Abstract:
Disclosed is a process of producing a frozen yeast fermented dough which involves first emulsifying the total amount of water required for the dough with fat or oil before mixing with other dough ingredients.

Description:
This is a continuation-in-part of U.S. Ser. No. 563,574, filed Dec. 20, 1983, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to a process of producing a frozen yeast fermented dough for a bread, a yeast doughnut and the like. 
     2. Description of Prior Art 
     Demand for the frozen yeast fermented dough has been increasing in recent years with rationalization of a breadmaking factory. 
     Hitherto, yeast fermented doughs have been generally prepared according to the straight dough method and the sponge dough method. The straight dough method comprises mixing together the whole amount of wheat flour, water having yeast dissolved therein, yeast food, and other ingredients than oil or fat to a considerable extent, adding oil or fat to a mixture, thoroughly mixing the ingredients to prepare a dough, after which the dough is subjected to fermenting, dividing, benching, molding, final proofing and baking. The sponge dough method comprises adding to a part of wheat flour the whole amounts of yeast and yeast food and a part of water, mixing them together to prepare a sponge dough, fermenting the dough, adding to a fermented dough the remaining wheat flour, other ingredients than oil or fat and the remaining water, mixing the dough to a considerable extent followed by addition of oil or fat, thoroughly mixing the ingredients to prepare a dough, giving the dough to a floor time, and dividing, after which the subsequent steps are performed in accordance with the straight sponge method. 
     However, the frozen doughs produced by the aforedescribed two methods suffer from the disadvantages of a deterioration in the quality of the baked product, which is due to the remarkable reduction in fermentation activity and the associated degradation of the dough which are considered to be caused by the formation of alcohol during fermentation of the dough, thus strongly damaging yeast cells upon freezing. Now, a modified straight dough method has been employed hitherto for producing the frozen yeast fermented dough. In the modified method, the same operations as employed in the straight dough method are performed up to the preparation of a dough, and subsequently the dough is not fermented at all or fermented for a short time to the extent of 1/10 as compared to the straight dough method, after which the fermented dough is subjected to dividing, benching, molding, freezing, thawing, proofing, and baking. However, the modified straight dough method has serious disadvantages that the prolonged frozen storage (about three weeks) of the dough gives rise to a reduction in the quality of the baked product and the length of time over a period of from thawing to final proof. 
     SUMMARY OF THE INVENTION 
     Now, we have made extensive studies in an effort to overcome the above disadvantages of the prior arts and found that such disadvantages are based on a major ground of any hindrance occurring in the structure of the dough, in addition to a ground of the reduction in yeast activity which has been considered hitherto. More particularly, we have found that when water present in the dough forms an ice crystal during freezing, an expanded volume of the ice crystal will injure the network of gluten structure to weaken it. This invention is based on the above finding and is characterized by preliminarily treating water required for a dough formulation with oil or fat and a nonionic emulsifier to enhance a frozen shelf life to the frozen dough. 
     An object of this invention is to provide a process of producing a frozen yeast fermented dough having excellent frozen shelf life and improved quality of baked product even after prolonged period of frozen storage. Another object of this invention is to provide saved energy and rationalized work by shortening the length of time over a period from start of thawing to completion of final proof. Further object of this invention is to make it possible to apply to the production of the frozen dough the prior straight dough and sponge dough methods which have not been suitable therefor. Other objects, features and advantages of this invention will be apparent from the following detailed description and appended claims. 
     To achieve the above objects, the present invention is to preliminarily treat water required for a dough formulation wih oil or fat and a nonionic emulsifier to keep a treated solution in the form of a perfect emulsion in the dough, whereby the ice crystals forming in the dough during freezing become small and do not injure the network structure of gluten with the result of providing a longer frozen shelf life to the dough. 
     According to the invention, there is provided a process of producing a frozen yeast fermented dough which comprises the steps of: 
     (a) treating a toal amount of water required for a dough formulation with oil or fat required for the dough in the presence of a nonionic emulsifier having the HLB value of 6 to 17 and at a temperature of about 25° to 50° C., 
     (b) mixing a treated solution with the rest of ingredients of the dough formulation to prepare a dough, 
     (c) fermenting the dough, 
     (d) dividing a fermented dough, 
     (e) molding each portion of the fermented dough into the desired shape, and 
     (f) freezing the dough to prepare a frozen dough. 
