Sugar super-tolerant yeast for confectionery and bakery

Abstract: The invention provides (1) yeasts with high leavening ability enough for bakery in an ultra-high sugar range and with high scar tolerance (osmotic pressure tolerance), and (2) yeasts with high leavening ability enough for bakery in an ultra-high sugar range and with high sugar tolerance (osmotic pressure tolerance) and high freezing tolerance which characteristically exert sufficient leavening ability of dough blended with sugar above 40 parts by weight per 100 parts by weight of flour, to enable the production of high-quality bread items including white bread in a low sugar range to sweet roil items or fermented confectioneries in a high sugar range, irrespective of the bakery process.

Description: Field of the Invention The present invention relates to novel yeasts and the use thereof. Description of the Related Art Bread is grouped in a wide variety of items, including French bread with no sugar added, white bread in a low sugar range, which is prepared by adding sugar at 5 to 6 % to flour, croissant and butter roll in a medium sugar range, which are prepared by adding sugar at 8 to 15 % to flour, Danish pastry and confectionery bread in a high sugar range, which are prepared by adding sugar at 20 to 30 % to flour, fermented confectioneries, such as beam-jam sweet, and coffee cake and brioche, which are prepared by adding sugar at 35 to 50 % to flour. Furthermore, bakeryprocess is divided in scratch process (including straight bakery process and intermediate seed bakery process) and frozen dough process. Therefore, these processes and bread items are used in such a wide variety of combinations. For producing the bread items in the low sugar range to the high sugar range, conventionally, various yeasts with various fermentative abilities have been used in such a complicated manner that yeast with high freezing tolerance should be used for the frozen dough process. However, no yeast with sugar tolerance enough for fermentation of dough items [for bean-jam sweet roll, fermented confectioneries, etc.] in a blend of sugar at a content as high as 35 % or more to flour has yet been present. Accordingly, many bakers have managed to treat such dough items by prolonging the duration of the fermentation more than necessary or raising the quantity of yeast, to prepare the products. Nevertheless, these products are currently of no bread quality primarily intended and have poor bulky appearance. Problems that the Invention is to Solve It is an object of the invention to provide yeasts with high sugar tolerance (or osmotic pressure tolerance) having high excellent fermentative abilities in a super-high sugar range, so as to solve the problems. In current circumstances where sweet bread and confectioneries with high sugar contents are desired in general, more specifically, the invention has been attained for the purpose of providing novel yeasts with super-high sugar tolerance, which conventionally have never existed and are hardly affected (of which the fermentative abilities are hardly reduced) by the osmotic pressure of high contents of fat or fatty oil or egg blended in dough at a super-high sugar content of 30 to 40 % or more. Conventional yeasts under the influence of osmotic pressure can never yield bread products of excellent quality from dough in a blend of fat or fatty oil or egg at a super-high sugar content of 30 to 40 % or more. Owing to the progress in bakery technology and the diversification of bread items in recent years, yeast should be selected and used, depending on the intended bread item. Thus, many types of yeast are essentially needed. In terms of laborious works in the use of a different yeast each time, which is not practical industrially, novel yeasts with excellent properties are provided, from the respect that one yeast concurrently having these properties can satisfy the whole aspect. In other words, the invention provides excellent yeasts with great specificity from the respect of super-high sugar tolerance. Additionally, the invention can firstly provide new useful yeasts satisfying all the needs, which has never been obtained conventionally and which does not require the proper use of yeasts having different properties, depending on the intended products. Subject of the Invention The invention relates to a method for obtaining yeast with high sugar tolerance (or osmotic pressure tolerance), according to a first aspect, and with both high sugar tolerance and freezing tolerance, according to a second aspect. According to the first aspect of this invention, a method is provided for obtaining yeast capable of generating at least 110 ml of CO 2 per 40 grams of dough containing 0.4 g of the yeast on a dry weight basis after fermenting at 30° C. for two hours, said method comprising: a. mixing 100 parts by weight of flour, 40 parts by weight of sucrose, 0.5 part by weight of sodium chloride, 6 parts by weight