Reading Bakery Systems: A balanced bake with the Emithermic oven

A balanced bake makes perfect

Better baking for biscuits and cookies means matching the intended baking curve of the product, stage by stage, consistently and efficiently. With its Emithermic oven, Reading Bakery Systems provides complete control over five baking parameters that create a more balanced bake.

+Flexibility is essential when the task is baking cookies and biscuits that can greatly vary in characteristics. Reading Bakery System’s Emithermic oven can be optimized for each type of product in this segment by controlling and combining five parameters on each oven zone: temperature, upper and lower air circulation, exhaust, and heating source. The Emithermic oven is a fairly new innovation combining traditional baking concepts and different equipment designs with the flexibility and efficiency of modern technology, enabling control over the different stages in the baking profile of a biscuit or a cookie, from development, through to setting, and drying and coloring.

Each of these stages has different requirements from the oven, which generates different effects on the product while fine-tuning parameters to the item’s profile. To accomplish this, flexibility is a must – especially regarding the different types of baking that it can provide, which should include both radiant and convective heating. The goal is to achieve a balanced bake efficiently, and this is reached by targeting each of the baking stages. “The Emithermic oven offers bakers the flexibility to have both radiant and convective baking and a combination of the two in order to target the development and setting stages with a high degree of accuracy, in comparison with an oven based on just one of the two heating technologies. It gives bakers the control and flexibility to create a baking profile that is best suited for the requirements of the specific product throughout the baking stages,” Joe Pocevicius, European sales manager, Reading Bakery Systems, explained in an interview. As it incorporates capabilities for both radiant baking (best suited for wire-cut and deposited cookies, for example) and convective baking (the choice for hard and soft biscuits), manufacturers with all types of cookies and biscuits in their portfolio stand to benefit the most from this technology, as it can easily switch between baking modes.

The PRISM Emithermic Oven Zone blueprints

A typical oven zone can be designed in different lengths ranging from 9 to 18 meters. Each zone of the oven can also be configured according to the product’s baking cycle and according to the stages within the baking cycle: developing, setting, and drying and coloring. For example, a three-zone oven could be configured so that the first zone mainly targets the product’s development stage. In this case, the first zone would have predominantly radiant baking to maintain humidity and support the development of the chemical reactions responsible for creating the flavors.

The second zone fulfills the needs of the setting stage, meaning it provides a combination of radiant and convective heating. With the chemical reactions completed, the focus is now on creating the shape and structure of the product, for which less radiant baking is needed. This is also the beginning of the drying process.

The third oven zone can provide convective heating exclusively for the final baking stage, so that the remaining moisture is extracted as quickly and efficiently as possible for the drying and coloring of the product.

While it can achieve three types of baking (radiant, convective, and conductive), the operating principle of the Emithermic oven is similar to that of convective forced air ovens. Each oven zone has a combustion penthouse where the air is directly heated using a gas burner, electric burner, or an alternate heat source. “We typically don’t use heat exchangers in order to maximize heat value,” Pocevicius explains. The hot air is then distributed to an air channel above the product and an air channel below the product. The lower channel blows air underneath the product belt and convectively heats the belt. The hot belt then conductively bakes

© RBS

the bottom of the biscuit or cookie. The upper air channel can distribute heat onto the product in two ways: 1. In the radiant baking mode, the hot air is not allowed to leave the air channel. Instead, it is forced onto radiant panels, which absorb the heat and radiantly bake the passing biscuit or cookie. 2. In combination mode, some of the hot air still heats up the radiant panels and radiantly bakes the product, while some of the air is also allowed to leave the channel and contact the product to bake it convectively.

The oven’s flexibility to closely match the requirements of each type of product is ensured by controlling and combining the five parameters on each oven zone. “For cookies, for example, the preferred baking type should be mostly radiant, at least at the beginning of the oven, with very low exhaust levels to preserve humidity. The airflow in the upper and lower channels can also be controlled, as well as the required temperature,” the specialist from Reading Bakery Systems illustrates. This makes the Emithermic oven very flexible for all types of hard and soft biscuits, as well as wire-cut deposited cookies, brownies, cookie brittles, or even baked granola.

To further optimize the oven’s settings according to the product’s characteristics, SCORPION data logging technology can be used to measure each of these five parameters. SCORPION profiling provides data, showing where in the oven each stage of the baking cycle is taking place. The logging system is sent through the oven to measure those parameters, along the width and the length of the oven belt. By following their progression, the start and finish of the different stages can be mapped out. Moreover, a probe can be placed inside the product itself, which details its temperature profile.

