According to the Wolff modified method of yeast test method for bread of Yeast Industry Association. Each medium is based on the medium of Schultz et al. And adjusted to the following sugar concentration.

FG (5) Dissolve 1 g of glucose in the medium to make 15 ml.

FSG (40) Dissolve 8 g sucrose and 1 g glucose in the medium to make 15 ml.

Fm (5) 1 g maltose is dissolved in the medium to make 15 ml.

5 ml of yeast suspension (containing 150 mg of yeast dry weight) was added to the above substrate, shaken at 30 ° C., and the amount of carbon dioxide gas generated (2 hours) was measured.

Example 1. (1) Saccharomyces cerevisiae IL-1, FERM BP-
3191 was inoculated into a YM agar slant medium, and one platinum loop was taken from the culture that was cultured at 30 ° C. for 48 hours. This was inoculated into the next 5 ml of YPG medium, and cultured with shaking at 30 ° C. for 24 hours.

(YPG medium) Glucose 2% Peptone 2% Yeast extract 1% (2) Commercial baker's yeast (manufactured by Oriental Yeast Co., Ltd.) was inoculated on YM agar slope medium and 1 platinum loop was taken from the culture cultivated at 30 ° C for 24 hours. , Inoculate 5 ml of the above YPG medium,
The cells were cultivated with shaking at 24 hours.

(3) Saccharomyces cerevisiae IL- of (1) above
5 ml of the culture solution of 1 and 0.0 of the culture solution of the commercially available baker's yeast of (2) above
Molasses medium containing 5 ml in a 500 ml flask (sugar content 3%, ammonium sulfate 0.2%, urea 0.2%, monobasic sodium phosphate 0.07%) 10
It was added to 0 ml and cultured at 30 ° C. for 48 hours with shaking.

400 ml of the obtained culture solution (for 4 flasks) was added to a mini jar containing auxiliary materials (nitrogen source and phosphorus source, sugar: nitrogen: phosphorus = 100: 4.0: 0.4), and the volume was adjusted to 0.8 l. Air flow rate 2 / m
Fed-batch culture was carried out for 8 hours at 600 rpm with stirring.

Molasses fed-batch was performed exponentially according to White's fed-batch method. (Hourly Growth rate = 1.22, moisture 68%, calculated as a sugar yield of 130% in live yeast) The obtained culture solution was centrifuged to obtain yeast cells, and 20 g of the yeast cells were added to water and an auxiliary material ( Nitrogen and phosphorus sources, sugar: Nitrogen:
Phosphorus = 100: 3.5: 0.3) was added to the mini jar and the liquid volume was adjusted to 0.8. Fed-batch main culture was carried out for 14 hours at an aeration rate of 2 / min and stirring at 600 rpm.

The molasses medium was fed by the White feeding method. (Hourly Growth rate = 1.22 in the first 10 hours, Ho in the second 4 hours
urly Growth rate = 1.06) When the invertase activity of the obtained yeast was measured,
It was invertase 20 units / g dry yeast, and was suitable as a baker's yeast for producing breads such as fructooligosaccharide-containing bread, confectionery bread, crackers, and dry bread.

Example 2. (1) Saccharomyces cerevisiae IL-1, FERM BP-
3191 was inoculated into a YM agar slant medium, and 1 platinum loop was taken from the culture cultivated at 30 ° C. for 24 hours. This was inoculated into 5 ml of YPG medium and cultivated with shaking at 30 ° C. for 24 hours.

(2) Commercially available baker's yeast (manufactured by Oriental Yeast Co., Ltd.) was inoculated into YM agar slant medium, and 1 platinum loop was taken from the culture cultivated at 30 ° C for 24 hours, and this was inoculated into 5 ml of YPG medium at 24 ° C at 30 ° C.
Culture was performed with shaking for an hour.

(3) Saccharomyces cerevisiae HU-20, FERM P-5
440 was inoculated on the YM agar slant medium and one platinum loop was taken from the culture cultivated at 30 ° C. for 24 hours, which was inoculated into 5 ml of YPG medium and shake-cultured at 30 ° C. for 24 hours.

(4) Add 5 ml of the culture solution of the commercial baker's yeast of the above (2) to 100 ml of molasses medium (sugar content 3%, ammonium sulfate 0.2%, urea 0.2%, monobasic sodium phosphate 0.07%) in a 500 ml flask, The cells were cultured at 30 ° C for 48 hours with shaking. Fed-batch main culture was carried out using a mini jar under the same conditions as in Example 1 using this 400 ml (for 4 flasks) as a seed.

(5) Saccharomyces cerevisiae IL- of (1) above
5m of the culture solution of 1 and the culture solution of the commercial baker's yeast of (2) 0.05
Add 100 ml to molasses medium in a 500 ml flask,
The cells were cultured at 30 ° C for 48 hours with shaking. Fed-batch main culture was carried out using a mini jar under the same conditions as in Example 1 using this 400 ml (for 4 flasks) as a seed.

(6) Saccharomyces cerevisiae IL- of the above (1)
5 ml of the culture broth of 1 and 1 ml of the culture broth of Saccharomyces cerevisiae HU-20 described in (3) above were added to 100 ml of molasses medium placed in a 500 ml flask, and shake-cultured at 30 ° C. for 48 hours. Fed-batch main culture was carried out using a mini jar under the same conditions as in Example 1 using this 400 ml (for 4 flasks) as a seed.

As described above, the yield (%) with respect to sugar and the invertase (unit) / g dry yeast product of the yeast cells obtained in (4), (5) and (6) were measured, and the results in Table 1 were obtained. As shown in Table 1, the cell yield by the mixed culture of the present invention was clearly higher than the yield of the single culture of commercial baker's yeast.

Is.

Test Example 1. 1. Cultured cells of (6) of Example 2 2. Cultured cells of (4) of Example 2 3. Add 5 ml of the culture solution of (3) of Example 2 to (4) of Example 2 Culture medium obtained by performing fed-batch main culture with a mini jar in the same manner as in 4.). 5 ml of the culture solution of (1) of Example 2 was prepared, and molasses converted by invertase was used under the same conditions as in Example 1. The liquid fermentation power and invertase (unit) / g were measured for the bacterial cells 1, 2, 3, and 4 obtained from the shaking culture to the fed-batch main culture with a mini jar, and the results in Table 2 were obtained.

The microbial cell 1 obtained by the mixed culture of the present invention showed liquid fermenting power comparable to that of the cultured microbial cell 2 of commercially available baker's yeast. Moreover, the invertase activity was 15, which was a very low value.

Production Example Bread was produced from the yeast product of the present invention obtained in (6) of Example 2 and a commercially available baker's yeast using fructooligosaccharide according to the intermediate-type bread making method.

The composition is as shown in Table 3 below.

The steps are shown in Table 4 below.

The results are shown in Table 5 below.

The medium-type fermentation of the yeast product of the present invention showed good results almost comparable to those of commercially available baker's yeast, and the resulting bread had good flavor and sudachi. The residual rate of fructooligosaccharides (using liquid chromatogram) was 90%. On the other hand, the product using commercially available baker's yeast hardly remained.

Claims (2)

[Claims] 1. A method for culturing baker's yeast, which comprises culturing sucrose-fermenting baker's yeast in a mixed manner when culturing sucrose non-fermentable baker's yeast using molasses as a carbon source. 2. The method for culturing baker's yeast according to claim 1, wherein the sucrose non-fermenting baker's yeast is Saccharomyces cerevisiae IL-1, FERM BP-3191.