of the yeast as wet yeast, and 50 parts by weight of water to form a dough; b. forming portions of the dough into 40 gram portions; c. fermenting the dough portions formed in step (b) at 30° C. for two hours and assaying the amount of CO 2 generated; and d. screening and recovering the yeast which is capable of generating at least 110 ml of CO 2 per 40 grams of dough. According to the second aspect of this invention, a method is provided for obtaining yeast capable of generating at least 100 ml of CO 2 per 40 grams of dough containing 0.4 g of the yeast on a dry weight basis after fermenting at 30° C. for two hours, comprising: a. mixing 100 parts by weight of flour, 40 parts by weight of sucrose, 0.5 part by weight of sodium chloride, 6 parts by weight of the yeast as wet yeast, and 50 parts by weight of water to form a dough; b. forming portions of the dough into 40 gram portions; c. fermenting the dough portions formed in step (b) at 28° C. for 15 minutes; d. freezing the portions fermented in step (c) at -40° C. for 30 minutes; e. storing the frozen portions at -20° C. for four weeks; f. thawing the stored portions at 20° C. for 60 minutes; g. fermenting the thawed portions at 30° C. for two hours to assay the amount of CO 2 generated; and h. screening and recovering the yeast capable of generating 100 ml or more CO 2 per 40 grams of dough. Detailed Disclosure of the Invention Specific characteristic properties of the yeasts according to the first aspect of this invention are as described below. 1. The yeasts have a leavening ability of dough blended with sugar at 5 to 25 % to flour for bread loaf and confectionery bread (in the low to high sugar range), at the same level as that of routine general types of yeast (for example, Regular Yeast manufactured by Oriental Yeast Co., Ltd.), at the straight dough method and the sponge dough method, to produce bread of large volume and stable quality. 2. The yeasts have sugar tolerance (osmotic pressure tolerance) capable of fermenting dough at a very high sugar concentration, such as dough containing sugar at 30 to 50 % to flour. Of course, the presentive yeasts may be used to make variants breads and sweet rolls by using dough containing other sugar inplaceof sucrose; examples of said other sugar are glucose, fructose, liquid inverted sugar, etc. Various routes can be adopted so as to obtain the yeasts according to the first aspect. By the mating method, for example, the intended strain can be obtained highly efficiently. Firstly, therefore, strains with high fermentative abilities and with a character raising sugar tolerance are selected among bakers' yeast strains of the individual yeast strains are inoculated on a spore forming culture medium in a conventional manner to form the spores; after the examination of the properties of the resulting spores, then, strains with the same bakery performance as general practical yeasts for bread making and also with a high leavening ability of 40 %- sugar blended dough is satisfactorily screened among strains grown by the traditional mating method. It is needless to say that the intended strains may be created by a mutation process. As the mutation process, routine methods can be adopted widely, including physical processes with γ ray, ultraviolet ray and temperature difference, etc. and processes with mutagens such as ethidium bromide, nitrogen mustard, diepoxybutane, colchicine, peroxide, and purine derivatives. One of the new yeast strains thus obtained was designated Saccharomyces cerevisiae P-712 and deposited under FERM BP-7034 at National Institute of Bioscience and Human-Technology Agency of Industrial Science and Technology (now International Patent Organism Depository, National Institute of Advanced Industrial Science and Technology). The bacteriological properties are described below. Bacteriological properties of the strain P-712 1. Growth state Good growth in YM liquid culture medium. Cell morphology: spherical to egg shape; 3 to 7 x 4 to 8 µ. MM agar culture medium: good growth; colony (white, glossy, and smooth). 2. Ascospore Formed in potassium acetate culture medium; ascospore of spherical shape. 3. Individual physiological properties 3-1. Optimum growth conditions: temperature of 28 to 32 °C; pH 4.5 to 6.5. 3-2. Growth range: temperature of 5 to 40 °C; pH 2.5 to 8.0. 3-3. Assimilation of nitrate salt: none. 3-4. Fat decomposition: none. 3-5. Carotenoid generation: none. 3-6. Prominent organic acid generation: none. 3-7. Vitamin requirement: biotin and pantothenic acid. 3-8. Sugar tolerance: sufficient leavening ability can be exerted in dough blended with sucrose above 30 to 40 parts by weight or more to 100 parts by weight of flour. 