Thermal Heating Technologies Create Natural Color in Ready-to-Eat Products

When it comes to ready-to-serve meals, deli products, frozen, and even fast food items, consumers are looking for products that feature authentic color as well as appealing textures and delicious taste. Now food processors can give customers what they want using advances in thermal heat technologies.

There are four principle methods for developing natural color with thermal heat: impinged air, flame, sear, and radiant infrared heat. With advancements in modern cooking technologies and natural browning agents, a whole range of authentic colors and surface effects can be achieved faster, more efficiently, and more consistently. This enables processors to create foods with subtle differences in appearance, ranging from products traditionally made at home to those prepared by top chefs.

“Regarding quality RTE (ready-to-eat) products, consumers are placing a higher demand on our industry to develop products that appear to be naturally processed,” said Adam Cowherd, vice president of International Sales at Unitherm Food Systems in Bristow, Okla. “In the case of a grill-marked chicken breast, customers are beginning to ‘read between the lines’ of the traditional bar marks and want to see the same naturally occurring flamed highlights and colors they see on chicken prepared on their barbecue grills at home.”

Unitherm has been developing its Flame Grill System for more than 15 years and offers current models with multiple independently controlled ribbon burners, adjustable bar markers, and relative temperature controls. “Everything characteristic of the flame can be adjusted, from the angle to the length,” Cowherd said.

Advanced flame grills are just one example of how equipment suppliers are using more flexible technology to provide a wider range of finished color and texture. Here is a breakdown of the four most common thermal heat technologies used by leading food companies:

Impinged air: With this thermal technique, high-velocity air is forced directly to the product surface. For product surfaces that are less uniform, this technology can be used to develop uniform color on the top, the bottom, and all sides of the product. High-temperature air, combined with steam to create super-heated vapor, can be used in combination with impinged air to speed up the browning process. This thermal heat method is appropriate for meat, poultry, pasta dishes, and a variety of baked foods, like pastries and pizza bases.

“The effect we see from products that are processed with impinged air is more uniform color without the shadowing that you see with radiant heat such as gas infrared,” explained Cowherd.

New impinging oven designs, such as Unitherm’s versatile RapidFlow Oven, offer touchscreen controls that allow processors to alter multiple parameters, including the velocity of the impinged air, temperature, and humidity control. If they choose, these parameters may be used to create new recipes that are stored for future use. Such features enable a processor to better control the appearance of the finished product.

Most recently, impinged air technology is being adapted for use in a spiral oven. Unitherm unveiled its impinging spiral oven at the Food Processing Suppliers Association show, held in Chicago Nov. 1-4.

Flame: Perhaps one of the oldest thermal heat methods for coloring products is flame. Currently, the term “flame grilled” is used to market everything from chicken wings to fire-roasted tomatoes for spaghetti sauce. Today’s flame grill machines can be used for an array of products, ranging from burgers to veggies, chicken, and fish.

The effects flame has on any product depend partly on the fat-to-protein breakdown of the product. The color result is anything but uniform, and the taste of a flame-grilled product is unmistakable.

Cowherd added that the combination of flame and surface marking create a much more authentic appearance and taste. Additionally, the flame grill can sear in moisture, which results in higher yield and significantly improves the “re-heated” quality product.