BACKGROUND OF THE INVENTION.

In the manufacture of bread, yeast is contacted with dough in conditions sufficient to allow the yeast to produce C02 gas. This causes"gassing"of the dough, which in turn causes rising or"proofing"of the dough.

It would be advantageous if yeast were capable of gassing the dough at a maximal rate at the time of, or soon after, contact with the dough, because this would reduce the amount of yeast required in the manufacture of bread, and also reduce the amount of time required for proofing of the dough.

However, in most processes for the manufacture of bread, the yeast is exposed to stresses caused by components added to the dough (including for example, salt, sugar, and agents for flavouring and preserving bread) and by the environment of the dough itself. These stresses have the effect of limiting the rate of gassing of the dough at the time of, or soon after, contact of the yeast with the dough.

SUMMARY OF THE INVENTION The present invention seeks to at least improve the above limitation and in a first aspect provides a process for producing a yeast capable of an increased initial gassing rate at the time of, or soon after, contact with a dough. The process comprises contacting a yeast cream with sources of energy and nitrogen for the yeast, in the absence of dough, at a temperature sufficient to allow the yeast to metabolise the sources, to produce the yeast. In the process, the concentrations of the sources in the yeast cream extracellular water are greater than

or equal to the concentrations of the sources in the aqueous phase of a dough in which the yeast is to be used.

An advantage of the process is that the initial gassing rate of the yeast (i. e. the rate of C02 production by the yeast at the time of, or soon after, contact with the dough) is increased, as compared with the initial gassing rate of yeast which is not produced by the process. This allows a maximal gassing rate to be achieved at an early stage of proofing. The process therefore reduces the cost of bread manufacture, because the amount of yeast necessary to produce the necessary gas during proofing is decreased. Further the process is capable of increasing the rate of bread manufacture because the time required to proof the dough is reduced.

An increased initial gassing rate is achieved because the process exposes yeast to stresses in the dough in which the yeast is to be used, prior to contact of the yeast with the dough. This causes the yeast to adapt to the dough environment by becoming tolerant to the stresses. Yeast produced by the process is therefore capable of an increased initial gassing rate in the dough in which the yeast is to be used despite the dough stress because the yeast has adapted to the dough environment prior to contact with the dough.

Yeast for the manufacture of bread and bread-like foods is available in liquid, compressed and dry forms, typically with a solids content of 18-22%, 29-34% and 92- 96% weight per volume respectively. Yeast cream (also known in the art as cream yeast, liquid yeast or bulk yeast) is a liquid yeast suspension comprising yeast cells suspended in extracellular water, and which has a solid content of about 18 to 22%.

The yeast is made tolerant to the stresses, specifically the stresses caused by the sources of energy and nitrogen for the yeast in the dough, by contacting the yeast with amounts of the sources sufficient to provide concentrations of these sources in the yeast

cream extracellular water which are greater than or equal to the concentrations of these sources in the aqueous phase of the dough. In one embodiment, the concentration of the sources in the yeast cream extracellular water is equal to the concentration of the sources in the aqueous phase of the dough in which the yeast is to be used. In another embodiment, the concentration of the sources in the yeast cream extracellular water is 10 times greater than the concentration of the sources in the aqueous phase of the dough in which the yeast is to be used. In another embodiment, the concentration of the sources in the yeast cream extracellular water is 20 times greater than the concentration of the sources in the aqueous phase of the dough in which the yeast is to be used.

It is not necessary that the concentrations of both sources in the yeast cream extracellular water be greater than or equal to the concentrations of these sources in the aqueous phase of the dough in which the yeast is to be used. The increased gassing rate can be achieved when the concentration of the source of energy, or the source of nitrogen in the yeast cream extracellular water is greater than the concentration in the aqueous phase of the dough in which the yeast is to be used.

Further, it is not necessary that the sources of energy and nitrogen which are contacted with the yeast be chemically the same as the sources of energy and nitrogen in the dough in which the yeast is to be used.