     DESCRIPTION OF THE INVENTION 
     The dough formulation of the invention includes the usual dough ingredients (except for the emulsifier) which have been used for the prior yeast fermented dough, e.g., wheat flour, yeast, yeast food, sugars such as monosaccharides or polysaccharides (e.g., glucose, fructose, sucrose, lactose, rice syrup, isomerized sugar), salt, oil or fat (e.g., butter, margarine, salad oil, shortening), eggs, dairy products (e.g., cow&#39;s milk, whole milk powder, skim milk powder, condensed milk), water and the like. The amounts of the above ingredients used are substantially the same as those used in the prior yeast fermented dough. 
     In the present invention, water required for the dough formulation is not mixed as it is, with the dough ingredients (except for oil or fat), but should be preliminarily treated with oil or fat and a nonionic emulsifier having the HLB value of 6 to 17 at a temperature of about 25° to 50° C. Any of nonionic emulsifiers for foodstuffs can be used which have the HLB value of 6 to 17, preferably 7 to 15, sucrose fatty acid esters being especially preferred. With the emulsifier having the HLB value outside the above range, there cannot be provided improved quality of baked product, e.g., the texture and taste of the bread. 
     Of the various properties of emulsifiers, HLB (Hydrophile-Lipophile Balance) is one of the most important. The HLB is an expression of the relative simultaneous attraction of an emulsifier for water and for oil (or for the two phases of the emulsion system being considered). The HLB value is an indication of the percentage weight of the hydrophilic portion of the molecule. If a nonionic emulsifier were 100% hydrophilic (which, of course, does not exist), it would be assigned an HLB value of 20, the factor 1/5 having been adopted because of the convenience of handling smaller numbers. 
     The amount of the emulsifier used is in the range of about 0.1 to 1% by weight, preferably about 0.2 to 0.8% by weight, based on the weight of wheat flour. With less than about 0.1% by weight, a perfect emulsion cannot be formed, and also improved quality of baked product cannot be desired. With more than about 1% by weight, the smell of the emulsifier becomes stronger, which may impair the product quality. 
     In such a water treatment as mentioned above, the other dough ingredients such as sugars, dairy product, yeast foods or the like are preferably mixed with water and oil or fat. In this case, however, wheat flour, yeast and salt must not be present during the water treatment. This is because the presence of wheat flour, yeast and salt is susceptible to provide the disadvantages that a perfect emulsion cannot be formed and yeast activity is reduced. 
     To promote the formation of a perfect emulsion, the water treatment is preferably performed at high speed by conventional agitation means, e.g., homogenizer, high-speed mixer, juicer, etc. Also, the water treatment is carried out at a temperature range of about 25° to 50° C. At the temperature outside the above range, a perfect emulsion is difficult to prepare, and the product is poor in quality, e.g., appearance, grain and crumb texture, and further taste and texture. When the process of the present invention is applied to the prior straight dough method, the total amount of water required for the dough formulation is preliminarily treated with oil or fat and the emulsifier. When the process of the present invention is applied to the prior sponge dough method, water is treated with oil or fat and the emulsifier in the dough mixing step. 
     In the production of the frozen dough according to the present invention, the treated solution is added to the rest of ingredients of the dough formulation, e.g., wheat flour, yeast and salt, in the prescribed mixing step, to prepare a dough. In the mixing step, conventional mixing method in the breadmaking is employed. The subsequent steps are somewhat changed depending on the difference in the breadmaking process. For instance, in the modified straight method which is the prior art process for producing the frozen dough, the dough thus formed may be either fermented not at all or fermented for a short time. In the conventional straight dough method, the dough thus formed is thoroughly fermented. In the conventional sponge dough method, a sponge dough is subjected to dough mixing after thorough fermentation to prepare the dough for final baking. 
     The dough thus prepared is subjected to the steps of fermentation, division, molding and freezing. Any process of freezing is acceptable, but rapid freezing is preferred. 
     The frozen doughs after frozen storage can be thawed at any desired time, led to final proof, and eventually baked (or fried in oil) to produce a final product. 
     The advantages provided by this invention are as follows: 
     The doughs are more durable in frozen storage than those by conventional methods, and the quality of the baked product e.g., appearance, grain and crumb texture are improved even after prolonged period of frozen storage. Furthermore, labor and energy are saved by shortened time from start of thawing to end of final proof. In additon, what is to be noted is that the prior straight and sponge dough methods which have been regarded to be unsuitable for the production of the frozen dough can be employed to obtain a final product in good taste and texture after baking. 
     This invention is further illustrated, but in no way limited by the following examples. 
    
