DE1956146B2 - METHOD FOR PRODUCING DRIED YEAST - Google Patents

Description

Table 1

Content of 0.5 to 5 percent, based on the dry matter, of a swelling agent and / or one Wetting agent uses

7. The method according to claim 1 to 6, characterized in that one uses a compressed yeast which by partially dehydrating with a hypertonic solution and rapidly washing out the solution from which yeast has been made.

Baker's yeast is generally used as compressed yeast with a dry matter content of about 26 to 32 Percent or as dry baker's yeast with a dry matter content of over 80 percent, in general Compressed yeast produced over 90 percent has the disadvantage of a relatively poor shelf life Compressed yeast is therefore only used in countries with a moderate climate and / or where fresh compressed yeast is used daily is available. Dry baker's yeast has the advantage of greater stability and lower moisture content, which saves storage and transport costs. However, dry yeast has the disadvantage of a relatively low driving force. Furthermore, it must be rehydrated and rehydrated before use thereby reactivated before it is mixed with the flour to make the dough. in the Generally, the dry baker's yeast is rehydrated by soaking in 38 to 43 ° C water low driving force of commercial dry baker's yeast compared to compressed yeast with a high protein content from Table I.

yeast shape Content of Protein content Phosphorus content test Gas sample Dry Ρ / ο Ν χ 6.25) (% P2O5) procreation Dimensions based on the dry based on the dry Dimensions Dimensions (ml)

1) Grains 92.7 42.4 2) Grains 92.6 41.9 3) Grains 92.4 41.5 4) small 91.6 42.7 Particle 5) powder 91.8 41.6 6) pressed 29.0 52.5

A. 500 B ' 295 A. 493 B ' 269 A. 444 A. 417 A. 369 B3 595

55

The gas generation values shown in the table were made according to that described below Test procedure received. The dry yeasts are of various origins and are used with the Numbers 1) to 5) denoted From this table it can be seen that the values of gas generation for the Dry baker's yeast only comparable with the gas production of compressed yeast with a high protein content (sample 6) is when considerably larger amounts of dry baker's yeast are used, d. H. 930 mg dry baking yeast in comparison with 450 mg of compressed yeast, based on the dry matter. Will studies of gas generation with the same amounts of yeast, calculated on the dry matter, carried out, the values of Gas production for dry baker's yeast well below the values for compressed yeast.

6s 1.90
1.97

1.92
1.36

3.36
3.20

Commercially available dry baker's yeast is generally made from compressed yeast with a protein content of the order of 30 to 36 percent (percent N χ 6.25; nitrogen determined according to the Kjeldahl method); see F. Reif f, "Die Hefen", Vol. II (1962), page 583, Verlag Hans Carl, Nuremberg. Such pressed yeasts are quite stable and withstand the usual, slow drying processes, as described, for example, in US Pat. No. 2,894,842, in which pressed yeast is mixed with 0.25 to 5 percent of a sorbitan fatty acid ester before drying, then to form spaghetti-like strings deformed and pre-dried in a forced air oven to a moisture content of about 8 percent. Further water is then removed from the predried yeast under reduced pressure. A thermostable drying

Obtain baker's yeast, which can be easily hydrated. GP-PS 1132 793 describes a similar process for the production of dry baker's yeast with a moisture content of 8 percent, in which 0.1 to 5 percent, for example, of a monoglyceride, sorbitan fatty acid ester or corn oil are incorporated into the compressed yeast before drying, and then the mixture granulated and dried in the fluidized bed process with 40 ⁰ C warm air within a period of 1 to 2 hours. Studies have shown that pressed yeasts with a high protein content, ie over 45 percent, are not suitable for the production of dry baker's yeast by the usual slow drying processes, which is due to the fact that great losses of activity occur during drying and, moreover, the product obtained is very unstable Rapid drying processes, for example spray drying, can be used with compressed yeast, but these processes also have the disadvantage that they lead to a noticeable loss of activity in the dry baker's yeast. In addition, very finely divided, powdery powders are obtained which are difficult to use when mixed with flour or rehydrated.