The source of energy for the yeast is typically a sugar capable of supporting the metabolism of yeast, which may or may not be the same as the sugar comprised in the dough in which the yeast is to be used. In one embodiment, the sugar is glucose, fructose or sucrose.

The source of nitrogen is any nitrogen source capable of supporting the metabolism of yeast which may or may not be the same as the nitrogen source comprised in the dough in which the yeast is to be used. In one embodiment, the source of nitrogen is an ammonium salt, amino nitrogen, urea or mono sodium glutamate (MSG).

To cause the yeast to be made tolerant to these stresses, it is necessary to allow the cellular processes of the yeast to adapt to the concentrations of the sources of energy and nitrogen that the yeast will be exposed to in the dough in which the yeast is to be used.

Adaptation occurs at a temperature which is sufficient to allow the yeast to metabolise the sources of energy and nitrogen. Typically, the temperature is about 19°C to 33°C. In one embodiment the temperature is about 32°C.

In one embodiment, the yeast is then cooled, preferably to about 13°C, or more preferably, to 0-4°C in the circumstance that the yeast is to be stored before use.

The contact of the yeast with the sources of energy and nitrogen at about 19°C to 33°C for about 20 minutes is sufficient time to allow the yeast to metabolise the sources of energy and nitrogen and therefore, to adapt to the dough environment, however, the period of contact can be longer. The yeast produce gas when the sources of energy and nitrogen are metabolised, thus one can detect metabolism of these sources by observing gas production by the yeast. It is not necessary that all of the sources of energy and nitrogen be metabolised for adaptation of the yeast to occur.

As additional components which are capable of causing the yeast to be stressed may be added to dough in a processes for bread manufacture, it may be necessary to additionally contact the yeast with these components.

Typically, these components are contacted with the yeast cream in amounts sufficient to provide a concentration of the component in the yeast cream extracellular water which is greater than or equal to the concentration of the component in the aqueous phase of the dough in which the yeast is to be used.

In one embodiment, the additional component is an agent for reducing or inhibiting the growth of microbial organisms capable of growing on bread or bread-like foods. An example of an agent is calcium propionate or acetic acid. Calcium propionate is typically used in the

bread manufacturing industry for reducing or inhibiting the growth of mould on bread.

In another embodiment, the additional component is water. It may be necessary to add water so that the yeast can be exposed to osmotic conditions which are the same or similar to the osmotic conditions of the dough in which the yeast is to be used. The addition of water is particularly necessary when the yeast cream has a low extracellular volume of water (for example, when the weight per volume of water is greater than 22%), or when the yeast is provided for use in the process of the invention as a dry or compressed form, rather than as a yeast cream.

In another embodiment, flour is added as an additional component. Flour is useful in the circumstance that the flour comprised in the dough in which the yeast is to be used contains certain endogenous factors which stress the yeast.

In another embodiment, the additional component is an agent for flavouring the dough, to provide a flavoured bread or bread-like food. Typically this agent is a microbial agent, but it may also be any other agent capable of flavouring the dough, for example, vinegar.

In another embodiment, the additional component is a buffer for controlling the pH of the yeast cream. The purpose of the buffer is to prevent the yeast from injury caused by exposure to acidic or basic conditions in the process of the invention, specifically when the metabolism of the sources of energy and nitrogen for the yeast causes the pH of the yeast cream to alter in a way which adversely affects the yeast.

The process of the invention can be incorporated as a step in an industrial bread making process. In this context, it is not necessary to terminate the metabolism of the sources of energy and nitrogen by the yeast, and the yeast produced by the process of the invention can then be contacted with the dough mixture, to produce a bread or bread-like food.

In one embodiment, the yeast produced by the process of the invention is contacted with dough in the "no time"dough process to manufacture a bread or bread- like food.

In another embodiment, the yeast produced by the process of the invention is contacted with a pre-ferment in a"sponge"or"brew system"to manufacture a bread or bread-like food.

It may be necessary to terminate the metabolism of the sources of energy and nitrogen by the yeast in the circumstance where the process of the invention is incorporated as a final step in the production of yeast by a yeast manufacturer. Any process which is capable of inhibiting this metabolism and which does not affect the gassing rate of the yeast in the dough is suitable for this purpose.

