Abstract:
A process for accelerating the proofing of chemically leavened dough when the ambient temeprature is below 70° F. by heating the dough in a proofing tunnel until the average dough temperature is about 80°-90° F., allowing the dough to develop about 10 psi pressure, and refrigerating the dough in a sealed container so that the internal pressure reaches about 20 psi. A modification using palm oil encapsulated glucono-delta-lactone acidulant and sodium bicarbonate as the chemical leavening system allows the dough to be refrigerated immediately after it leaves the proofing tunnel and still develop 20 psi internal pressure in the dough container.

Description:
This is a divisional of co-pending application Ser. No. 922,524, now U.S. Pat. No. 4,792,456, filed on Oct. 24, 1986. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to the field of refrigerated dough products and, in particular, it relates to processes and equipment for the accelerated proofing of the uncooked dough before the container in which it is stored is refrigerated. With the present process, the dough can be proofed either before or after it is sealed in its container. 
     The commercial refrigerated dough products which are the subject of this invention are formulated with a chemical leavening agent known in the trade as baking soda. This leavening agent may be encapsulated or in the free form depending on the product. 
     The chemical leavening agent proofs the product in the can by releasing CO 2  and expanding the dough to seal the can. The proofing of the dough in the can before refrigeration is necessary to avoid development of pyrophosphate crystals which look like glass. Proofing also seals the can to maintain a positive pressure in the can after refrigeration. Conventionally, it is preferred that a pressure of at least 10 psi be developed in the can before refrigerating the can so that an eventual pressure of approximately 15-20 psi will be in the can after refrigeration, i.e., when the can is on the grocer&#39;s shelf or in the consumer&#39;s hands. 
     During the summer months when ambient temperatures are 80°-100° F. in the plant, proofing normally takes less than 6 hours. However, in the winter months when inside ambient temperature is 60°-70° F., proofing may take up to 24 hours or even longer, depending on the product and the ambient air conditions. In any case, product can not be moved under ambient proofing to the refrigerator until a can pressure of at least 10 psi has been achieved on the proofing floor. If the product is refrigerated before 10 psi is generated, the desired final pressure is not developed in the refrigerator. 
     The two products that give the most proofing problems are refrigerated dough that is made into a &#34;small&#34; bread loaf and bread sticks. Other types of products which require proofing are biscuits, crescent rolls and cinnamon rolls. 
     A principal object of this invention is to accelerate the proofing time at 60°-70° F. ambient temperatures to less than 6 hours, which is equivalent to proofing time under hot summer conditions. 
     We have developed a process using a proofing tunnel where the raw dough is heated until the temperature of the dough is about 80°-90° F. which accelerates the proofing so that it is equivalent to hot summer proofing conditions, even when the ambient temperature is below about 70° F. 
     Surprisingly we also have found that using a preferred chemical leavening system, we can move the product directly into the refrigerator from the proofing tunnel without a floor holding period, thus eliminating double handling of the product and saving floor space in the plant. 
     Heretofore, production of CO 2  has been slowed or stopped when the product is moved into the refrigerator, unless a pressure of at least 10 psi had been developed prior to refrigeration. 
     We have found that by using encapsulated glucono-delta-lactone and regular baking soda as a chemical leavening combination we are able to heat the dough in a proofing tunnel to 80°-90° F. and then immediately move the dough into a refrigerator and it still will develop the desired container pressure of about 20 psi. 
     Faster proofing is desired to retard microbiological growth and improve shelf life of the product and to optimize product quality. 
     These and other objects and advantages will become apparent hereinafter. 
     SUMMARY OF THE INVENTION 
     This invention comprises a process for rapidly proofing chemically leavened dough which is to be refrigerated and specifically relates to the accelerated proofing of dough when the ambient conditions are unfavorable for such proofing. In the process the temperature of the dough is raised to about 80°-90° F. prior to refrigerating the dough for shipping and storage. This causes the dough to discharge CO 2  and to develop a desired pressure in the container in which it is or will be packed. When a chemical leavening agent combination of encapsulated glucono-delta-lactone and normal baking soda are utilized, the heated dough can be moved directly into the refrigerator with holding and it still will develop the desired 20 psi internal pressure in the package. 
    
    
     DESCRIPTION OF THE DRAWING 
     The drawing is a graphical representation of the results from moving a bread dough from preproofing directly into a refrigerator when encapsulated glucono-delta-lactone and sodium bicarbonate is the chemical leavening system, 
    