4. Fermentability and assimilability of carbon source Fermentability Assimilability D-Glucose + + D-Galactose + + Maltose + + Sucrose + + In accordance with the second invention, furthermore, aspect of this new yeast strains are provided, having a high leavening ability in a super-high sugar range as well as freezing tolerance. Various routes can be adopted so as to obtain the yeasts according to the second aspect. By the mating method, for example, the intended strain can be obtained highly efficiently. Firstly, therefore, strains with high fermentative abilities and with a character raising both freezing tolerance and sugar tolerance are selected among bakers' yeast strains of the individual yeast strains are inoculated on a spore forming culture medium in a conventional manner to form the spores; after the examination of the properties of the resulting spores, then, strains with the same bakery performance as general practical yeasts for bread making and also with a high leavening ability of 40 %- sugar blended dough and freezing tolerance is satisfactorily screened among strains grown by the traditional mating method. It is needless to say that the intended strains may be created by a mutation process. As the mutation process, routine methods can be adopted widely, including physical processes with γ ray, ultraviolet ray and temperature difference, etc. and processes with mutagens such as ethidium bromide, nitrogen mustard, diepoxybutane, colchicine, peroxide, and purine derivatives. One of the new yeast strains was designated Saccharomyces cerevisiae P-731 and deposited under FERM BP-7035 at National Institute of Bioscience and Human-Technology Agency of Industrial Science and Technology (now International Patent Organism Depository, National Institute of Advanced Industrial Science and Technology). The bacteriological properties are described below. Bacteriological properties of the strain P-731 1. Growth state Good growth in YM liquid culture medium. Cell morphology: spherical to egg shape; 3 to 7 × 4 to 8 µ. MM agar culture medium: good growth; colony (white, glossy, and smooth). 2. Ascospore Formed in potassium acetate culture medium; ascospore of spherical shape. 3. Individual physiological properties 3-1. Optimum growth conditions: temperature of 28 to 32 °C; pH 4.5 to 6.5. 3-2. Growth range: temperature of 5 to 40 °C; pH 2.5 to 8.0. 3-3. Assimilation of nitrate salt: none. 3-4. Fat decomposition: none. 3-5. Carotenoid generation: none. 3-6. Prominent organic acid generation: none. 3-7. Vitamin requirement: biotin and pantothenic acid. 3-8. Freezing tolerance/sugar tolerance: after thawing of the frozen dough containing 40 parts by weight of sucrose per 100 parts by weight of flour (under 4-week storage), the strain generates CO 2 100 ml or more per 40 g of the dough containing 0.4 g yeast on a dry weight basis at 30 °C for 2 hours. 4. Fermentability and assimilability of carbon source Fermentability Assimilability D-Glucose + + D-Galactose + + Maltose + + Sucrose + + The above-mentioned two yeast strains deposited are considered to belong to Saccharomyces cerevisiae ; the strains have the bacteriological properties described above, but the strains have high fermentation potencies in the super-high sugar range and also in the low to medium sugar range. Such strains have never been found among conventionally known yeast strains. Hence, the two yeast strains are designated new strains. (1) The yeast strains with high leavening abilities the super-high sugar range may be selected and grown in the manner described below. The strains with the sugar tolerance can be obtained by separating each yeast strain generating CO 2 110 ml or more at 30 °C for 2 hours, per 40 g of dough containing 0.4 g of said each yeast strain on a dry weight basis containing sucrose of 40 parts by weight per 100 parts by weight of flour. The inventive strains are sometimes referred to as "US yeast". (2) The yeast strains with a high leavening ability in the super-high sugar range and freezing tolerance may be selected and grown in the manner described below. After the thawing of frozen dough containing 40 parts by weight of sucrose to 100 parts by weight of flour, each yeast strain generating CO 2 100 ml or more at 30 °C for 2 hours per 40 g of the frozen dough containing 0.4 g of said each yeast strain on a dry weight basis is satisfactorily separated. The inventive strains are hereinafter sometimes referred to as "FD-2 yeast". In accordance with the invention, occasionally, the aforementioned two yeast strains (1) and (2) are collectively called "sugar super-tolerant yeast strain. Owing to the excellent sugar tolerance capable of overthrowing the state of art, the sugar super-tolerant yeast can be used widely for the production of bread items with no sugar to bread items in a low sugar range, like French bread and white of bread, as well as confectionery bread to fermented confectioneries prepared from dough at super-high sugar contents, and also for the production of various bread items using fat or fatty oil or egg or the like. The sugar super-tolerant yeast can be used, for example, for producing coffee cake (bread suitable with coffee, which