In one embodiment, the metabolism is terminated by the step of contacting the yeast with an amount of salt sufficient to inhibit metabolism of the sources of energy or nitrogen by the yeast.

In another embodiment, metabolism is terminated by reducing the temperature of the yeast cream to a temperature at which the yeast is not capable of metabolising the sources of energy or nitrogen.

Typically, the temperature is reduced to no less than 0°C.

It is not necessary that the yeast be made to metabolise the sources of energy and nitrogen immediately after contact of the yeast cream with these sources. In one embodiment, after contact of the yeast cream with these sources, the cream may be dried to provide a dry form yeast. The dry form yeast may then be reconstituted by addition of water to produce a yeast cream. The yeast cream may then be brought to a temperature sufficient to allow the yeast to metabolise the sources, to produce the yeast.

It is not necessary to remove the composition from the yeast cream prior to contacting the yeast with the dough. In some circumstances, particularly where the

yeast is to be stored prior to use, it may be important to maintain the yeast cream in contact with the composition. However, where necessary, the composition can be removed from the yeast cream by a further step of washing the yeast to remove the composition from the yeast. Alternatively, the composition can be removed by decanting the composition from the yeast.

In a second aspect, the invention provides a yeast produced by the process of the first aspect of the invention.

In a third aspect, the invention provides bread or a bread-like food produced using the yeast of the second aspect of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In the following Examples, various batches of cream yeast with different solids contents or activities were used.

Example 1 This example demonstrates the magnitude of the impact of calcium propionate on the gassing power of yeast.

A typical bakers yeast plain dough activity (gassing power) testing dough as described in U. S. Patent No.

05543161 was prepared from ingredients shown in Table 1.1. The yeast was in the form known as"cream"or "liquid"yeast, which has a nominal solids content of 18- 22%. The dry ingredients were placed in a Brabender Farinograph mixing bowl and mixed for one minute. The liquid ingredients were then added and the dough mixed for a further 3 minutes. The temperature of the dough water and farinograph water bath were adjusted to achieve a finished dough temperature of 30.0°C=/O. 1C°. At the completion of mixing the dough was transferred in its entirety into a Brabender Fermentograph balloon, which was sealed and placed in the Fermentograph water bath as specified in the operating instructions for the apparatus. The amount of gas produced after incubation for one hour was read directly from the Fermentograph trace.

Table 1.1 Dough formulation in Example 1

Plain Dough CP Dough Dough component Quantity Quantity Flour 280g 280g Bread Improver (generic) 1. 5g 1. 5g Calcium Propionate Og 0.67g Water 98. 0 ml 98. 0 ml Salt solution (9.5% w/v) 57.0 ml 57. 0 ml Yeast Cream 7.5 ml 7. 5 ml A second dough was prepared in an identical manner except that 0.67g Calcium Propionate was added to the dough mix (see Table 1. 1, column 2). The gassing power of the cream yeast in this dough, referred to herein as a CP dough, is shown together with that in a plain dough in Table 1.2.

Table 1.2 Gassing Power results, Example 1 Plain Dough CP Dough Activity (ml gas in Ihr) 510 345 % Plain dough activity 100% 67.6% The results show that in the presence of Calcium Propionate, the gassing power of the yeast is severely inhibited, resulting in a 32.4% loss of gassing power.

Example 2 A nutrient mixture as summarised in Table 2.1 was prepared and added directly to 45ml chilled (4°C) yeast (being sufficient for 6 normal activity tests) in a beaker and stirred to ensure adequate mixing. The yeast used in this experiment was of higher solids content and gassing power than that used in experiment 1.

Table 2.1 Acclimate ingredients, in Example 2 Ingredient Quantity Sugar 10. Og Monosodium glutamate l. Og

The resulting mixture (acclimate 2a) was incubated as described in Example 1 in a 33°C water bath for 20 minutes measured from the time the temperature of the acclimate reached 25°C. It was then placed in an ice water bath and stirred gently until the temperature dropped to less than 13°C, by which time gassing had essentially ceased.