The invention is based on the object of a high-performance method for producing a dry baker's yeast to create a shelf life that is as good as that of the well-known dry yeast, which, however, is characterized by a high level of activity or driving force, which is similar to that of high-quality is comparable to fresh pressed yeast and is easy to handle, d. H. not be rehydrated must, but can be mixed directly with the flour and homogeneously distributed in the dough.

This object is achieved according to the invention by a process for the production of dry baker's yeast by crushing compressed yeast, optionally mixed with a wetting agent, and drying the particles in a hot air stream in the fluidized bed to a dry matter content of at least 85 percent by weight, which is characterized in that compressed yeast is mixed with a Protein content of 45 to 60 percent, based on the dry matter, is used, and the particles are dried within a period of 30 to 50 minutes, the temperature of the air stream at the beginning of the drying treatment being at most 160 ^° C. and the particles being in a temperature range during drying from 20 to 50 ° C.

Advantageous embodiments of the invention are specified in the subclaims.

The dry yeast produced according to the invention has a dry matter content of at least 85 percent by weight, a protein content of 45 to 60 percent, based on the dry matter, and an activity value of 420 to 600 mg of dry yeast are mixed with 100 g of flour in a mixer, then 55 ml of an aqueous solution containing 2 g of NaCl are added, the mass is kneaded for 6 minutes at 28 ° C to form a dough, the dough is kept in a water bath at 28 ° C and the amount of gas evolved in the period from 10 to 175 minutes after the start of kneading is determined. The amount of gas is given in cm ³ at 28 ^° C. and 760 Torr. This test method is hereinafter referred to as Test B ^2.

The dry yeast produced according to the invention has a much higher driving force than those previously available Dry baker's yeast, and it does not need to be rehydrated separately to develop its activity.

The dry yeast produced according to the invention most advantageously has a dry matter content of 90 to 96 percent by weight, a protein content of 48 to 54 percent and an activity value of 440 to 580, in particular 480 to 580, determined ^{according to test B 2} comparable to commercial dry yeast.

The dry yeast produced according to the invention can be used for the production of bread directly with the flour mixed and immediately distributed homogeneously in the dough. When mixing the yeast with flour and water for In the preparation of the dough, it is very advantageous that the yeast particles and the yeast largely dissolve is distributed homogeneously in the dough.

Most dry yeasts do not have this property

In order to achieve the highest possible driving force, the compressed yeast used according to the process is best a swelling agent and / or a wetting agent incorporated. Suitable swelling agents that are beneficial in amounts of Methyl cellulose is 0.5 to 5 percent, preferably 1 to 2 percent, based on the dry matter and carboxymethyl cellulose. Suitable wetting agents, which are beneficial in amounts of 0.5 to 5 percent, best to use 1 to 2 percent, based on dry matter, are esters of Fatty acids such as fatty acid esters of sorbitan, e.g. B. sorbitan monolaurate, sorbitan monoplamitate, sorbitan monostearate or sorbitan monooleate, fatty acid esters of glycerin, e.g. B. glyceryl monostearate, glyceryl distearate or glyceryl monoplamitate, fatty acid esters of propylene glycol, e.g. B. propylene glycol monostearate, or Mixtures of two or more of the aforementioned compounds.

The drying time in the process according to the invention is less than 50 minutes and in particular less than 20 minutes. To keep the particles within the aforementioned temperature range, it is favorable if the temperature of the drying gas stream at the end of the drying treatment is lower than at the beginning of the same. At the beginning of the drying treatment, the temperature of the drying gas stream up to 160 ° C.

