PART TWO- (A) --principles of bread production Including the Latest Developments in Dough Processing Procedures and Dough Processing Equipment
Bread production operations must be carefully planned, for once ingredient mixing has begun, the process cannot be interrupted without serious damage to the baked product. Dough formulas and dough schedules are determined in advance and followed as closely as possible. In preparation of the production schedule, the previous day's schedule is used as a guide. Formulas must be constructed so that only enough dough is mixed to fill the oven to capacity. There are seven major steps involved in the production of bread using the conventional method of bread production. The continuous mixing method will be discussed briefly.
PREPARATION OF INGREDIENTS:
STEP 1. The first step in preparation for mixing is assembling and weighing the ingredients. Some ingredients require special preparation. The yeast, whether compressed or dry must be be suspended in water in according to manufacturer's instructions.
NOTE: NEVER SUSPEND DRY YEAST IN COLD WATER. If you do, reducing agents contained in the yeast will be released into the dough which will weaken the gluten. Some, but not all bakers put Compressed Yeast directly into the dough without suspending it in water, especially when using some of the new types of yeast.
The temperature of the water is important in controlling dough temperature. If mechanical refrigeration equipment is not available to chill the ingredient water, ice may be required. Most bakeries are equipped with mixing machines that circulate chilled water or refrigerants through coils between the walls of the mixing bowl. In that case ice would not be required. However, if ice is required, the procedure for determining how much ice to use will be demonstrated following the demonstration on how to determine the required water temperature to get the dough out of the mixer at the proper temperature. Following are the procedures used to determine the required water temperature:
To control the dough temperature during mixing, the following factors must be known and applied:
A. Desired dough temperature at completion of mixing.
B. In this example, desired dough temperature is 80 degrees F.
C. Available water temperature.
D. Pounds of water in the formula.
E. Number of BTU's of heat that one pound of ice removes from it's surrounding area when it melts from a solid to a liquid ( 144 BTU's )
F. Temperature of mixing room.
G. Temperature of flour.
H. FRICTION FACTOR. This is the amount of heat that is created during the mixing process. At the end of this lesson, the procedure for computing the Friction Factor of a mixing machine will be demonstrated.
Assuming the following conditions exist, calculate the required water temperature, pounds of ice to use when required, and pounds of water to be subtracted from the formula, depending upon how many pounds of ice will be required.
A. Mixing room temperature= 85 degrees F.
B. Flour temperature= 82 degrees F.
C. Friction Factor= 30 degrees F. for this example.
Temperature of available water= 70 degrees F.
PROCEED AS FOLLOWS:
A. Add 85 plus 82 plus 30 which equals 197.
B. Multiply desired dough temperature which is 80 times 3 = 240.
C. Subtract 197 from 240 which equals 43 degrees which is the temperature that the water needs to be for the dough to come out of the mixer at 80 degrees F.
To determine how much ice is required when the water is warmer than the required 43 degrees F. proceed as follows:
A. Subtract 43 degrees (desired water temperature) from 70 degrees (temperature of water available). The answer is 27 degrees — the number of BTU's of heat that must be removed from each pound of water in the formula. NOTE: One pound of ice will remove 144 BTU"s of heat from one pound of water.
B. Multiply 27 degrees times 379.7 (the total number of pounds of water in the formula). The answer is10,251.9 (the total number of BTU's to remove from the water).
C. Divide 10,251.9, the total number of BTU's to remove by 144, the number of BTU's that one pound of ice removes. The answer is 71.2 pounds of ice to use.
D. Subtract 71.2 pounds of ice from the number of pounds of water called for in the formula. Therefore, 308.5 pounds of water plus 71.2 pounds of ice equals 379.7 pounds of liquid called for in the formula.
E. Therefore, in this situation, the dough will come out of the mixer at 80 degrees F.
NOTE: The factor varies with different mixing machines, and mixing times. The faster the mixing machine operates, and the longer the mixing times the greater the friction factor will be. Therefore, the friction factor will need to be determined when a different machine or different mixing time is used.
To determine the friction factor for a particular machine and mixing time, a test dough must be run. Assuming the following conditions exists, proceed as follows:
A. Room temperature is 85 degrees F.
B. Flour temperature is 82 degrees F.
C. Temperature of water used was 43 degrees F.
D. The total of the 3 factors above is 210. Note: In this example, the bakery is equipped with a water chilling machine, so no ice will be required.