The acclimate was used to prepare a plain dough. The dough formulation is shown in Table 2.2.

Table 2.2 Dough formulation in Example 2 Acclimate 2a Standard Plain dough Plain Dough Flour 280g 280g Bread Improver (generic) 1. 5g 1. 5g Calcium Propionate 0 0 Water 98 ml 98 ml Salt solution (9.5% w/v) 57.0 ml 57. 0 ml Yeast Cream 0 7. 5 ml Acclimate 10. 2 g 0 The gassing power of plain dough with acclimate 2a was almost 10% greater than the gassing power of the standard plain dough. Table 2.3 shows that contact of the yeast with the sample of energy and nitrogen in acclimate 2a increases the gassing power of the agent in plain dough.

Table 2.3 Gassing Power results, Example 2 Acclimate 2a Standard Plain dough Plain Dough Activity (ml gas in Ihr) 650 600 Activity as % of plain 108% 100% dough activity with standardyeast

Example 3 A nutrient mixture as summarised in Table 3.1 was prepared and held at less than 20°C. When all nutrients had completely dissolved, the solution was added to 45ml chilled (4°C) yeast (being sufficient for 6 normal activity tests) in a beaker and stirred to ensure adequate mixing.

Table 3.1 Acclimate ingredients, in Example 3 Ingredient Quantity Water 20. Og Sugar 5. Og Monosodium glutamate 0. 25g Salt 0. 8g The resulting mixture (referred to here as the acclimate) was placed in a 33°C water bath and incubated with intermittent gentle stirring. The temperature was monitored throughout the experiment. As the temperature reached 25.0°C, timing commenced and the incubation was continued for 20 minutes, during which time the temperature rose to 32°C.

After 20 minutes had elapsed, the acclimate was removed from the water bath and placed in an ice water bath.

Stirring continued until the acclimate temperature dropped to less than 13°C, by which time vigorous gassing had essentially ceased. A volume of acclimate equivalent to 7.5ml of original yeast (1/6th of the acclimate) was taken and used in an activity test as described in

Example 1. The activity test component levels were modified to account for the water and salt already added to the acclimate. The. dough formulation is given in Table 3.2. A control CP dough was prepared from untreated cream yeast as described in example 1.

Table 3.2 Dough formulation in Example 3 Acclimate Standard CP Dough Dough Dough component Quantity Quantity Flour 280g 280g Bread Improver (generic) 1. 5g 1. 5g Calcium Propionate 0. 67g 0. 67g Water 103. 1 ml 98 ml Salt solution (9.5% w/v) 48. 6 ml 57 ml Yeast Cream 0 7. 5 ml Acclimate 12. lg Og

The results of the gassing power test are shown in Table 3.3. The acclimate treated yeast gassing power was increased by 40% relative to the standard CP dough with the same amount of bakers yeast.

Table 3.3 Gassing Power results, Example 3 Acclimate Standard CP Dough Dough Activity (ml gas in Ihr) 490 350 % Standard CP dough activity 140%100%

Example 4 A nutrient mixture as summarised in Table 4.1 was prepared and added directly to 45ml chilled (4°C) yeast in a beaker and stirred to ensure adequate mixing and dissolution.

Table 4.1 Acclimate ingredients, in Example 4 Ingredient Quantity Sugar lO. Og Monosodium glutamate l. Og

The resulting mixture (acclimate 4a) was incubated as described in Example 1 in a 33°C water bath for 20 minutes measured from the time the temperature of the acclimate reached 25°C. It was then placed in an ice water bath and stirred gently until the temperature dropped to less than 13°C, by which time gassing had essentially ceased.

A second acclimate (4b) was prepared, containing the same ingredients as described above but with 150ml added water. Once again it was added to 45ml cream yeast and the resulting mixture was treated in the same way as was the acclimate with yeast and nutrients alone. The gassing power of the two acclimates was compared in CP doughs, adjusted for the non yeast additives in the acclimates (Table 4.2). The inoculum levels of the acclimates in the doughs was adjusted to deliver the equivalent of 7.5ml cream yeast to each test. A third CP dough was prepared from standard cream yeast.