To facilitate the drying process and to obtain a dry yeast that can be easily spread in the dough, the compressed yeast is divided into small particles, e.g. B. by extruding the yeast to form threads or by breaking these threads to form particles, the particles preferably having a cross-section in Range from 0.2 to 2 mm. From yeast particles of this size you get a dry baking yeast in Particle shape with a cross section in the range from 0.1 to 1 mm.

The process of the invention can be carried out batchwise, but it is particularly suitable for continuous implementation.

The method according to the invention is most conveniently carried out with that in British patent specification 9 89 247 described strain Saccharomyces cerevisiae Ng 1777 (CBS 4877) carried out, which is characterized by a good Excellent drying resistance.

The compressed yeast used according to the process is best according to that in British Patent 7 63 926 described method has been prepared in which yeast by a hypertonic solution, e.g. Legs

Saline, partially dehydrated and the solution is washed out quickly.

The dry yeast according to the invention can be used for storage in conventional containers, such as cans and plastic bags, preferably under greatly reduced Packaged under pressure or under nitrogen as a protective gas.

The examples illustrate the invention. Reference is made to the test methods A, B ¹ , B ² and B ^{3 described below.}

Description of the test procedures used:
Test A (for common dry yeast)

930 mg of dry yeast are soaked for 10 minutes in 6 ml of water at 35 ° C. The yeast suspension obtained is mixed with 100 g of flour and 47 ml of a solution containing 2 g of NaCl *, the temperature of the flour and the salt solution being 28 ° C. The resulting mixture is blended for 6 minutes to form a dough which is placed in a 28 ° C water bath. The amount of gas evolved in the period from 10 to 175 minutes after the start of mixing is determined in ml at 28 ° C. and 760 torr

Test B ¹

This test is carried out in the same way as Test A, except that 480 mg is used instead of 930 mg of active dried yeast can be used.

Test B ²

480 mg of dried active yeast are mixed directly with 100 g of flour in a mixer. After addition 55 ml of a solution containing 2 g of NaCl are mixed for 6 minutes at 28 ° C. Otherwise will Proceed as in test A.

Test B ³ (for compressed yeast)

An amount of pressed yeast corresponding to 450 mg dry matter is dissolved in 55 ml of a 2 g NaCl containing Solution suspended. After adding 100 g of flour, a dough is made by mixing at 28 ° C for one minute. The rest of the procedure is as in test A.

example 1

A centrifuged and washed yeast suspension with a dry matter content of 170 g / liter is used with such an amount of sorbitan monostearate suspension (wetting agent) mixed in water that the Mixture contains 1 g of sorbitan monostearate per 100 g of dry yeast. The suspension is filtered off a compressed yeast mix with a dry matter content of about 30 percent and a protein content of 52.5 Percent based on the dry matter, and a wetting agent content of 1 percent based on the Dry matter.

The pressed yeast is pressed through a perforated plate with openings of 0.6 mm diameter. The product obtained is dried to 92 to 95 percent dry matter by passing a stream of dry air through the yeast mass while keeping it in a fluidized bed. The temperature of this air is during of the drying process changed. During the first 6 minutes it is 60 ^{° C. and is lowered to 40 °} C. during the next 6 minutes so that the temperature of the yeast can be kept ^{below 40 ° C.} The total drying time

is 12 minutes. The product thus obtained is fine-grained and consists of particles approximately 2 mm in length and approximately 0.4 mm in cross-section. Analysis of the product shows: dry matter content 93.4 percent, protein content 54.0 percent, based on dry matter; Phosphorus content as P2O5, based on dry matter, 3.20 percent. This product can be added directly to the flour without prior soaking to make a dough and can be completely dispersed in the dough. The gas generation according to test B ² is 516 ml.

Example 2

For comparison purposes, gas generation tests with (a) a low protein yeast and with (b) of a high protein yeast. Both yeasts are (I) before drying, (II) after usual drum drying lasting about 18 hours and (IH) using the rapid drying method investigated the invention. The results are summarized in Table II.

