JPS6196982A - Preparation of yeast having low decomposition capability of fructo-oligosaccharide - Google Patents

Abstract

PURPOSE:To prepare yeast having low fructo-oligosaccharide decomposition activity and usable in the baking of bread without causing the degradation of fructo-oligosaccharide, by treating a yeast having fructo-oligosaccharide decomposition activity with an inorganic acid. CONSTITUTION:A yeast having fructo-oligosaccharide decomposition activity, e.g. the yeast used usually in the baking of bread, is dispersed in water, added with an inorganic acid such as sulfuric acid, hydrochloric acid, etc., and treated at <=2pH and about <=40 deg.C to reduce the fructo-oligosaccharide decomposition activity of the yeast to <=100 unit per 1g of dried yeast cell.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing yeast with low glycolytic activity.

Fructooligosaccharide has 1 to 3 lactose residues in 7 lactose residues of sucrose.
The 7:7 ctose of the molecule is β-bonded between C8 and C8, and its chemical structure is as follows.

These fructooligosaccharides are widely distributed in higher plants in nature, such as asparagus.

It is known to be contained in onions, Jerusalem artichokes, honey, etc. However, recently, with the establishment of a technology for producing large quantities of fructooligosaccharides, these fructooligosaccharides are indigestible sugars, have an effect on promoting the growth of bifidobacteria in the intestine, an effect on improving lipid metabolism such as cholesterol,
It was found that it has excellent physiological effects such as i5 corrosive properties,
Its usefulness as a new material in the food field has become clear.

In order to bring about the excellent physiological effects of fructooligosaccharide on maintaining health, it is preferable to continuously ingest the fructooligosaccharide.

To this end, it is appropriate to incorporate fructooligosaccharide into foods that are consumed daily, and the amount is approximately 5 g per day.

Bread is a typical food that meets these conditions. Bread usually has a fairly large amount of sucrose added to its dough, but all or part of this sucrose can be replaced with fructooligosaccharide.

By the way, yeast is used in most cases to make bread. The present inventors confirmed that fructooligosaccharides are degraded by these baker's yeasts. In this case, the main degrading enzymes are thought to be invertase, α-glucosidase, etc., but the details of their behavior in bread dough are not yet well understood.

Even if K, the fructooligosaccharide is decomposed in bread making using the usual method, and its excellent physiological effects are greatly diminished. The present inventors believe that yeast is responsible for the decomposition of fructooligosaccharides, and have conducted extensive studies on measures to prevent fructooligosaccharides from being decomposed.

As a result, they discovered that by treating the yeast normally used in bread making with acid, the fructooligosaccharide remains in the dough without being decomposed, allowing the production of good bread.Based on this knowledge, the present invention was developed. completed.

That is, the present invention provides a method for reducing fructooligosaccharides, which is characterized in that yeast having fructooligosaccharide decomposition activity is treated with an inorganic acid at a concentration of 2 or less to reduce the fructooligosaccharide decomposition activity of the yeast to 100 units/i/dry cell body or less. This is a method for producing degradable yeast.

The method of treating yeast with acid has already been described by Gunge et al.
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These experiments were conducted to discuss the yeast invertase titer and the fermentability of yeast via sucrose.

In addition, the acid treatment of yeast that is commonly carried out at present is to treat the yeast cells using phosphoric acid or the like at a concentration of about 2,000 ml, but this operation is aimed at sterilizing germs.

As mentioned above, there has never been any mention of the decomposition of fructooligosaccharides by yeast, and there is no knowledge of how to make the fructooligosaccharides remain without being decomposed when added to bread dough.

Next, the method of the present invention will be explained in detail, including various test results.

First, regarding the yeast used in the present invention, any yeast can be used as long as it is suitable for bread making. In particular, yeast commonly used for bread production is suitable because it is easily available. Commercially available baker's yeast was used in all of the following tests and examples.

We investigated the effect of the type of acid when suspending baker's yeast in water and reducing its concentration with acid to inactivate the fructooligosaccharide degrading activity of the yeast. The temperature condition □ may be any temperature that does not kill the yeast, and is generally carried out at a temperature of 40°C or lower, usually around 30°C. Furthermore, the time may be determined as appropriate. The results are shown in Table 1.

Table 1 As is clear from Table 1, hydrochloric acid and sulfuric acid are suitable among the acids that can be used in foods. When organic acids such as tartaric acid are made into a suspension with yeast, the water content does not decrease sufficiently. On the other hand, phosphoric acid requires high concentrations to lower the state, making both unsuitable. Furthermore, the survival rate of yeast with this treatment is almost 100%.
Met.

The fructooligosaccharide decomposition activity measured here was determined as follows. Yeast was dissolved in 0.1 M citric acid warm solution (P
15% (''/v) 1 diluted to a predetermined concentration in H4,5) and suspended, one portion of which was heated in advance.
- Kesdose (GF, ) IJltK added, 30°C
Let it react for 15 minutes. In order to make the reaction conditions uniform,
Use a mono-shaker. After reaction, 5 ml of DNS reagent
and immerse it in boiling water for 5 minutes to stop the reaction. After cooling with running water, centrifugation (300 rpm, 115 min)
) The supernatant obtained is diluted 6 times, and the absorbance of this diluted solution is measured at 500 nm using a spectrophotometer. At the same time, calculate and correct blind values for yeast, substrate, and reagents. The calibration curve is performed using glucose, and the amount of enzyme that produces reducing sugar corresponding to 1 β mole of glucose per minute is defined as 1 unit. Any commonly used DNS reagent may be used.