Table 4.2 Dough formulations in Example 4 Dough component Acclimat Acclimate Standard e 4a 4b dough CP dough Dough Flour 280g 280g 280g Bread Improver (generic) 1. 5g 1. 5g 1. 5g Calcium Propionate 0. 67g 0.67g 0.67g Water 98ml 73. Oml 98. Oml Salt solution (9.5% w/v) 57. Oml 57ml 57. Oml YeastCream 0 0 7. 5ml Acclimate 9. 7g 34. 7g 0

The results of the gassing power test are shown in Table 4.3. Acclimate 4b resulted in a significantly larger improvement in gassing power than did acclimate 4a with the same nutrient additions. This demonstrates the importance of the addition of water to the acclimate.

Table 4.3 Gassing Power results, Example 4 Acclimat Acclimate Standard e 4a 4b dough CP dough Dough Activity (ml gas in lhr) 400 460 350 % standard CP dough 114% 131% 100% activity Example 5 Two nutrient mixtures, 5a and 5b, as summarised in Table 5.1 were prepared. Each mixture was then added directly to its own 45ml chilled (4°C) cream yeast sample (being sufficient for 6 normal activity tests). The resulting acclimates were each stirred to ensure adequate mixing and were then placed in a 33°C water bath for 20 minutes measured from the time the temperature of the acclimate reached 25°C. They were then placed in an ice water bath and stirred gently until the temperature dropped to less than 13°C, by which time gassing had essentially ceased.

Table 5.1 Acclimate ingredients, in Example 5 Ingredient Acclimate 5a Acclimate 5b Water 20g 20g Sugar l0g 5. 0g Monosodium l. Og l. Og Glutamate Salt 0 0. 8g The gassing power of the two acclimates was compared in CP doughs, adjusted for the non-yeast additives in the acclimates (Table 5.2). The inoculum levels of the acclimates in the doughs were adjusted to deliver the equivalent of 7.5ml cream yeast to each test. A third CP dough was prepared from standard cream yeast.

Table 5.2 Dough formulations in Example 5

Dough component Acclimate Acclimate Standard 5a dough 5b dough CP Dough Flour 280g 280g 280g Bread Improver 1.5g 1.5g 1.5g (generic) Calcium Propionate 0. 67g 0. 67g 0. 67g Water 94. 8ml 103. lml 98. Oml Salt solution (9.5% 57. Oml 48.6ml 57. Oml w/v) YeastCream 0 0 7. 5ml Acclimate 12. 89g 12. 52g 0 The results of the gassing power test are shown in Table 5.3. Both acclimate 5a and acclimate 5b resulted in significant improvement in gassing power relative to that of the control cream yeast. The reduction in sugar level in the acclimate was compensated for by the addition of salt to maintain a similar osmotic pressure. As a result, the gassing power was essentially maintained whilst reducing the energy substrate concentration. This demonstrates the importance of osmotic stress in the acclimate for the improvement of gassing power.

Table 5.3 Gassing Power results, Example 5 Acclimate Acclimate Standard 5a Dough 5b Dough CP Dough Activity (ml gas in 445 425 300 Ihr) % Standard CP dough 148% 142% 100% activity

Example 6 A batch of nutrient mix as described in Table 6.1 was prepared and added to 90ml cream yeast (sufficient yeast for 12 standard gassing power tests). The buffer solution referred to in Table 6.1 was prepared by adding 0.6g Ammonium Dihydrogen Phosphate and 17.9g Disodium Hydrogen Phosphate to 100ml water. The resulting nutrient mixture was stirred to ensure adequate mixing and an initial 12.25g sample taken and placed in an ice water bath. The remainder of the acclimate was then placed in a 33°C water bath for 80 minutes, measured from the time the temperature of the acclimate reached 25°C.

At certain intervals detailed in Table 6.2 further acclimate samples were taken and placed in an ice water bath and stirred gently until the temperature dropped to less than 13°C, by which time gassing had essentially ceased.