Table II

Drying process shape o / _o protein phosphorus Loading Gaser yeast Dry salary salary sünj- new Dimensions (% N χ 6.25) (0 / 0P2O5) mingling supply related to related to ver the dry the dry travel Dimensions Dimensions pressed 30.0 41.5 1.76 B ³ 432 (a) (I) Usual slow drying Grains 92.8 42.7 1.82 B ² i) (a) (H) Quick drying (like small 93.0 41.6 1.78 B ² 398 (a) (HI) described) Particle - pressed 29.0 52.5 3.20 B ³ 595 (b) (I) Usual slow drying Grains 92.7 53.2 3.24 B ² ') (b) 00 Quick drying (like small 93.4 52.6 3.20 B ² 516 (b) (III) described) Particle

The gas generation was not measured because the grains did not distribute homogeneously in the dough.

It can be seen from Table II that yeast (a) (III) has a lower activity than yeast (b) (III) .

Likewise, undried yeast (a) (I) has a lower activity than dried yeast (b) (III), i.e. the Undried pressed low protein yeast (a) (I) has a lower activity than the dried yeast O) (HI).

The yeasts (a) (II) and (b) (II) were dried according to the usual method. That's why they broke up Particles were absent and had little activity.

Example 3

A yeast suspension with the following properties is used: dry matter content 135 g / liter; Protein content, based on dry matter, 54.4 percent; Phosphorus content as P ₂ Os, based on dry matter, 3.25 percent. The yeast is propagated under such conditions that maximum activity is achieved when fresh. The yeast is treated in the same manner as in Example 1 using the same amount of wetting agent. The product obtained has the following properties: dry matter content 93.0 percent; Protein content, based on dry matter, 54.5 percent; Phosphorus is P ₂ Os, based on dry matter, 3.21 percent; Gas generation according to test B ₂ 560 ml.

• o Example 4

Three yeast suspensions obtained by propagating the yeast under conditions one maximum activity in the fresh state can be demonstrated in the same manner as in Example 1 Using the same amount of wetting agent dried. The properties of the obtained dry baker's yeast are summarized in Table III.

Table III

% Dry Protein content Phosphorus content Determination Gas Dimensions (° / o N χ 6.25) (o / o P2O5) procedure procreation based on the based on the (ml) Dry matter Dry matter

49.2
51.3
53.2

3.02
3.13
3.18

B2 B2

545
564
556

Example 5.

The process of Example 1 is repeated, but the drying is carried out in such a way that the temperature of the yeast is always 30 ^° C. during the drying. For this purpose, air at 100 ° C is first blown through the yeast mass and then the air temperature is gradually reduced during the drying process. The total drying time is 10 minutes. Analysis of the end product shows: dry matter content 92.4 percent; Protein content based on dry matter. 55.4 percent; Phosphorus content as P2O5, based on dry matter, 3.20 percent; Gas generation according to test B ₂ 528 528 ml.

Example 6

The procedure of Example 1 is repeated, however, air of 160 ° C is first blown through the yeast mass and the air temperature is gradually lowered during the drying, taking care that the temperature of the yeast is maintained below 40 ⁰ C. The total drying time is 8 minutes. The analysis of the end product shows: dry matter content 5 « 933 percent; Protein content, based on dry matter, 52.4 percent; Phosphorus content as P ₂ O ₅ , based on the dry matter, 3.15 percent; Gas generation after

Example 8

The process of Example 1 is repeated, but instead of sorbitan monostearate, 1.5 percent by weight is used Sorbitan monolaurate is used

When using yeasts that have been grown in such a way that pressed yeasts with different protein contents the results summarized in Table IV are obtained.

Table IV Example 7

The procedure of Example 4 is repeated, however, a mixture of glyceryl monostearate and glyceryl distearate is used as a wetting agent. The analysis of the end product shows: Protein content related to dry matter. 53.2 percent; Phosphorus stops from P2O5, based on the dry matter. 3.16 percent; Gas generation according to test B ² 521 ml.