    
     EXAMPLE 1 
     
         ______________________________________Ingredient          Part by weight______________________________________Wheat flour         100Yeast               5Salt                1.5Sugar               12Margarine           14Yeast food          0.1Eggs                12Skim milk powder    2Sucrose fatty acid ester (HLB 11)               0.5Water               43______________________________________ 
    
     The above ingredients were processed in the following steps to prepare a frozen dough for butter rolls. 
     
         ______________________________________Step          Operation______________________________________Water treatment         Water, margarine, sucrose fatty         acid ester, eggs and sugar were         stirred for 10 min. with a juicer         at 7000 r.p.m., at a temperature         of 35° C.Mixing        A treated solution and the rest of         ingredients were mixed for 2 min.         at low speed and for 9 min. at medium         speed.Temperature of         26° C.mixingFermentation  30 min. at 27° C. and 78% relative         humidityDivision      40 g pieceBench time    15 min.Molding       Degassed and roundedFreezing      Rapid freezing (-40° C., 30 min.)Storage       -18° C.______________________________________ 
    
     EXAMPLE 2 
     
         ______________________________________Ingredient          Part by weight______________________________________Wheat flour         100Yeast               5Salt                1Sugar               22Shortening          12Yeast food          0.1Eggs                8Skim milk powder    2Sucrose fatty acid ester (HLB 7)               0.5Water               48______________________________________ 
    
     The above ingredients were processed in the following steps to prepare a frozen dough for sweet bread (with red bean paste). 
     
         ______________________________________Step           Operation______________________________________Water treatment          Water, shortening, eggs, sugar,          yeast food, skim milk powder and          sucrose fatty acid ester were          stirred for 10 min. with high-          speed mixer at 10000 r.p.m., at          a temperature of 25° C.Mixing         A treated solution and the rest          of ingredients were mixed for 2          min. at low speed and for 10 min.          at medium speed.Temperature of 26° C.mixingFermentation   Not excercisedDivision       40 g pieceBench time     20 min.Molding        Stuffed with 30 g of red bean          pasteFreezing       Rapid freezing (-40° C., 20 min.)Storage        -18° C.______________________________________ 
    
     EXAMPLE 3 
     
         ______________________________________Ingredient          Part by weight______________________________________Wheat flour         100Yeast               6Salt                1.5Isomerized sugar    12Eggs                15Skim milk powder    4Margarine           20Baking powder       1Sucrose fatty acid ester (HLB 15)               0.5Water               45______________________________________ 
    
     The above ingredients were processed in the following steps to prepare a frozen dough for yeast doughnuts. 
     