Table 6.1 Acclimate ingredients, in Example 6 Ingredient Quantity Water 30. Og Buffersolution 10. Og Sugar 10. 0g Monosodiumglutamate 0. 50g Salt1. 6g Table 6.2 Results of acclimates incubated for varying lengths of time in Example 6. Incubation Gassing % of initial time @>25°C Power gassing power 0 335 100% l2 365 109% 21 405 121% 35 400 119% 43 430 128% 56 405 121% 65 420 125% 80 385 115%

The gassing powers of the samples were compared in CP doughs, adjusted for the non-yeast additives in the acclimate (Table 6.3). The inoculum levels of the acclimates in the doughs were adjusted to deliver the equivalent of 7.5ml cream yeast to each test.

Table 6.3 Dough formulations in Example 6 Dough component Acclimate dough 6 Standard CP Dough Flour 280g 280g Bread Improver 1.5g 1.5g (generic) Calcium Propionate 0.67g 0.67g Water 103. lml 98 Oml Salt solution 48.6ml 57. Oml (9.5% w/v) Yeast Cream 0 7. 5ml Acclimate 12. 23g 0

The results of the gassing power test are shown in Table 6.2. The gassing power increased very rapidly over the first 20 minutes, before reaching a relatively constant value. There was no evidence of a loss of gassing power when the incubation exceeded 20 minutes. The results demonstrate the importance of allowing suitable time for

acclimation to occur and the fact that the acclimation is essentially over in less than 30 minutes.

Example 7 A nutrient mixture (7a) as summarised in Table 7.1 was prepared and added to 45ml chilled (4°C) yeast (being sufficient yeast for 6 normal activity tests) in a beaker and stirred to ensure adequate mixing.

Table 7.1 Acclimate ingredients, in Example 7 Ingredient Acclimate 7a Sugar 10. Og Monosodium glutamate l. 0g Calcium Propionate 0. 5g The resulting mixture (referred to here as the acclimate) was placed in a 33°C water bath and incubated with intermittent gentle stirring. The temperature was monitored throughout the experiment. As the temperature reached 25.0°C, timing commenced and the incubation was continued for 20 minutes, during which time the temperature rose to 32°C.

After 20 minutes has elapsed, the acclimate was removed from the water bath and placed in an ice water bath.

Stirring continued until the acclimate temperature dropped to less than 13°C, by which time vigorous gassing had essentially ceased. A volume of acclimate equivalent to 7.5ml of original yeast (1/6th of the acclimate) was taken and used in an activity test as described in Example 1. The activity test component levels were modified to account for the dough ingredients already added to the acclimate. The dough formulation is given in Table 7.2. A control CP dough was prepared from untreated cream yeast as described in example 1.

Table 7.2 Dough formulations in Example 7 Dough component Acclimate 7a Dough Standard CP Dough Flour 280g 280g Bread Improver 1.5g 1.5g (generic) Calcium Propionate 0.59g 0.67g Water 98. Oml 98. Oml Salt solution 57. Oml 57. Oml (9.5% w/v) Yeast Cream 0 7. 5ml Acclimate 10. 25g 0

The results of the gassing power test are shown in Table 7.3. The acclimate, containing Calcium Propionate, showed higher gassing power then untreated yeast.

Table 7.3 Gassing Power results, Example 7 Acclimate 7a Standard CP Dough Dough Activity (ml gas in 490 415 Ihr) % Standard CP dough 118% 100% activity Example 8 A batch of nutrient mix as described in Table 8.1 was prepared and added to 2150ml cream yeast. The buffer solution referred to in Table 8.1 was prepared by adding 1. 8g Ammonium Dihydrogen Phosphate and 54g Disodium Hydrogen Phosphate to 300ml water. The resulting nutrient/yeast mixture was stirred to ensure adequate mixing and then placed in a 33°C water bath for 20 minutes, measured from the time the temperature of the acclimate reached 25°C.