We will assume that the dough came out of the machine at 80 degrees F. Proceed as follows:
E. Subtract 210 from 240. The answer is 30 which is the friction factor that must be used when this particular machine and particular mixing time is used.
Mixing the Dough: All production procedures discussed in this part are demonstrated in the part titled "BREAD BAKING DEMONSTRATIONS"
STEP 2. The purpose of mixing the dough is to distribute the yeast cells throughout the dough, distribute food for the yeast, and to form and develop the gluten. Gluten is formed when the two proteins of the flour, gliadin and glutenen come in contact with water. The time required to develop the gluten depends on the strength of the flour, and the speed of the machine. Generally speaking, the stronger the flour proteins the longer it takes to develop the gluten and the faster the machine, the shorter the mixing time. An experienced baker can easily determine when the gluten has been fully developed by taking a small piece of dough out of the mixer and stretching the dough between the fingers.
NOTE: THIS IS DEMONSTRATED IN PART TWELVE TITLED "BREAD BAKING DEMONSTRATIONS". A properly developed dough will not be sticky and the dough will stretch paper thin. It becomes almost transparent to where you can almost see through it.
STEP 2a. In small and medium size bakeries, the two methods used to mix dough’s are the Straight Dough Method and the Sponge and Dough Method. Most of the large commercial wholesale bakeries use the Continuous Mixing Method which will be discussed in a later paragraph.
STEP 2b. STRAIGHT DOUGH METHOD. In the straight dough method of mixing all dough ingredients are mixed at one time, and prepared for a single fermentation process. Generally, the fermentation time for the straight dough will vary from 2-1/2 hours to 3 hours. These dough’s are also punched after about 80 percent of the fermentation time has elapsed and given an additional 20 percent fermentation before make-up. This is covered in more detail in a later paragraph. Dough produced by this method results in breads with course grain and texture and the crumb is not as soft as that produced by other methods. The baked loaf will not have as much volume as one made with the Sponge and Dough Method. The Straight Dough Method is demonstrated in PART TWELVE titled "BREAD BAKING DEMONSTRATIONS".
STEP 2c. SPONGE AND DOUGH METHOD. In the Sponge and Dough Method, there are two mixing periods and two fermentation periods. Part of the formula ingredients are mixed and allowed to ferment for 4 to 6 hours. How to determine the length of the fermentation of sponges is covered in a later paragraph. This is called the sponge. After the fermentation process is completed, the second part is called the Dough. Basically, the fermented sponge is thrown back into the mixer and the ingredients for the second part are added. The fermented sponge and all the second ingredients are mixed together to form the dough. After the gluten has been fully developed, the dough is dumped into a stainless steel dough trough and given a second fermentation time. As compared to the sponge, the fermentation time of the dough is very short (15 to 20 minutes).
Dough Transfer Systems - There are many methods used to transfer dough from one point to another. Briefly they are:
1. Cutting the dough in large pieces by hand and transferring it from the dough trough to the mixing machine or to the divider.
2. By locating the mixer on the second floor, the dough is dumped from the dough trough through a hole in the floor into the divider hopper.
3. Dough Trough Hoists have been designed to lift dough troughs filled with fermented sponges to be returned to the mixer to be mixed into dough. They are also designed to lift remixed doughs to be dumped into the divider hopper.
4. Other methods available are, Conveyor Transfer Systems, Dough Pumps, and Rotary Dough Feeders or Chunkers. Some dough’s such as Frozen Dough, Bread Dough and Stiff Dough are not suitable to be transferred by the Dough Pump. One reason why it is not suitable for some types of dough is because it creates heat during the transfer process.
CONTINUOUS MIXING METHOD
The Continuous Mixing Method is very popular among large commercial bakeries. The bread produced by this method has very fine tight grain similar to the grain of cake. The Continuous Bread Making System uses the following basic elements:
A liquid ferment, brew or liquid sponge is prepared and allowed to ferment in stainless steel tanks under controlled temperature conditions for several hours. The fermented mixtures are cooled by the use of refrigerated coils between the walls of the tanks until ready to be used. This process eliminates setting individual sponges and dough’s, and the need for dough troughs and large fermentation rooms — a method of bringing together continuously all the ingredients in the right proportion for the dough. After going through the developer, what happens next varies with different bakeries. Some bakeries run the dough through conventional make-up equipment, rather than extruding the dough directly into the pan as was done a few years ago, because it is claimed that a better quality loaf results.
