Baking on any scale is a delicate process. It involves combining the correct ratios of ingredients and applying the proper thermal energy to conduct the chemical reactions that change the separate ingredients into a delicious and cohesive new product. On an industrial scale, the need to be precise is even more pronounced. Temperature control is important at all stages: when storing ingredients, during mixing, while baking and for packaging. Every step of the process seems to need some sort of temperature control in order to produce the best baked goods.
Fortunately, having a reliable industrial chiller system involved can stabilize these thermal needs. In the world of industrial baking, however, what does a cooling system look like? Within any industry baking setting, of course, many different food products are made. Each process has slightly different needs depending on the end product. Still, across the spectrum of baked goods, there often are commonalities in the process cooling needs. In general, at least one step of the industrial baking process will involve some large-scale cooling.
One of the most common places in the baking process to require cooling is chilling ingredients.
Certain baked goods such as doughs are especially delicate. When adding water as an ingredient during the mixing process, it must be at the correct temperature. If the water is too warm, it could stop the yeast growth and cause flat, dull bread. If the water temperature is too cold, the dough can become too sticky and not taste as light and fluffy as desired. Though a seemingly simple ingredient, mixing water must be provided within a rather tight temperature band in order to produce consistency from batch to batch
Ingredient water can be maintained at the proper temperature by cooling it with chilled glycol in a double-wall heat exchanger. As the name implies, double-wall heat exchangers have two walls separating the hot (ingredient water) and the cold (chilled glycol) fluids from each other. The heat exchanger is assembled to create a small gap between the two walls. In some designs, this gap is vented to the atmosphere. Should either wall develop a leak, the hot or cold fluid will flow into the gap and seep out, providing a visual indication of a problem. In other designs, the gap is filled with a harmless fluid. Pressure within the gap is monitored electronically. Should a leak occur in either wall, hot or cold fluid flows into the gap and raises the pressure. The system then produces an alarm signal to alert the user of a failure in the exchanger. Thus, a double-wall heat exchanger can withstand a leak without contaminating the ingredient water, and the user is alerted to any leak visually or via an alarm signal.
By comparison, in a single-wall heat exchanger, a leak in the single wall allows the hot and cold fluids to mix, contaminating the ingredient water with glycol. In this case, the leak can go undetected until the contamination shows up in the product or in other equipment downstream of the heat exchanger. Obviously, these are not acceptable outcomes for a food operation.
Cooling During Mixing
Another common industrial baking step that often requires cooling is the mixing stage. When ingredients are mixed together, thermal energy is released both from the mixing equipment itself as well as from the chemical reaction occurring between the ingredients. On a small scale, this thermal byproduct is negligible. However, on a larger industrial scale with multiple repeated batches throughout the day, the produced heat can be problematic.
One way to manage produced heat is by cooling the mixing machine itself. Chilled process fluid can be sent from a process chiller and pumped into a jacket portion of the mixer base. The mixer is exposed to cooling fluid consistently, which removes any thermal byproduct from the mixing process. The cooling fluid exits the jacketed mixer and returns to the process chiller. There, it cycles through the refrigeration circuit and is returned to the proper temperature before recirculating to again cool the mixing bowl. Regardless of how frequently the mixing equipment has been used or the ambient conditions, this cooling method helps ensure consistent temperature from batch to batch.
Certain products require rapid cooling after baking has been completed. Whether the cooling is needed for taste preservation, packaging purposes or some other reason, a process chiller may provide the cooling service.
The cooling purpose and the type of product often will dictate the final cooling setup. For instance, the product may need to be cooled to freezing very quickly; in such cases, the product is passed through a blast chiller. Blast chillers work by blowing very cold air over a product to bring it to the necessary temperature. By contrast, in cases where the product needs to cool more slowly, chilled cooling racks may be used. These use a similar technique to cool the product as the jacketed mixers.
Cooling After Baking
To meet food safety standards, prior to final packaging, many products must be cooled. Being at the appropriate temperature will minimize excess moisture in the product and within the packaging. When a product is packaged while it is too warm, the extra moisture can increase the growth of bacteria and contribute to product degradation.
In addition, after final packaging, food must be stored at the appropriate temperature and moisture level in order to prevent harmful changes such as mold or bacteria growth. Keeping the storage room appropriately cooled typically is an important step. The room may utilize room-wide refrigeration, or the product can be stored in specific coolers. A Cooled storage design can have as many options as the rest of the cooling system combined.
Maintaining Flavor Profile
The flavor profile is another element with which process cooling can assist. For instance, foods that use yeast in their process can be very sensitive to temperature changes. The rate of yeast growth and fermentation affects the starch and sugar level of the final product. When it grows at a steady rate under consistent temperatures, the end result is a product with fewer air pockets and more consistency. Using either refrigeration or the jacketed cooling techniques discussed above can ensure the yeast’s environment is warmed as desired for the best taste. In industrial baking, product consistency from batch to batch is desired. A constant, dependable flavor profile is best and can be delivered using industrial cooling systems.
So, why is industrial process cooling the best cooling solution as opposed to simple air or natural cooling options? As mentioned earlier, certain baked products can be particularly delicate. The smallest of adjustments between batches can cause the outcome to be drastically different. Obviously, that is not acceptable for a large-scale operation. Industrial cooling can eliminate minute temperature differences and keep temperature control tight. Typically process chillers are able to deliver temperature control that is ±2°F. If desired, a chiller can be equipped with controls that provide ±0.2°F stability for processes that are especially temperature sensitive. Natural air cooling cannot guarantee that ingredients will maintain the correct temperature to that level of accuracy. But how does a baking system find the best cooling system match?
Selecting the best chiller for any application starts by determining the rate at which heat is generated by the process. Other important factors include the desired temperature, pressure and flow rate of the chilled fluid (usually a glycol mixture). This information may be available from the equipment manufacturer, through detailed engineering calculations, from past experience or by trial and error. At times, using a combination of these methods may suit the application.
The selected chiller also must be suitable for the planned location, whether it is an indoor or an outdoor installation. Indoor installations provide a more stable and predictable environment for the chiller, but an indoor installation requires advanced planning to manage the heat rejected to the surroundings. When installed outdoors, the chiller must be equipped for operation at the minimum and maximum expected ambient temperatures and in inclement weather. In any case, appropriate access and clearances must be provided for preventive maintenance and repair of the chiller.
Available power supply at the facility is another consideration. Some older industrial areas do not have 460/3 power (commonly required for large chillers), or they may have only single-phase power. Any initial discussions with a chiller manufacturer should include the available power in order to prevent last-minute surprises and unexpected expenses.
On the whole, industrial baking tends to rely heavily on cooling processes. Though many people think of adding heat to make baked goods, taking it away is equally as important in industrial settings. In order to produce consistent, flavorful foods, the temperature of the ingredients and materials must be controlled throughout the baking process. From ingredient temperatures to final storage, process cooling appears in different forms. It affects the uniformity of the product and flavor complexes. In fact, when temperature control is incorrectly performed, it may be the reason a final product is not quite right.