is preferred by many Americans), bean-jam sweet roll, fruit bread, pastry, butter roll and croissant. The process of producing bread using the yeast of the present invention is satisfactorily any scratch process (straight dough method and sponge dough method) in a conventional manner and is applicable to frozen bread dough in addition to general bread dough. Examples of the invention are described below. Example 1 The inventive sugar super-tolerant yeast strain (FERM BP-7034) was cultured under the following conditions, using a 30-liter jar fermenter, to produce much thereof. Seed culture Sucrose content (on a glucose basis) 1035 g Urea 103 g Monosodium phosphate · dihydrate 20.7 g Quantity of seed yeast (wet basis) 20g 30-liter jar culture Sucrose content (on a glucose basis) 1400 g Urea 140 g Monosodium phosphate · dihydrate 28 g Quantity of seed yeast (wet basis) 420g Example 2 According to the assay method of the gas generated by yeast, as defined by Japan Yeast Industry/Association, the sugar tolerance of each yeast was assayed. By using the inventive yeast (sugar super-tolerant yeast) FERM BP-7034 and a commercially available regular yeast (product manufactured by Oriental Yeast Co., Ltd.), more specifically, the gas generated from the following blends at 30 °C for 120 minutes was assayed under the following conditions by Fermograph. The results are shown in Table 2. Process conditions Mixer: Hobart mixer Mixing: low speed for 3 minutes Kneading temperature: 30 °C Fermentation temperature: 30 °C Assay: total gas volume from dough weight of 40 g at 30 °C for 2 hours assayed by Fermograph (manufactured by Atto Co., Ltd.). Comparison of leavening abilities (unit: ml/40g · dough/2 hr) Sucrose content Inventive US yeast Regular yeast 0 219 220 5 301 303 10 330 328 15 325 325 20 301 295 25 275 235 30 235 171 35 175 114 40 134 75 45 80 38 50 45 18 The quantity of yeast contained in 40 g of the dough corresponds to 0.40 g on a dry weight basis. As apparently shown in the results of Table 2, it was confirmed that the sugar super-tolerant yeast of the invention still retained sugar tolerance (osmotic pressure tolerance) capable of sufficiently fermenting dough at a very high sugar concentration, such as dough containing sucrose at 30 to 50 % to flour. Example 3 Using the inventive US yeast (FERM BP-7034), mini-type bean-jam sweet roll was prepared from the following blend, by the following process; Table 3 and 4. (Formula ratio per flour part by weight) Formula Sponge Dough mixing Flour 70.0 30.0 "US yeast" 4.0 1.0 "Saka-rich" 15.0 Dough improve 0.5 0.2 Sugar (Glucose) 5.0 (Sucrose) 5.0 Shortening 10.0 Skim milk powder 3.0 Sucrose 40.0 Sodium chloride 0.35 Whole egg 10.0 Water 19.0 Process conditions Sponge Dough mixing Mixing time (minutes) L2M2 L2M3↓M3H1 Dough temperature 26 °C 28 °C Fermentation (floor) 2 hours 90 minutes Fermentation Conditions 28 °C 28 °C Dividing weight 15 g Bench time 15 minutes Bean-jam weight (per dough) 10 g Final proof condition 35 °C · 85 % RH about 70 minutes Baking conditions 200 °C for 8 minutes Example 4 Using the inventive US yeast, roll with sucrose was prepared from the following blend at the following conditions; Table 5 and 6. At a sucrose content of 15 to 25 parts by weight, the US yeast was effective, advantageously. (Formula ratio per flour part by weight) Formula Sponge Dough mixing Flour 70.0 30.0 "US yeast" 3.0 Dough improve 0.1 Sugar (Glucose) 3.0 (Sucrose) 20.0 Shortening 10.0 Skim milk powder 3.0 Sodium chloride 1.0 Whole egg 10.0 Water 34.0 20.0 Process conditions Sponge Dough mixing Mixing time (minutes) L2M2 L2M3↓M3H1 Dough temperature 26 °C 28 °C Fermentation (floor) 2 hours 50 minutes Fermentation Conditions 28 °C 28 °C Dividing weight 60 g Bench time 15 minutes Final proof condition 35 °C · 85 % RH about 60 minutes Baking conditions 200 ° C · 9 minutes Example 5 Using the inventive US yeast, fruit bread was prepared from the following blend at the following conditions; Table 7 and 8. The resulting product was a confectionery-like bread item at a high content of fruit used therein and with fluffy taste; owing to the combined use of the fermentation flavor liquid "Budou Dane #2" (product of Oriental Yeast Co., Ltd.), the resulting bread was very flavorful and delicious. (Formula ratio per flour part by weight) Formula Sponge Dough mixing Flour 70.0 30.0 "US yeast" 3.0 "Budou Dane #2" 5.0 Dough improve 0.1 Sugar (Glucose) 3.0 (Sucrose) 20.0 Fats and fatty oils (shortening) 10.0 Sodium chloride 1.5 Whole egg 10.0 Skim milk powder 3.0 Raisin 70.0 Water 30.0 14.0 Process conditions Sponge Dough mixing Mixing time (minutes) L2M2 L2M3↓M3H1↓L3 Dough temperature 26 °C 28 °C Fermentation (floor) 2 hours 60 minutes Fermentation Conditions 28 °C 28 °C Dividing weight 60 g Bench time 15 minutes Molding Final proof condition 35 °C · 85 % RH about 60 minutes Baking conditions 200 °C · 10 minutes Example 6 Using the inventive US yeast, a fermented confectionery (cookie) was prepared from the following blend at the following conditions; Table 9. The resulting product was very sweet with fluffy touch on teeth. (Formula ratio per flour part by weight) Formula Flour 100.0 "US yeast" 5.0 Sucrose 40.0 Margarine 40.0 Whole egg 10.0 Condensed milk 0.5 Vanilla oil 0.3 Water 10.0 Sodium chloride 0.5 Process conditions 1. Mixed sucrose, margarine, condensed milk and sodium chloride with a beater. 