Next, we investigated the influence of acid concentration and rice field using sulfuric acid. The results are shown in Table 2.

As is clear from the table, the concentration of sulfuric acid is 0.05-0.2
A range of 5N was sufficient. Furthermore, in the case of hydrochloric acid, there was almost no difference from that in the case of sulfuric acid, but the fructooligosaccharide decomposition activity showed a slightly lower value.

After completing the acid treatment, be careful not to kill the yeast more than necessary.
It is preferable to return the rice field using Lucari, in which case the pH
4 to 7 is appropriate. After neutralization, the yeast suspension is collected by centrifugation or filtration, washed with water if necessary, and can be used as fresh yeast. This acid-treated raw yeast was stable for more than one month when refrigerated at 5°C, and had sufficient stability for industrial use. Furthermore, it is also possible to dehydrate and dry the yeast and store it as dry yeast, and there is no difference in handling compared to conventional yeast.

Using the yeast thus obtained, a bread making test was carried out using the straight method according to the following recipe.

The results are shown in Table 3.

Recipe list Wheat flour 100 parts Fructooligosaccharide syrup (solid content 75%) 3
0 parts (57% fructooligosaccharide, 8% sucrose, 33% glucose.

2% fructose) Unsalted butter 7 parts Skimmed milk powder 3 parts Refined salt 2 parts Yeast food 0.1 part Yeast (approx. 65% water) 3 parts As is clear from the table, the fructooligosaccharide residual rate should be about 80% or more. To achieve this, it is necessary to reduce the fructooligosaccharide decomposition activity to 100 units or less.

In this test, there was almost no difference between acid-treated yeast and normal yeast in terms of fermentation time and workability. A test was also conducted using the Nakadane method, but the results were similar. Therefore, it was found that acid-treated yeast has no disadvantages when used in current industrial production processes.

Examples of the present invention are shown below.

Example 1 Suspended in 600 g of ionized water, and added 0.0 g to this. IN sulfuric acid 75
0 ml was added and stirred at 30°C for 3 hours. 3 hours later
The field was 1.8. After neutralizing the yeast by adding a 5N sodium hydroxide solution to a concentration of 4.8 mm, the yeast was collected using a centrifuge and washed twice with 500 M1 of deionized water. Yeast 1
97 g was obtained, the moisture content was 74.45, the fructooligosaccharide decomposition activity was 10 units/I, dry yeast, and the number of viable bacteria was 3.
9 x 10" pieces/I dry yeast. Using this yeast, bread was made by the straight method according to the recipe listed above. For comparison, a bread making test was also conducted using untreated yeast. As a result, there was almost no difference between the two in terms of workability and bread quality, but the bread made with untreated yeast, in which more fructooligosaccharides were degraded, was significantly sweeter. 92
%, and 48% for untreated yeast.

Example 2 Bread yeast (commercial fresh yeast, moisture 66.5%, fructooligosaccharide decomposition activity 420 units/I, dry yeast).

Number of viable bacteria: 3.4 x 10”/g/dry yeast) 1.5k
l! 6. Deionized water. Suspended in O7. 0.25 for this
7.5 tons of N-hydrochloric acid was added and stirred at 30°C for 20 minutes. The final value was 0.9. After treatment, the yeast was concentrated with 40% sodium hydroxide, collected using a basket centrifuge, and further washed with 101 deionized water.

1.5 kg of acid-treated yeast was obtained, and the water content was 70.2%, the fructooligosaccharide decomposition activity was less than 1 unit/y of dry yeast, and the number of viable bacteria was 3.4 x 10''/I of dry yeast. Using this yeast, a loaf of bread was produced using the 7.7m dough method according to the following recipe.

Medium wheat flour 70 parts Acid-treated yeast 2.2 parts Yeast food 0.1 part Water 40 parts Dough flour 30 parts Fructooligosaccharide syrup (same as listed in the recipe) 1
0 parts Salt 2 parts Shortening 4 parts Water 19 parts The bread-making properties were good, it could be handled in exactly the same way as regular bread, and the bread was in good condition. The fructooligosaccharide residual rate of this bread was 94%.

Example 3 50g of baker's yeast used in Example 2 was suspended in tap water,
It was set as 200/117. The same volume of 0.5N hydrochloric acid was added to this, and the mixture was stirred at 37°C for 10 minutes. The field was 0.5. After the treatment, 5N sodium hydroxide was added to make the yeast 4.5 mm thick, and the yeast was collected by centrifugation and further washed with 500 m of tap water. Yeast 63I was obtained, and the moisture content was 73%, the fructooligosaccharide decomposition activity was approximately 1 unit/g dry yeast, and the number of viable bacteria was 3.6 x 1010 cells/g dry yeast. Using the yeast obtained here, butter rolls were manufactured by the straight method according to the following recipe.

Wheat flour 100 parts Acid-treated yeast 2.7 parts Fructooligosaccharide syrup (same as listed in the recipe list)
30 parts salt 1.8 parts unsalted putter
15 parts Total #lO part Yeast food 0.1 part Water 38 parts A delicious butter roll with good bread-making properties and finished product was produced. The residual rate of fructooligosaccharides in this bread is 95%.
Met.

Claims (1)

[Scope of Claims] 1. Fructooligosaccharide degrading activity of yeast having fructooligosaccharide degrading activity is treated with an inorganic acid at pH 2 or lower to reduce the fructooligosaccharide degrading activity of the yeast to 100 units/g dry bacterial cells or less. Method for producing sugar-lowly degrading yeast. 2. Claim 1 in which the inorganic acid is sulfuric acid or hydrochloric acid
Manufacturing method described in section.