         ______________________________________Step          Operation______________________________________Water treatment         Water, margarine and sucrose fatty         acid ester were stirred for 10         min. with a homogenizer at 6000 r.p.m.,         at a temperature of 45° C.Mixing        A treated solution was mixed with         the rest of ingredients for 2 min.         at low speed and for 11 min. at medium         speed.Temperature of         27° C.mixingFermentation  15 min.Sheeting      Thinned to 1 cmShaping       Circles 9 cm in diameterFreezing      Rapid freezing (-40° C., 20 min.)Storage       -18° C.______________________________________ 
    
     EXAMPLE 4 
     
         ______________________________________Ingredient    Part by weight______________________________________Wheat flour   70Yeast         3.5Yeast food    0.1Glucose       5Water         40______________________________________ 
    
     The above ingredients were processed in the following steps (sugar-enriched sponge dough method) to prepare a sponge dough. 
     
         ______________________________________Step           Operation______________________________________Mixing         2 min at low speed and 2 min.          at medium speedTemperature of 24° C.mixingSponge fermen- 2.5 hr. (at 27° C. and 78% relativetation         humidity)______________________________________ 
    
     The sponge dough was added with the following ingredients and processed in the following steps to prepare a frozen dough for butter rolls. 
     
         ______________________________________Ingredient          Part by weight______________________________________Wheat flour         30Salt                1.5Sugar               10Margarine           12Eggs                12Skim milk powder     2Sucrose fatty acid ester (HLB 11)               0.5Water                5______________________________________Step          Operation______________________________________Water treatment         Water, margarine and sucrose fatty         acid ester were stirred for 10         min. with a juicer at 7000 r.p.m.,         at a temperature of 35° C.Mixing        A treated solution and the rest of         ingredients were mixed with the         sponge dough for 2 min. at low         speed and for 6 min. at medium speed.Temperature of         27° C.mixingFloor time    40 min.Division      40 g pieceBench time    15 min.Molding       Degassed and roundedFreezing      Rapid freezing (-40° C. 30 min.)Storage       -18° C.______________________________________ 
    
     COMPARATIVE EXAMPLES 1-3 
     The frozen doughs for butter rolls were prepared in the same manner as illustrated in Example 1, but using as the emulsifier those shown in Table 1 below. 
     
                       TABLE 1______________________________________    Comparative              Comparative                         Comparative    Example 1 Example 2  Example 3______________________________________Emulsifier Distilled   Soybean    Sucrose fatty      monoglyceride                  lecitin    acid esterHLB        3.7         1.5        18______________________________________ 
    
     COMPARATIVE EXAMPLES 4-5 
     The frozen doughs for butter rolls were prepared in the same manner as illustrated in Example 1, but controlling the temperature of the treated solution as shown in Table 2 below. 
     
                       TABLE 2______________________________________        Comparative                 Comparative        Example 4                 Example 5______________________________________Temperature of 55         20treated solu-tion (°C.)______________________________________ 
    
     TESTING 1 
     Frozen doughs for butter rolls prepared in Example 1 and Comparative Examples 1-3, respectively, were stored frozen for 1 to 10 week(s). Samples were withdrawn in the 1st, 3rd, 5th, 7th and 10th week, and processed thereafter as the following to make final products, namely butter rolls. Qualitative comparison of these products is shown is Table 4. 
     
         ______________________________________Step         Operation______________________________________Thawing and      Frozen dough pieces were placedfinal proof      on baking sheet pan and kept in a            fermentation chamber at 32° C. and            78% relative humidity.Baking           210° C. for 10 min.Notes:     (1)   To judge the end point of final proof,            150 g each of the doughs prepared            in Examples and Comparative Examples            were molded in rolls, stored frozen,            and panned in 490 cc one-loaf pans,            thawed and proofed as described above;            end of final proof was judged at            the time when top surface of the            dough has reached the upper end of            one-loaf pan.      (2)   Scoring was made according to the            criteria shown in Table 3.      (3)   Testing was carried out by a panel            of 25 tasters; scoring was made            by 4-point choice on eating quality            and flavor.______________________________________ 
    
     
                       TABLE 3______________________________________Criteria for scoring the bread quality     Rating           Features______________________________________Appearance  A       Crust is well expandable; color               is uniform and sheeny.       B       Crust is a little expandable;               color is less uniform but somewhat               sheeny.       C       Crust is not expandable; color               is not uniform without sheen.Grain       A       Uniform and thin cell walls       B       Less uniform but thin cell walls       C       Not uniform and thick cell wallsCrumb texture       A       Very soft       B       Soft       C       Not soft______________________________________ 
    
