Gaining flexibility with hybrids
Multi-mode ovens combine different heat transfer methods to benefit product structure, thickness and texture.
BakingBusiness.com, August 1, 2013
by Shane Whitaker, Baking & Snack

Baking — the high-energy reaction phase that maximizes the chemical and physical transformations of raw dough into finished goods — represents a critical operation in cookie and cracker manufacturing. While traditional baking has relied on direct-gas-fired and convection ovens, radiant and microwave energy have recently been added to these heat transfer methods to create multi-mode ovens that permit effective control of the reactions, according to Mihaelos N. Mihalos of Mondel─ôz International, East Hanover, NJ.

As a senior associate principal engineer for the company’s North America Region Biscuits Research, Development & Quality (RD&Q) Group Process Development & Innovation Technology, Mr. Mihaelos manages complex, leading-edge technology development projects. He joined Nabisco in 1988 as a process engineer in biscuit engineering and has held many technical positions in his 25 years with the company. Mr. Mihalos holds US patents for his development work. In 2011, he received Kraft Foods’ Technical Leadership Award for RD&Q.

He earned his BS in chemistry from Fordham University, as well as a BS and MS in chemical engineering from Columbia University, and he edited a processing section for “Baking Science & Technology,” 4th ed., Vol. II, published by Sosland Publishing Co.

Mr. Mihalos spoke at this year’s Biscuit & Cracker Manu-facturers’ Association’s technical conference on multi-mode baking technology, and here, he provides details about this technology that can help bakers create optimal cookies and crackers.

Shane Whitaker: What are the common mistakes cookie and cracker bakeries may still make relating to the baking process, and why would they still be making these errors?

Mihaelos N. Mihalos: The biggest mistake is trying to bake products on an oven that is not the correct oven mode. For example, certain ovens such as direct-gas-fired ovens are conducive for most cracker products. But if you have a product that is thick in nature, this will require a forced-convection mode. Unfortunately, most bakeries are fixed in their capital assets, so they will try to bake the product on the existing asset and, therefore, produce a suboptimal product.

What are the greatest challenges cookie and cracker manufacturers encounter when baking cookies?

The biggest challenge is trying to keep the critical product attributes of the final product in balance to meet the specifications. Attributes such as stack height, moisture and color are always challenges as in typical baking unit operations, and the attributes are coupled, meaning that if you try to adjust one attribute, the other two will also be affected.

How have newer baking technologies helped bakers to address these issues?

Multi-mode baking ovens in general provide bakers with more flexibility in baking an assortment of different products by using these different oven modes as well as proving additional adjustment capabilities in the bake time and overall oven profile. Also, the introduction of data loggers and heat flux sensors have permitted the oven to be documented in much more detail in terms of its operational performance and provide an avenue to support maintenance and troubleshooting activities to a level not possible  the past.

Please define multi-mode baking technology and how these systems came about.

Multi-mode baking is defined as using various oven modes to control the baking reactions — the Maillard reaction or browning — that determine final finished product attributes through decoupling of conduction, convection, radiant and dielectric heat transfer modes.

For example, microwave, direct-gas-fired and radiant heat mainly impact structure, thickness and texture. Microwave and convection have the greatest impact on moisture and weight. Finally, color can be readily adjusted by radiant and direct-gas-fired heat.

This approach to baking ┬şprocesses through multi-mode ovens, also called hybrid ovens, develops an understanding of the fundamental characteristics and interactions for baking reactions in terms of materials, process and product. It permits optimized process and oven designs through specific heat transfer data for scale-up from pilot plant to production.

These systems came about based on experience and significant research and development investigations and by understanding the fundamentals and characteristic heat transfer properties of the different modes. When these oven modes are used in combination with one another, this permits: 1) a more flexible oven allowing different types of products to be baked in the same oven and 2) the development of new and unique products that the consumer desires.

What impact does multi-mode baking technology have on final product quality?

As we discussed above, the traditional baking process consists of convection, conduction and radiant heat transfer mechanisms. By understanding the fundamentals of the different oven modes and how they behave, one can change the heat generation systems by altering the different forms of convection, direct-gas-fired and radiant heat and surrounding them with dielectric modes, which results in changing the heat transfer rates. This altering of the baking constants allows the product attributes or characteristics to be manipulated to achieve the desired products and product quality consumers seek in the marketplace.

How can newer oven technologies affect other processing steps or systems?

As newer oven technologies are implemented, it becomes much more important that the upstream unit operations such as mixing and forming be more consistent. Meaning dough mixing from batch to batch must be consistent so that every dough batch has the same rheological properties as possible, minimizing any dough variations which will become apparent in the baking stage.

It all begins with mixing because it is the key unit operation in the biscuit process. In addition, the forming unit operation will need to be as consistent as well to have constant product flow to the oven and uniform dough weights. If these attributes are maintained, then the final baked product attributes will be consistent and, therefore, minimize any packaging concerns downstream of the ovens.

What’s the way to best fine-tune ovens to ensure consistent quality?

The ovens need to be under constant observation and properly maintained via preventive maintenance so they are operating in the most efficient manner.

This is accomplished by using portable data loggers and the new heat flux sensors currently on the market that accurately record the oven conditions and identify any anomalies such as hot-cold spots, burners not operating properly, over exhausting, etc. By using these devices along with preventive maintenance, the ovens are able to be fine-tuned to ensure proper product quality.

What other new developments do you see on the horizon, and what impact will these have on the industry?

In the next few years, more ovens will be implementing dielectric modes — microwave and radio frequency — as well as radiant and electric modes as the technology matures to further increase the flexibility of the baking unit operations.