This article originally appeared in the October 2013 issue of Food Manufacturing.
Interview with Stephen Rogers, Co-Founder, AMTek Microwaves
Industrial microwave systems can offer food processors unique benefits, including increased energy efficiency as well as precise process control.
Q&A: What are the benefits of choosing an industrial microwave system versus another thermal processing solution?
A: Using microwave energy for food processing offers many advantages over conventional thermal processing systems. Benefits include: instant on and off, less start up time, faster heating, high energy efficiency, smaller equipment footprint, precise process control and clean heat technology. Conventional methods of heating and drying do not compare to the efficiency of an industrial microwave system. Payback based on energy savings is variable; however, additional cost savings come from higher production speed, waste reduction and product quality.
Microwave heating technologies are unique in that heat is developed within the product itself. This is known as volumetric heating. It allows more uniform heating at an accelerated rate. For example, in conventional drying, heat is transferred to the surface of the material by conduction, convection or radiation and into the interior of the material. Moisture is initially flashed off from the surface and the remaining water diffuses to the surface. This is often a slow process and the diffusion rate is limited, requiring high external temperatures to generate the temperature differences required.
Rather than heating from the surface through to the center, microwave dryers heat throughout the material. Heat can be applied deep within a mass at lower drying temperatures without waiting for the heat to “soak” through. As a result there is significant operational efficiency such as yield gains, increased throughput, labor reductions, reduction in heat load in the plant, reduced maintenance costs and reduction in product fouling. A short processing time and lower temperatures are desirable in terms of less nutritive loss in microwave process foods.
Q: What services does AMTek provide to food processors regarding microwave systems and support?
A: We offer product testing and design assistance to customers considering the purchase of a microwave system. Once a processor decides to purchase a system, we commission the system with startup, debugging and operator training.
For processors with existing systems we provide technical support on our equipment, as well as industrial microwave systems from other manufacturers, 24 hours a day, seven days a week. We carry a full line of service parts inventory. We also provide several optional upgrades to enhance the operation of the equipment. These robust assemblies have been designed as cost-effective kits to help minimize system downtime and maximize plant production.
Q: For which food products and processes does a microwave system work best?
A: The use of microwaves for food processing is continuously developing worldwide. The most widespread use of industrial microwave processing in the food industry is for applications such as boost heating, tempering, drying and cooking. Microwave systems can perform many of the functions of conventional ovens, but typically are used where speed and unique heating requirements are dictated. Microwave processing has been successfully applied on an industrial scale to cooking of meat and bacon, tempering of meat, poultry, fish, vegetables and fruit, drying of snacks, vegetables and soybeans, and pasteurizing of ready meals and pasta.
Food products prone to case hardening, in many cases, are optimal candidates for microwave drying. The high susceptibility of water to microwave energy means that the drying process is self-equalizing. Areas of high moisture content draw more power than dryer ones. This is extremely useful for moisture leveling and conditioning of grains, as well as foods like cookies and crackers.
Q: In the event that a microwave system needs repair, what steps should a manufacturer take to ensure their line is up and running again as soon as possible?
A: The first step is a call to technical support for a determination of the problem. Most times when a system needs repair, the problem can be diagnosed with our technical service team over the phone. The second step is to follow the technical support suggestions for repairing the system. If spare parts are available on-site, repairs can be made immediately and downtime is minimized. We always recommend having spare parts on hand for this reason. If the manufacturer is unable to affect the repair with internal maintenance personnel, then request a service call.
Make sure your microwave vendor is accessible and capable of providing prompt and reliable service when you need it, ideally 24/7. Also make sure your vendor stocks a full line of replacement parts and is capable of responding quickly because prompt and reliable field service is a must.
The best practice is ongoing preventative maintenance. Frequent visual inspection of the overall system process and the operating condition of all motors and drives associated with process will reduce system down time; this includes checking the cleanliness of the waveguides.
Establish a program to re-evaluate the efficiency of your microwave system. Once a system is installed for a designed application, the efficiency will remain the same until the product parameters change. Any change in the material, e.g. a change in width, depth or weight will require a re-evaluation of the system in order to maintain system efficiency.
Q: What challenges do food manufacturers face when implementing a microwave system into their processes?
A: When evaluating the suitability of an industrial microwave system for a particular application, it is necessary to consider the goal, materials and process requirements. In some instances, using microwaves for the process is already well established. For these situations, the challenges are internal and include calculating and communicating the benefits, risks, requirements and costs to management. We can help you answer your questions and work through the process to determine if using microwaves for the process is beneficial.
When the process being considered is new or not well established, then development costs and risk of failure become more important. Testing becomes crucial. Seek a microwave vendor with a well-equipped test facility. Since all processors have unique needs and parameters, it’s important to integrate their industrial microwave system into their operations and understand the economical and quality production benefits that will result.