Case Studies

Cryogenic Flour Chilling System Helps Coles Produce Quality Frozen Breads with a Twist

September 20, 2013

Founded as a neighborhood bakery in 1943, Coles Quality Foods, Inc., Grand Rapids, Mich., became synonymous with frozen garlic bread. Today, Coles offers a complete line of frozen bread, including Big Texan toast, cheesesticks and breadsticks, “that goes from freezer to table in 10 minutes or less.”

Cold processing is critical to Coles’ product quality and coast-to-coast success. All Coles products have a 1-year frozen shelf life. Cases are shipped to national distribution centers and sold through major supermarkets such as Shop-Rite, Winn-Dixie, Wal-Mart, Piggly-Wiggly, Kroger, Food Lion, Meijer and others. Increasing demand for Coles’ unique frozen breads tested Coles’ North Liberty, Iowa, production operations in the summer of 2012.

“The driving force for us in wanting to make a change was extrusion quality,” says Aaron Scott, plant manager of the baking and freeze processing facility in North Liberty, Iowa.

After dough is mixed and processed through the proprietary extrusion systems, Coles proofs product prior to baking, then applies the toppings. Breads then move by conveyor to a Linde cryogenic spiral freezer for a highly controlled freeze with carbon dioxide (CO2).

“The spiral works well for that at the volumes we are running,” says Scott. “But, we were experiencing issues with the dough going into our extrusion and finishing operations.”

The plant performs continuous quality control, and samples product hourly to monitor processes. Problems with the dough though can be visible, especially during and after extrusion operations.

“We then need to discard product before it goes through the applicator and into the spiral. That can slow you down,” Scott adds. “And, no one likes to discard product, because at that point, you’ve lost not only the ingredients, but all the overhead that went into production.”

Following an in-plant assessment, Linde North America, New Providence, N.J., recommended an in-line cryogenic flour chilling system to achieve more consistent dough mixing performance. Like many well-established bakeries, the plant relied on chilling the mixer with water ice in warmer weather, particularly from May to October. An operator would retrieve two 25-pound bags of ice from a machine (one flight down) and pour the ice into the 1,000-pound Peerless mixer, with a new mixing cycle every 20-30 minutes. First, the dry ingredients would be added, then the liquids, with the water portion of the recipe adjusted down to compensate for the ice.

Scott scheduled the installation of the new flour chilling system during a planned holiday weekend ahead of the spring warmup. The Linde system injects liquid CO2 into the pneumatic system as flour is conveyed to the mixer from an outdoor silo through a 4-inch line. The temperature of the flour is continuously monitored just before the inlet to the mixing vessel, and a feedback system controls the precise injection of CO2 to ensure a consistent flour temperature to within +/- 1°F of the set point. The precision feedback system also minimizes cryogen use to keep operating costs low.

Linde installed the chilling system, including all supply lines and venting over an extended weekend (Friday to Sunday), and trained the staff on the system’s operation and safety when they returned on Monday. The use of cryogenics takes advantage of the existing CO2 supply (used to freeze the final product in a cryogenic spiral freezer) and provides for improved mixer operation, eliminating all the variations associated with the ice chilling. Product losses were reduced 0.2%—significant in a high-volume operation like Coles. And, since there is no ice to carry, a worker safety issue was also eliminated.

Cryogenic control of incoming flour temperatures can also mean more consistent baking performance. Leavening agents are sensitive to warmer temperatures. And, quality is always the bottom line at Coles. Consistent batch-to-batch dough quality means smoother year-round production—from mixing all the way to the signature twist.

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