Horizontal mixers are the workhorses of U.S. bakeries. They are big and sturdy, and handle multiple types of dough with either roller bars or single- and double-sigma arms.
However, changing product attributes, such as stiffer doughs, have complicated a once standard bakery function. Today’s product formulations require bakeries to evaluate their horizontal mixers to ensure ideal performance.
Increased demand for stiffer doughs, such as whole grain and multigrain breads, has necessitated increased horsepower usage to maintain batch size. One manufacturer of horizontal mixers estimates that bakers may have to reduce batch size by as much as 30% if they use standard, 100 horsepower horizontal mixers to mix whole grain products.
If this reduced capacity is unacceptable, bakers must increase horsepower. Unfortunately, bakers simply cannot add horsepower by upgrading existing horizontal mixers. "Bakers have to look at buying a new mixer or be content with smaller batch sizes," one mixer manufacturer says. "You have to buy new equipment because you have to design around an increased horsepower motor."
The amount of horsepower needed depends on absorption rates. One equipment manufacturer has built 200 horsepower mixers to handle stiff doughs. When constructing a mixer with increased horsepower, equipment manufacturers design from the ground up, engineering new agitators, drives and bowl construction to accommodate the increased horsepower.
"It’s not like dropping a Corvette motor into a Chevy Cavalier," one mixer manufacturer says.
Besides increased horsepower, mixer manufacturers also are seeing increased demand for variable frequency drives. In the past, horizontal mixers mainly used two-speed starters, but falling prices for variable frequency drives have spurred bakers to ask for this added flexibility.
Variable frequency drives allow bakers to change agitator rpm. This benefits bakers who mix many types of doughs in one mixer. Variable frequency drives also minimize shock load and energy spikes because the agitator bars ramp up and down.
On the quality control side of mixing, maintaining the proper temperature of breads, rolls, English muffins and frozen dough is imperative to the quality of a final product. One equipment manufacturer offers many different refrigeration options based on a baker’s temperature needs. These options include:
• Bowl jacket and end cooling: Many manufacturers offer this form of refrigeration for cooling dough temperature.
• Breaker bar cooling: One manufacturer’s system goes a step further than jacket and bowl end cooling by adding breaker bar cooling.
• Agitator bar cooling: Pushing the boundaries of mixer cooling, one manufacturer’s system includes jacket and bowl end cooling, and agitator bar cooling. The system cools dough by as much as 8°F less than standard cooling because dough always is in contact with a refrigerated surface.
The investment to include refrigeration options on a mixer ranges from no cost (because refrigeration comes standard on some mixers) to several thousand dollars. However, throughout the life of a mixer, the investment pays for itself many times over when compared to adding ice to dough. Adding ice also brings health and safety concerns, including injuries incurred from lifting heavy ice bags/buckets and cutting the ice bag. Increasing condensation around ice machines also raises safety concerns. It also is more time consuming to add ice manually than to use refrigeration during the normal mix cycle.
Problem Solver Quick Tip
Bakers may have to reduce batch size by as much as 30% if they use standard, 100 horsepower horizontal mixers to mix whole grain products.