STEP 3. Fermentation starts immediately after the yeast is put into the mixture. However, the fermentation period is considered to begin when the sponge or dough is dumped out of the mixer into the dough trough and rolled into the fermentation room which is maintained at a temperature of 80 degrees F. and 75 percent relative humidity. The chemical changes that occur, continue until the yeast is killed by the heat of the oven. This is when the internal temperature reaches about 140 degrees F. The fermentation period is considered to end when the dough goes to the divider to be divided into individual loaf pieces (loaves).
STEP 3a. Leavening the dough is one of the essential things that take place during fermentation. Carbon dioxide gas is produced and held by the gluten network. This causes the whole dough mass to expand which helps to condition the gluten as was mentioned previously.
STEP 3b. Alcoholic fermentation is the most desirable type of fermentation. To insure that this type of fermentation predominates, the dough should come out of the mixer between 78 degrees F. and 82 degrees F. and kept in an 80 degree F. fermentation room with 75 percent relative humidity. NOTE: The instrument used to determine percent relative humidity is called a Wet and Dry Bulb Thermometer and a Relative Humidity Table can be found in PART 1A-TEMPERATURE AND HUMIDITY.
Due to chemical changes that take place during fermentation, the sponge or dough will increase to about 85 degrees F. and 90 degrees F. which is still in the range of alcoholic fermentation. In the alcoholic range, a small amount of acetic acid and lactic is produced which is beneficial. However, at higher temperatures a lot more of these acids are produced along with butyric acid which is very undesirable. This results in a poor quality product that will have a strong undesirable taste and flavor. The crust will have a pale straw color and the loaf will have poor symmetry of form and a very open grain. The crumb will have a yellowish color rather than a bright white color.
STEP 3c. Fermentation of Straight Dough’s. Because fermentation time before the punch varies, dough’s must be tested at different intervals. The time to punch is determined by inserting the hand as far as the wrist gently into the dough and observing the dough closely when the hand is withdrawn. When the proper fermentation time has been reached, the dough will neither collapse nor spring back, but will sink slightly around the depression. NOTE: This is demonstrated in PART TWELVE titled "BREAD BAKING DEMONSTRATIONS".
STEP 3d. Punching the dough. When the proper time for punching has arrived, use both hands and punch down through the center from one end of the dough trough to the other. Then with both hands, grasp one side of the dough and pull on top. Repeat the operation, folding the opposite side of the dough. Punching equalizes the temperature of the dough; the gluten has been relaxed after its constant tension during the period of expansion. This helps to strengthen and further develop the gluten. This is also demonstrated in PART TWELVE titled "Bread Baking Demonstrations.
|STEP 3e. Fermentation time after the punch. Time after punch can be determined accurately by using fermentation ratios. For example, if dough ferments for 2 hours before the punch and a generally used 80/20 fermentation ratio is used, the time after the punch can be determined by dividing 120 minutes by 80 percent, (120/80) equals 150 minutes which represents 100 percent of the time. Subtract 120 minutes which equals 80 percent of the time from150 minutes which represents 100 percent of the fermentation time (150-120=30 minutes (fermentation time remaining after the punch).
STEP 3f. Fermentation of the sponge. Fermentation time for sponges vary from 4 to 6 hours depending upon the strength of the proteins of the flour, temperature of the sponge, and the amount of yeast used. Basically the same procedure is used to determine fermentation time of the sponge as for straight dough’s, with the exception that the sponge is not punched, but observation is made to determine when the sponge begins to recede slightly. This is normally known as the breaking point of the sponge. Another method used by some bakers is to observe when the sponge becomes wavy on top. When this occurs, this represents 80 percent of the total fermentation time. The remaining 20 percent fermentation time is calculated the same way as was used to determine time after the punch for straight dough’s.
Makeup consists of iving, Rounding, Intermediate Proofing, Molding and Panning.
NOTE: Major improvements have been made in recent years on Make-Up Equipment due to the development of Dough Conditioners, Oxidation Agents and Enzymes. The baker is able to produce more extensible dough’s by fully developing them in the mixer. Dough Dividers have been developed which “punishes” the dough a great deal less than those used in the past. Also, a Belt Rounder is capable of rounding and sealing the dough without the use of dusting flour. The most significant new development is in Intermediate Proofing — where the proofing time has been reduced to three minutes or less due to development of new ingredients and Extrusion Dividers. The information below explains Make-Up Procedures used prior to the new development and which are still being used by many bakeries.