    
     DETAILED DESCRIPTION 
     We have developed two methods for proofing dough before it is refrigerated. The first involves heating the individual flat dough pieces before they are packed and sealed into a container. The second involves packing and sealing the dough in its container and then heating in a tunnel oven. We have utilized different ovens, including a jet sweep oven, a forced convection oven, and a no convection oven. 
     In all methods, the object of the invention is to heat the dough to a temperature of about 80°-90° F., preferably 85°-88° F. The temperature ranges apply whether the dough is heated before being placed in its container or is heated inside its sealed container. 
     If the dough temperature is substantially higher than 90° F., the dough is damaged with no improvement in proofing. For economic reasons, it is desired to heat the dough as rapidly as possible to minimize equipment size and holding capacity. However, if one heats the dough at too high a temperature, problems are created. One of these is the formation of a brownish color on the outside of the dough. Another is the creation of a large temperature gradient across the dough which means the inside dough is too cool to be properly proofed and the outside dough is damaged because it is too warm. If the overall dough temperature is too high (above about 90° F.) the dough is damaged with no improvement in proofing. 
     This invention not only defines the required internal dough temperature in the can for accelerated proofing, but also defines the optimum external heating temperature. If these conditions are not followed an unacceptable product is produced. 
     LEAVENING SYSTEM 
     The leavening system is a combination of glucono-delta-lactone and sodium bicarbonate. One of the components is coated with a partially hydrogenated vegetable oil, preferably, palm oil. Suitable systems include DURKOTE GDL and plain sodium bicarbonate and DURKOTE Sodium Bicarb 135-70 and uncoated glucono-delta-lactone. 
     The DURKOTE products are made by Durkee Industrial Foods of Cleveland, Ohio. 
     Glucono-delta-lactone is an inner ester of gluconic acid. When it hydrolyzes, gluconic acid is formed and this reacts with soda. 
     The preferred encapsulated glucono-delta-lactone comprises by weight 48-72% glucono-delta-lactone, coated with 28-52% partially hydrogenated palm oil. The coating melts at 97°-143° F. and the material is in the form of a free flowing white powder of which a maximum of 2% is retained on 10 mesh and a maximum of 10% passes through 140 mesh. 
     EXAMPLE NO. 1 
     Dough Pieces Heated Before Being Place In Cans 
     High intensity radiant heaters with current density up to 20 watts/in 2  are used. The 1/4&#34; thick flat dough pieces are kept under the heaters at 1&#34; to 2&#34; distance from the top of the dough piece to the heater. At 1&#34; it took about 5 seconds to get 18° F. dough temperature rise from 68° F. to 85° F. and at 2&#34; height it took 7-13 seconds or an average of about 10 seconds. 
     This pad heating is very time-temperature sensitive and close control of temperature with venting of excess heat is necessary to avoid overheating dough. 
     Higher dough temperatures (over 90° F.) showed some discoloration of the dough toward the warm surface. Temperatures about 90° F. also take longer to cool during the refrigeration cycle. In some cases the higher temperatures resulted in slower proofing rates. This is attributed to probably premature loss of CO 2  gas. Overheating of dough also may expand the dough so that it does not fit well into cans. 
     An advantage of this heating system is that it is very fast. 
     
         ______________________________________Wattage Range:     10-40 watts/in.sup.2Preferred Wattage: 20 watts/in.sup.2Distance of Heaters              1/4&#34;-12&#34;to Top of Dough:Preferred Range:   1&#34;-2&#34;Retention Time for 10-20° F. Temperature RiseRange at 1&#34; distance              3-7 secondsPreferred Range    4-5 secondsRange at 2&#34; distance              4-14 secondsPreferred Range    8-12 seconds______________________________________ 
    
     EXAMPLE NO. 2 
     Heating Tunnel-Dough Filled Cans 
     The air temperature in the heating tunnel may be between about 90°-200° F. with a preferred range of about 110°-130° F. and an optimum temperature of 120° F. 
     Lower air temperatures require too long a retention time for the dough in the tunnel and too large a tunnel oven to reach desired dough temperature range. 
     Higher air temperatures heat the dough faster but create a problem in that the outside dough gets discolored, that is, it turns a pale brown which is unattractive to the consumer. 
     Higher air temperatures also create a large temperature gradient across the dough. The outside dough is too warm and the inside dough is too cool. If the dough temperature is too high, it damages the dough with no improvement in proofing. 
     It is desired to keep the average dough temperature below 90° F. and any particle of the dough below 120° F. 
     Using a no convection tunnel and canned bread dough, we use a chemical leavening agent which can be either encapsulated baking soda and plain GDL (an acidulant) or encapsulated GDL and plain (unencapsulated) baking soda. Either combination is satisfactory. Other doughs, such as bread sticks, biscuits, dinner rolls and breakfast rolls also can be used in place of bread. 
     Under those conditions, starting from a dough temperature of 70° F., Table No. 1 shows the retention time and heating air temperatures to reach 87° F. 
     
                       TABLE NO. 1______________________________________Oven Temp.     Minutes______________________________________100° F. 60-80120° F. 25-45135° F. 15-25150° F. 10-15180° F.  8-14250° F. 3-6______________________________________ 
    
     We found 120° F.±10° F. to be the optimum oven temperature for acceleration of proofing. Higher heating temperatures (&gt;135° F.) caused some damage to the dough in the can, thus reducing overall product quality. 
     Jet Sweep Oven 
     This oven uses 20-30 mile/hr. velocity out of hundreds of jets. Table No. 2 shows temperature and times for cans standing up as they passed through the jet swept oven. 
     