2. Add egg in a two-divided manner and emulsify the egg. 3. Add sifted flour, US yeast, and water and mix the resulting mixture together. 4. Gently mixed the mixture with hands. 5. Place the dough in a polyethylene bag and elongate flat wise the dough with hands; cool the dough in a refrigerator to a final stiffness easily moldable enough for molding and punch it. 6. Ferment the dough at room temperature for 20 to 30 minutes and bake the dough at 220 °C for about 13 minutes. Example 7 Using the inventive US yeast and a commercially available regular yeast (manufactured by Oriental Yeast Co., Ltd.), a white bread and a sweet roll item were prepared from the following formulas at the following conditions; Table 10 and 11, according to the scratch bakery process. The results are shown in Table 12. (Formula ratio per flour part by weight) Formula Low sugar content (white bread) dough blend High sugar content (sweet roll) dough blend Flour 100.0 100.0 Sucrose 5.0 25.0 Sodium chloride 2.0 0.5 Yeast 2.0 3.0 Shortening 5.0 6.0 Skim milk powder 0.0 2.0 Water 65.0 52.0 Process conditions Low sugar content (white bread) dough blend High sugar content (sweet roll) dough blend Mixing time (minutes) L2M2↓L2M2H2 L2M4↓L1M4H Dough temperature 28 °C 28 °C Dividing weight 450 g 60 g Bench conditions 30 °C for 15 minutes 30 °C for 15 minutes Molding one loaf molded into sweet roll Baking conditions 200 °C for 25 minutes 200 °C for 10 minutes Comparison by the scratch process Straight process Inventive US yeast Regular yeast White bread First fermentation conditions 30 °C for 73 minutes 30 °C for 75 minutes Final proof conditions 38 °C for 56 minutes 38 °C for 57 minutes Specific bread volume 4.38 4.32 Bread quality (softness) soft ordinary Bread quality (aging) slow ordinary Bread quality (texture) uniform ordinary Bread flavor good good Bread texture soft ordinary Sweet roll first fermentation conditions 76 minutes 81 minutes Final proof conditions 38 °C for 55 minutes 38 °C for 56 minutes Specific bread volume 5.21 5.09 Bread quality (softness) soft ordinary Bread quality (aging) slow ordinary Bread quality (texture) uniform ordinary Bread flavor good good Bread texture soft ordinary In the same manner, subsequently, a white bread was prepared according to the scratch process (sponge dough method) from the following formula and under the following conditions. The results are shown below in Table 13. (Formula ratio per flour part by weight) 70 % intermediate seed bakery process (bread loaf) Formula Sponge Dough mixing Flour 70.0 30.0 Sucrose 5.0 Sodium chloride 2.0 Yeast 2.0 Dough improver (Ammonium chloride, calcium carbonate) 0.1 Water 38.5 25.0 Process conditions Sponge Dough mixing Mixing time (minutes) L1M2 L1M6H3 Dough temperature 24 °C 28 °C Fermentation conditions 30 °C 28 °C for 4 hours 30 °C for 15 minutes Dividing weight 450 g Fermentation (floor) 15 minutes or 30 minutes Bench time 15 minutes Final proof 35 °C · 85 % RH Baking conditions 200 °C for 20 minutes Comparison by the scratch process Sponge dough method Inventive US yeast Regular yeast Sponge leavening volume for 1 hr 145 ml 120 ml Dough leavening volume for 1 hr 315 ml 300 ml Final proof 35 °C for 52 minutes 35 °C for 55 minutes Specific bread volume 6.0 5.8 Bread quality (softness) soft ordinary Bread quality (aging) slow ordinary Bread quality (texture) uniform ordinary Bread flavor good good Texture soft ordinary As apparently shown above in the results of Table 15, it was confirmed that the inventive US yeast had a leavening ability at the same level as that of regular yeast (for example, Regular Yeast manufactured by Oriental Yeast Co., Ltd.) and produce excellent bread of stable quality and softness and with large volume, from dough blended with sugar at 5 to 25 % to flour (in the low to high sucrose range) for white bread and sweet roll, according to any of the straight bakery method and the sponge dough method. Example 8 The inventive FD-2 yeast (FERM BP-7035) was cultured and prepared on a large scale, using a 30-liter jar fermenter under the following conditions. Seed culture Sugar content (on a glucose basis) 1035 g Urea 103 g Monosodium phosphate dihydrate 20.7 g Quantity of seed yeast (wet basis) 20g 30-liter jar culture Sugar content (on a glucose basis) 1400 g Urea 140 g Monoscdium phosphate · dihydrate 28 g Quantity of seed yeast (wet basis) 420g Maker: Oriental Bio-Service Co., Ltd. Name: Fermenter CONTROL SYSTEM MC-10 Volume: 30 liters Agitation: 600 rpm Aeration volume: 16 liters/min