After 20 minutes incubation, the acclimate was placed in an ice water bath and stirred until the temperature reached 13°C. Samples of the chilled acclimate taken as

required for baking trials. The samples were warmed to 19°C immediately prior to use so as to minimise any aberrations in the dough temperature. 715g of the acclimate was added to a dough, the ingredients of which are shown in Table 8.590g of control (untreated) yeast was added to a standard CP dough.

Table 8.1 Acclimate ingredients, in Example 8 Ingredient Quantity Water 715g Buffersolution 238g Sugar 238g Monosodium glutamate 11. 9g Salt 38. 2g

Doughs were mixed on a Tweedy mixer to 175 Watt hrs. The dough was given 10 minutes rest time, scaled to 500g, moulded, and placed in baking tins. The tins were then placed in a proofing cabinet set at 40°C and 80% relative humidity. The doughs were proofed to a standard height and the time taken to reach that height (the proof time) was recorded. The doughs were baked at 210°C for 25 minutes and were examined for volume and loaf structure and colour after 24 hours. The results of this bake test are shown in Table 8.3.

Table 8.2 Dough formulations in Example 8

Dough component Acclimate 8a Standard CP dough Dough Flour 10000g 10000g Bread Improver 100g 100g (generic) Calcium Propionate 24g 24g Water 5525ml 5695ml Salt 200g 200g Yeast Cream0 590g Acclimate 715g 0 Table 8.3 Bake testing results, example 8 Proof Time (min) 24hr volume (ml) Cream Yeast 68 mins 2150 (control) Acclimate 7a 66 mins 2110

Acclimate 8a contained 64.3% yeast cream. Thus the 715g acclimate used in the bake test contained 460g cream yeast. This is 22% less yeast than was used in the standard dough and the acclimate still had a slightly faster proof time. The loaf volumes and the internal structure were essentially the same as the control bread.

The softness was similar as was the colour. These results demonstrate the success of the acclimate in the acceleration of gassing and the reduction of bakers yeast usage.

Experiment 9 A nutrient mixture as summarised in Table 9.1 was prepared and added directly to 45ml chilled (4°C) yeast (being sufficient for 6 normal activity tests) in a beaker and stirred to ensure adequate mixing.

Table 9.1 Acclimate ingredients, in Example 9 Ingredient Quality Sugar 10. Og Monosodium glutamate l. 0g The resulting mixture (acclimate 9a) was incubated as described in Example 1 in a 33°C water bath for 20 minutes measured from the time the temperature of the acclimate reached 25°C. It was then placed in an ice water bath and stirred gently until the temperature dropped to less than 13°C, by which time gassing had essentially ceased.

The acclimate was used to prepare a plain dough and also

one containing calcium propionate. The dough formulation is shown in Table 9.2. Untreated cream yeast was added to a control plain and a control CP dough as shown in Table 9.2.

Table 9.2 Dough formulations in Example 9 Dough component Acclima Acclimate Standard Standard te 9a 9a CP Plain CP Plain Dough Dough Dough Dough Flour 280g 280g 280g 280g Bread Improver 1.5g 1.5g 1.5 1.5g (generic) Calcium 0 0.67g 0 0.67g Propionate Water 98ml 98. Oml 98. Oml 98. Oml Salt solution 57. Oml 57ml 57.0ml 57. Oml (9.5% w/v) Yeast Cream007. 5ml7. 5ml Acclimate 10. 2g 10.2g 0 0 The results of the gassing power testing are shown in Table 9.3. The standard yeast gassing power was reduced by 31% in the presence of the CP, whereas the acclimated yeast was reduced by only 17%. The inhibition caused by CP was therefore reduced by use of the acclimate. The demonstrates that the acclimate reduces CP sensitivity without having to treat the yeast with propionate, acetic acid, sorbate or similar organic acids. The results show also that the acclimate increased the CP dough gassing power by 20%. It also increased the plain dough gassing power by 8%, demonstrating the versatility of the acclimate in doughs with varying CP levels.

Table 9.3 Gassing Power results, Example 9 Acclimate Acclimate Standard Standard 9a 9a Plain CP Dough Plain CP Dough Dough Dough Activity (ml 650 500 600 415 gas in Ihr) Activity as 83% 69% % of plain dough activity