                       TABLE NO. 2______________________________________      Approx. Retention Time Range To      Reach 87° F. Dough Temp. Starting      at 70° F. Dough Temp.Oven Temp. (Minutes)______________________________________100° F.      18-22120° F.      15-19150° F.       8-11200° F.      5-7______________________________________ 
    
     Again we found that about 120° F. is optimum air temperature. 
     Convection Heating Tunnel (Oven) 
     This is a hybrid between a no convection and a jet sweep oven. It uses recirculating air to accelerate heat transfer. An Industrial Washing Machine Hot Air Drier (typical of this equipment) was used to develop the data in Table No. 3 which shows conditions necessary to achieve 87° F. optimum dough temperatures in cans. 
     
                                           TABLE NO. 3__________________________________________________________________________                          Retention Time Range                     Wt. of                          To Reach 87° F., Starting                     Dough                          With 70° F. Dough Temp.Oven Temp. °F.    Product  Can Size                     (ounces)                          (Minutes)__________________________________________________________________________120° F.    Bread Dough             2&#34; dia. × 71/4&#34;                     10   9-13120° F.    Crescent Rolls             13/4&#34; dia. × 7&#34;                     8    13-17120° F.    Cinnamon Rolls             21/4&#34; dia. × 61/2&#34;                     91/2&#34;                          18-22102° F.-105° F.    Bread Dough             2&#34; dia. × 71/4&#34;                     10   26-29102° F.-105° F.    Cinnamon Rolls             21/4&#34; dia. × 61/2&#34;                     91/2&#34;                          41-47__________________________________________________________________________ 
    
     EXAMPLE NO. 3 
     This example illustrates the use of encapsulated glucono-delta-lactone to eliminate hold time after heating. The dough is placed directly from the proofing tunnel into the refrigerator. 
     The refrigerated bread dough is a conventional formula and contains a chemical leavening agent which is formulated from glucono-delta-lactone encapsulated in a vegetable oil and unencapsulated sodium bicarbonate. The acidulant is about 68-72% glucono-delta-lactone and coated with about 28-32% partially hydrogenated palm oil. The palm oil has a melting point of about 136°-143° F. The acidulant product is a free flowing white powder of which a maximum of 2% is retained on a 10 mesh screen and a maximum of 10% passes through a 140 mesh screen. 
     After the dough is mixed, it is formed into loaves to fit a 2&#34; dia.×71/4&#34; can, placed into a container of this size, and heated in a 120° F. convection tunnel until the dough temperature reaches 89° F. The containers of dough then are placed into a case containing 12 cans, and the case is placed in a 40° F. refrigerator. The internal pressure reaches 20 psi after 24 hours, whereas the internal can temperature reaches 50° F. after about 51/2 hours. 
     This Example is illustrated graphically in the drawing accompanying this application. 
     Following is a summary of the various aspects of this invention as they relate to the radiant heaters and to the different types of heating tunnels. 
     
         ______________________________________A.   Short time heating of raw dough pieces beforeputting dough into can.1.      Use high intensity radiant heater.2.      Current Density: 10-40 watts/in.sup.2   Preferred: 20 watts/in.sup.23.      Desired average dough temperature:   Range: 80-90° F.   Preferred: 85-88° F.4.      Distance from top of dough to heating element.   Range: 1/4&#34;-12&#34;   Preferred: 1&#34;-2&#34;5.      Retention time under heater:   Range: 3-14 seconds   Preferred at 1&#34; distance: 4-5 seconds   Preferred at 2&#34; distance: 8-12 secondsB.   Heating tunnel oven - no convectionHeat dough in sealed cans.Desired average dough temp.Range: 80-90° F.Preferred: 85-88° F.Desired oven temp.Range: 110-130° F.Preferred: 115-125° F.Retention time at 120° F. (Bread dough)2&#34; dia. × 71/4&#34; can (10 oz. dough)Desired range: 25-45 minutesPreferred: 30-35 minutesC.   Jet Sweep OvenHeat dough in sealed cans.Desired average dough temp.Range: 80-90° F.Preferred: 85-88° F.Preferred oven temp.Range: 110-130° F.Preferred: 115-125° F.Retention time at 120° F. oven temperature forbread dough:15-19 minutesD.   Convection ovenHeat dough in sealed cansDesired average dough temp.Range: 80-90° F.Preferred: 85-88° F.Desired oven temp.Range: 110-130° F.Preferred: 115-125° F.______________________________________Retention time at 120° F. oven temp.                  Minutes______________________________________Bread dough 2&#34; dia. × 71/4&#34; can (10 oz.)                   9-13Crescent rolls 13/4&#34; dia. × 7&#34; can (8 oz.)                  13-17Cinnamon rolls 21/4&#34; dia. × 61/2&#34; can (91/2 oz.)                  18-22______________________________________ 
    
     This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.