Example 9 The freezing tolerance was compared between the inventive yeast (P-731 FERM BP-7035: FD-2 yeast) and a commercially available freezing tolerant yeast (without sugar tolerance) (FD-1 yeast: product of Oriental Yeast Industry, Co., Ltd.) in various blends with sugar. More specifically, the inventive yeast prepared as described above was added to and mixed and kneaded with bread dough at the following Table 16. After mixing and kneading, the resulting dough was divided into 40-g portions, which were then fermented at 30 °C and molded thereafter; then, the molded portions were frozen and stored for given periods of time at -20 °C. As a control, the commercially available freezing tolerant yeast was used, to prepare such frozen dough in the same manner, for storage. Process conditions Mixer: Hobart mixer Mixing: low speed for 3 minutes Dough temperature: 24 °C Quantity of divided dough portion: 40 g Fermentation prior to dough freezing (floor time): 15 minutes (28 °C) Dough freezing: -40 °C for 30 minutes Storage of frozen dough: -20 °C Thawing: 20 °C for 60 minutes Assay: total gas volume from dough weight of 40 g at 30 °C for 2 hours was assayed by Fermograph (manufactured by Atto Co., Ltd.). Comparison of fermentability (mg/40g · dough/2 hr) Inventive FD-2 yeast Commercially available freezing tolerant yeast Period of under freezing dough storage 1 day 4 weeks 8 weeks 1 day 4 weeks 8 weeks sucrose content 0% 205 185 155 210 192 156 5% 262 248 224 265 252 221 10 % 292 272 251 288 269 249 15% 280 260 243 279 255 241 20% 258 243 230 256 239 228 25% 237 225 211 231 218 205 30% 204 192 180 195 182 169 40% 118 107 103 85 66 45 50% 47 40 35 28 19 12 As apparently shown Table 17 in the results, it was confirmed that the inventive freezing tolerant yeast (FD-2 yeast) had freezing tolerant at the same level as that of the commercially available freezing tolerance yeast and still had sugar super-tolerance capable of sufficiently fermenting dough at a high sugar concentration (even dough at a very high sugar concentration, such as dough containing sucrose at 30 to 50 % to flour). Example 10 Using the inventive FD-2 yeast (FERM BP-7035), coffee cake was prepared from the following blend at the following steps of the following bakery process (general bakery process: scratch process, frozen dough method). Formula per flour part by weight Flour 100 Yeast (FD-2 yeast) 8 Dough improver 2 ("010" for frozen dough: product manufactured by Oriental Co., Ltd.) Sucrose 40 Margarine 25 Sodium chloride 0.8 Skim milk powder 6 Whole egg 25 Water 20 Flour paste (per dough) 60 ("Tokachi milk": product manufactured by Oriental Co., Ltd) Process condition Mixing time (minutes L 2 M 4 H 6 ↓M 3 H 10 Dough temperature 25 °C Floor time 40 minutes Retard temperature 5 °C Retard time 15 to 20 minutes Roll-in being folded in four: once Dividing weigh 70 g Dough freezing - 40 °C for 30 minutes Dough storage under freezing - 20 °C for 6 weeks Thawing 20 °C for 60 minutes Final proof 70 minutes Final proof conditions 35 °C · 85 % RH Baking conditions 200 °C for about 12 minutes Because of the high content of sugar, coffee cake with a new taste, such as sweet taste and soft touch, like sponge cake was obtained by baking the dough after thawing, which was a brand-new bread product having new flavor and giving new texture. Furthermore, blend doughs with addition of sucrose at 10 to 25 % to flour in the medium to high sugar range were individually prepared (100 g of flour, 10 to 25 g of sucrose, 0.5 g of sodium chloride, 6 g of yeast and 52 ml of water); the doughs were kneaded and divided into 30-g portions on a flour basis, which were preliminarily fermented at 30 °C for 30 minutes; each portion was molded, frozen and stored for 1 to 3 weeks; after thawing, the gas generated at 30 °C for 120 minutes was assayed by Fermograph. Consequently, it was verified that the inventive freezing tolerant/sugar super-tolerant yeast (FD-2 yeast) had freezing tolerance at the same level as that of standard yeast for frozen dough (for example, FD-1 yeast: product of Oriental Yeast Co., Ltd.), to produce high-quality bread even after the yeast was stored in frozen bakery dough for a long term. Example 11 Frozen dough of the following Table 18 prepared by using the inventive FD-2 yeast at the following Table 19 was thawed, to prepare mini-type bean-jam sweet roll. Herein, "Saka-rich" is a fermentation flavor solution like "Sakadane". These are products of Oriental Yeast Industry, Co., Ltd. Formula (Formula ratio per flour part by weight) Formula Flour 100.0 "FD-2 yeast" 5.0 " Saka-rich" 15.0 Dough improve 1.0 Sucrose 10.0 Shortening 10.0 Skim milk powder 3.0 Liquid inverted sugar 40.0 Sodium chloride 0.35 Whole egg 10.0 Water 19.0 Process conditions Mixing time (minutes) L 2 M 4 H 6 ↓M 3 H 10 Dough temperature 25 °C Fermentation (floor) 40 minutes Fermentation temperature 28 °C Dividing weight 15 g Bench time 15 minutes Bean-jam weight (per