STEP 4a. Dividing and scaling consists of cutting the dough (by hand or machinery) into loaf size pieces and weighing the pieces to insure uniformity. Because of the average loss of about 12 percent during make-up, proofing, baking and cooling, this loss must be taken into account. To produce a loaf of bread weighing 1 pound (16 oz) the dough piece must be scaled about 18 ounces.
STEP4a(1). Rounding is the process of rounding the scaled pieces of dough into a round ball with smooth unbroken skin over its entire surface. The unbroken skin will retain the gas generated within the dough piece during the intermediate proofing period.
STEP4a(2). Intermediate proofing is the process of giving the rounded dough pieces a short rest period (about 12 to 15 minutes) to recover from the effects of the dividing and rounding machine. The rest period allows the dough to relax after undergoing a great deal of punishment while being forced under a lot of pressure while being extruded from the divider pockets. Without the rest period the dough would be tight and rubbery and would not go through the molder sheeting rollers without tearing. The intermediate proofing machine has small pockets or baskets covered with canvas traveling within an enclosed draft free area.
STEP 4a(3). MOLDING. Upon completion of the intermediate proofing period, the dough pieces are molded into the shape desired. In the molder the dough passes through three distinct stages. Flattening is done in the head rollers of the molder. Second, the sheeting rollers sheet the dough into a flat piece of dough and the curling rollers and thread rollers twirl each piece of sheeted dough and give it a cylindrical shape. Next, the drum or pressure plate rolls and seals the loaf into its final form. Conventional molders curl the dough in the same direction that it was sheeted. It is difficult to produce bread with a close uniform grain with this type of molder. For this reason some bakers twist two pieces of dough together or use cross grain molders. Cross grain molders curl the dough in the opposite direction from which it was sheeted. That is, the dough is caused to turn right or left after it has been sheeted and is then curled. This is called cross grain molding. Cross grain molding and twisting two pieces of dough together prior to putting them into the baking pan both produces loaves with a close smooth grain and texture.
STEP 4a(4). Pan proofing is the process of rolling the panned and racked molded dough pieces quickly into the dough proofing cabinet. The cabinet is well insulated and maintains a temperature of 95 degrees F. to 98 degrees F., and a relative humidity of 85 percent.
NOTE: In recent years, bakers have increased the temperature of proof boxes to110-120 degrees F. with a relative humidity of 90 percent. Under these conditions the loaves are allowed to proof for about 45 to 60 minutes. At the end of the proofing period, they double in size.
STEP 5. Baking the bread.
At the end of the pan proofing period, the loaves are loaded quickly, but carefully into the oven for baking. In large commercial bakeries the panned loaves are carried automatically on conveyor belts and loaded automatically into the oven. Oven temperatures vary from about 425 degrees F. to 450 degrees F. During the first minutes of the baking process the carbon dioxide gas within the dough expands. This expansion causes a very rapid rise of the dough known as oven spring. Fermentation is more vigorous and more rapid at this stage than at any previous stage. When the inside temperature of the loaf reaches 140 degrees F. the yeast is killed and fermentation ceases. Alcohol produced during fermentation evaporates in the form of vapor. After the oven spring, the pliability of the dough gradually lessons and the dough becomes set and slowly changes to bread. Some of the moisture evaporates, the starch becomes gelatinized and more digestible gluten and other proteins become coagulated.
After the loaf sets, the intense heat dries out the part exposed to the air and causes a crust to form. The golden brown color of the crust is the result of chemical changes in the starch, sugar and milk known as a browning reaction (Mailard reaction) also known as carmelization.
Within the loaf, the crumb near the crust is subjected to a temperature as high as 300 degrees F. The temperature gradually decreases towards the center of the loaf at which point it reaches about 212 degrees F. the same temperature at which water boils at sea level. At this temperature the gluten becomes stiff enough to give the loaf permanent form and retain its structure. When the baking process is complete, the loaves are unloaded manually or automatically and either dumped on cooling racks or travel on enclosed air conditioned conveyor belts to the cooling area. The loaves are allowed to cool for about 1 hour at which point the internal temperature of the loaf drops to about 100 degrees F. and is ready to be sliced and wrapped or bagged.
STEP 7. Slicing and packaging. Automatic slicing, wrapping or bagging machines and tying machines, completes the seven major steps in bread production. The bread is ready to be shipped to grocery stores and other food establishments to be consumed by the public.
Reference and acknowledgement - Willie Prejean - www.bakingandbakingscience.com