The color and shape of food are two highly valued qualities. But nowhere are they more important than in the fast-food industry, where consumers demand a uniform quality of product each time they visit a restaurant, writes Dave Wilson.
Unsurprisingly, the bakeries that supply the buns and rolls to customers such as Burger King and McDonald are always looking for ways to improve the measures by which they can quantify the quality of bun size and color.
Current means to inspect such products are labor intensive. Examining a product for shape and color correctness, for example, involves the removal of a few samples of the product each hour from a production line and the manual inspection of the bun against customer specifications.
In many cases, the color matching procedure is carried out using a baking colorimeter a handheld device that can measure lightness and darkness, reporting results in the commonly used CIE L*a*b* color space and scale.
But despite their effectiveness, the accurate control of the color quality of the buns coming out of the ovens is still a challenge, partly owing to production rates that can see buns produced at rates as high as 1,000 per minute.
In most large bakeries, once the buns leave the oven, they are transferred to cooling racks and then to a bagging area to be packed. Only once they arrive there are they checked for color uniformity and shape. At this late stage, however, any color imperfections that are identified could potentially mean that hours of unusable products may have already been cooked and racked before the parameters of the baking oven can be adjusted to redress the issue.
Obviously, it would be beneficial to both the bakery and its customers if a more accurate assessment process could be deployed, enabling the oven parameters to be controlled through the use of an automated system that could correct the color of the products produced in them long before it drifts out of specification.
Now, researchers at Georgia Tech, led by Dr Doug Britton, have designed a supervisory oven control system that can do just that capturing color images of the buns and using this data to control the temperature of the ovens the buns are cooked in.
Since developing the system, the research team has licensed it to Baketech, a developer of process monitoring systems that can be either added to existing bakery lines or incorporated into new lines. And now, Baketech has installed a first prototype of the system at a plant owned by the Flowers Baking Company, which has several baking facilities across Georgia.
To identify potential defects, the system employs high luminescent stroboscopic LED strobe lights, which illuminate the buns as they leave the oven, and a pair of cameras that then capture images of them. Both cameras and the light sources sit just 2ft over the belt carrying the buns out of the oven and are controlled by a personal computer sitting in an independent rack on the production floor.
The images of the buns captured by the cameras are transferred to the personal computer, where proprietary image processing algorithms calculate the shape and the color of the buns in the CIE L*a*b* color space matching the existing color manual inspection standards already in place at the bakery. The color data is then sent to an existing controller on the oven that uses it to adjust the temperature of the burners inside it.

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