dough) 10 g Dough freezing - 40 °C for 30 minutes Dough storage under freezing - 20 °C for 4weeks Thawing: 20 °C for 60 minutes Final proof condition 35 °C - 85 % RH about 70 minutes Baking conditions 200 °C for about 8minutes Example 12 Sweet roll using sucrose was prepared , by using the inventive FD-2 yeast from the following Table 20 at the following Table 21. Even at a sucrose content of 15 to 25 parts by weight, the FD-2 yeast was effective. (Formula ratio per flour part by weight) Formula Flour 100.0 FD-2 yeast 3.0 Dough improve 1.0 Sucrose 23.0 Fats and fatty oils (shortening) 10.0 Skim milk powder 3.0 Sodium chloride 1.0 Whole egg 10.0 Water 54.0 Process conditions Mixing time (minutes) L 2 M 4 H 6 ↓M 3 H 10 Dough temperature 25 °C Fermentation (floor) 30 minutes Fermentation temperature 28 °C Dividing weight 60 g Bench time 15 minutes Dough freezing - 40 °C for 30 minutes Dough storage under freezing - 20 °C for 5weeks Thawing: 20 °C for 60 minutes Final proof condition 35 °C · 85 % RH about 60 minutes Baking conditions 200 °C for about 9minutes Example 13 Fruit bread was prepared by using the inventive FD-2 yeast, after thawing the frozen dough of the following Table 22 as prepared at the following Table 23. The resulting product was a confectionery-like bread item at a high content of fruit used therein and with fluffy taste; owing to the combined use of the fermentation flavor liquid "Budou Dane #2" (product of Oriental Yeast Co., Ltd.) the resulting bread was very flavorful and delicious. Formula Flour 100.0 FD-2 yeast 3.0 "Budou Dane #2" 5.0 Dough improver 1.0 Sucrose 25.0 Shortening 10.0 Sodium chloride 1.5 Whole egg 10.0 Skim milk powder 3.0 Raisin 70.0 Water 44.0 Process conditions Mixing time (minutes) L 2 M 8 ↓M 5 H 6 ↓L 8 Dough temperature 26 °C Fermentation (floor) 60 minutes Fermentation temperature 28 °C Dividing weight 60 g Bench time 15 minutes Molding Dough freezing - 40 °C for 30 minutes Dough storage under freezing - 20 °C for 6 weeks Thawing: 20 °C for 60 minutes Final proof condition 35 °C · 85 % RH about 60 minutes Baking conditions 200 °C for about 10 minutes Example 14 Using the inventive FD-2 yeast, a fermented confectionery (cookie) was prepared from the frozen dough of the following Table 24 as prepared at the following process. The resulting product was a fermented confectionery, very sweet with fluffy touch on teeth. (Formula ratio per flour part by weight) Flour 100.0 FD-2 yeast 5.0 Sucrose 40.0 Margarine 40.0 Whole egg 10.0 Condensed milk 0.5 Vanilla oil 0.3 Water 10.0 Sodium chloride 0.5 Process condition 1. Mixed refined sucrose, margarine, condensed milk and sodium chloride with a beater. 2. Add egg in a two-divided manner and emulsify the egg. 3. Add sifted flour, FD-2 yeast and water and mix the resulting mixture together. 4. Gently knead the mixture with hands. 5. Place the dough in a polyethylene bag and flat wise and the dough with hands; cool the dough in a refrigerator to a final stiffness easily moldable enough for molding and punch it. 6. Ferment the dough at room temperature for 20 to 30 minutes. 7. Freeze the molded dough at - 40 °C for 30 minutes. 8. Store the dough at -20 °C for 6 weeks. 9. Thaw the dough at 20 °C for 60 minutes. 10. Bake the dough at 220 °C for about 13 minutes. Example 15 Using the inventive FD-2 yeast and a commercially available regular yeast (manufactured by Oriental Yeast Industry, Co., Ltd.), a white bread and a sweet roll item were prepared from the following Table 25 under the following conditions, according to the scratch bakery process (straight bakery process). The results are shown in Table 27. (Formula ratio per flour part by weight) Formula Low sugar content (white bread) High sugar content (sweet roll) Flour 100 100 Sucrose 5 25 Sodium chloride 2 0.5 Yeast 2 3 Shortening 5 6 Skim milk powder 0 2 Water 65 52 Process conditions Mixing time (minutes) L2M2↓L2M2H2 L2M4↓L1M4H Dough temperature 28 °C 28 °C Dividing weight 450 g 60 g Bench time 30 °C for 15 minutes 30 °C for 15 minutes Molding one loaf molded into sweet roll Baking conditions 200 °C for 25 minutes 200 °C for 10 minutes Comparison by the scratch bakery process Straight process Inventive FD-2 yeast Regular yeast White bread loaf: first fermentation 30 °C for 70 minutes 30 °C for 75 minutes Final proof 38 °C for 58 minutes 38 °C for 57 minutes Specific bread volume 4.42 4.32 Bread quality (softness) soft ordinary Bread quality (aging) slow ordinary Bread quality (texture) uniform ordinary Bread flavor good good Bread texture soft ordinary Sweet roll: first fermentation 75 minutes 81 minutes Final proof 38 °C for 56 minutes 38 °C for 56 minutes Specific bread volume 5.30 5.09 Bread quality (softness) soft ordinary Bread quality (aging) slow ordinary Bread quality (texture) uniform ordinary Bread flavor good good Bread texture soft ordinary Additionally, it is verified from the aforementioned examples that the freezing tolerant, sugar