     
                                           TABLE 4__________________________________________________________________________       Storage             Volume of        Crumb                                  Number of tasters       period             bread (cc)                   Appearance                          Grain                              texture                                  who judged good__________________________________________________________________________Bread product from       1 week.sup.             220   A      A   A   8a frozen dough       3 weeks             230   A      A   A   9according to       5 weeks             225   A      A   A   25Example 1   7 weeks             220   A      A   A   25       10 weeks             225   A      A   A   25Bread product from       1 week.sup.             220   A      A   A   7a frozen dough       3 weeks             220   A      A   B   5according to       5 weeks             205   B      B   B   0Comparative Example 1       7 weeks             190   C      C   B   0       10 weeks             175   C      C   C   0Bread product from       1 week.sup.             225   A      A   A   6a frozen dough       3 weeks             220   A      A   A   6according to       5 weeks             200   B      B   B   0Comparative Example 2       7 weeks             185   C      C   C   0       10 weeks             170   C      C   C   0Bread product from       1 week.sup.             220   A      A   A   4a frozen dough       3 weeks             215   A      A   B   5according to       5 weeks             195   B      C   B   0Comparative Example 3       7 weeks             180   C      C   C   0       10 weeks             165   C      C   C   0__________________________________________________________________________ 
    
     TESTING 2 
     Frozen doughs for butter rolls prepared in Example 1 and Comparative Examples 4-5, respectively, were stored frozen for 1 to 10 week(s). Samples were withdrawn in the 1st, 3rd, 5th, 7th and 10 week, and processed in the same manner as mentioned in Testing 1 to make final products, namely butter rolls. Qualitative comparison of these products is shown in Table 5. 
     To judge the end point of final proof and to evaluate the quality of the bread, the method mentioned in Testing 1 was used. 
     
                                           TABLE 5__________________________________________________________________________       Storage             Volume of        Crumb                                  Number of tasters       period             bread (cc)                   Appearance                          Grain                              texture                                  who judged good__________________________________________________________________________Bread product from       1 week.sup.             220   A      A   A   10a frozen dough       3 weeks             230   A      A   A   12according to       5 weeks             225   A      A   A   21Example 1   7 weeks             220   A      A   A   23       10 weeks             225   A      A   A   24Bread product from       1 week.sup.             220   A      A   A   8a frozen dough       3 weeks             225   A      A   A   9according to       5 weeks             205   A      B   B   4Comparative Example 4       7 weeks             195   B      B   B   2       10 weeks             190   B      B   B   1Bread product from       1 week.sup.             225   A      A   A   7a frozen dough       3 weeks             210   A      B   A   4according to       5 weeks             200   B      B   B   0Comparative Example 5       7 weeks             185   B      C   C   0       10 weeks             165   C      C   C   0__________________________________________________________________________ 
    
     TESTING 3 
     Frozen doughs for butter rolls prepared according to Example 1 and Comparative Example 1, respectively, were stored frozen for 1 to 10 week(s). Samples were withdrawn in the 1st, 3rd, 5th, 7th and 10th week, and processed in the same manner as mentioned in Testing 1 to make final products, namely butter rolls. The time lengths required from starting thawing to completion of final proof are shown in Table 6. 
     To judge the end point of final proof, frozen doughs were packed in 1,700 cc one-loaf pans and kept in chamber for final proof (30° C., 78% relative humidity). End point was judged at the time when top surface of the dough has reached upper end of the one-loaf pan. 
     
                       TABLE 6______________________________________Time length (min.) required from startingthawing to completion of final proofStorageperiod  Dough of Example 1                  Dough of Compa. Example 1______________________________________1 week  92             1013 weeks 94             1095 weeks 90             1257 weeks 92             Not measured10 weeks   92             Not measured______________________________________