Technology, improved

By comparison with previous-generation technologies found in either cyclothermic or recirculating ovens, the features built into the Emithermic oven sought to simplify concepts used by both of its predecessors. This also makes the oven very easy to operate. Improvements resulted in the five control points (temperature, upper/lower air circulation, exhaust, and type of baking technology). “Most importantly, all of these settings can be stored in the recipe control, so there is no need for operators to learn and remember them. On the contrary, both the recirculation oven and the cyclothermic oven have many more control points that need to be learned and understood by the operator,” Pocevicius adds.

For example, the cyclothermic oven bakes the product using a series of steel tubes above and below the product belt and the airflow in each one of these tubes is controlled using a manual plunger. Depending on the width of the oven, each oven zone can have several plungers that the operator has to set up and understand. Similarly, the recirculation oven also has many dampers that control the airflow to upper plenums, lower plenums, for radiant baking, for convective baking, and other functions. Manual commands that traditionally adjusted airflow were removed in the Emithermic oven.

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Developing Interiors Begin flavor developing reactions. High temperature and low exhaust settings. Setting Textures Set the product shape by removing moisture faster with heat and air. Starches crystallize. Increase exhaust.

Coloring & Drying Caramelizing and Maillard reactions create flavors and color the product. Lower temperature and high exhaust to dry.

F) Temperature ( o

200

150

100

50 Internal Temperature of a Biscuit/ Cookie

Dough Development (105-160 oF, 40-70oC)

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0,0 1,0 2,0 3,0 4,0 Time (Min)

Ovens and the baking process

Source: RBS

Emithermic Zones Used in the first 33-50% of an oven. Helps to develop products with minimal airflow allowing products to spread and lift without air currents skinning over the surface of the product which causes cracking. Convection Zones Used in the last 50-66% of the oven to increase drying efficiency and uniformity. Able to dry products and control coloring by adjusting the air flow or increasing the temperature.

RBS Hybrid Ovens for Biscuits and Cookies

“Also, although the recirculation oven can offer both radiant and convective baking, airflows are difficult to control and there’s a lot of heat loss due to design inefficiencies,” the specialist highlights.

Energy savings were also factored into the design of the Emithermic cookie and biscuit oven from RBS. Its convective capabilities alone make it more effective than a pure cyclothermic oven, which relies on radiant heat for all three stages of the baking cycle. While great for development, radiant baking is not optimal for quickly removing moisture from the product in the drying and coloring stage. Also, using the cyclothermic oven’s steel tubes to radiantly heat the oven’s belt creates a lot of heat loss. For example, air first needs to be heated in the combustion penthouse, then the hot air needs to heat the steel tubes below the belt, and finally the steel tubes need to radiantly heat the travelling belt. RBS reduced the number of heat transfers by blowing hot air directly from the lower channel onto the belt, heating it convectively. Compared to traditional recirculation baking technology, the Emithermic oven features a specially designed Thermatec radiant ceiling, with high-emissivity panels that absorb and retain heat for longer periods of time. The emissivity of these Thermatec panels ranks as high as oven bricks and ultimately results in energy savings for the manufacturer, as less heat is needed to heat and maintain the temperature of these panels.

Developments over time

When designing this oven, Reading Bakery Systems aimed for top performance that can be easily achieved with a user-friendly interface. Each product or recipe variation can be stored in the oven’s controls history for fast and easy start-up at the touch of a button. “This level of automation and simplicity can eliminate a lot of the problems caused by high turnover and shortage of skilled operators. Our clients don’t need a lot of time and resources to train operators on how to run our oven,” the specialist points out. As with any equipment, longevity depends on proper maintenance and whether the oven is used within its design limits. As long as it is properly maintained, the Emithermic oven will run well and will last for decades.

Although the oven is still a new technology, RBS is already working on new features and capabilities. As a standard, the oven can be customized with features such as belt cleaners, tracking systems, band temperature monitors, infrared moisture meters, gas flow meters, etc. “More exciting is perhaps how we’re using these ovens and what new and unique equipment we’re placing before and after these ovens. For example, we recently designed a production line using this Emithermic oven that can produce a variety of biscuits, cookies, as well as baked granola,” Pocevicius adds. This could be a perfect line for a manufacturer who has limited space but wants a lot of flexibility and a broad portfolio of products. Compelling work is also underway to make the oven even more ecofriendly, the specialist anticipates: “We can already offer our ovens as completely electric and are working at a fast pace to make them compatible with alternate heat sources such as hydrogen.” With sustainability taking center stage as the underlying trend from all points of view and throughout applications, such features can only make the equipment a more attractive and logical choice for baking all types of cookie and biscuit products. +++