super-tolerant yeast of the invention has an excellent leavening ability of non-frozen dough, to produce various bakery products. The inventive yeast exerted sufficient freezing tolerance and sugar super-tolerance in frozen dough, to prepare excellent bakery products from the frozen dough, even by the frozen dough process. Example 16 Using the inventive P-731 strain (FERM BP-7035), Danish pastry was prepared from the following Table 28 under the following Table 29 according to the process of refrigerated dough in large portions. The resulting Danish pastry was highly suppressed of acid odor and fermentation smell and was greatly flavorful with butter and tasted very delicious. As described above, it was confirmed that the inventive yeast could be used for the refrigerated dough process. Pastry process conditions (Formula ratio per flour part by weight) Flour 100.0 Sucrose 20.0 Sodium chloride 1.0 Skim milk powder 3.0 Margarine 20.0 Whole egg 20.0 Dough improver 0.5 Yeast 6.0 Water 40.0 Roll-in fats and fatty oils 50.0 Process conditions Mixing time (minutes) L 2 M 3 ↓L 1 M 3 H 1 Dough temperature 25 °C Fermentation (floor) 60 minutes Retard Dough weight in large portions Storage temperature (°C) 2 kg 5 °C for 12 hours Roll-in Being folded in tree : thrice Molding square type Final proof condition 35 °C ·75 % RH 75inutes Baking conditions 210 °C for about 12 minutes Advantages of the Invention In accordance with the invention, yeasts have been developed, having leavening abilities and high sugar tolerance in the ultra-high sugar range, and yeasts with a high leavening ability in the super-high sugar range and freezing tolerance in the ultra-high sugar range. The inventive sugar super-tolerant yeasts are applicable widely to the production of from confectionery bread to fermented confectionery from dough formula of ultra-high sugar content, in addition to bread in the low sugar range, and are additionally applicable to various bread items using fat or fatty oil or eggs, and are widely applicable to frozen dough process as well as general bakery process. For example, the inventive yeasts can be used for producing coffee cake (bread suitable for coffee, which is popular among many Americans), sweet roll, fruit bread, pastry, butter roll, croissant and the like.

Claims: A method for obtaining yeast capable of generating at least 110 ml of CO 2 per 40 grams of dough containing 0.4 g of the yeast on a dry weight basis after fermenting at 30° C. for two hours, comprising: a. mixing 100 parts by weight of flour, 40 parts by weight of sucrose, 0.5 part by weight of sodium chloride, 6 parts by weight of the yeast as wet yeast, and 50 parts by weight of water to form a dough; b. forming portions of the dough into 40 gram portions; c. fermenting the dough portions formed in step (b) at 30° C. for two hours and assaying the amount of CO 2 generated; and d. screening and recovering the yeast which is capable of generating at least 110 ml of CO 2 per 40 grams of dough. A biologically pure culture of Saccharomyces cerevisiae FERM BP-7034 obtainable according to the method of claim 1. A method for obtaining yeast capable of generating at least 100 ml of CO 2 per 40 grams of dough containing 0.4 g of the yeast on a dry weight basis after fermenting at 30° C. for two hours, comprising: a. mixing 100 parts by weight of flour, 40 parts by weight of sucrose, 0.5 part by weight of sodium chloride, 6 parts by weight of the yeast as wet yeast, and 50 parts by weight of water to form a dough; b. forming portions of the dough into 40 gram portions; c. fermenting the dough portions formed in step (b) at 28° C. for 15 minutes; d. freezing the portions fermented in step (c) at -40° C. for 30 minutes; e. storing the frozen portions at -20° C. for four weeks; f. thawing the stored portions at 20° C. for 60 minutes; g. fermenting the thawed portions at 30° C. for two hours to assay the amount of CO 2 generated; and h. screening and recovering the yeast capable of generating 100 ml or more CO 2 per 40 grams of dough. A biologically pure culture of Saccharomyces cerevisiae FERM BP-7035 obtainable according to the method of claim 3. Confectionery or bread dough containing Saccharomyces cerevisiae FERM BP-7034 or yeast obtained according to the method of claim 1. Confectionery or bread dough containing Saccharomyces cerevisiae FERM BP-7035 or yeast obtained according to the method of claim 3. A confectionery or a bread item prepared by fermenting the confectionery or bread dough according to claim 5 and subsequently baking the dough. A confectionery or a bread item prepared by fermenting the confectionery or bread dough according to claim 6 and subsequently baking the dough.

Inventors: ANDO MASAYASU, NAKAMURA NATUKO, SHINOMIYA YOSHIAKI, ANDO, MASAYASU, NAKAMURA, NATUKO, SHINOMIYA, YOSHIAKI
Applicants: ORIENTAL YEAST CO LTD, ORIENTAL YEAST CO., LTD.
Application year: 2000
Main classification: C12N1
IPC codes: A21D13, A21D8, C12R1