% 0/0 protein phosphorus Gas Dry salary salary procreation Dimensions (% N χ 6.25) (% P2O5) Test B * related to related to the dry the dry Dimensions Dimensions 92.4 45.9 2.81 452 93.5 47.4 2.85 473 933 493 3.05 492 93.5 513 3.12 516 92.7 53.4 3.13 514 92 ^ 55.6 3.20 500 93.5 56.7 3.19 489 93.0 5SJ5 3.20 481

Example 9

The procedure of Example 1 is repeated, however the sorbitan monostearate is replaced by 1 percent methyl cellulose, which the compressed yeast before Drying is added. The results are summarized in Table V.

Ä »582/20!

V

Table V

% protein Phosphorus- Gas Dry salary went procreation Dimensions (% N χ 6.25) (% PjOs) Test B * related to related to the dry the dry Dimensions Dimensions

51.6
52.6

3.06
3.09

Example 10

493
500

To explain the baking properties of the yeast of the dry baker's yeast produced according to the invention are Comparative baking tests carried out.

The following yeasts are used for these tests: A commercially available compressed yeast with a protein content of 46.1 percent, a dry matter content of 30 percent and an activity of 408 (test B ³ ) (sample A), a commercially available compressed yeast with a protein content of 52, 5 percent, a dry matter content of 29.0 percent and an activity of 595 (test B ³ ) (sample B) and a dry yeast produced by the method according to the invention with a high protein content of 52.6 percent, a dry matter content of 93.4 percent and an activity of 516 (test B ² ) (sample C).

For these investigations, 100 parts of flour, 53 parts of water, 2 parts of NaCl and yeast are mixed together

mixed. The dry yeast is mixed with the other ingredients without pre-soaking. 1.8 parts of compressed yeast are used. The amount of dry yeast used (sample C) corresponds the dry matter content of the pressed yeast. The mixtures thus obtained are kneaded for 15 minutes, with care is taken that the temperature of the dough is 26 ° C. The following drive times are used:

First shoot
Second shoot
Intermediate drive
Final drive

30 minutes 25 minutes 30 minutes 60 minutes 145 minutes

The shoot temperature is 28 to 30 ° C. The dough weight for each loaf is 890 g. After 30 minutes of baking at a temperature of 250 ⁰ C, the loaves of bread have the following volume:

^{2925 cm 3} loaf made with sample A

Loaf made with sample B 3540 cm ³

^{3495 cm 3} loaf made with sample C

From these values it can be seen that the baking properties of dry baker's yeast are high in protein (Sample C) comparable to those of the compressed yeast from which it was made and those of fresh compressed yeast with low protein are far superior.

H

Claims (6)

Patent claims: 1. A process for the production of dry baker's yeast by crushing compressed yeast optionally mixed with a wetting agent and drying the particles in a hot air stream in a fluidized bed to a dry matter content of at least 85 percent by weight, characterized in that compressed yeast with a protein content of 45 to 60 Percent, based on the dry matter, used, and the particles dries within eh.es period of 3 to 50 minutes, the temperature of the air stream at the beginning of the drying treatment is at most 160 ⁰ C and the particles during drying in a temperature range of 20 to 50 ° C are kept. 2. The method according to claim 1, characterized in that that you can dry within a period of less than 20 minutes and up to a dry matter content of 90 to 95 percent by weight. 3. The method according to claim 1 and 2, characterized in that the particles are kept in a temperature range of 20 to 40 ⁰ C during the drying. 4. The method according to claim 1 to 3, characterized in that pressed yeast particles with a cross-section of 0.2 to 2 mm is used. 5. The method according to claim 1 to 4, characterized in that one pressed yeast with a Protein content of 48 to 54 percent begins. 6. The method according to claim 1 to 5, characterized in that one pressed yeast with a